From BMJ 30 Nov 19
A retrospective analysis from Quebec of 2 million pregnant women who had delivered between 1989 and 2016 showed that offspring of women who had become pregnant after bariatric surgery had roughly twice the risk of birth defects compared to women who were not obese or who were obese but had not had surgery.
The defects were mainly heart and musculoskeletal defects.
My comment: This short report does not go into possible causes for this. You would have thought that the risk would have been reduced to the level of the non obese women. I wonder if nutritional issues have a part to play as after bariatric surgery long term vitamin supplements need to be taken.