Background: After many cycles of weight loss and weight gain, more and more morbidly obese patients undergo bariatric surgery, like gastric banding or gastric bypass, as the ultimate treatment for their obesity-problem. Since women of reproductive age are candidates for bariatric surgery, concerns arise regarding the potential impact on future pregnancy.

Methods: English-language articles were identified in a PUBMED search from 1982 to January 2008 using the keywords for pregnancy and bariatric surgery or gastric bypass or gastric banding.

Results: The few reported case-control and cohort studies clearly show improved fertility and a reduced risk in obstetrical complications, including gestational diabetes, macrosomia and hypertensive disorders of pregnancy, in women after operatively induced weight loss when compared with morbidly obesity women. The incidence of intrauterine growth restriction (IUGR) appears to be increased, however. No conclusions can be drawn concerning the risk for preterm labour and miscarriage, although these risks are probably increased compared with controls matched for body mass index. Operative complications are not uncommon with bariatric surgery and several cases have pointed to the increased risk for intestinal hernias and nutritional deficiencies in subsequent pregnancy. Deficiencies in iron, vitamin A, vitamin B(12), vitamin K, folate and calcium can result in both maternal complications, such as severe anaemia, and fetal complications, such as congenital abnormalities, IUGR and failure to thrive.

Conclusions: Close supervision before, during and after pregnancy following bariatric surgery and nutrient supplementation adapted to the patient's individual requirements can help to prevent nutrition-related complications and improve maternal and fetal health, in this high-risk obstetric population.