Women who gain too much weight during pregnancy face increased risk of complications including birth defects, problems during labor and delivery, fetal deaths, and large infants. A study in the American Journal of Obstetrics and Gynecology observed over 1,000 pairs of mothers and three year olds and compared weight gain in the mother with the BMI of their child.
The study found that women who gained excessive or "adequate" weight during pregnancy were four times more likely to have a child who was overweight by the age of three compared to women with inadequate weight gain. According to Raul Artal of St. Louis University School of Medicine, "The reality is for too long we are telling pregnant women to take it easy during pregnancy, be confined and to eat for two."
Experts believe that this has been a factor in the obesity epidemic that is spreading through the U.S. Although more research is needed, most experts recommend that women follow the current IOM guidelines until new ones are announced.