Risks and Benefits of Weight Loss Surgery Before Pregnancy

Pregnancy after bariatric surgery was tied to reduced risk of gestational diabetes and raised risk of underweight babies

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) Pregnancy is an exciting time, but many women have a few anxious moments. Women who have had weight loss surgery may have more anxious moments than others. Some of those moments, however, may not be warranted.

A new study from Sweden found that while there were some risks involved with bariatric surgery, there were also benefits for both mother and child. Researchers from the Karolinska Institutet in Solna found that women who became pregnant after weight loss surgery were less likely to have gestational diabetes or to have extra large babies.

On the down side, these women were more likely to deliver early and to have babies who were smaller than average. The authors of this study said women who become pregnant after bariatric surgery should be carefully monitored.

"Since bariatric surgery followed by pregnancy has both positive and negative effects, these women, when expecting, should be regarded as risk pregnancies," said lead study author Kari Johansson, PhD, in a press release. "They ought to be given special care from the maternal health services, such as extra ultrasound scans to monitor fetal growth, detailed dietary advice that includes checking the intake of the necessary post-surgery supplements."

Bariatric surgery is performed on people who are severely obese but have been unable to lose weight by other means. There are several different types of weight loss surgery. All decrease the size of the stomach and/or limit the ability of the intestines to absorb nutrients.

In this study, 98 percent of the women had a procedure called a gastric bypass.

Dr. Johansson and colleagues collected data on nearly 600 pregnancies that occurred after women had weight loss surgery between 2006 and 2011.

They compared these pregnancies to a second group of nearly 2,400 pregnancies in women who had not had the surgery (called a control group).

The second group had the same body mass index (BMI) as the women in the first group before surgery. BMI is a height- and weight-based measure of body fat.

Dr. Johansson and team found that only 2 percent of the women who had had bariatric surgery developed gestational diabetes. Seven percent of the women in the control group developed gestational diabetes.

Gestational diabetes is diabetes that only occurs during pregnancy and results in high blood sugar for the mother.

Nine percent of women who had surgery had babies who were much larger for their age. Twenty-two percent of women in the control group had large babies.

However, the women who had surgery were twice as likely as the control group to have babies who were small for their age. Women who had surgery were also more likely to have slightly shorter pregnancies.

Dr. Johansson and team cautioned that their results could only be applied to whites and that women who have other types of bariatric surgery may have different outcomes.

Andre F. Hall, MD, a board-certified OB-GYN, told dailyRX News that women who have had weight loss surgery are often told to not become pregnant for between a year and a year and a half.

"This is during the time of greatest weight loss and also during the time when the nutritional challenges are the greatest," Dr. Hall said. "Once this timeframe has elapsed and the weight-loss has stabilized, management of these patients is similar to other patients. The one noted caveat however is that the overall nutritional status must be monitored closely as women who have had bariatric surgery often have altered absorption of nutrients to include vitamins and minerals. Poor nutritional status in mothers can lead to poor nutritional status in developing fetuses and lead to developmental problems ..."

This study was published Feb. 25 in the New England Journal of Medicine.

The Swedish Research Council, the Obesity Society, the Karolinska Institutet and the Stockholm County Council funded this research. Co-author Dr. Neovius received consulting fees from Itrim and Strategic Health Resources.

Review Date: 
February 27, 2015
Last Updated:
March 3, 2015