Women have leukocyte telomeres that are hundreds of base pairs longer than men's, a difference present at birth.
"For example, women have much longer telomeres, like hundreds of base pairs longer, and that starts at birth, and that's probably related to sex hormones." (said at 0:30:55)
Systematic reviews and meta-analyses confirm that females, on average, have longer leukocyte telomeres than males across the lifespan. However, the claim requires nuance: the effect size is small (standardized difference of approximately 0.09 SDs, typically translating to tens to a few hundred base pairs depending on measurement method and age), and whether this difference is definitively present at birth or arises and widens early in life remains debated in the literature (with some neonatal studies finding significant differences at birth while others find comparable terminal restriction fragment lengths at birth).
- context: Telomere length in the newborn. (Pediatric research 2002)
"TRF length was not different between male and female newborns. It was highly synchronized among the DNA samples from white blood cells, umbilical artery and skin within individual donors but exhibited a high variability among donors. We conclude that there is no evidence for the effect of sex on telomere length at birth, suggesting that longer telomeres in women than men arise from a slower rate of telomeric attrition in women." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Gender and telomere length: systematic review and meta-analysis. (Experimental gerontology 2014)
"Meta-analyses from 36 cohorts (36,230 participants) showed that on average females had longer telomeres than males (standardised difference in telomere length between females and males 0.090, 95% CI 0.015, 0.166; age-adjusted). There was little evidence that these associations varied by age group (p=1.00) or cell type (p=0.29)." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Sex differences in telomere length, lifespan, and embryonic dyskerin levels. (Aging cell 2022)
"At any given age, the average telomere length in leukocytes shows considerably variation between individuals with females having, on average, longer telomeres than males. Sex differences in average telomere length are already present at birth and correspond to reported differences in the average life expectancy between the sexes." (abstract, passage verified)
pubmedfull study (doi)