After repetitive surgery for recurrent endometriosis, 20 of 89 (22%) women achieved spontaneous pregnancy, compared with 165 of 411 (40%) after first-line procedure (adjusted incidence rate ratio, 0.51; 95% confidence interval, 0.32 to 0.82), and the 12- and 24-month cumulative pregnancy rates were 14% and 26% in the former group compared with 32% and 38% in the latter. Among infertile patients at baseline, 13 of 67 (19%) conceived after reoperation compared with 98 of 290 (34%) after primary surgery (adjusted incidence rate ratio, 0.55; 95% confidence interval, 0.30 to 0.99), and the 12- and 24-month cumulative pregnancy rates were 13% and 22% in the former group and 25% and 30% in the latter.