Vitamin A and D Intake in Pregnancy, Infant Supplementation and Asthma Development

This study was conducted as part of the research project "Causal pathways for asthma" funded by the Norwegian Research Council (2013-2017). The overall objective was to study if different pregnancy and early life exposures affect the risk of asthma and allergic diseases in children, and if these exposures exert their effects through epigenetic mechanisms, more specifically DNA methylation. For this project, including the current study, existing data from the Norwegian Mother and Child Study (MoBa file version 9, 115 398 children and 95 248 mothers) were linked with the Medical Birth Registry of Norway and the Norwegian Prescription Database. The MoBa study recruited pregnant women between 1999 and 2008, at approximately 18 weeks of gestation. Beginning 2002, women completed a food frequency questionnaire about dietary intake (food and supplements) in pregnancy. A panel of maternal plasma biomarkers, including plasma retinol and 25-hydroxyvitamin D2 and D3, was available for a random sample of around 3,000 women who gave birth in 2002 and 2003.