Women who undergo weight-loss surgery, known as bariatric surgery, and later become pregnant after losing weight may be at lower risk for pregnancy-related diabetes and high blood pressure—complications that can seriously affect the mother or her baby—than pregnant women who are obese. The findings are part of an evidence review that was led by Melinda A. Maggard, M.D., M.S.H.S., of the University of California at Los Angeles, and the RAND Corporation in Santa Monica, California, and performed by the Agency for Healthcare Research and Quality's (AHRQ) Southern California Evidence-based Practice Center at RAND (contract no. 290-02-0003).
The review was based on findings from 75 studies, including 3 that compared pregnancies of nonobese women with those of obese women as well as with pregnancies of women who lost weight surgically. In one study of laparoscopic gastric banding, a type of bariatric surgery, the authors found that none of the women who underwent surgery developed gestational diabetes or high blood pressure during their pregnancies. By comparison, 22 percent of obese pregnant women developed diabetes and 3 percent developed high blood pressure in the same study. Thirteen other studies supported these findings. Neonatal outcomes, like preterm delivery, low birth weight, and high birth weight, were also likely to be better in pregnancies of women following bariatric surgery than in pregnancies of obese women.
The evidence report also found that:
- Nutritional problems during pregnancy following two types of bariatric surgeries, gastric bypass and laparoscopic gastric band procedures, appear to be uncommon and may result from not following instructions for taking supplements. Nutritional problems appear to be more frequent and severe in mothers who undergo another bariatric surgical procedure, biliopancreatic diversion surgery.
- There is not enough evidence to determine if having bariatric surgery affects the likelihood of needing a cesarean section to give birth.
- There is some evidence to guide a woman's decision as to how long she should wait after having bariatric surgery to become pregnant. The typical recommended time period is 1 year, which usually coincides with the period of most rapid weight loss.
- The effects of bariatric surgery on a woman's fertility have not been well studied. Studies including a small number of patients report possible improvement in the ability to conceive and deliver a child following bariatric surgery.
These results, along with reports of normalization of sex hormones and menstrual irregularities, as well as improvement in polycystic ovary syndrome—a health problem that can affect a woman's ability to have children—following surgery suggest that fertility may improve. Some pregnancy-related complications are minimized for women who have had weight-loss surgery. Adverse events following bariatric surgery are probably uncommon; their true incidence is not known and case reports tend to be the main source to date capturing such events. Bowel obstruction, which is most commonly due to internal hernia, is the more frequently reported surgical complication in pregnant women following bariatric surgery procedures. Deaths of mothers and fetuses have been reported in some of these cases. Of note, bowel obstruction also occurs in bariatric surgery patients who do not become pregnant.
Details are in "Pregnancy and fertility following bariatric surgery: A systematic review," by Dr. Maggard, Irina Yermilov, M.D., M.P.H., Zhaoping Li, M.D., Ph.D., and others, in the November 19, 2008 JAMA, 300(19), pp. 2286-2296.
The evidence report, Bariatric Surgery in Women of Reproductive Age: Special Concerns for Pregnancy, AHRQ Publication No. 08-E013, is available online at https://www.ahrq.gov/clinic/tp/barireptp.htm.�Printed copies of the report are also available from the AHRQ Publications Clearinghouse.