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

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.

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.