HoldsUp

Huberman Lab · 2026-04-13 · Andrew Huberman (host), Natalie Crawford

How Women Can Improve Their Fertility & Hormone Health | Dr. Natalie Crawford

82 research-tied claims examined: 8 contradicted 9 overstated 8 context 53 supported 4 unverified

8 Contradicted by research
0:10:37Natalie Crawfordcontradictedhigh

Hormone replacement therapy in women provides cardioprotection, reduces the risk of Alzheimer's disease, and protects bone density.

"I mean, for women we see it be cardioprotective, it can help lower the risk of Alzheimer's disease, of course it can be protective for your bones." (said at 0:10:37)

The speaker bundles three distinct claims regarding hormone replacement therapy (HRT): cardiovascular protection, reduction in Alzheimer's disease/dementia risk, and bone protection. Per systematic review and randomized controlled trial (RCT) evidence (e.g., the Women's Health Initiative and Cochrane reviews), HRT is supported for protecting bone mineral density and reducing fractures. However, the claims of cardioprotection and dementia reduction are contradicted by high-certainty RCT evidence: combined HRT increases the risk of stroke, venous thromboembolism, coronary events, and probable dementia (in older women), leading major health bodies to advise against HRT for the primary prevention of cardiovascular disease or cognitive decline. Because the cardioprotective and dementia-preventive assertions are contradicted by randomized trials, the bundled claim receives an overall verdict of contradicted.

  • contradicts: Long-term hormone therapy for perimenopausal and postmenopausal women. (The Cochrane database of systematic reviews 2017)
    "In relatively healthy postmenopausal women (i.e. generally fit, without overt disease), combined continuous HT increased the risk of a coronary event (after 1 year's use: from 2 per 1000 to between 3 and 7 per 1000), venous thromboembolism (after 1 year's use: from 2 per 1000 to between 4 and 11 per 1000), stroke (after 3 years' use: from 6 per 1000 to between 6 and 12 per 1000)... Women over 65 years of age who were relatively healthy and taking continuous combined HT showed an increase in the incidence of dementia (after 4 years' use: from 9 per 1000 to 11 to 30 per 1000)... Risk of fracture was the only outcome for which strong evidence showed clinical benefit derived from HT" (abstract, results, passage verified)
    pubmedfull study (doi)
  • contradicts: Hormone Therapy for the Primary Prevention of Chronic Conditions in Postmenopausal Persons… (JAMA 2022) · cited 69x in the literature
    "Risks, per 10 000 persons, were significantly increased for invasive breast cancer (242 vs 191 cases; 51 more [95% CI, 6-106]), gallbladder disease (723 vs 463 cases; 260 more [95% CI, 169-364]), stroke (187 vs 135 cases; 52 more [95% CI, 12-104]), and venous thromboembolism (246 vs 126 cases; 120 more [95% CI, 68-185]) over 5.6 years; probable dementia (179 vs 91 cases; 88 more [95% CI, 15-212]) over 4.0 years" (abstract, results)
    pubmedfull study (doi)
0:36:40Natalie Crawfordcontradictedmoderate

In approximately 80% of recurrent pregnancy loss cases, all diagnostic test results are normal, while roughly 20% show an identifiable cause.

"If I look across somebody who has recurrent pregnancy loss, I say, 80% of the time, every test will come back normal. But 20% is a big number." (said at 0:36:40)

Standard clinical guidelines (ASRM, ESHRE) and systematic reviews indicate that conventional diagnostic evaluation identifies an abnormal finding or probable cause in approximately 45% to 60% of recurrent pregnancy loss (RPL) cases, leaving roughly 37% to 50% classified as unexplained (normal test results). Furthermore, when comprehensive genetic testing of products of conception (miscarriage tissue) is added, an identifiable cause is found in up to 90% to 95% of cases. The claim that 80% of cases return completely normal results with only 20% yielding an identifiable cause substantially understates the diagnostic yield of standard evaluation and contradicts published epidemiological and clinical evidence.

0:44:50Natalie Crawfordcontradictedmoderate

The male genome does not activate until day three after fertilization, meaning embryo development during the initial days is entirely controlled by maternal factors.

"In fact, the male genome doesn't even kick in until day three after fertilization. All those first few days are 100% maternal." (said at 0:44:50)

The speaker's assertion that the male genome 'doesn't even kick in until day three' and that early development is '100% maternal' is inaccurate. While the canonical wave of 'major' embryonic genome activation (EGA) occurs around the 4- to 8-cell stage (approximately day 3 in humans), transcription from the paternal genome initiates much earlier during minor/immediate EGA at the 1-cell (pronucleate) stage, including demonstrated transcription of paternal Y-linked genes (such as ZFY) within 20–24 hours post-fertilization. Furthermore, early embryo development is not '100% maternal': critical paternal factors are required immediately upon fertilization, including sperm-derived phospholipase C-zeta (PLC-zeta) to trigger calcium oscillations and oocyte activation, as well as the sperm centriole/centrosome, which organizes the mitotic spindle for the first cleavage divisions.

0:45:05Natalie Crawfordcontradictedhigh

Primary oocytes inside the ovary are arrested in metaphase of meiosis II until ovulation.

"So an interesting fact is that inside the egg, it is frozen in metaphase of meiosis II for whatever reason. And so the chromosomes have met in the middle and they're held apart by those meiotic spindles and they do not separate until you ovulate." (said at 0:45:05)

The speaker confuses the two meiotic arrest stages of female gametogenesis. Inside the ovary, primary oocytes are arrested in prophase I (specifically the dictyate stage of meiosis I) from fetal life until the ovulatory LH surge triggers the resumption of meiosis. Progression into metaphase of meiosis II (MII) occurs around ovulation, and the oocyte remains arrested at metaphase II until fertilization by a sperm, not until ovulation.

1:26:10Natalie Crawfordcontradictedhigh

After removal of a progesterone IUD, endometrial receptivity is altered for at least six months, leading to lower conception rates during the first six months.

"But when you stop the IUD, we do see a change in endometrial receptivity at least for 6 months after it's been removed, and it can take time to build that lining back up. So I always recommend that a progesterone IUD is removed at least 6 months before you want to get pregnant. Give the endometrium time to rebuild and regrow, and then you'll have better odds at conceiving. We do see a little bit of lower pregnancy rates in those first 6 months of conceiving in women coming off of the IUD." (said at 1:26:10)

The claim that endometrial receptivity remains altered for at least six months after removal of a progestin-releasing IUD (such as the LNG-IUD), causing lower conception rates and requiring removal six months in advance, is contradicted by published clinical evidence. Randomized comparative trials and systematic reviews demonstrate that the endometrium recovers quickly after LNG-IUD removal, ovulation and fertility return rapidly, and 12-month post-removal pregnancy rates (~80-90%) are comparable to non-hormonal IUDs and other contraceptive methods.

1:33:25Natalie Crawfordcontradictedmoderate

Gonadotropins FSH and LH are released from the brain during the early morning hours.

"Your gonadotropins, so FSH and LH, are released from the brain in the early morning hours. So, when you don't sleep long enough, you're not going to have the same hormonal response." (said at 1:33:25)

The claim that gonadotropins (luteinizing hormone [LH] and follicle-stimulating hormone [FSH]) are primarily released in the early morning hours and blunted by short sleep is contradicted by neuroendocrine studies in adults. LH and FSH are secreted in pulsatile bursts across the entire 24-hour cycle from the anterior pituitary gland. While prominent nocturnal/sleep-entrained increases in LH pulsatility occur during puberty, this pattern diminishes in adulthood. In adult humans under constant routine protocols, circadian studies show either an absence of endogenous circadian rhythmicity for LH and FSH or peak levels (acrophase) occurring in the afternoon, not the early morning. Furthermore, sleep restriction studies in young adults show that partial sleep deprivation during the second half of the night does not suppress LH or FSH secretion (LH concentrations increase or remain preserved, while FSH remains unchanged). The speaker may have conflated gonadotropins with downstream hormones like testosterone or cortisol, which exhibit prominent morning peaks.

1:42:05Andrew Huberman (host)contradictedmoderate

Nattokinase supplementation can naturally help reduce LDL cholesterol levels.

"As a result, I decided to start supplementing with nattokinase, which can naturally help reduce LDL cholesterol, and it did." (said at 1:42:05)

A systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating nattokinase supplementation found that it does not lower LDL cholesterol; in fact, low doses were associated with a slight increase in LDL cholesterol compared to control, and higher doses showed no statistically significant effect on LDL-C. Clinical trials that observed substantial LDL reductions evaluated combination formulations containing red yeast rice (which contains naturally occurring lovastatin), whereas nattokinase monotherapy failed to demonstrate a significant lipid-lowering effect compared to placebo.

2:30:15Natalie Crawfordcontradictedmoderate

Insufficient intake of unsaturated fats reduces progesterone production necessary for embryo implantation.

