CONTEXT: The use of bariatric surgery for treating severe obesity has increased dramatically over the past 10 years; about half of patients who undergo these procedures are women of reproductive age. This report was commissioned to measure the incidence of bariatric surgery in this population and review the evidence on the impact of bariatric surgery on fertility and subsequent pregnancy. OBJECTIVES: To measure the incidence of contemporary bariatric surgery procedures in women age 18-45 and to assess its impact on fertility, contraception, prepregnancy risk factors, and pregnancy outcomes, including those of neonates. DATA SOURCES AND STUDY SELECTION: Nationwide Inpatient Sample (NIS), a national sample of over 1,000 hospitals, to measure the trend in the number of women of reproductive age who underwent bariatric procedures from 1998-2005. We searched numerous electronic databases, including MEDLINE and Embase, for potentially relevant studies involving bariatric surgery (gastric bypass, laparoscopic adjustable gastric band, vertical-banded gastroplasty, biliopancreatic diversion), and consequent fertility, contraception, pregnancy, weight management, maternal and neonatal outcomes, and nutritional deficiencies. We scanned reference lists for additional relevant articles and contacted experts in the fields of bariatric surgery and obstetrics/gynecology (OB/GYN). Of 223 screened articles, we accepted 57 that reported on fertility following surgery (19 articles), contraception use/recommendations (11), maternal weight or nutrition management (28), maternal outcomes including morbidity and mortality (48), cesarean-section rates (16), and neonatal outcomes (44). These articles included reports on gastric bypass, both open and laparoscopic (27 articles), laparoscopic adjustable band (15), biliopancreatic diversion (16), and vertical-banded gastroplasty (6). Studies could contribute to one or more analyses. We found one case-control study and the observational data accepted included 12 cohort studies, 21 case series, and 23 individual case reports. DATA EXTRACTION: We abstracted information about study design, fertility history, fertility outcomes, prepregnancy weight loss, nutritional management, outcomes following pregnancy, and adverse events (during pregnancy) related to surgery. DATA SYNTHESIS: Nationally representative data showed a six-fold increase in bariatric surgery inpatient procedures from 1998 to 2005. Women age 18-45 accounted for about half of the patients undergoing bariatric surgery; over 50,000 have these procedures as inpatients annually. An unknown number have outpatient bariatric procedures. We identified one case-control study that directly addressed some of the key questions, but no randomized controlled trials or prospective cohort studies, which would be the strongest study designs to answer questions about effectiveness, risk and prognosis. Consequently, all of our conclusions are limited by the available data, and are cautious.The evidence suggests that bariatric surgery results in improved fertility; the strongest evidence is in women with the polycystic ovarian syndrome, where biochemical studies showing normalization of hormones after surgery support case series data. Observational studies (retrospective cohorts and case series) suggest that fertility improves following bariatric procedures and weight loss; similar to that seen when obese women lose weight through nonsurgical means. There is almost no evidence on post-surgical contraceptive efficacy or use. Research is needed to determine whether differences in absorption, particularly for oral contraceptives, affect contraceptive efficacy. Nutrient deficiencies were reported in infants born to women who underwent procedures that resulted in malabsorption, as well as women who did not take prenatal vitamins or had difficulty with their own nutrition (i.e., from chronic vomiting). Literature suggests that gastric bypass and laparoscopic adjustable band procedures confer only minimal, if any, increased risk of nutritional or congenital problems if supplemental vitamins are taken and maternal nutrition is otherwise adequate. Biliopancreatic diversion has an appreciable risk for nutritional problems in some patients. Women who have undergone bariatric surgery may have less risk than obese women for certain pregnancy complications such as gestational diabetes, preeclampsia, and pregnancy induced hypertension. There is no evidence that cesarean section rates and delivery complications are higher in the post-surgery group, but data are limited. CONCLUSIONS: Weight loss procedures are being performed more frequently to treat morbid obesity, with a six-fold increase over a recent 7-year time span; almost half of all patients are women of reproductive age. The level of evidence on fertility, contraception, and pregnancy outcomes is limited to observational studies. Data suggest that fertility improves after bariatric surgical procedures, nutritional deficiencies for mother and child are minimal, and maternal and neonatal outcomes are acceptable with laparoscopic adjustable band and gastric bypass as long as adequate maternal nutrition and vitamin supplementation are maintained. There is no evidence that delivery complications are higher in post-surgery pregnancies.