Pregnant Women Who Underwent Weight Loss Surgery Tend to Have Premature Babies

Children of women who have previously undergone weight loss surgery, such as biatric surgery, should be treated as high-risk pregnancies as children are more likely to be born premature and small in size for their gestational age.

Researchers from the Karolinska Institutet in Sweden say their findings show that pregnancies for women who have undergone weight loss (bariatric) surgery should be treated as high-risk pregnancies and that these women should receive more attentive prenatal care. The study is published online in BMJ. 

For their study, the investigators analyzed 2,500 babies who were born between 1992 and 2009. All of these infants were born to women who had undergone bariatric surgery. These were compared with 12,500 babies of mothers who had not had bariatric surgery.

The researchers warned that pregnancies of moms who had undergone biatric surgery should be considered risk pregnancies and that prenatal care should monitor them extra carefully.

The study is relevant as the number of bariatric operations has considerably increased in recent years. Most of these operations are performed on women, and as a result the number of babies born to women with a history of bariatric surgery is also increasing. The study, which is the most extensive ever done in the field, was based on data from the Swedish Medical Birth Register and the Patient Register.

"Mothers with the same BMI gave birth to babies of varying weights depending on whether or not they had undergone bariatric surgery, so there is some kind of association between the two," says Dr Olof Stephansson, obstetrician and Associate Professor at the Clinical Epidemiology Unit at Karolinska Institutet. "The mechanism behind how surgery influences fetal growth we don't yet know, but we do know that people who have bariatric surgery are at increased risk of micronutrient deficiencies."

On the flip side, there are numerous benefits for mothers who undergo biatric surgery, such as lowering the risk of diabetes, cardiovascular disease, cancer and stroke. Furthermore, untreated obesity is a known risk factor for both mother and baby during pregnancy and childbirth.