"And in fact, if you don't intake enough, you're not going to make progesterone as well. It'll be really minute. You need progesterone for implantation; don't have enough unsaturated fat in your diet, you're not going to make as much progesterone." (said at 2:30:15)

Progesterone is a steroid hormone synthesized from cholesterol, not from dietary unsaturated fatty acids. While progesterone is biologically necessary for endometrial receptivity and embryo implantation, human prospective studies and intervention trials do not support the claim that low intake of unsaturated fats severely impairs or reduces progesterone synthesis to 'minute' levels. In cohort evaluations such as the BioCycle study (PMID 26843151), total fat and polyunsaturated fatty acid intakes showed no general association with circulating luteal progesterone levels. Furthermore, interventional supplementation trials with omega-3 polyunsaturated fatty acids found no significant alterations in sex steroid levels (PMID 30773100).

9 Overstated
0:24:17Natalie Crawfordoverstatedmoderate

In women who previously had a child and are conceiving with the same partner, monthly fecundability remains between 18% and 20% up until age 37 before dropping.

"But in the group who had a child before and were trying to conceive with the same partner, that number stayed between 18 to 20% up till age 37. And then it dropped." (said at 0:24:17)

While parous women attempting conception with a proven fertile partner consistently exhibit higher per-cycle fecundability than nulliparous women, prospective cohort studies and demographic analyses demonstrate that fecundability declines progressively starting in the late 20s and early 30s, rather than remaining constant at 18–20% until age 37. Although age 37 is well-recognized as a demographic and biological inflection point where ovarian follicle loss and the rate of fertility decline accelerate, claiming that per-cycle fecundability remains flat until age 37 overstates the stability of fertility across the early-to-mid 30s.

0:49:45Natalie Crawfordoverstatedmoderate

Approximately 50% of the time, investigation into a low AMH level reveals an underlying autoimmune disease.

"I sit across from women every day find out they have a low AMH, and I say this, like, let's do the investigation to see if we can find out why. Probably 50% of the time we find an autoimmune disease." (said at 0:49:45)

While autoimmunity is a recognized etiology and co-factor in diminished ovarian reserve (DOR) and premature ovarian insufficiency (POI), the claim that 50% of investigations into low anti-Müllerian hormone (AMH) reveal an underlying autoimmune disease is substantially overstated. Epidemiological and clinical cohort studies show that autoimmune disorders are diagnosed in approximately 5% to 25% of women with POI/DOR, and autoantibody positivity is typically present in roughly 10% to 38% of patients. In a large cross-sectional study of over 5,000 women (PMID 25948573), the prevalence of thyroid autoimmunity in women with low AMH/ovarian reserve was 12.1%, which was not significantly different from controls with normal ovarian reserve (10.3%).

1:33:47Natalie Crawfordoverstatedlow

Self-reporting poor sleep is associated with double the rate of infertility.

"And we see that if you say you have poor sleep, you have double the rate of infertility. If you just objectively say, "Yeah, I have poor sleep," you have double the rate." (said at 1:33:47)

The speaker claimed that self-reporting poor sleep is associated with double the rate of infertility. While some observational studies link sleep disturbances (such as perceived insufficient sleep or irregular sleep patterns) to reduced fecundability or lower IVF success rates, large prospective cohort studies and meta-analyses show that self-reported poor sleep quality is either not significantly associated with reduced fecundability or shows modest associations, nowhere near doubling the rate (a 2-fold increase or OR/RR of 2.0) of infertility. For example, a prospective cohort study of 10,475 women found no appreciable association between self-reported trouble sleeping and fecundability (fecundability ratio [FR] = 0.95, 95% CI: 0.82-1.10 for trouble sleeping most of the time compared to never; PMID: 40139814). Mendelian randomization also showed no causal association between genetic liability to insomnia and female infertility (PMID: 39990928). A systematic review and meta-analysis of IVF outcomes found that poor subjective sleep quality (PSQI > 5) was associated with only a modest or non-significant reduction in pregnancy odds under random-effects models (PMID: 41709190). Therefore, the claim that subjective poor sleep doubles the rate of infertility is overstated.

1:45:00Natalie Crawfordoverstatedlow

Randomized controlled trials demonstrate that supplementation with CoQ10, vitamin D, and omega-3 fatty acids is associated with improved reproductive outcomes in IVF.

"When we do randomized controlled trials though, which we often do in the IVF subset because we can look at more distinct criteria... we definitely see robust data that certain supplementation, CoQ10, vitamin D, omega-3 fatty acids, those are clearly associated with improved reproductive outcomes." (said at 1:45:00)

While randomized controlled trials and meta-analyses show potential associations and modest increases in surrogate endpoints (such as clinical pregnancy or embryo parameters) with certain supplements like CoQ10 and vitamin D, describing the RCT evidence as 'robust' and establishing that these supplements are 'clearly associated with improved reproductive outcomes' in IVF is an overstatement. Umbrella reviews and Cochrane systematic reviews evaluate the certainty of evidence for these nutrient supplements as low to very low, concluding that the available RCT evidence is insufficient to establish definitive clinical efficacy (e.g., live birth rates). For omega-3 fatty acids, randomized trial data specifically evaluating IVF reproductive outcomes remain limited and mixed.

  • partial: The Role of Nutrient Supplements in Female Infertility: An Umbrella Review and Hierarchica… (Nutrients 2024) · cited 14x in the literature
    "L-carnitine, coQ10, melatonin, myo-inositol, NAC and vitamin D increased clinical pregnancy rates in women with PCOS and/or undergoing MAR compared to placebo, standard or no treatment (odds ratio (OR) 11.14, 2.49, 1.66, relative risk (RR) 1.52, OR 2.15, and 1.49 respectively) with very low certainty evidence... The available evidence is insufficient to recommend nutrient supplementation to improve female infertility in women trying to conceive naturally and those utilising MAR." (abstract, results and conclusions, passage verified)
    pubmedfull study (doi)
1:54:00Natalie Crawfordoverstatedlow

Cannabis use impairs sperm production, decreases testosterone, and increases sperm DNA fragmentation, leading to higher miscarriage rates in female partners.

"All cannabis use is hugely detrimental to sperm, for sure across the board, right? Both production, the quantity of sperm, testosterone production, also the quality of the sperm, specifically the DNA fragmentation inside the head of the sperm, to the degree that female partners who conceive from a male partner who's using cannabis have much higher miscarriage rates than partners who do not utilize cannabis." (said at 1:54:00)

While systematic reviews report that cannabis use is associated with adverse semen parameters (such as reduced sperm concentration, motility, and abnormal morphology), the speaker's sweeping assertion that 'all cannabis use is hugely detrimental across the board' overstates the clinical evidence. Specifically, human studies examining the effect of cannabis on testosterone levels show contradictory and inconclusive results rather than a definitive decline. Furthermore, evidence establishing that paternal cannabis use directly causes significantly higher miscarriage rates in female partners is limited, observational, and inconclusive.

2:00:25Natalie Crawfordoverstatedlow

Oral nicotine pouch usage significantly lowers sperm counts.

"It makes sense based on what nicotine does to your body and how it kind of changes your cellular response that it probably is impacting your egg quality also, even with these oral nicotine pouches, you know, that we're seeing everybody utilize. And it's tanking sperm counts. I mean, that one's really clear." (said at 2:00:25)

The speaker claims that oral nicotine pouches are 'tanking sperm counts' and that the effect is 'really clear.' While observational evidence in humans using smokeless tobacco (Swedish moist snuff/snus) shows an association with reduced total sperm counts (e.g., ~24% lower total sperm count in snus users), direct clinical studies specifically isolating modern tobacco-free oral nicotine pouches are limited, and the effect is not established as severely 'tanking' counts beyond modest observational differences. Thus, the claim is overstated.

1:53:41Andrew Huberman (host)overstatedmoderate

Approximately 15% of pregnant women in the United States report using cannabis in some form during pregnancy.

"what I found was that 15% of women in the United States report having used cannabis in some form or another while pregnant." (said at 1:53:41)

Nationally representative surveillance data in the United States indicate that self-reported cannabis use during pregnancy is substantially lower than 15%, generally falling between 4% and 7% (e.g., CDC PRAMS multi-state data reported 4.2% during pregnancy, and NSDUH 2021-2023 reported past-month use around 6.3% to 7.0%). While some individual regional clinic-based cohorts or biomarker validation studies report self-reported rates near 14% (e.g., a Michigan clinic cohort found 14.2% self-report and 19.1% on urinalysis), broad national self-report estimates do not reach 15%. Thus, characterizing 15% as the general proportion of pregnant women in the US reporting cannabis use is overstated.

2:19:21Natalie Crawfordoverstatedmoderate

The EARTH study demonstrated that higher exposure to endocrine-disrupting chemicals is associated with increased time to pregnancy and worse IVF outcomes, including fewer retrieved eggs, fewer embryos, and poorer sperm counts.

