Gravidity is not associated with telomere length in a biracial cohort of middle-aged women: The Coronary Artery Risk Development in Young Adults (CARDIA) study

Objective: Having experienced 2–3 births is associated with reduced mortality versus women with <2 or 4 births. The effect of 2–3 births on lifespan may be associated with delayed cellular aging. We hypothesized telomere length, a marker of cellular aging, would be longer in women who had 2–3 pregnancies. Methods: Leukocyte telomere length was measured using quantitative real-time polymerase chain reaction in 620 women in CARDIA at the year 15 and 20 exams, expressed as the ratio of telomere repeat copy number to single-copy gene copy number (T/S). Number of pregnancies at the time of telomere length measurement was obtained (mean age = 41±0.1 years, average gravidity = 2.64±0.1 pregnancies). Participants were divided into 4 groups by number of pregnancies: 0, 1, 2–3, and 4, to test for differences in telomere length by gravidity group. Results: The mean and SD for telomere length was 0.98 ± 0.20 T/S in the whole cohort. There were no differences in mean telomere length between groups; 0.98±0.02 T/S in women with 0 pregnancies, 1.01±0.02 T/S in women with 1 pregnancy, 0.97±0.01 T/S in women with 2–3 pregnancies, and 0.99±0.02 T/S in women with 4 pregnancies (p = 0.51). We defined high-risk (shorter) telomere length as 25^th percentile, and low-risk (longer) telomere length as 75 percentile. There were no differences in the prevalence of high-risk or low-risk telomere length between gravidity groups. Conclusions: Gravidity was not associated with telomere length in early middle age; the protective association of 2–3 births may act through other mechanisms.