The Risk of Pregnancy After Vasectomy

In Brief OBJECTIVE: To describe the pregnancy rates among women whose husbands underwent vasectomy. METHODS: Between 1985 and 1987, 573 women aged 18–44 years whose husbands underwent vasectomy in medical centers in 5 U.S. cities were enrolled in the U.S. Collaborative Review of Sterilization, a prospective cohort study of male and female sterilization. Women were interviewed by telephone at 1, 2, 3, and 5 years after their husbands underwent vasectomy. RESULTS: Among the 540 eligible women at risk for pregnancy, there were 6 pregnancies occurring from 6 to 72 weeks after vasectomy. The cumulative probability of failure per 1,000 procedures (95% confidence interval) was 9.4 (1.2, 17.5) 1 year after vasectomy and 11.3 (2.3, 20.3) at years 2, 3, and 5. CONCLUSION: Couples considering vasectomy should be counseled about the small, but real, risk of pregnancy following the procedure and that men are not sterile immediately after vasectomy. LEVEL OF EVIDENCE: II-2 Among 540 women whose husbands underwent vasectomy, the cumulative probability of pregnancy (per 1,000 procedures) was 9.4 at 1 year after vasectomy and 11.3 at years 2, 3, and 5.