Breastfeeding, overweight and asthma in Dutch children. The PIAMA birth cohort study

Abstract

Breastfeeding has been linked to a lower risk of overweight and asthma in children, however the results of previous studies are conflicting and controversy remains. An important gap in the current knowledge on the association between breastfeeding and overweight and asthma is whether and how the association changes with age of the child. These topics were investigated in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) study. This is a prospective birth cohort study of 3963 Dutch children from the general population followed from birth to 8 years of age. Data were mainly collected by yearly questionnaires. At 4 and at 8 years a subgroup of the total study population was invited for a medical examination. In the PIAMA study, 82% of the children was breastfed and about one third of the children was breastfed for more than 16 weeks. At 8 years of age, 14.5% of the children in the total study population was overweight and 13.8% had asthma. Breastfed children had a lower BMI at 1 year of age compared to non-breastfed children. Longitudinal analyses showed that children breastfed for more that 16 weeks had a significantly lower BMI from 1 to 7 years of age than non-breastfed children. However, when BMI at 1 year of age was taken into account, breastfeeding for more than 16 weeks was not associated with BMI from 1 to 7 years of age. Breastfed children had a more healthy eating pattern at 7 years of age compared to non-breastfed children, independently of maternal characteristics. However, the healthier eating pattern could not explain the lower overweight prevalence among breastfed children compared to non-breastfed children. Breastfeeding for more than 16 weeks was significantly associated with a lower asthma prevalence from 3 to 8 years of age compared to no breastfeeding. The associations were similar in children from allergic and non-allergic parents. Also, children breastfed for more than 16 weeks were less likely to be sensitised to inhalant allergens, but breastfeeding was not related with bronchial hyperresponsiveness. Children who had a high BMI at 6-7 years had an increased risk of asthma and bronchial hyperresponsiveness at 8 years of age. Children who had a high BMI at a younger age, but who had a normal BMI at 6-7 years of age did not have an increased risk of asthma or BHR at 8 years of age. A high BMI was not associated with sensitisation at 8 years of age. The most important conclusions of the thesis were, firstly, that breastfed children had lower risk to become overweight compared to non-breastfed children, which was probably mainly due to the lower weight gain during infancy in breastfed children and less to the healthier diet of breastfed children. Secondly, breastfed children had a lower asthma risk compared to non-breastfed children regardless of the age of the child and the family history of allergy or asthma. Finally, overweight was a risk factor for asthma at 8 years of age.