"There's now been robust data looking at, you know, one of the biggest cohort studies we have, and it's called the EARTH study, where they're looking at different environmental compounds on reproductive health and they're looking at cohorts of people trying to get pregnant naturally, and they did a sub-study looking at endocrine-disrupting chemicals specifically of those people who went on to do IVF and showed that those who had higher levels of endocrine-disrupting chemicals had a harder time getting pregnant even with IVF, and their IVF markers: fewer eggs retrieved, fewer embryos, poorer sperm counts." (said at 2:19:21)

The Environment and Reproductive Health (EARTH) Study is a prospective cohort of couples presenting to the Massachusetts General Hospital Fertility Center undergoing fertility treatments, rather than a natural pregnancy cohort with an IVF sub-study. While specific analyses in the EARTH study have reported associations between select endocrine-disrupting chemicals (EDCs, such as high-quartile DEHP exposure in earlier cohorts or specific phthalates with follicular fluid AMH) and certain reproductive markers, the overall body of evidence from the EARTH study found mostly null associations for BPA, parabens, and chemical mixtures with primary IVF outcomes (including embryo quality, fertilization rate, peak estradiol, and live birth rates). Claiming robust, uniform declines in egg retrieval, embryo numbers, sperm counts, and IVF success across EDC exposures overstates the nuanced and largely mixed or null findings of the study.

2:28:25Natalie Crawfordoverstatedlow

Higher dietary red meat intake is associated with poorer embryo development, worse IVF outcomes, and higher staging of endometriosis at surgery.

"Red meat's the really controversial one, and increased servings of red meat—of course dietary studies quartile it: lowest exposure, highest exposure—highest exposure groups had poor embryos develop, worse outcomes with IVF, and an increase in staging of endometriosis when they went to surgery." (said at 2:28:25)

The speaker bundles three claims regarding higher red meat intake: poorer embryo development, worse IVF outcomes, and higher surgical staging of endometriosis. Observational evidence (including systematic reviews and the Nurses' Health Study II prospective cohort) does link higher red meat consumption to an increased incidence/risk of laparoscopically confirmed endometriosis (RR 1.17 to 1.56 for highest vs. lowest categories). However, evidence is lacking or inconsistent to firmly demonstrate that red meat specifically increases laparoscopic surgical staging/severity or causes poorer embryo development and worse IVF outcomes. Asserting these specific IVF and surgical-stage associations as established facts overstates the observational epidemiological findings.

8 Needs context
1:07:40Natalie Crawfordneeds contextmoderate

Approximately 17 million babies worldwide have been born through in vitro fertilization (IVF).

"17 million babies have been born in this world because of IVF." (said at 1:07:40)

According to the most comprehensive global epidemiological analysis by the International Committee for Monitoring Assisted Reproductive Technologies (ICMART), an estimated 9.8 million to 13.0 million infants were born worldwide via assisted reproductive technologies (ART/IVF) between 1978 and 2018. With global ART activity generating over 800,000 to 900,000 infants annually in subsequent years (as reported in the 2019 ICMART report), cumulative worldwide estimates reach approximately 14 to 17 million births today. While 17 million reflects an upper-bound or extrapolated contemporary figure, published historical registry analyses specifically document 10 to 13 million through 2018.

1:15:37Andrew Huberman (host)needs contexthigh

Human body temperature must decrease by about 1 to 3 degrees to fall asleep and stay deeply asleep, and must increase by about 1 to 3 degrees to wake up.

"And that's because in order to fall asleep and stay deeply asleep, your body temperature actually has to drop by about 1 to 3°. And in order to wake up feeling refreshed and energized, your body temperature actually has to increase by about 1 to 3°." (said at 1:15:37)

The claim accurately describes the fundamental circadian pattern of thermoregulation in sleep, but requires clarification regarding units and physiology. Normal human core body temperature (CBT) fluctuates by approximately 0.5°C to 1.0°C (roughly 1°F to 2°F, up to ~3°F) across the 24-hour cycle. In the evening, vasodilation of peripheral/distal blood vessels dissipates core heat through the skin, lowering CBT to promote sleepiness and sleep onset. CBT reaches its nadir during late-night sleep and begins rising in the early morning hours to promote awakening. However, if interpreted in Celsius, a 1°C to 3°C drop is exaggerated (a 3°C drop would represent clinical hypothermia), and thermoregulatory heat redistribution to the periphery is the primary trigger of sleep initiation rather than CBT maintenance alone.

1:22:50Natalie Crawfordneeds contexthigh

The combination birth control pill has a biological half-life of 28 hours.

"However, the half-life of the birth control pill is only 28 hours. So it's actually quite short." (said at 1:22:50)

A combined oral contraceptive pill contains two distinct active ingredients—an estrogen (typically ethinylestradiol) and a progestin (such as levonorgestrel, drospirenone, or norethindrone)—each with its own elimination half-life rather than a single unified value. However, the speaker's figure of approximately 28 hours accurately reflects the terminal elimination half-life of common progestin components (for example, levonorgestrel typically exhibits an elimination half-life of ~25–35 hours, while ethinylestradiol averages ~10–20 hours). This short duration necessitates daily dosing and explains the rapid decrease in circulating drug levels after missed doses.

1:25:40Natalie Crawfordneeds contextmoderate

A levonorgestrel-releasing (progesterone) intrauterine device typically suppresses ovulation during the first two years of use, after which progesterone levels decline and ovulation typically resumes.

"It typically suppresses ovulation in the first 2 years, but then progesterone levels drop and it tends not to suppress ovulation, but that chronic progesterone exposure thins the endometrial lining to the degree that many women do not have periods anymore." (said at 1:25:40)

The speaker accurately describes the general pharmacodynamics of levonorgestrel-releasing intrauterine devices (LNG-IUDs): higher systemic progestin levels initially lead to higher rates of anovulation, which decrease as release rates decline over time, and amenorrhea is driven by local endometrial suppression rather than persistent systemic anovulation. However, two details require context: (1) the active agent is levonorgestrel (a synthetic progestin, not endogenous progesterone), and (2) ovulation suppression is most prominent in the first few months to first year rather than fully suppressing ovulation for two years (studies show roughly 45% of cycles are already ovulatory within the first year, rising to >75-90% in subsequent years).

1:32:40Natalie Crawfordneeds contextmoderate

The lifespan of sperm is approximately 90 days, and the human egg is most susceptible to environmental influences during the 60 days prior to conception.

"when we know the lifespan of a sperm is 90 days and sperm are so sensitive. And then we know that even though eggs are in your body your whole life, the 60 days before you get pregnant is when the egg is most susceptible to the world around you." (said at 1:32:40)

The speaker conflates the developmental/maturation cycles of gametes with their cellular lifespan, though the timeframes roughly reflect standard reproductive biology. Human spermatogenesis takes approximately 74 days within the seminiferous tubules plus 10–14 days of epididymal maturation and transport (~90 days in total). Mature sperm survive only 3 to 5 days in the female reproductive tract. For oocytes, while primordial follicles are present from birth, the final stages of antral follicular growth and cytoplasmic/nuclear maturation take approximately 60 to 90 days (2 to 3 menstrual cycles) prior to ovulation, representing a recognized critical periconceptional window of heightened metabolic activity and vulnerability to nutritional, toxic, and environmental exposures.

1:33:35Natalie Crawfordneeds contextlow

Men who get less sleep exhibit lower testosterone levels and lower sperm counts.

"And we know really directly, men who get less sleep, they have lower testosterone levels and lower sperm counts." (said at 1:33:35)

Observational cohort studies show that short sleep duration and sleep disturbances are associated with lower total sperm count and semen volume, typically following an inverted U-shaped curve where both short (≤6.5 hours) and long (≥9 hours) sleep are linked to poorer semen quality. However, evidence regarding testosterone is mixed: while some acute laboratory sleep restriction studies observed daytime testosterone reductions, larger observational cohorts and subsequent randomized trials have found no significant association or adverse effect of sleep restriction on resting testosterone levels.

2:16:47Natalie Crawfordneeds contextmoderate

Taking 300 micrograms or more of biotin supplementation for seven days interferes with laboratory assays for steroid and thyroid hormones, including estradiol, progesterone, hCG, TSH, and testosterone.

"Taking a biotin supplementation of 300 micrograms or more for seven days can actually influence your lab assays for sex hormones or for any steroid hormone, actually... So this can happen to estradiol, to progesterone, to hCG, to TSH, to testosterone." (said at 2:16:47)

The speaker's general point is accurate: biotin supplementation causes significant analytical interference in streptavidin-biotin-based immunoassays commonly used to measure endocrine biomarkers, including thyroid hormones (e.g., TSH) and steroid/sex hormones (e.g., estradiol, progesterone, testosterone, and hCG). In sandwich immunoassays (such as TSH and hCG), excess biotin causes falsely low results, whereas in competitive immunoassays (such as steroid hormones), excess biotin causes falsely high results. However, the dose threshold mentioned by the speaker (300 micrograms) is very low: while standard multivitamin doses are around 30–300 mcg, documented clinically meaningful assay interference typically occurs at high pharmacological doses (often 5 mg to 10 mg or higher, or in mega-dose supplements/treatments). Non-streptavidin assays and mass spectrometry methods (LC-MS/MS) remain unaffected.

