We read the study by Sheiner et al with great interest and commend them for confirming the absence of adverse effects of early pregnancy after maternal bariatric surgery. The article, however, fails to mention some limitations.

Gastric restrictive (eg, banding) and diversionary (bypass) bariatric operations fundamentally differ in their effects on satiety, digestion, absorption, and neuroendocrine function. They also have specific patterns of weight loss and postoperative side effects and complications, with divergent consequences for maternal-fetal health.

The authors generalize their conclusions to early pregnancy after any bariatric surgery, yet their case series, which is comprised almost exclusively of restrictive procedures (88%), is not powered to analyze early pregnancy outcomes after diversionary operations. The early pregnancy group comprised only 4 patients among 58 patients with gastric bypass, which renders stratification meaningless. Several other articles have clearly demonstrated the safety of early pregnancy after diversionary operations, such as gastric bypass, and the malabsorptive, more complex biliopancreatic bypass.

There is mounting evidence that maternal surgical weight loss before pregnancy is not only safe but also may be beneficial to both mother and child. Initial caution in reproductive-aged women who underwent obesity surgery was based on the speculation that undernutrition and intrauterine growth restriction might follow. However, pregestational weight loss and abrogation of excess gestational weight gain improve obstetric outcomes and normalize birthweights by ameliorating maternal glucose and lipid metabolism and hormonal function. This optimization of intrauterine milieu after maternal biliopancreatic bypass has been shown to modify growth and body composition through childhood, with improved glucose metabolism and decreased incidence of obesity later in adolescence and young adulthood.

Bariatric surgery has primary preventive capacity; we agree that anxiety over adverse pregnancy outcomes during the first year after bariatric surgery is unwarranted in well-managed pregnancies in which vitamin and mineral supplementation has been monitored. Given substantial evidence for the vertical transmission of obesity and metabolic disease risk, it is important to emphasize additional potential benefits of obesity surgery. Obstetricians and other primary care specialists should be aware of the opportunity that surgical weight loss presents for effective primary prevention of chronic disease.