Bariatric surgery is performed mostly on obese women of reproductive age. Many studies have analyzed pregnancy outcomes after bariatric surgery, but only a small number have studied the impact of pregnancy on the postoperative outcomes. To study the effect of pregnancy on outcomes after bariatric surgery in women of childbearing age. From January 2010 to October 2017, a retrospective study of a prospectively maintained database was conducted at the University Hospital of Geneva (HUG), where 287 women between the ages of 18 and 45years had undergone Roux-en-Y gastric bypass (RYGB). A comparison of the results during a 5-year follow-up was performed between women who became pregnant after their bariatric surgery (pregnancy group, n = 40) and postoperative non-pregnant women (non-pregnancy group, n = 247). The two groups were compared for weight loss, complications, and nutritional deficiencies. The pregnancy group was significantly younger (29.2 ± 5.5 vs. 36.4± 6.3years, p < 0.001) and heavier (124.0 ± 18.0kg vs. 114.7 ± 17.1, p < 0.001) compared with the non-pregnancy group at the time of surgery. The percentage of excess BMI loss (%EBMI loss) was similar in both groups during the 5-year follow-up. Complications after RYGB and nutritional deficiencies were nearly identical in the two groups. The interval of time between bariatric surgery and first pregnancy was a median of 20.8months. Out of 40 first pregnancies, 28 women completed pregnancy successfully with live birth. Pregnancy after bariatric surgery is safe and does not adversely affect outcomes after RYGB.