Maternal age at last birth and leukocyte telomere length in a nationally representative population of perimenopausal and postmenopausal women

Objective: The primary aim of this study was to evaluate if maternal age at birth of last child is associated with leukocyte telomere length in a nationally representative population of perimenopausal and postmenopausal women. Methods: We conducted a cross-sectional analysis of 1,232 women from the National Health and Nutrition Examination Survey to examine maternal age at last birth and telomere length, surveyed between 1999 and 2002. We included perimenopausal and postmenopausal women age 40 years and older. Maternal age at last live birth was self-reported, and leukocyte telomere length was measured using quantitative polymerase chain reaction. We calculated least-squares geometric mean telomere length across categories of maternal age adjusted for age, race/ethnicity, number of live births, survey cycle, and history of hysterectomy or oophorectomy. P trend < 0.05 was considered statistically significant. For hypothesis-generation, we explored modification by reproductive and sociodemographic factors. Results: Maternal age at last birth was positively associated with telomere length: the multivariable-adjusted least-squares geometric mean leukocyte telomere length across categories of age at last birth (<25, 25-29, 30-34, 35-39, >= 40 y) was 0.90, 0.93, 0.93, 0.95, and 0.96, respectively (P trend = 0.04). There was suggestive evidence this association may be restricted to those women with one or two live births or women who reported ever using oral contraceptives (P interaction <0.10 for both). Conclusions: Later maternal age was associated with longer telomere length in a nationally representative population of women. These data provide new insight into the biological relationship between reproductive history and long-term health.