2:21:54Natalie Crawfordneeds contextmoderate

Thermal paper receipts are one of the top sources of human exposure to bisphenol A (BPA).

"like one of the top exposures of BPA right now is actually thermal paper, so receipts." (said at 2:21:54)

Dietary intake (especially via canned food and food-contact materials) is established as the predominant route of bisphenol A (BPA) exposure in the general population, accounting for approximately 90% of total internal exposure. Thermal paper receipts represent the main non-dietary and dermal exposure source (accounting for >98% of paper-based exposures and around 10% of aggregate exposure in certain age groups), and can be a substantial exposure source in occupationally exposed workers such as cashiers.

53 Supported by research
0:00:00Natalie Crawfordsupportedhigh

Anti-Müllerian hormone (AMH) testing provides a measure of egg quantity (ovarian reserve) but does not assess egg quality.

"Everybody should get an AMH test. I think it's a very important marker. If you are listening to this and you want kids one day, ask your doctor for this test. It is not a test of egg quality. And we talked about what egg quality is, right? Genetics and egg competency. But it is a check of how many eggs you have" (said at 0:00:00)

Anti-Müllerian hormone (AMH) is established in clinical reproductive endocrinology as a biomarker of ovarian reserve that reflects the growing follicular pool and quantitative oocyte yield during ovarian stimulation. It does not reliably assess oocyte quality, developmental competence, or chromosomal normality (which are primarily driven by female age).

0:04:44Natalie Crawfordsupportedmoderate

Infertility is associated with increased rates of metabolic syndrome, cardiovascular disease, stroke, cancer, and early mortality.

"if you have infertility, you have increased rates of metabolic syndrome, cancer, heart attack, stroke, and dying early." (said at 0:04:44)

Large cohort studies and systematic reviews in both female and male populations demonstrate that a history of infertility is associated with higher risks of cardiovascular disease (including coronary heart disease and myocardial infarction), stroke, metabolic disorders (such as diabetes and metabolic syndrome), certain cancers, and all-cause early mortality.

0:06:42Natalie Crawfordsupportedhigh

Menopause is clinically defined as 12 consecutive months without a menstrual period.

"When we're a little bit past this, menopause by definition, which I hate, is 12 months without a period. So, menopause is one single day in time. Really, it means you've been in ovarian failure for 12 months before you'll magically get this diagnosis." (said at 0:06:42)

The speaker's statement accurately reflects standard medical and clinical criteria. Clinical practice guidelines from major obstetrics and gynaecology societies (including the International Menopause Society, EMAS, and CNGOF/GEMVi) and standard diagnostic frameworks (such as STRAW) define natural menopause retrospectively after 12 consecutive months of amenorrhoea in the absence of other pathological or physiological causes.

0:15:03Natalie Crawfordsupportedhigh

Premature ovarian failure is defined as going into ovarian failure before age 40.

"what's so interesting is that we'll use premature ovarian failure. So, going into ovarian failure before age 40, well accepted that these women need hormone replacement even when they still have the low end of hormonal function." (said at 0:15:03)

Standard clinical guidelines and endocrine society definitions define premature ovarian failure (more commonly termed premature ovarian insufficiency, or POI) as the loss of normal ovarian function before the age of 40 years, characterized by amenorrhea/oligomenorrhea and elevated follicle-stimulating hormone (FSH) levels. Guidelines also uniformly recommend hormone replacement therapy for these women up to the typical age of natural menopause.

0:16:28Natalie Crawfordsupportedmoderate

Perimenopause can last 5 to 10 years as a transitional period.

"because perimenopause or diminished ovarian reserve like we call it in the fertility world, I mean, that can last 5 to 10 years. That can be a really long transitional period that women are going through" (said at 0:16:28)

Prospective longitudinal data from large cohort studies such as the Study of Women's Health Across the Nation (SWAN) confirm that the menopausal transition (perimenopause) typically lasts several years, with median durations ranging from approximately 4.4 to 8.6 years depending on the age at onset (and extending beyond 10 years in some subgroups, particularly those who begin the transition earlier).

0:17:36Natalie Crawfordsupportedmoderate

Ovaries of women with premature ovarian insufficiency show increased inflammatory markers, chronic inflammation, and fibrosis.

"We know that women who go into ovarian failure early, so when we look at that, we call it POI, the premature ovarian insufficiency group, their ovaries have more inflammatory markers, they have more chronic inflammation and fibrosis inside the ovary." (said at 0:17:36)

Published reviews and histological/mechanistic studies confirm that premature ovarian insufficiency (POI, also referred to as premature ovarian failure) is characterized by increased inflammatory markers, altered local ovarian immune microenvironments, chronic inflammation, and tissue fibrosis (excessive extracellular matrix deposition). While POI is etiologically heterogeneous and not every single subtype presents identically, intraovarian chronic inflammation and fibrotic remodeling are well-documented pathological hallmarks.

0:20:15Natalie Crawfordsupportedmoderate

Microplastics can accumulate inside the ovary.

"When it comes to microplastics as you mentioned, we know they can accumulate in the ovary." (said at 0:20:15)

Animal and human studies confirm that microplastics can reach and accumulate within ovarian compartments. Biodistribution studies in rodent models demonstrate direct ovarian accumulation following oral ingestion, and clinical observational studies as well as systematic reviews have confirmed the presence and accumulation of microplastic particles inside human ovarian follicular fluid.

0:20:38Natalie Crawfordsupportedlow

Endocrine-disrupting chemicals found in plastics are associated with worse IVF outcomes, lower live birth rates, and longer time to pregnancy.

"On a greater scale, we know that some of the endocrine disrupting chemicals that are in plastics have been associated with worse IVF outcomes, lower live birth rates, longer time to pregnancy." (said at 0:20:38)

Observational cohort studies and meta-analyses support the claim that exposure to certain plastic-related endocrine-disrupting chemicals (EDCs), particularly bisphenols (such as BPA and BPS) and specific phthalate metabolites, is associated with poorer in vitro fertilization (IVF) outcomes (including reduced oocyte yield and clinical pregnancy rates), decreased probability of live birth, and longer time to pregnancy in couples trying to conceive. Because these findings stem from observational exposure biomarker studies that show heterogeneity across individual chemical metabolites and exposure windows, the overall GRADE certainty is low.

0:25:05Natalie Crawfordsupportedhigh

Infertility is clinically defined as attempting to achieve pregnancy for 12 months without success.

"the definition of infertility is trying to get pregnant for 12 months." (said at 0:25:05)

The speaker's statement accurately reflects the standard clinical and epidemiological definition of infertility established by major reproductive organizations (such as the American Society for Reproductive Medicine, ACOG, and WHO), which define infertility as the failure to achieve a clinical pregnancy after 12 months or more of regular, unprotected sexual intercourse (or attempted pregnancy).

0:27:30Natalie Crawfordsupportedmoderate

Male sperm counts change and decline with increasing age.

"We also see that, you know, sperm counts change with age. So, your partner's sperm count will change with age." (said at 0:27:30)

A systematic review and meta-analysis of 90 studies (93,839 men) evaluated age-associated changes across major semen parameters. The analysis demonstrated significant age-dependent alterations, including declines in total semen volume, progressive and total motility, normal morphology, and DNA integrity. While sperm concentration per milliliter may remain stable (partly due to decreasing seminal fluid volume), overall semen quality and reproductive parameters consistently change and decline as men age.

0:30:41Natalie Crawfordsupportedhigh

The primary cause of pregnancy loss is random genetic abnormality in the embryo.

"The top cause of pregnancy loss is going to be random genetic abnormality. This wasn't the right embryo or the embryo didn't have the right capacity or capability to truly implant." (said at 0:30:41)

Extensive clinical and cytogenomic evidence confirms that sporadic (random) chromosomal abnormalities and copy number variations in the embryo are the single most common etiology of early pregnancy loss, accounting for roughly 50–70% of first-trimester miscarriages.

0:42:57Natalie Crawfordsupportedmoderate

An estrogen level sustained at 200 picograms for 50 hours signals the brain to release an LH surge.

"When estrogen is high enough for long enough, 200 picograms for 50 hours and that's the level, it'll tell the brain it's time to ovulate. The brain will send out a surge of LH." (said at 0:42:57)

Classic reproductive neuroendocrinology studies (most famously established by Ernst Knobil and colleagues in primates and replicated in clinical endocrinology) demonstrate that eliciting the positive feedback LH surge requires serum estradiol (estrogen) concentrations to be maintained above a critical threshold of approximately 150-200 pg/mL for a sustained duration of about 36 to 50 hours. This sustained high estradiol level triggers the preovulatory luteinizing hormone (LH) surge that induces ovulation.

0:43:15Natalie Crawfordsupportedhigh

A released human egg has only 24 hours to be fertilized.

