To examine overweight trends over a 22-year period among preschool-aged children from primarily middle-income families enrolled in a health maintenance organization. From well-child care visits to a Massachusetts health maintenance organization, we randomly selected one visit per child per calendar year, yielding a study sample of 120,680 children seen at 366,109 visits from 1980 through 2001. Using multivariate logistic regression models accounting for repeated observations of individual children across years, we estimated trends in prevalence of overweight (weight-for-length/height > or = 95th percentile) and at-risk-for-overweight (85th to 95th percentile). Over the 22-year study period, the observed prevalence of overweight increased from 6.3% to 10.0% and at-risk-for-overweight increased from 11.1% to 14.4%. These increases were evident among all groups of children including infants < 6 months of age. Overall, the adjusted odds ratios were 1.21 per decade (95% confidence interval, 1.17 to 1.25) for overweight and 1.06 per decade (95% confidence interval, 1.03 to 1.08) for at-risk-for-overweight. Rates of overweight are increasing in very young children, even infants, from primarily middle-class families.
