"The obesity epidemic has spared no age group, even our youngest children," says Matthew Gillman, MD, senior author of the study and associate professor in the Department of Ambulatory Care and Prevention (of Harvard Medical School and Harvard Pilgrim Health Care).
Over the course of the study, the prevalence of overweight children increased from 6.3 percent to 10 percent, a 59 percent jump (based on weight and height measures documented in medical records). The proportion of children at risk of becoming overweight grew from 11.1 percent to 14.4 percent overall, a 30 percent jump.
Infants from birth to six months of age, an age group seldom studied before, had particularly surprising results. Of all the age groups studied, these infants had the greatest jump in risk of becoming overweight, at 59 percent, and the number of overweight infants increased by 74 percent. "This information is important to public health because previous studies show that accelerated weight gain in the first few months after birth is associated with obesity later in life," says Gillman.
According to the Centers for Disease Control and Prevention's national reference data, children with a weight-for-height index between the national 85th and 95th percentiles for age and gender are classified as at risk for becoming overweight, and those with a weight-for-height index greater than the 95th percentile are classified as overweight. Access the CDC's growth charts at http://www.cdc.gov/growthcharts/.
"In addition to demonstrating that we are seeing more heavy infants today than we did 20 years ago, this study illustrates the usefulness of routinely collected information from doctors' offices to address a key public health issue," says Juhee Kim, PhD, first author of the study. Kim performed this research at DACP while she was a research fellow in the Public Health Nutrition Program at the Harvard School of Public Health.
Gillman and colleagues collected data from well-child visits among more than 120,000 children younger than 6 years old at 14 Harvard Vanguard Medical Associates practices in eastern Massachusetts from 1980 through 2001. All of the children were enrolled in an HMO, which, throughout the study, used a completely electronic medical record system that contained demographic and growth data for the children.
"These results show that efforts to prevent obesity must start at the earliest stages of human development, even before birth," says Gillman. "These efforts should include avoiding smoking and excessive weight gain during pregnancy, preventing gestational diabetes, and promoting breastfeeding, all of which researchers have shown to be associated with reductions in childhood overweight."