FRIDAY, Aug. 10, 2012 (HealthDay News) -- Babies with overweight or obese mothers appear to gain less weight and grow more slowly during the first three months of life than babies born to normal-weight women, according to a new study.
Researchers from the University of Iowa and their colleagues also found these infants gained less fat mass, which is critical for proper brain growth and development.
"We've found these children are not growing normally," said Katie Larson Ode, an assistant clinical professor in pediatric endocrinology and diabetes at the University of Iowa, in a university news release. "If what we have found is true, it implies that the obesity epidemic is harming children while they are still in utero and increases the importance of addressing the risk of obesity before females enter the child-bearing years, where the negative effects can affect the next generation."
The study, recently published in the Journal of Pediatrics, included nearly 100 mothers. Of this group, 38 were overweight or obese. The researchers noted none of the women had diabetes.
The study found babies of overweight or obese mothers gained 11 fewer ounces than those born to normal-weight mothers from the time they were 2 weeks old until they were 3 months old. These babies also gained 0.3 fewer ounces in fat mass and grew nearly half an inch less than infants born to normal-weight mothers.
Although infants born to overweight or obese mothers are slower growers initially, they are at greater risk for rapid weight gain as teenagers and becoming overweight themselves, the study's authors noted.
"A message from this study is, 'Don't panic,'" Larson Ode said. "Pediatricians see a lack of (initial) growth, and they assume the child is not getting enough nutrition. But we believe the baby is in fact getting plenty."
The researchers suggested this slowed growth has to do with inflammation. Fat cells flare up when an adult is overweight, they explained. As a result, the immune systems of overweight pregnant women could inflame their unborn baby's developing immune system as well. That may means energy the babies need for development is being used elsewhere.
"These (fat tissue-derived) hormones and inflammatory factors tend to have appetite/satiety 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," noted study senior author Ellen Demerath, who was Larson Ode's university advisor, in the news release.
Moreover, the researchers said overweight or obese pregnant women could be inundating their babies with free fatty acids while in the womb. This, in turn, could slow growth hormone production in the pituitary gland in their brains. After birth, the baby's pituitary gland is not able to produce enough growth hormone on its own.
"It's just not mature yet," Larson Ode explained.
The researchers said their findings need confirmation in a larger study.
According to a 2010 study published in the Journal of the American Medical Association, 60 percent of U.S. women of childbearing age are overweight or obese.
The U.S. National Institutes of Health provides more information on obesity.