Weight-loss surgery before pregnancy may lower obese women's odds of having a baby with major birth defects, new research suggests.
For the study, the researchers examined data on more than 33,000 births in Sweden between 2007 and 2014.
Of these, nearly 3,000 children were born to mothers who had a type of weight-loss surgery called gastric bypass before getting pregnant. The rest were born to women who weighed about the same as the others did before weight-loss surgery -- more than 260 pounds.
Women in the surgery group lost an average 88 pounds and weighed about 181 pounds at their first prenatal checkup. In addition, their use of diabetes medications fell from 9.7% to 1.5%.
The risk of major birth defects was about 30% lower in children whose mothers had weight-loss surgery than in those of the obese mothers, the findings showed.
The risk of major birth defects was 3.4% in children born to women who had gastric bypass surgery -- similar to the 3.5% rate among those born to normal-weight women, the researchers reported.
The risk of major birth defects was 4.9% in children born to the women who were still obese, according to the study published Oct. 15 in the Journal of the American Medical Association.
The findings challenge long-held concerns that weight-loss surgery could increase the odds of major birth defects, according to the researchers.
"This study shows that weight-loss and improved blood sugar control in the mother can actually result in a lower risk of birth defects in the child," said study author Martin Neovius, a professor of medicine at Karolinska Institute in Solna, Sweden.
"It should help reduce fears that bariatric [weight-loss] surgery increases the risk of birth defects in the event of future pregnancy, assuming that surgery patients take their recommended nutritional supplements," he said in a university news release.
The American College of Obstetricians and Gynecologists has more on obesity and pregnancy.