Overweight and obese women who gain too few pounds, or even lose weight, during pregnancy may be putting their unborn child at risk, a new study suggests.
"While many people recommend that weight loss in pregnancy, particularly for very obese women is ok . . . (there) may be adverse effects," said Dr. Patrick Catalano, director of the Center for Reproductive Health at MetroHealth in Cleveland, Ohio.
"We don't have much data, in particular on body composition changes in overweight (or) obese women who lose weight," said Catalano, who led the new study. "Maybe we need to be a little bit more careful before we are just glib about saying it's ok."
Research has offered evidence of many risks posed by obesity to mother and fetus during pregnancy, up to and beyond the point of delivery.
Obese mothers are at raised risk of early spontaneous abortion and fetal birth defects. Later on, there is a higher chance of gestational diabetes and preeclampsia. At delivery, obese mothers are more likely to need a cesarean-section and to have postpartum wound infections.
The newborns of obese mothers are at risk of being overly large for their gestational age and that has been tied to childhood obesity.
The U.S. Institute of Medicine (IOM) issued guidelines in 2009 recommending that obese women gain between 5 and 9 kilograms (11 to 20 pounds) during pregnancy, which is somewhat less than the gain recommended for women who start pregnancy at a normal weight.
However, some researchers have suggested that for obese women, little to no weight gain, and even weight loss, is preferable during pregnancy to minimize the risks associated with obesity.
The American Congress of Obstetricians and Gynecologists recommends that individualized care be given to overweight or obese women who wish to gain less weight than recommended by the IOM.
Yet, little is known about the fetal health risks associated with weight loss or limited weight gain by overweight or obese women during pregnancy.
To investigate, Catalano, who was involved in developing the 2009 IOM guidelines, and his co-authors examined the effects of any weight loss or a weight gain of less than IOM's minimum 5 kg (11lbs).
They looked at 1,241 full-term singleton pregnancies among overweight and obese women.
Most (85 percent) of the women gained more than the IOM's minimum 5 kg during pregnancy, averaging a gain of 14.4 kg (32 lbs).
In contrast, 15 percent of the study participants had weight gains below IOM's minimum, averaging