Aim: To study a potential link between breastfeeding in infancy and obesity at age 4.
Materials and methods: A total of 30,508 infants born during 2002-2007 from the databases of the Preventive Child Health Services in two Swedish counties and from national registers were studied. The outcome variable was obesity at age 4. Analyses were conducted by logistic regression models using the methodology of generalized estimating equations. Analyses were adjusted for child sex and maternal anthropometric and sociodemographic variables.
Results: In unadjusted analyses, any breastfeeding up to 9 months was linked to successively decreasing odds ratios (ORs) for obesity at age 4 (ORs 0.78-0.33), however, not significantly for 1 week and 2 months of breastfeeding. In adjusted analyses, the same pattern remained statistically significant for breastfeeding for 4 (OR 0.51), 6 (OR 0.55), and 9 (OR 0.47) months. Child sex, maternal education, maternal body mass index, and maternal smoking additionally influenced child obesity.
Conclusion: Breastfeeding duration for at least 4 months may contribute independently to a reduced risk for childhood obesity at 4 years.
Keywords: breastfeeding; childhood obesity; epidemiology; socioeconomic factors.