Women who undergo weight loss surgery (or bariatric surgery) before becoming pregnant have a lower chance of developing gestational diabetes and giving birth to large babies, according to a recent study. On the other hand, these women are at risk for giving birth to small babies, researchers reported in the February 26 issue of the New England Journal of Medicine.
“Since bariatric surgery followed by pregnancy has both positive and negative effects, these women, when expecting, should be regarded as high risk pregnancies,” said Kari Johansson, PhD, a nutritionist in the Department of Medicine, Solna, Karolinska Institutet, Stockholm, Sweden. Dr. Johansson said that these women should be closely followed during pregnancy and given advice on healthy eating, and taking supplements if necessary.
Women with obesity are at risk for a number of complications during pregnancy, including having high blood sugar (gestational diabetes), babies born prematurely (more than 3 weeks before their due date), stillbirth (death of a baby during pregnancy), problems during delivery, and development of obesity in their children. Thus, the researchers wanted to study whether weight loss surgery had any effect on these risks.
“The effects of bariatric surgery on health outcomes such as diabetes and cardiovascular [heart] disease have been studied, but less is known about the effects on pregnancy and perinatal [the time during or around birth] outcomes,” said Dr. Johansson.
Using data from nationwide Swedish health registries, the researchers found 596 pregnancies in women who had given birth after bariatric surgery between 2006 and 2011. These pregnancies were then compared with 2,356 pregnancies in women with obesity who did not have bariatric surgery, but had the same body mass index (BMI, weight divided by height squared) as the first group before surgery.
Weight Loss Surgery Linked to Lower Risk for Gestational Diabetes
Women who underwent bariatric surgery had a markedly lower risk of gestational diabetes (1.9% vs. 6.8%) or giving birth to large babies (8.6% vs. 22.4%) compared with women who did not have bariatric surgery. In contrast, women who underwent bariatric surgery were more than twice as likely to give birth to small babies (15.6% vs. 7.6%). While the risk of babies born prematurely was similar among the 2 groups, women in the bariatric surgery group were more likely to have shorter pregnancies.
Similar Results Found in Second Study
Similar findings were reported in a recent study in the March issue of the International Journal of Gynaecology and Obstetrics. The study was a meta-analysis, which is a summary of all published studies on the topic of weight loss surgery and pregnancy. The findings showed that women who had weight loss surgery were at lower risk for gestational diabetes, high blood pressure, and giving birth to large babies. On the other hand, women who had weight loss surgery had a higher risk of giving birth to small babies, compared to women with obesity who did not have bariatric surgery.
“We think bariatric surgery is beneficial to women with morbid obesity,” said lead author of the study Zhi-hong Wang, MD, PhD, who is an endocrinologist at First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
Dr. Wang added that women with obesity who are thinking about weight loss surgery before pregnancy should have a full understanding of the pros and cons of each type of surgery. In addition, she recommended that doctors closely follow the baby’s weight during pregnancy, and that mothers meet with nutritionists during and after pregnancy.
Johansson K, Cnattingius S, Näslund I, et al. Outcomes of pregnancy after bariatric surgery. N Engl J Med. 2015;372(9):814-824.
Yi XY, Li QF, Zhang J, Wang ZH. A meta-analysis of maternal and fetal outcomes of pregnancy after bariatric surgery. Int J Gynaecol Obstet. 2015 Mar 25. pii: S0020-7292(15)00149-6. doi: 10.1016/j.ijgo.2015.01.011. [Epub ahead of print]