Objective To determine the relationship between age at first delivery and subsequent risk of pelvic organ prolapse. Study Design We performed a retrospective cross-sectional study using the National Health and Nutrition Examination Survey data from 2005 to 2012. Our primary outcome was self-reported prolapse. Survival analyses and Cox proportional hazard models were used to estimate parous women's risks of reporting prolapse in terms of time since first delivery, adjusting for parity, body mass index, prior hysterectomy, ethnicity, and education. We performed subgroup analyses on women with at least 1 vaginal delivery and those with only cesarean deliveries. Results The survey-weighted prevalence of prolapse was 2.82%. A total of 6203 women, 79% of all parous women surveyed, reported age at first delivery. Kaplan-Meier curves were different for women based on age at first delivery (P = 0.034). For each year increase in age at first delivery, there was a 6% increase in the rate of developing prolapse (adjusted hazard ratio, 1.06; 95% confidence interval, 1.01-1.11; P = 0.011). Compared with a woman who was 20 years at her first delivery, someone who was 30 years had 1.79 times the risk, while at 40 years the risk was 3.21 times. Among women with at least 1 vaginal delivery, the same relationship was found (adjusted hazard ratio, 1.06; 95% confidence interval, 1.01-1.12; P = 0.019). However, this was not significant for women with only cesarean deliveries (P = 0.367). Conclusions Older age at the time of first delivery was associated with a higher risk of subsequent prolapse. These results should be interpreted with caution given the limitations of cross-sectional survey data.