Impact of female age and nulligravidity on fecundity in an older reproductive age cohort

OBJECTIVE: To provide female age-related estimates of fecundity and incidence of infertility by history of prior pregnancy among women 30-44 years of age. DESIGN: Prospective, time-to-pregnancy cohort study. SETTING: Not applicable. PATIENT(S): Women, between 30 and 44 years of age, attempting to conceive for ≤3 months, and no known history of infertility, polycystic ovarian syndrome (PCOS), or endometriosis. INTERVENTION(S): Not applicable. MAIN OUTCOME MEASURE(S): Fecundability and incidence of infertility. RESULT(S): Compared to women aged 30-31 years, fecundability was reduced by 14% in women 34-35 years of age (fecundability ratio [FR] 0.86, 95% confidence interval [CI] 0.68-1.08), 19% in women 36-37 years of age (FR 0.81, 95% CI 0.60-1.08, 30% in women 38-39 years of age (FR 0.70, 95% CI 0.48-1.01), 53% in women 40-41 years of age (FR 0.47, 95% CI 0.28-0.78), and 59% in women 42-44 years of age (FR 0.39, 95% CI 0.16-0.93). Fecundability did not differ between women aged 30-31 years and 32-33 years. In general, fecundability and cumulative probability of pregnancy was lower for women who had never had a prior pregnancy. CONCLUSION(S): Women experience a significant reduction in fecundity and increase in the probability of infertility in their late thirties. At any age >30 years, women who have never conceived have a lower probability of achieving a pregnancy. CLINICAL TRIAL REGISTRATION NUMBER: NCT01028365.