Childhood obesity researchers have begun looking back to infancy for clues to explain why some children become overweight while others don't.
A baby's birth weight and weight gain in the first days and weeks of life can predict obesity, studies have shown. A new Boston study in Pediatrics that factored in weight as well as length -- a baby's Body Mass Index -- says it's not just how much a newborn weighs, but how quickly weight is gained in the first six months that raises the risk of obesity at age 3.
Dr. Elsie Taveras of Children's Hospital Boston and her colleagues from Harvard and Harvard Pilgrim Health Care studied more than 500 children in Project Viva, an ongoing Boston-based study of pregnant women and their children. They measured each child's weight and length at birth and 6 months, and then weight and height at 3 years. After accounting for babies who were premature or underweight at birth, they divided them into four groups based on their weight-for-length gain.
The children in the highest quartile at 6 months had a 40 percent risk of being obese at 3 years old compared to a 1 percent risk for children in the lowest quartile.
Breastfeeding versus bottle feeding didn't explain the difference in how rapidly the babies increased their weight, the researchers found. Their sleep duration -- an obesity risk factor in another Taveras study -- also didn't make a difference.
"We related weight gain in the first six months of life with obesity," she said in an interview. "But we're not at a point yet where we know how to intervene to prevent this rapid weight gain. We're not even close to knowing what predicts that fast growth in the first months of life."
Excessive weight gain during pregnancy could be a factor, Taveras said. Or parents might not be picking up on their infant's hunger or satiety cues. Even beliefs that "baby fat" will go away could be affecting how parents think about feeding their children.
"There are a lot of parents who think children who top the growth charts are healthier than children who don't," she said. "The [study] results could really be a wake-up call that we might have some misconceptions about what healthy growth is."
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