The question of why most studies find birth defects more common among IVF-conceived babies remains to be answered.
"I think that it is very complex reasons that we don't fully understand yet," said Dr. Charlotte Hobbs, director of the Arkansas Center for Birth Defects Research and Prevention and a professor at the University of Arkansas for Medical Sciences, who did not participate in the review.
It's possible that the same reasons people have trouble conceiving and seek out fertility treatment could influence their increased risk of having a baby with a birth defect.