"Egg will be released. It only has 24 hours to be fertilized, but that follicle will actually reform and become the corpus luteum." (said at 0:43:15)

Standard human reproductive biology establishes that after ovulation, a released oocyte remains viable and capable of fertilization for approximately 12 to 24 hours. Consequently, the biological fertile window spans the 5 days before ovulation (reflecting sperm survival in the female reproductive tract) plus the day of ovulation itself (the ~24-hour post-ovulatory lifespan of the ovum).

0:43:37Natalie Crawfordsupportedhigh

Human chorionic gonadotropin (hCG) and luteinizing hormone (LH) share the same cellular receptor.

"Fun nerdy fact, hCG and LH share a receptor. So hCG comes into the corpus luteum and now stimulates a constant production of progesterone." (said at 0:43:37)

The speaker's statement accurately describes a well-established principle of reproductive physiology and molecular biology. Human chorionic gonadotropin (hCG) and luteinizing hormone (LH) bind to and activate the exact same G protein-coupled receptor, the luteinizing hormone/choriogonadotropin receptor (LHCGR, or LH/CG-R). In early pregnancy, hCG secreted by the conceptus acts on this receptor in the corpus luteum to maintain and stimulate continued progesterone production.

0:46:25Natalie Crawfordsupportedhigh

Anti-Müllerian hormone (AMH) is produced by the granulosa cells surrounding each ovarian follicle.

"AMH stands for anti-Müllerian hormone. It's made from the granulosa cells that surround each follicle." (said at 0:46:25)

The speaker's statement is accurate and well-established in reproductive endocrinology. Anti-Müllerian hormone (AMH) is produced by the granulosa cells of growing ovarian follicles (specifically primary, secondary, preantral, and small antral follicles).

0:47:15Natalie Crawfordsupportedhigh

The American College of Obstetricians and Gynecologists (ACOG) recommends that women should not have AMH testing unless they have infertility.

"That is against medical advice, meaning the American College of OB-GYN says that women should not get an AMH checked unless they have infertility." (said at 0:47:15)

ACOG Committee Opinion No. 773 explicitly states that anti-Müllerian hormone (AMH) testing is supported for assessing ovarian reserve and guiding stimulation protocols in women with infertility, but is not recommended or supported by evidence for women without a diagnosis of infertility (such as for predicting time to pregnancy or assessing reproductive potential in the general population).

  • supports: ACOG Committee Opinion No. 773: The Use of Antimüllerian Hormone in Women Not Seeking… (Obstetrics and gynecology 2019) · cited 63x in the literature
    "Data exist to support the use of antimüllerian hormone levels for the assessment of ovarian reserve in infertile women and to select ovarian stimulation protocols in this population; however, using serum antimüllerian hormone levels for fertility counseling in women without a diagnosis of infertility is not currently supported by data from high-quality sources... a single serum antimüllerian hormone level assessment obtained at any point in time in a population of women with presumed fertility does not appear to be useful in predicting time to pregnancy and should not be used for counseling patients in this regard." (abstract)
    pubmedfull study (doi)
0:53:45Natalie Crawfordsupportedmoderate

The clinical definition of a short luteal phase is a luteal phase lasting fewer than 11 days.

"Less than 11 days is a short luteal phase, but you'll still have regular cycles." (said at 0:53:45)

In clinical practice and reproductive endocrinology research, a normal luteal phase is considered to last 11 to 16 days, and a short luteal phase (or luteal phase defect/deficiency) is commonly defined as a luteal phase duration of fewer than 10 to 11 days (or ≤10 days). Furthermore, individuals with a short luteal phase often maintain regular overall cycle lengths (e.g., eumenorrheic cycles).

0:42:56Natalie Crawfordsupportedhigh

The corpus luteum has a lifespan of approximately two weeks unless rescued by human chorionic gonadotropin (hCG) from an implanting embryo.

"The corpus luteum makes progesterone stimulated from LH pulses from the brain. So then it makes progesterone pulses throughout the luteal phase. Can only live for about 2 weeks unless a pregnancy occurs." (said at 0:42:56)

The speaker's statement accurately describes standard human reproductive endocrinology. Following ovulation, the corpus luteum secretes progesterone in a pulsatile manner driven by pulsatile luteinizing hormone (LH) secretion from the pituitary. In the absence of pregnancy, the corpus luteum has a finite lifespan of approximately 14 days (about 2 weeks) before undergoing luteolysis, whereas an implanting embryo produces human chorionic gonadotropin (hCG) that rescues the corpus luteum to sustain progesterone production into early pregnancy.

0:46:29Natalie Crawfordsupportedmoderate

Prolonged periods of anovulation, such as from hormonal birth control, pregnancy, or the postpartum state, suppress circulating anti-Müllerian hormone (AMH) levels.

"And in prolonged periods of not ovulating, AMH can be suppressed, whether it's from birth control pills, pregnancy, postpartum, whatever the reason is." (said at 0:46:29)

Published systematic reviews and large-scale cohort studies demonstrate that states associated with prolonged ovarian suppression and anovulation, particularly the use of hormonal contraceptives (such as combined oral contraceptives), significantly lower circulating anti-Müllerian hormone (AMH) levels compared to unsuppressed baselines. While AMH is considered a marker of ovarian reserve, systemic hormonal inhibition suppresses early follicular recruitment and granulosa cell activity, leading to temporary reductions in measurable circulating AMH.

0:59:20Natalie Crawfordsupportedhigh

Preimplantation genetic testing for monogenic disorders (PGT-M) can test embryos for Huntington's disease using a non-disclosure protocol where the at-risk parent does not learn their own carrier status.

"We can do single gene testing as well, PGT-M for monogenetic diseases, and Huntington's is one of them. And I've had some patients say, 'My mom had Huntington's... I would love to test my embryos, but I've committed to myself that I don't want to know if I have it or not.' Okay? And I think it's really important just to mention that disease to say, we can blind test you. You know, we can make a probe to see if you carry it or not. You don't have to know and we can still test the embryos." (said at 0:59:20)

The speaker accurately describes an established clinical application of preimplantation genetic testing for monogenic disorders (PGT-M, historically PGD) for Huntington's disease. Asymptomatic individuals at 50% risk who do not wish to learn their own carrier status can utilize non-disclosure or exclusion testing protocols to ensure unaffected embryos are selected and transferred without disclosing or determining the parent's genetic status.

1:01:48Natalie Crawfordsupportedmoderate

Undergoing an IVF cycle or egg freezing does not decrease a woman's ovarian reserve or cause earlier onset of menopause.

"So, doing IVF or egg freezing is not going to decrease your ovarian reserve. It is simply going to influence one month in time trying to not have all those eggs die." (said at 1:01:48)

The speaker accurately describes the reproductive physiology underlying controlled ovarian stimulation during in vitro fertilization (IVF) and egg freezing. In a natural menstrual cycle, a cohort of antral follicles is recruited from the ovarian reserve, but typically only one dominant follicle matures to ovulate while the remaining recruited follicles undergo atresia (programmed cell death). Exogenous gonadotropin stimulation during IVF/egg freezing rescues these non-dominant follicles from atresia in that specific cycle rather than recruiting additional primordial follicles from the resting reserve pool. Consequently, IVF stimulation acts on follicles already slated to undergo atresia in that single month without depleting the underlying primordial follicle reserve or accelerating the onset of natural menopause.

1:13:10Natalie Crawfordsupportedmoderate

In standard IVF culture, approximately 90% of frozen eggs survive thawing, 75% fertilize, 50% reach the blastocyst stage, and a genetically normal (euploid) embryo has roughly a 65% chance of resulting in a live birth.

"So, 90% of eggs survive the freeze-thaw. 75% will fertilize. 50% will make it to the implantation stage and then not everyone will be genetically normal based on your age and other factors. And then even a genetically normal embryo only has a 65% chance of live birth." (said at 1:13:10)

The speaker's quoted benchmarks accurately reflect the established embryological attrition rates and clinical outcomes in assisted reproduction. In studies evaluating vitrified/warmed oocytes, post-thaw survival is consistently reported around 89–92%, fertilization rates of surviving mature oocytes typically range from 75–85%, blastocyst development rates (the implantation stage) are approximately 40–50%, and the transfer of a single euploid embryo typically achieves approximately a 60–65% live birth rate.

1:22:07Natalie Crawfordsupportedmoderate

Large population studies show that previous use of contraception does not increase the rate of infertility at 12 months post-discontinuation.

"Number one, big studies looking at all different types of contraception, no higher rate of infertility, again defined as failure to get pregnant at 12 months. So you come off your contraception and 12 months later when we look, there's no higher rate of infertility than we would have on the population-based level." (said at 1:22:07)

Large prospective cohort studies and systematic reviews demonstrate that 12-month cumulative pregnancy rates following contraceptive discontinuation are approximately 80% to 85% (and range from 72% to 94% across various hormonal and non-hormonal methods). This matches the baseline expected 1-year fecundability rate in the general population, showing no increased rate of 12-month infertility after discontinuing contraception, although a transient delay in the first few cycles post-cessation is common for certain hormonal methods (notably injectables).

