Adriëtte Oostvogels

198 Chapter 8 Abstract Introduction: Children from a low socioeconomic background and from ethnic minorities are at increased risk of overweight. This study compared BMI growth patterns from birth onwards of boys and girls with overweight at 5-6 years, according to the socioeconomic and ethnic background, in order to gain more insight into the critical periods of growth to overweight in these subgroups. Methods: 3714 singletons of the multi-ethnic ABCD-study were included. Overweight status was determined at age 5-6 years. Within children with overweight at age 5-6 years, BMI growth patterns from birth onwards (12.8 serial measurements; SD=3.1) were compared between children from European and non-European mothers, and between children from low, middle or high socioeconomic status (SES; based on maternal educational level). Results: BMI growth to overweight did not differ between children of European or non-European mothers, but it did differ according to maternal SES. Overweight children in the low and middle SES group had a lower BMI in the first 2 years of life, an earlier adiposity rebound and increased in BMI more rapidly after age 2, resulting in a higher BMI at age 5-6 years compared to overweight children in the high SES group. Conclusion: Overweight children of low SES have an early adiposity rebound and accelerated growth to a higher BMI at age 5-6 years compared to children with overweight from the high SES group. These results imply that timing of critical periods for overweight development is earlier in children with a low socioeconomic background as compared to other children.