Maternal body mass index, neonatal lung function and respiratory symptoms in childhood.

Recent studies have shown that maternal obesity is associated with increased risk of wheezing in the offspring. We assessed whether impaired neonatal lung function could explain this association. We measured neonatal lung function in 2606 children of our prospective birth cohort. Information about daily symptoms of wheezing was obtained using questionnaires. Consultations and prescriptions for wheezing illnesses were derived from general practitioner patient files. Higher maternal body mass index (BMI) was associated with increased risk of wheezing in the first year of life and more consultations and prescriptions for wheezing illnesses until the age of 5 years. Lung function could partially explain the association with wheezing in the first year of life. Adding respiratory resistance to the model decreased the incidence rate ratio from 1.023 (95% CI 1.008-1.039) to 1.015 (95% CI 0.998-1.032). Anthropometrics of the 5-year-olds largely explained the association with consultations. Intermediates or confounders could not explain the association with prescriptions. There is an association between higher maternal BMI and increased risk of wheezing illnesses. In the first year of life, it is largely explained by an impaired lung function in early life, especially in children of nonatopic mothers. At the age of 5 years, infant lung function is of minor influence in this association.