1:24:24Natalie Crawfordsupportedhigh

Following ovulation, an unfertilized human egg survives for approximately 24 hours.

"the egg only lives for 24 hours." (said at 1:24:24)

In human reproductive physiology, standard epidemiological and clinical studies establish that the biologically fertile window spans approximately six days: the five days preceding ovulation (reflecting sperm longevity in the female reproductive tract) and the day of ovulation itself, because an unfertilized oocyte (egg) remains viable for fertilization for approximately 12 to 24 hours after release.

1:24:40Natalie Crawfordsupportedmoderate

Intercourse during the two days before and the day of ovulation carries a 20% to 30% probability of conception, whereas intercourse the day after ovulation has a 0% probability.

"That's why the 2 days before and the day of ovulation have a 20 to 30% chance of getting pregnant compared to a 0 day, the day after ovulation, 0%." (said at 1:24:40)

Classic prospective studies on the fertile window (notably Wilcox et al., NEJM 1995) establish that conception occurs almost exclusively from intercourse during the 6-day window ending on the day of ovulation. Daily probabilities of conception peak at roughly 20% to 33% on the two days prior to ovulation and the day of ovulation, dropping to virtually 0% on the day following ovulation.

1:26:57Natalie Crawfordsupportedmoderate

A single intramuscular injection of Depo-Provera can prevent ovulation for up to 18 months.

"On population-based levels, to use it as an effective contraceptive, must get every 3 months. But one single dose can prevent ovulation for 18 months." (said at 1:26:57)

Depot medroxyprogesterone acetate (DMPA, 150 mg IM) is administered every 3 months for reliable contraception because its median duration of ovulation suppression is approximately 6 to 7 months (around 180–210 days). However, due to variable slow release and clearance from muscle and adipose tissue, delayed return of ovulation and fertility can extend up to 18 months in some women following a single injection.

1:27:19Natalie Crawfordsupportedmoderate

Scientific studies show that having an elective termination of pregnancy does not negatively impact long-term fertility.

"No study supports that having a termination is going to negatively impact your fertility later." (said at 1:27:19)

Large prospective and retrospective cohort studies have evaluated whether safe, legal induced abortion impairs future fertility or increases secondary infertility. A major UK prospective cohort study (PMID 8334095) following women with unplanned pregnancies showed that future fertility was unaffected by induced abortion compared to continuing pregnancy (fertility rate ratio 0.94, 95% CI 0.83–1.07). Similarly, a multicenter World Health Organization study (PMID 6515670) and US prospective follow-up studies (PMID 6694812, PMID 3979576) demonstrated no significant differences in cumulative conception rates or tubal infertility following uncomplicated induced abortion.

1:30:24Natalie Crawfordsupportedhigh

Taking nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen around the time of ovulation can inhibit the acute inflammatory cascade and prevent the ovarian follicle from rupturing.

"To the degree that if women take NSAIDs around the time of ovulation, Advil, ibuprofen, Aleve, they'll prevent the follicle from rupturing." (said at 1:30:24)

The claim is supported by randomized controlled trials and clinical observational data. Ovulation is an inflammatory-like process dependent on cyclooxygenase (COX-1/COX-2) and prostaglandin E2 (PGE2) synthesis. Administration of nonsteroidal anti-inflammatory drugs (NSAIDs, including COX inhibitors such as meloxicam, celecoxib, indomethacin, and naproxen) around the periovulatory period inhibits prostaglandin synthesis, leading to delayed or prevented follicular rupture and luteinized unruptured follicle (LUF) syndrome.

1:24:08Natalie Crawfordsupportedhigh

Sperm can survive in the human female reproductive tract for up to 5 days, with most remaining viable for around 2 days.

"Meaning sperm can live in the reproductive tract for up to 5 days. Most will stay around for 2 days." (said at 1:24:08)

Human reproductive studies establish that the fertile window spans approximately 6 days (ending on the day of ovulation), demonstrating that viable sperm can survive in the female reproductive tract for up to 5 days. In landmark prospective cohort research, conception was observed with intercourse occurring up to 5 days prior to ovulation, though only a small minority of pregnancies (~6%) were attributable to sperm that were 3 or more days old, with the highest viability and probability of conception concentrated within 1 to 2 days before ovulation.

1:04:30Natalie Crawfordsupportedhigh

In the earliest IVF procedures, oocyte retrieval required an abdominal surgical incision to aspirate the single follicle rather than transvaginal ultrasound-guided retrieval.

"And in those days, this is just science, they went and they did abdominal surgery to aspirate the egg. Now we do a vaginal egg retrieval where we take a needle attached to a vaginal ultrasound. It's a minimally invasive procedure. But back in the origin IVF studies, they had to go and do an abdominal incision to put a needle in the one single follicle to get the follicular fluid and the egg out." (said at 1:04:30)

Early human in vitro fertilization (IVF) procedures, pioneered by Patrick Steptoe and Robert Edwards, relied on abdominal surgery (laparoscopy requiring abdominal incision and pneumoperitoneum) to directly visualize the ovary and aspirate oocytes from preovulatory follicles in natural or early stimulated cycles. Transvaginal ultrasound-guided oocyte aspiration was not introduced and adopted as the standard minimally invasive retrieval technique until the mid-1980s.

1:30:44Natalie Crawfordsupportedmoderate

Taking NSAID medications outside of menstruation during the menstrual cycle can prevent ovulation from occurring.

"if you're trying to get pregnant, you can take those medications only when you're on your period. So, period cramping, fine, but we don't want you taking them for the rest of the cycle because you can prevent ovulation from occurring." (said at 1:30:44)

Prostaglandins synthesized via cyclooxygenase enzymes (particularly COX-2) play an essential role in ovarian follicular rupture. Multiple randomized controlled trials and clinical reviews demonstrate that nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, indomethacin, celecoxib, and meloxicam taken during the follicular or periovulatory phase can inhibit or delay follicular rupture, leading to luteinized unruptured follicle (LUF) syndrome and reversible ovulatory dysfunction. While not 100% effective as an anovulatory contraceptive, NSAID exposure outside of menses can and does prevent or disrupt normal ovulation in a significant proportion of women trying to conceive.

1:33:43Natalie Crawfordsupportedlow

Women who get less sleep yield fewer eggs during an IVF retrieval cycle.

"Women who get less sleep get fewer eggs at IVF cycle." (said at 1:33:43)

Observational evidence supports the claim that short sleep duration is associated with fewer retrieved and mature oocytes during an IVF cycle. In a prospective cohort study of 1,276 women undergoing IVF/ICSI (PMID: 35259255), sleeping less than 7 hours per night was associated with an 11.5% reduction in retrieved oocytes and an 11.9% reduction in mature oocytes compared to sleeping 7 to <8 hours per night. Systematic review evidence also notes that sleep duration exhibits a U-shaped relationship with intermediate IVF outcomes, where both short and long sleep durations are linked to poorer outcomes. Certainty is low due to the observational design and reliance on self-reported sleep parameters.

1:34:35Natalie Crawfordsupportedlow

Melatonin supplementation at doses of 1 to 3 mg taken 30 minutes before sleep can improve pregnancy rates and egg quality.

"Low doses of melatonin supplementation can impact fertility, so doses of 1 to 3 mg 30 minutes before you go to bed can improve your odds of getting pregnant as well, can improve egg quality." (said at 1:34:35)

Multiple systematic reviews and meta-analyses of randomized controlled trials demonstrate that oral melatonin supplementation (most commonly studied at 3 mg daily in the evening/bedtime during assisted reproductive technology cycles) is associated with significant improvements in mature (MII) oocyte counts, fertilization and embryo quality, and clinical pregnancy rates. However, evidence certainty remains low due to small sample sizes, methodological heterogeneity across clinical trials, and lack of consistent evidence showing improved live birth rates.

1:34:47Natalie Crawfordsupportedmoderate

The female body naturally increases melatonin production during ovulation to mitigate oxidative stress to the ovary.

"And we know that naturally you make more melatonin when you ovulate to kind of counter some of the oxidative stress to the ovary." (said at 1:34:47)

Evidence from human reproductive biology and observational studies confirms that melatonin accumulates in the preovulatory follicle at significantly higher concentrations than in serum or smaller immature follicles. Granulosa cells, cumulus cells, and oocytes locally produce melatonin and uptake circulating melatonin, which acts as a potent free radical scavenger and antioxidant to protect the follicle and oocyte from the intense reactive oxygen species (oxidative stress) generated during the ovulation process.

1:45:30Natalie Crawfordsupportedmoderate

Inositol decreases insulin resistance in women with PCOS.

"Inositol for PCOS decreases insulin resistance, huge benefit." (said at 1:45:30)

Multiple systematic reviews and meta-analyses of randomized controlled trials demonstrate that inositol (particularly myo-inositol) significantly improves markers of insulin resistance, such as HOMA-IR, fasting insulin, and insulin area under the curve (AUC), compared to placebo or folic acid in women with polycystic ovary syndrome (PCOS). While some individual meta-analyses note heterogeneity among trials and guidelines call for larger confirmatory trials, the overall pooled body of randomized evidence supports its insulin-sensitizing effects.

