Objective: The purpose of this study was to identify obstetric risk factors for symptomatic prolapse. Study design: This was a population-based case-control study of prolapse prevalence. Results: Four hundred fifty-four women with self-reported symptomatic pelvic organ prolapse who were identified among 5489 women who participated in a population survey (cases) and 405 control subjects without symptoms were selected randomly from the same survey. All cases and control subjects received a mailed questionnaire with 72 questions about factors that were suspected to be linked to risk and that included obstetric history. The response rate was 76%. Among parous women, the odds for symptomatic pelvic organ prolapse increased with number of childbirths and were 3.3-fold higher among mothers of 4 than among mothers of 1. Indices of excessive stretching and tearing during labor (vaginal lacerations or episiotomies) were associated with increased risk for symptomatic pelvic organ prolapse. Instrumental delivery with forceps or vacuum did not seem to increase the risk of symptomatic pelvic organ prolapse, nor did length of delivery or maternal age at time for delivery. Abdominal deliveries appeared to be protective; the age-and parity-adjusted odds ratio of symptomatic pelvic organ prolapse after ≥1 abdominal deliveries was 0.5 (95%CI, 0.3-0.9), relative to women who had had only vaginal deliveries. A positive association with child birth weight in unadjusted analyses disappeared after adjustments for attained age and parity of the mother. Conclusion: Excessive stretching and tearing and multiple deliveries seem to be the main predisposing obstetric factors for symptomatic pelvic organ prolapse. Abdominal delivery emerged as a comparably strong protective factor. Objective: The purpose of this study was to identify obstetric risk factors for symptomatic prolapse. Study design: This was a population-based case-control study of prolapse prevalence. Results: Four hundred fifty-four women with self-reported symptomatic pelvic organ prolapse who were identified among a population survey (cases) and 405 control subjects without symptoms were selected randomly from the same survey. All cases and control subjects received a mailed questionnaire with 72 questions about factors that were suspected to be linked to The response rate was 76%. Among parous women, the odds for symptomatic pelvic organ prolapse increased with number of childbirths and were 3.3-fold higher among mothers of 4 than among mothers of 1. Indices of excessive stretching and tearing during labor (vaginal lacerations or episiotomies) were associated with increased risk for symptomatic pelvic organ prolapse. Instru mental delivery with forceps or vacuum did not seem to increase the risk of symptomatic pelvic organ prolapse, nor did length of delivery or maternal age at time for delivery. pelvic organ prolapse after ≥1 abdominal deliveries was 0.5 (95% CI, 0.3-0.9), relative to women who had had only vaginal deliveries. A positive association with child birth weight in unadjusted analyses disappeared after adjustments for attained age and parity of the mother. Conclusion: Excessive stretching and tearing and multiple deliveries seem to be the main predisposing obstetric factors for symptomatic pelvic organ prolapse. Abdominal delivery emerged as a comparably strong protective factor.