Weight-loss Surgery May Increase Risk of Giving Birth Prematurely

Weight-loss surgery may put women at increased risk of giving birth prematurely, a new study published in the British Medical Journal found.

Led by researchers from the Karolinska Institutet, the report compared more than 2,500 babies born between 1992-2003 to women who had previously undergone weight-loss surgery, to 12,500 babies born to women who had not.

After controlling for variables such as the mother's age, BMI, previous births and educational background, the scientists found that a little more than 5 percent of those born to mothers with a history of weight-loss surgery were small for their gestational age, compared to 3 percent in the control group.

Furthermore, roughly 4 percent were larger than average for their gestational age, compared to some 7 percent in the control group. Finally, nearly 10 percent were born before the 37th week, compared to roughly 6 percent of the control group. No difference, however, was identified between the two groups in terms of stillbirths or neonatal death.

"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," Dr. Olof Stephansson, obstetrician and associate professor at the Clinical Epidemiology Unit at Karolinska Institutet, said in a statement. "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."

Based on the results, the researchers argue that women who have undergone weight-loss surgery should be considered a risk group during pregnancy. They also note that weight-loss surgery offers a wide variety of benefits for mothers, including lowering the risk of diabetes, cardiovascular and stroke.

"Furthermore, untreated obesity," officials from the Karolinksa Institutet added, "is a known risk factor for both mother and baby during pregnancy."