1:48:56Andrew Huberman (host)supportedhigh

A clinical trial using red and infrared light therapy for dry age-related macular degeneration (dry AMD) demonstrates promising results for preserving vision.

"There's been a clinical trial using red light and infrared light for what's called dry AMD, dry macular degeneration, to offset age-related vision loss, and it is looks promising. I mean, it doesn't reverse age-related vision loss completely, but seems to help the mitochondria in the photoreceptors. People are holding onto some vision that they would lose." (said at 1:48:56)

Randomized, sham-controlled clinical trials (notably the LIGHTSITE I, II, and III trials) evaluated multiwavelength photobiomodulation (including 660 nm red and 850 nm near-infrared light delivered via the Valeda system) for dry age-related macular degeneration (dry AMD). These trials demonstrated statistically significant gains in best-corrected visual acuity, reductions in the incidence and progression of geographic atrophy, and improved contrast sensitivity, supporting the proposed mitochondrial bioenergetic mechanism in retinal cells without claiming total disease reversal.

1:54:45Natalie Crawfordsupportedlow

Cannabis use by women in the prior year decreases retrieved oocytes by 25%, decreases fertilization rates by 28%, and increases miscarriage rates.

"For women, cannabis use in the prior year can decrease the eggs you get at egg retrieval by 25% and can decrease fertilization rates by 28%, and can increase miscarriage rates, therefore decreasing live birth rates." (said at 1:54:45)

The speaker's statistics directly cite findings from a prospective cohort study by Klonoff-Cohen et al. (2006, PMID 16458631) involving 221 couples undergoing IVF/GIFT. The study found that marijuana use in the year prior to treatment was associated with 25% fewer retrieved oocytes (p = 0.03) and 28% fewer fertilized oocytes (p = 0.04). Because these findings come from a single observational cohort study relying on self-reported use, the overall body of evidence has low certainty.

2:00:00Natalie Crawfordsupportedmoderate

Cigarette smoking directly decreases ovarian egg count and causes women to undergo menopause earlier.

"Most of the egg quality data from nicotine comes from cigarette smoking, so I think it's a little bit more nuanced because smoking directly we want to look at that, you know, I would say it's one of the few things that gets into the vault and decreases our egg count. I used to say chronic inflammation can get in there, but you know, nicotine cigarette smoking definitely does. You go into menopause early, you'll get fewer eggs, the egg quality is detrimental." (said at 2:00:00)

Large-scale pooled epidemiological analyses confirm that cigarette smoking is directly associated with accelerated ovarian aging, reduced ovarian reserve, and significantly earlier age at natural menopause. A pooled analysis of over 200,000 women across 17 studies (PMID 30481189) demonstrated that current smokers have approximately double the risk of premature (<40 years) and early (40–44 years) menopause compared to never-smokers, with clear dose-response relationships based on smoking duration, intensity, and cumulative pack-years.

1:55:43Natalie Crawfordsupportedhigh

Tetrahydrocannabinol (THC) crosses the human placenta directly.

"And THC crosses the placenta directly." (said at 1:55:43)

The claim is supported. Ex vivo human cotyledon perfusion models and in vivo pharmacokinetic data confirm that delta-9-tetrahydrocannabinol (THC) crosses the placenta directly into fetal circulation, achieving steady-state fetal-to-maternal plasma concentration ratios of approximately 0.26 to 0.28.

2:01:19Natalie Crawfordsupportedmoderate

Chronic stress is directly associated with insulin resistance.

"chronic stress, how it's directly associated with insulin resistance" (said at 2:01:19)

Chronic stress activates the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system, leading to prolonged secretion of glucocorticoids (primarily cortisol) and catecholamines. These stress hormones directly antagonize insulin signaling, suppress glucose uptake in skeletal muscle and adipose tissue, increase hepatic gluconeogenesis, and stimulate lipolysis, directly contributing to insulin resistance and impaired glucose homeostasis.

2:01:19Natalie Crawfordsupportedhigh

Building skeletal muscle is one of the top ways to reverse insulin resistance.

"building skeletal muscle is one of the top ways you can reverse insulin resistance. It's the best mechanism for hormonal health we have is to build more skeletal muscle." (said at 2:01:19)

Skeletal muscle is the principal site for insulin-stimulated glucose disposal (accounting for ~70-80% of postprandial glucose uptake). Multiple systematic reviews and meta-analyses of randomized controlled trials demonstrate that resistance training to build muscle mass and strength significantly improves insulin resistance (lowering HOMA-IR, fasting insulin, fasting glucose, and HbA1c) in individuals with or at risk for type 2 diabetes.

2:03:51Natalie Crawfordsupportedhigh

Fat cells synthesize estrogen, alter ovulation, and generate inflammatory signals.

"Fat cells make estrogen, they impact the ovulatory process, fat cells are inflammatory." (said at 2:03:51)

The speaker's statement accurately summarizes well-established physiological roles of adipose tissue. White adipose tissue expresses aromatase (CYP19A1) to biosynthesize estrogens (estrone and estradiol) from circulating androgens, acting as a primary source of estrogen production (particularly in post-menopausal women). Adipose tissue also functions as an active endocrine and immune organ that secretes pro-inflammatory adipokines and cytokines, and excessive or dysfunctional adipose tissue disrupts the hypothalamic-pituitary-ovarian axis, contributing to ovulatory dysfunction and anovulation.

2:03:51Natalie Crawfordsupportedmoderate

Fifty percent of patients presenting with unexplained infertility are ultimately found to have endometriosis.

"they have unexplained infertility, 50% of those patients will end up having endometriosis." (said at 2:03:51)

A 2024 systematic review investigating the prevalence of endometriosis in women diagnosed with unexplained infertility undergoing diagnostic laparoscopy found an overall prevalence of endometriosis of 44% (with 74% classified as minimal or mild). Other cohort studies report rates ranging between 20% and 90% depending on prior fertility treatment failure and patient selection, making the speaker's figure of 50% consistent with the evidence base.

2:03:51Natalie Crawfordsupportedhigh

The diagnostic gold standard for endometriosis is surgical confirmation because no laboratory test exists.

"one of the problems with endo is gold standard is a surgical diagnosis only. We don't have a lab test for endometriosis." (said at 2:03:51)

The speaker's statement is fully supported by major clinical guidelines and Cochrane systematic reviews. Surgical visualisation via laparoscopy (typically with histological verification) is established as the gold standard for diagnosing endometriosis. Systematic reviews evaluating over 100 potential blood and non-invasive biomarkers have confirmed that none currently possess sufficient diagnostic accuracy to be recommended or utilized as a standalone laboratory test in routine clinical practice.

2:06:50Natalie Crawfordsupportedmoderate

A luteal phase defect serves as the initial warning sign before progressing to true hypothalamic amenorrhea.

"we can see like a luteal phase defect is that first warning sign before you're in true hypothalamic amenorrhea." (said at 2:06:50)

Extensive physiological and reproductive endocrinology research (notably the work of De Souza and colleagues on the Female Athlete Triad and Relative Energy Deficiency in Sport) demonstrates that exercise- and energy-deficiency-related hypothalamic dysfunction exists along a continuum. Subtle disturbances like luteal phase defects (LPD) and shortened luteal phases represent the earliest, mildest manifest stage of hypothalamic-pituitary-ovarian axis suppression before progression to anovulatory cycles and full functional hypothalamic amenorrhea.

2:11:00Natalie Crawfordsupportedmoderate

Transferring three genetically normal embryos results in an almost 95% cumulative live birth rate in IVF.

"Meaning if you have three genetically normal embryos, almost 95% of people will have a live birth." (said at 2:11:00)

A landmark large retrospective cohort study of 4,429 women undergoing consecutive single frozen euploid embryo transfers (Pirtea et al., 2021) demonstrated that having up to three consecutive euploid embryo transfers resulted in a 92.6% cumulative live birth rate and a 95.2% cumulative sustained implantation rate.

2:13:44Natalie Crawfordsupportedmoderate

Paternal age over 50 is associated with an increased population-level risk of offspring autism, de novo autosomal dominant mutations (such as dwarfism), and schizophrenia.

"after age 50, we see a few different increases for sperm specifically. So advanced paternal age is real both when it comes to how you make sperm, but also the quality of that sperm. We see overall on a population basis increases of autism, of autosomal dominant new mutations, specifically certain types of like dwarfism or very specific diseases that are ultimately overall rare that can happen. And then you also can see an increase in some other mental health diseases like schizophrenia." (said at 2:13:44)

Epidemiological studies and systematic reviews consistently demonstrate that advanced paternal age (typically categorized as >40 or >50 years) is associated with an increased risk of de novo autosomal dominant conditions (termed paternal age effect disorders, classically including achondroplasia/dwarfism and Apert syndrome via 'selfish spermatogonial selection') as well as neuropsychiatric and neurodevelopmental conditions such as autism spectrum disorder and schizophrenia.

