1. ¹Institute for Social Paediatrics and Adolescent Medicine, Ludwig-Maximilians University, Munich, Germany
2. ²gsf—National Research Center for Environment and Health, Institute of Epidemiology, Neuherberg, Germany
3. ³Dr von Haunersches Kinderspital, Ludwig-Maximilians-University, Munich, Germany

Correspondence: Professor R von Kries, Institute for Social Paediatrics and Adolescent Medicine, Ludwig-Maximilians-University, Heiglhofstr. 63, D-81377 Munich, Germany. E-mail: prof.von.kries@gmx.de

Received 9 October 2003; Revised 18 May 2004; Accepted 14 June 2004; Published online 17 August 2004.

Abstract

OBJECTIVE: To investigate the relationship between breast-feeding and obesity in childhood.

DESIGN: Systematic review and meta-analysis of published epidemiological studies (cohort, case–control or cross-sectional studies) comparing early feeding-mode and adjusting for potential confounding factors. Electronic databases were searched and reference lists of relevant articles were checked. Calculations of pooled estimates were conducted in fixed- and random-effects models. Heterogeneity was tested by Q-test. Publication bias was assessed from funnel plots and by a linear regression method.

OUTCOME MEASURES: Odds ratio (OR) for obesity in childhood defined as body mass index (BMI) percentiles.

RESULTS: Nine studies with more than 69 000 participants met the inclusion criteria. The meta-analysis showed that breast-feeding reduced the risk of obesity in childhood significantly. The adjusted odds ratio was 0.78, 95% CI (0.71, 0.85) in the fixed model. The assumption of homogeneity of results of the included studies could not be refuted (Q-test for heterogeneity, P>0.3), stratified analyses showed no differences regarding different study types, age groups, definition of breast-feeding or obesity and number of confounding factors adjusted for. A dose-dependent effect of breast-feeding duration on the prevalence of obesity was reported in four studies. Funnel plot regression gave no indication of publication bias.

CONCLUSION: Breast-feeding seems to have a small but consistent protective effect against obesity in children.