Pregnancy Outcomes after Weight Loss Surgery

In the last 30 years, the number of adults with obesity, defined as a body mass index of 30 or higher has increased in the United States. For individuals with a BMI greater than or equal to 25 who become pregnant, there is an increased risk for a number of complications, including preeclampsia, gestational diabetes or the need for a Cesarean delivery all of which may put the baby's health at risk.

People have increasingly turned to bariatric surgery to lose weight, with 40 percent of the surgeries being performed on individuals who are of childbearing age, and an estimated 30 percent planning to become pregnant. Although many complications related to obesity can resolve following weight loss surgery, there is an increased risk for nutritional deficiencies, which can influence the outcome of a healthy pregnancy.

Screening for micronutrient deficiencies is highly recommended for individuals who become pregnant after bariatric surgery and for all patients, monitoring is recommended 3 to 4 months following the procedure and once a year after that. Although dosing strategies for supplementation exist, depending on the bariatric procedure and its risk of malabsorption, the research to support a definitive nutrient supplementation regimen during pregnancy is currently lacking. The timing of conception after weight loss surgery is also an important consideration. Waiting to become pregnant for 12 to 24 months or longer following weight loss surgery has been recommended by the American College of Obstetricians and Gynecologists in order to reduce the risk of adverse outcomes.

In 2019, the Academy's Evidence Analysis Center published a systematic review to evaluate the effect of bariatric surgery on both maternal and infant health outcomes of pregnancy. The findings did not reflect an influence on total gestational weight gain. However, factors that could affect this outcome include the type of weight loss procedure and the time from surgery to conception and/or delivery. Inconsistent findings were reported regarding the incidence of gestational diabetes and pre-eclampsia, but no effect was found on the risk of miscarriage or preterm birth.

Babies born to individuals who had undergone bariatric surgery tended to weigh less at birth (but did not meet the criteria of low birth weight) when compared to babies born to individuals with similar BMIs and no history of surgery. Although it was noted that the risk of small-for-gestational-age may be increased in pregnancies following bariatric surgery.

To help minimize the risk of pregnancy-related complications that may occur following weight-loss surgery, individualized medical nutrition therapy goals should be established to meet the patient's unique needs. The Academy of Nutrition and Dietetics Pocket Guide to Bariatric Surgery, 3rd ed. includes the following nutrition therapy goals for pregnancy after weight-loss surgery:

• Adequate gestational weight gain to promote fetal growth
• Vitamin and mineral supplementation to correct or prevent deficiencies
• Education on nutrition and hydration during pregnancy and lactation and post bariatric surgery issues that affect pregnancy

It is also recommended that risks associated with pregnancy be discussed with individuals of childbearing age who are considering weight loss surgery. And for individuals who are currently pregnant following a bariatric procedure, close monitoring by a multidisciplinary team, which includes a registered dietitian nutritionist with expertise in obstetrics and bariatric surgery, is needed.

References:

• Gadgil MD, Chang HY, Richards TM, Gudzune KA, Huizinga MM, Clark JM, Bennett WL. Laboratory Testing for and Diagnosis of Nutritional Deficiencies in Pregnancy Before and After Bariatric Surgery. J Womens Health. 2014; 23(2):129-137.
• Al-Nimr RI, Hakeem R, Moreschi JM, Gallo S, McDermid JM, Pari-Keener M, Stahnke B, Papoutsakis C, Handu D, Cheng FW. Effects of Bariatric Surgery on Maternal and Infant Outcomes of Pregnancy-An Evidence Analysis Center Systematic Review. J Acad Nutr Diet. 2019;119(11):1921-1943.
• Academy of Nutrition and Dietetics' Weight Management Practice Group. Academy of Nutrition and Dietetics Pocket Guide to Bariatric Surgery. 3rd ed. Academy of Nutrition and Dietetics, 2022