BACKGROUND: The means of primary prevention of asthma are limited. Maternal physical activity during pregnancy promotes fetal lung development and the newborn's lung function
thus, it could lower asthma risk and aid in asthma prevention. The objective of this study is to determine whether maternal physical activity during pregnancy is associated with asthma development in the child. METHODS: The study population included 963 mother-infant pairs from the prospective Kuopio Birth Cohort study. Data on maternal physical activity during pregnancy, confounding factors, and children's asthma at 5 to 7 years of age were obtained from the Kuopio University Hospital birth registry and questionnaires. FINDINGS: Maternal physical activity during pregnancy, when practiced three or more times per week, was associated with a reduced risk of asthma in the child, with an adjusted odds ratio of 0.54 (95% confidence interval 0.33-0.89
p = 0.02). The association was stable across a comprehensive set of adjustments, including length of gestation, mode of delivery, and maternal health indicators (e.g., asthma, smoking, pre-pregnancy body mass index and weight gain during pregnancy, infections, medication, healthy diet, stress), as well as various family environment variables. CONCLUSIONS: Maternal physical activity during pregnancy may be associated with marked protection of asthma in childhood and should be studied further as an applicable measure for asthma prevention. FUNDING: The study has been financially supported by grants from the Academy of Finland (no. 349427), the Emil Aaltonen Foundation, the Finnish Cultural Foundation, the Yrjö Jahnsson Foundation, the Juho Vainio Foundation (no. 202200461), the Kuopio Area Respiratory Foundation, and the Ida Montini Foundation.