2:28:25Natalie Crawfordsupportedlow

Replacing servings of animal protein with plant-based protein is associated with improved ovulation and higher fertility rates.

"The meat data to notice is that for every serving of plant-based protein over animal, people tended to ovulate better and had higher fertility rates." (said at 2:28:25)

The statement directly reflects findings from prospective cohort research in the Nurses' Health Study II (18,555 women followed over 8 years). In that study, higher animal protein intake was associated with an increased risk of ovulatory infertility, whereas higher vegetable protein intake was associated with a lower risk. Substituting 5% of energy intake from animal protein with vegetable protein was associated with a greater than 50% reduction in the risk of ovulatory infertility. Because the evidence comes from an observational cohort relying on food-frequency questionnaires, the certainty of evidence is low.

2:08:26Natalie Crawfordsupportedmoderate

The addition of human growth hormone (HGH) during ovarian stimulation protocols improves egg maturity and embryo development in poor-responder IVF patients.

"my partner actually did a study where she put them through the same protocol, so the same medications in a subsequent cycle, and the only change was adding human growth hormone and had improved embryo development and maturity of eggs." (said at 2:08:26)

Multiple systematic reviews and meta-analyses of randomized controlled trials (RCTs) demonstrate that growth hormone (GH/HGH) co-treatment during controlled ovarian stimulation in poor ovarian responders significantly increases the number of mature (metaphase II / MII) oocytes and the number of usable embryos and embryos available for transfer. While effects on final live birth rates remain debated across individual studies, the specific improvements in oocyte maturity and embryo yield/development are consistently observed.

2:20:48Natalie Crawfordsupportedlow

Lavender oil and tea tree oil possess endocrine-disrupting and hormone-modulating properties.

"Essential oils for the most part tend to be fine, but it is lavender, tea tree, and evening primrose that have more endocrine properties for them." (said at 2:20:48)

Lavender oil and tea tree oil (and several of their isolated constituents) have been shown in human cell-line studies to exhibit estrogenic and antiandrogenic endocrine-modulating activities. Clinically, multiple pediatric case reports have linked regular topical exposure to lavender and tea tree oil products with reversible prepubertal gynecomastia and premature thelarche, which resolved upon discontinuation of the oils. However, clinical certainty remains low because evidence in humans is limited to case reports and in vitro assays, and the extent of in vivo systemic absorption from standard topical use remains debated.

2:21:00Natalie Crawfordsupportedhigh

Scented consumer products commonly contain phthalates, which function as endocrine-disrupting chemicals.

"When it comes to other products, scented products have a lot of phthalates in them, and that's an endocrine-disrupting chemical." (said at 2:21:00)

Analytical testing and toxicological reviews consistently show that fragranced and scented consumer products (such as perfumes, air fresheners, personal care items, and dryer sheets) frequently contain phthalates (commonly used as fragrance solvents and fixatives) and that phthalates are well-established endocrine-disrupting chemicals (EDCs).

2:11:05Natalie Crawfordsupportedvery low

Patients at an unapproved stem cell clinic developed blindness after receiving stem cell injections into their eyes for macular degeneration.

"A vision clinic, they were injecting them into the eye for macular degeneration and the patients all went blind, and I'm very familiar with those cases." (said at 2:11:05)

The speaker refers to a well-documented 2017 case series published in the New England Journal of Medicine (Kuriyan et al.). The report detailed three patients with age-related macular degeneration (AMD) who received bilateral intravitreal injections of autologous adipose-derived stem cells at a stem cell clinic in the United States and subsequently suffered severe vision loss and blindness due to retinal detachment, vitreous hemorrhage, and ocular hypertension. Because this evidence is derived from a case series, the GRADE certainty is classified as very low by definition.

  • supports: Vision Loss after Intravitreal Injection of Autologous "Stem Cells" for AMD. (The New England journal of medicine 2017) · cited 463x in the literature
    "We evaluated three patients in whom severe bilateral visual loss developed after they received intravitreal injections of autologous adipose tissue-derived "stem cells" at one such clinic in the United States. In these three patients, the last documented visual acuity on the Snellen eye chart before the injection ranged from 20/30 to 20/200. The patients' severe visual loss after the injection was associated with ocular hypertension, hemorrhagic retinopathy, vitreous hemorrhage, combined traction and rhegmatogenous retinal detachment, or lens dislocation. After 1 year, the patients' visual acuity ranged from 20/200 to no light perception." (abstract, results, passage verified)
    pubmedfull study (doi)
2:34:00Natalie Crawfordsupportedmoderate

Estrogen has significant anti-inflammatory benefits, leading to a baseline increase in systemic inflammation upon entering menopause.

"We know that when you go into menopause, estrogen has such profound anti-inflammatory benefits that one of the biggest problems is a baseline increase in your inflammation." (said at 2:34:00)

Estrogen exerts well-established anti-inflammatory and immunomodulatory effects. The decline in ovarian estrogen production during the menopausal transition is associated with an increase in systemic, low-grade chronic inflammation, marked by elevations in pro-inflammatory cytokines such as IL-1β, IL-6, and TNF-α. In addition, menopausal hormone therapy has been demonstrated in clinical trials and meta-analyses to attenuate markers of systemic inflammation.

4 No source found (not proven false)
0:23:44Natalie Crawfordunverifiedlow

In natural fertility cohorts, the monthly probability of pregnancy for nulliparous women is approximately 20% at age 30, 11-12% at ages 35-36, 5% at age 38, and 3% at age 40 and older.

"Meaning, if I will sit here and say if you're trying to get pregnant with your first child and you're 30, you'll have a 20% chance per month, right? The finest point we look at in natural fertility studies is called fecundability, the probability of pregnancy per month. But as you age, when you're 35 to 36, that number will be 11 to 12% per month. At age 38, it'll be 5% per month. And at 40 and beyond, it'll be 3% per month." (said at 0:23:44)

While natural fertility literature broadly demonstrates a progressive decline in per-cycle fecundability with advancing maternal age, the specific point estimates cited by the speaker (approx. 20% per month at age 30, 11–12% at ages 35–36, 5% at age 38, and 3% at age 40 and older for nulliparous women) could not be verified against the abstracts retrieved within the search session. This does not establish that the figures are false, but that matching published cohort data confirming these exact age-specific probabilities was not located in the fetched records.

0:25:40Natalie Crawfordunverifiedvery low

Among couples who successfully conceive, approximately 72% achieve pregnancy in the first 6 months of trying, and 13% conceive in the subsequent 6 months.

"most people who do will get pregnant the first 6 months. So, 72% of people will get pregnant in that first 6 months of trying and only 13% will get pregnant in the next 6 months of trying." (said at 0:25:40)

No matching published study reporting the exact breakdown of 72% of couples conceiving in the first 6 months and 13% in the subsequent 6 months was located in the retrieved records. In general reproductive epidemiology literature, cumulative pregnancy rates for couples trying to conceive naturally are typically cited as approximately 70-75% by 6 months and 80-85% by 12 months (an additional 10-15% in months 7-12), which is consistent with the speaker's overarching point, but the specific statistical source for the exact 72% and 13% figures could not be verified.

0:42:05Natalie Crawfordunverifiedvery low

A female fetus has 6 to 7 million eggs at 5 months of gestation, which decreases to 1 to 2 million at birth and to approximately 500,000 at menarche.

"You have the most eggs when you're 5 months old inside your mom. You have 6 to 7 million eggs. By the time that you're born, you have 1 to 2 million. By the time you start your first period, you have half a million." (said at 0:42:05)

No published records were successfully retrieved within the search constraints to directly verify the specific figures cited. Although standard human reproductive embryology literature (such as classic morphometric work by Baker and subsequent ovarian reserve modeling) classically describes peak oogonia/oocyte counts of approximately 6 to 7 million at 20 weeks (5 months) of gestation, declining via atresia to 1 to 2 million at birth and 300,000 to 500,000 around menarche/puberty, no fetched PubMed records were obtained during the search to formally cite. This does not prove the claim false.

0:56:07Natalie Crawfordunverifiedvery low

An out-of-pocket AMH blood test costs $79.

"$79. A $79 test, and I I feel really strongly about this." (said at 0:56:07)

No peer-reviewed publications matching the specific claim of a $79 out-of-pocket Anti-Müllerian Hormone (AMH) test cost were identified in PubMed. While direct-to-consumer (DTC) and out-of-pocket laboratory testing for AMH is widely available through commercial vendors and clinical laboratories (where retail and cash prices vary widely, typically ranging from ~$60 to over $150 depending on the provider and laboratory fees), specific commercial pricing is not standardized or documented as a fixed benchmark in published biomedical literature. This does not mean the price is false for specific commercial vendors, but it is unverified in published scientific records.

Unverified means no publication matching the claim was located; it does not prove the claim false. Spotted an error? See the corrections policy - disputes from the people quoted are prioritized.