Prenatal determinants of neonatal lung function in high-risk newborns

Neonatal lung function is suspected to be associated with wheezy disorders, but little is known about risk factors for the early lung function.

To study prenatal determinants of neonatal lung function.

This is a clinical, prospective birth cohort study of 411 newborns, the Copenhagen Prospective Study on Asthma in Childhood, in a single-center research clinic dedicated solely to this longitudinal birth cohort study. Lung function was determined at 1 month of age by infant spirometry (the raised volume rapid thoraco-abdominal compression technique) and bronchial responsiveness to methacholine by transcutaneous oxygen measurements. Risk factor analyses included anthropometrics; demographics; socioeconomic factors; parental atopic history; previous deliveries; exposures during the third trimester to the mother's smoking, alcohol, and medicines; third trimester pregnancy complications including mother's asthma status; and mode of delivery.

Lung function was determined in 404 neonates, age 6 weeks. Neonates with body mass index in the upper quartile had 14% lower baseline forced expiratory volume at 0.5 second, and neonates of mothers smoking during the third trimester had 7% lower baseline forced expiratory volume at 0.5 second. Sex or parental atopic disease did not affect the neonatal lung function and bronchial responsiveness. Maternal intake of paracetamol during the third trimester was associated with doubling of the bronchial responsiveness in the neonates, but the statistical significance may have been driven by outliers. Bronchial responsiveness exhibited a parabola development with tripling of bronchial responsiveness reaching the nadir at 3 months of age, but this needs replication in a study with repetitive measurements within individuals.

High body mass index in newborns and mothers smoking is associated with reduced neonatal lung function. This suggests that the association between body proportion and wheezing disorders may be a result of shared genes or prenatal nutrition.