Tracking of overweight from early childhood to adolescence in cohorts born 1988 and 1994: overweight in a high birth weight population

Objective: To investigate the prevalence and tracking of overweight and obesity in childhood cohorts born 1988 and 1994 in a population of high birth weight. Subjects: Icelandic cohorts born in 1988 and 1994. Materials and methods: Out of 1328, 9- and 15-year-old children from 18 randomly selected schools all over Iceland, 934 participated (71%). Height and mass were measured by the investigators. Also, height and mass at birth, and at age 2.5, 6, 9, and 12 years, were collected from maternity wards and school health registers. Results: The prevalence of overweight children ranged from 10.1% for 2.5-year-olds to 18.7% for 9-year-olds. No difference was observed between the two cohorts or sex. The prevalence of obesity in the 1994 cohort (4.3%) was significantly higher (P = 0.01) at age 6 years, compared to the 1988 cohort (1.1%). The children who were overweight at age 2.5 years were more likely to be overweight at age 6 (OR = 12.2) and 9 years (OR = 4.9), but not significantly at age 12 or 15 years, compared with normal weight 2.5-year-olds. Overweight children at age 6 or 9 years were much more likely (OR 10.4 and OR 18.6, respectively) to be overweight at age 15 years compared to their normal weight peers. Of overweight 6-year-olds, 51% were overweight at 15 years, and were about one-third of all overweight children at that age. The children that weighed above the 85th percentile at birth were more likely than the other children to be overweight at the age of 6 years (OR = 1.8), 9 years (OR = 2.1), and 15 (OR = 2.0) years. Conclusion: The results show high prevalence of overweight and obesity even before the start of compulsory schooling. Approximately, 51% of overweight 6-year-olds were still overweight after puberty. Therefore, preschool overweight prevention, along with prevention at school age, seems to be of uttermost importance.