Researchers from the University of Iowa and University of Minnesota found that babies of overweight or obese mothers gained 11 ounces less than those born to normal-weight mothers from two weeks to three months.
They also put on 0.3 ounces less fat mass and grew nearly a half-inch less.
"We've found these children are not growing normally," Katie Larson Ode, assistant clinical professor in pediatric endocrinology and diabetes at the University, said.
The researchers believe there are two reasons why babies of overweight or obese women lag initially in their physical development.
The first deals with inflammation, fat cells that normally help suppress a person's immune system flare up when an adult is overweight, studies have shown.
This state of warfare being waged in an overweight or obese pregnant mother's immune system may also inflame the fetus's developing immune system, diverting energy that otherwise would go to the baby's development.
"These (fat tissue-derived) hormones and inflammatory factors tend to have appetite regulating effects early on, and may exert their negative effects on growth both during gestation and through passage into the breast milk during postnatal development as well," Ellen Demerath, Larson Ode's advisor at Minnesota and senior author on the paper said.
The second cause has to do with how babies grow in the womb. One is through free fatty acids delivered by the mother via a growth hormone called IGF-1. The other is through a growth hormone secreted by the pituitary gland in the baby's brain.
The researchers believe the cosseted baby gets so many free fatty acid-derived growth hormones from its overweight mother that the other growth generator