Breast feeding and obesity: cross sectional study

Objective To assess the impact of breast feeding on the risk of obesity and risk of being overweight in children at the time of entry to school. Design Cross sectional survey. Setting Bavaria, southern Germany. Methods Routine data were collected on the height and weight of 134 577 chi ldren participating in the obligatory health examination at the time of sch ool entry in Bavaria. In a subsample of 13 345 children, early feeding, die t, and lifestyle factors were assessed using responses to a questionnaire c ompleted by parents. Subjects 9357 children aged 5 and 6 who had German nationality. Main outcome measures Being overweight was defined as having a body mass in dex above the 90th centile and obesity was defined as body mass index above the 97th centile of all enrolled German children. Exclusive breast feeding was defined as the child being fed no food other than breast milk. Results The prevalence of obesity in children who had never been breast fed was 4.5% as compared with 2.8% in breastfed children. A clear dose-respons e effect was identified for the duration of breast feeding on the prevalenc e of obesity: the prevalence was 3.8% for 2 months of exclusive breast feed ing, 2.3% for 3-5 months, 1.7% for 6-12 months, and 0.8% for more than 12 m onths. Similar relations were found with the prevalence of being overweight . The protective effect of breast feeding was not attributable to differenc es in social class or lifestyle. After adjusting for potential confounding factors, breast feeding remained a significant protective factor against th e development of obesity (odds ratio 0.75, 95% CI 0.57 to 0.98) and being o verweight (0.79, 0.68 to 0.93). Conclusions In industrialised countries promoting prolonged breast feeding may help decrease the prevalence of obesity in childhood. Since obese child ren have a high risk of becoming obese adults, such preventive measures may eventually result in a reduction in the prevalence of cardiovascular disea ses and other diseases related to obesity.