CHICAGO — Rapid weight gain during the first six months of infancy appears to increase the chances that a child will be obese by age 3, according to a new study in the April issue of the journal Pediatrics.
The study found that sudden weight gain in early infancy was more significant than the baby's weight at birth, the parents' weight or the number of pounds put on by the mother during pregnancy.
"The perception has been that a chubby baby and a baby that grows fast early in life is healthier and all the baby fat will disappear," said the paper's lead author, Dr. Elsie Taveras, an assistant professor in Harvard Medical School's ambulatory care and prevention department. "But [that] is not the case."
Taveras was quick to point out, however, that parents should not put their chunky babies on diets.
"More work needs to be done to determine why rapid weight gain in infancy occurs before we can develop policy, clinical protocols and interventions," said Taveras, who is also co-director of the One Step Ahead clinic, a pediatric overweight prevention program at Children's Hospital Boston.
Health professionals have been struggling to understand why the nation's children are ballooning, as childhood obesity has been linked to a host of chronic diseases later in life.
Other studies have looked at the link between obesity and birth weight, but the Pediatrics study was the first to look at rates of weight gain in relation to body length during infancy.
The study involved 559 mother-child pairs living in the Boston area. Researchers used measures of weight and length together -- referred to as weight-for-length -- because the combination gives a better picture of a child's body fat composition than weight alone, much in the same way that body mass index is used as a measure of adult body fat.
The link between rapid infant weight gain and obesity by age 3 was striking, even after adjusting for factors such as premature birth. An infant weighing 18.4 pounds after six months had a 40% greater risk of obesity at age 3 than did an infant of the same birth weight who grew to 16.9 pounds.
Taveras said the study, funded by the National Institutes of Health, did not look at why some infants gained weight suddenly; possibilities include prenatal factors or too frequent feeding.
Dr. Samuel Grief, associate professor in clinical family medicine at the University of Illinois at Chicago, said he wasn't sold on the idea that a child could be predisposed to obesity so young.
"My gut reaction is that I take this as another piece of the puzzle," said Grief, an expert on obesity who was not involved in the study.