CHICAGO — Rapid weight gain in the first week of life in formula-fed infants is associated with increased risk of obesity 2–3 decades later, Dr. Nicolas Stettler said at the annual scientific sessions of the American Heart Association.
“The neonatal period may be a sensitive period for the programming of energy balance regulation,” said Dr. Stettler of Children's Hospital of Philadelphia.
He presented an observational study conducted over several decades. It involved 653 formula-fed white infants born in the Iowa City area. At age 20–32 years, 32% of them were overweight or obese.
Using a relatively recent statistical analysis method called life-course modeling, Dr. Stettler and coworkers were able to identify the first 8 days of infancy as a critical period of weight gain associated with adult obesity.
The median weight gain during the first 8 days of life was about 200 g. After the researchers adjusted for birth weight, maternal overweight, and other potential confounders, early weight gain remained an independent predictor of adult overweight; for each 100-g increase in weight, the risk of adult overweight or obesity rose by about 28%. This was true even among babies with a low birth weight and rapid catch-up.
Thus, an individual who gained 200 g in the first week of life had a 32% chance of becoming an overweight adult, one who gained 300 g had a 41% risk, and a 400-g weight gain was associated with a 55% risk, Dr. Stettler said.
The importance of this large study of early weight gain isn't so much that it permits identification of individuals at risk for adult obesity; after all, obesity is now so common. Rather, the study is important mainly for its public health and research implications. The results, Dr. Stettler said, may eventually open the door to novel brief interventions in infancy to prevent later obesity. For example, the findings are consistent with animal studies that suggest overfeeding in the first few days of life may result in neurologic or endocrinologic imprinting leading to later obesity.
The first week of life is the first time an individual has to regulate energy intake, he noted. During the fetal period, nutrients are provided passively.