Simone Collins

Simone Collins is an author and pronatalist advocate. Her work focuses on global fertility rates and demographic decline.

What they said on air - context

3:34:32needs contextmoderateBirth Rate Debate: “40% Of Girls Will Never Be Mothers”

A woman's ability to conceive declines linearly starting from age 20.

"Ability to conceive declines literally linearly for women from age 20?" (said at 3:34:32)

Preconception cohort studies and historical demographic analyses demonstrate that natural fecundability (the per-cycle probability of conception) peaks in the early 20s and decreases progressively with age. Some prospective cohorts (e.g., Wesselink et al., 2017) and historical natural-fertility models (e.g., Wood, 2000) describe an approximately linear decline in per-cycle conception rates from age 20–24 through age 45. However, the term "literally linear" requires context: several studies find that fecundability remains relatively stable or decreases gradually through the late 20s and early 30s, followed by a steeper, accelerated decline in the mid-to-late 30s.

context: The age pattern of fecundability: an analysis of French Canadian and Hutterite birth histo… (Social biology 2000) · cited 32x in the literature
"2) effective fecundability peaks at age 20 for the Hutterites, and in the early to mid-20s for the French Canadians; 3) Hutterite effective fecundability declines almost linearly from age 20 to 45, and French Canadian effective fecundability declines slowly from its peak to the early 30s, and more rapidly at older ages" (abstract, results, passage verified)
pubmed full study (doi)
context: Increased infertility with age in men and women. (Obstetrics and gynecology 2004) · cited 521x in the literature
"The percentage infertility was estimated at 8% for women aged 19-26 years, 13-14% for women aged 27-34 years and 18% for women aged 35-39 years." (abstract, results, passage verified)
pubmed full study (doi)
context: Age and fecundability in a North American preconception cohort study. (American journal of obstetrics and gynecology 2017) · cited 118x in the literature
"In this preconception cohort study of North American pregnancy planners, increasing female age was associated with an approximately linear decline in fecundability." (abstract, conclusions, passage verified)
pubmed full study (doi)

3:34:38needs contexthighBirth Rate Debate: “40% Of Girls Will Never Be Mothers”

De novo mutations in male sperm begin rising at age 18.

"Men's mutations in their sperm start rising at age 18?" (said at 3:34:38)

Paternal de novo germline mutations accumulate continuously with paternal age at a rate of approximately 1.5 to 2 mutations per year. However, this accumulation is driven by ongoing spermatogonial stem cell divisions, a process that begins at puberty (typically around age 12 to 14) rather than starting specifically at age 18. Age 18 is commonly used as an early-adulthood reference baseline in demographic and genetic modeling, but biological mutation accumulation begins earlier.

context: Rate of de novo mutations and the importance of father's age to disease risk. (Nature 2012) · cited 2278x in the literature
"Most notably, the diversity in mutation rate of single nucleotide polymorphisms is dominated by the age of the father at conception of the child. The effect is an increase of about two mutations per year." (abstract, results, passage verified)
pubmed full study (doi)
context: Parental influence on human germline de novo mutations in 1,548 trios from Iceland. (Nature 2017) · cited 670x in the literature
"The number of de novo mutations from mothers increases by 0.37 per year of age (95% CI 0.32-0.43), a quarter of the 1.51 per year from fathers (95% CI 1.45-1.57)." (abstract, results, passage verified)
pubmed full study (doi)

Simone Collins

What they said on air - context

A woman's ability to conceive declines linearly starting from age 20.

De novo mutations in male sperm begin rising at age 18.

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