For many years, obstetricians have urged obese women to lose weight prior to becoming pregnant because of the increased risk of reproductive complications in the setting of obesity (Table 9.1) [1, 2].

Because of lack of success with conventional weight loss programs, many women of childbearing age are currently seeking bariatric surgery as a means of achieving major weight loss and safer pregnancies. At present, nearly 80 % of bariatric surgery patients are females, with a large majority in the reproductive age group. The increasing popularity of bariatric surgery among obese women introduces additional responsibility for bariatric surgery programs to provide information and guidance in the area of fertility, pregnancy, contraception, nutrition, and mental preparedness for pregnancy after bariatric surgery. Although the risks of many reproductive complications of obesity like gestational weight gain and hypertensive disorders of pregnancy are reduced by surgical weight loss [1, 3], bariatric surgery does introduce other important risks, which will be discussed in this chapter.

Obesity is a well-known cause of infertility because of hyperandrogenism and polycystic ovarian syndrome resulting in irregular menses, anovulatory cycles, and amenorrhea. Weight loss is recommended for obese women who desire pregnancy in order to correct ovarian dysfunction and restore fertility. Candidates for bariatric surgery must be advised that menstrual cycles are likely to improve promptly during weight loss with normalization of fertility [4]. This fertility rebound during weight loss may result in surprise and unwanted pregnancies, which may introduce additional stressors during a difficult period for patients after bariatric surgery. In order to avoid these difficulties during the period of rapid weight loss, female candidates for bariatric surgery should consider the use of contraception for 1 year after bariatric surgery [5].

Although there is controversy about how long to postpone pregnancy after bariatric surgery, most agree that the period of rapid weight loss is an inopportune time for a pregnancy and may increase the risk of nutritional complications for the fetus. Bariatric surgery patients need to understand that pregnancy is a period of increased nutritional requirements for many of the micronutrients discussed in the previous chapters, and that the period of rapid weight loss is usually a period of negative body balance for many of these important micronutrients because of reduced food intake and altered absorption. Although there are scattered reports of successful and uncomplicated pregnancies during the first year after bariatric surgery [6, 7], most agree that the recommended interval should be 1 year, which encompasses the period of rapid weight loss for most patients [8, 9].

Recommendations for maternal weight gain during pregnancy have been established by the Institute of Medicine. For normal weight individuals (BMI 18.5–24.9 kg/m²), recommended weight gain with pregnancy is 11.5–16 kg, and for overweight individuals (BMI 25–29.9 kg/m²), it is 7–11.5 kg [10]. Adequate weight gain during pregnancy is felt to be essential for a healthy intrauterine environment and for promotion of normal fetal growth. There are many controlled and retrospective cohort studies which show that gestational weight gain is less in patients after bariatric surgery [11–15], and that weight gain is greater when pregnancy occurs ≥18 months after bariatric surgery [16]. Gastric band patients may have an advantage, because frequent band adjustments during pregnancy may allow optimization of dietary intake during pregnancy [14]. The studies comparing maternal weight gain after bariatric surgery with either community or obese controls have not demonstrated clinically relevant neonatal complications associated with less maternal weight gain. The clinical significance of maternal weight gain in the patient with extreme obesity who is losing weight after bariatric surgery remains to be proven because of the potentially offsetting favorable effects of patient education, judicious nutritional supplementation, and focused high-risk obstetrical care [17].

Nutritional deficiencies are a major cause for concern for women who become pregnant after bariatric surgery, because mild nutritional deficiencies are common, especially during rapid weight loss. Factors that contribute to nutritional deficiencies during pregnancy following bariatric surgery are summarized in Table 9.2.

Nutritional abnormalities can potentially affect the intrauterine environment, which influences fetal development and possibly future health. The influence of nutrition on these processes is poorly understood. The concern for micronutrient deficiencies stems from the growing number of case reports demonstrating significant maternal nutritional deficiencies during pregnancy and associated adverse neonatal outcomes (Table 9.3) [1, 2, 18–26].

Unfortunately, few prospective studies address this issue, and the prevalence of adverse neonatal outcomes related to maternal nutritional deficiency is unknown. The retrospective cohort studies that involve small patient numbers suggest that the prevalence is small and may be related to poor nutritional follow-up and/or poor patient compliance. The few more systematic studies suggest that close nutritional follow-up and aggressive supplementation can improve nutrition and lessen the risk of adverse outcome [22, 23], but more prospective longitudinal nutritional studies of pregnant post-bariatric surgery patients are needed.

Another cause for concern in the management of pregnancy in patients following bariatric surgery is the potential for the development of maternal gastrointestinal complications related to the bariatric procedure during pregnancy. The sudden onset of acute gastrointestinal symptoms (abdominal pain, nausea, and vomiting) is always a concern for the patient after bariatric surgery. The development of acute gastrointestinal disease in a pregnant patient should be considered a surgical emergency and mandates the involvement of the bariatric surgeon in the management. Failure to promptly treat or inappropriate conservative treatment invites additional risk both to the mother and fetus.