title: Folic acid supplements in pregnancy and early childhood respiratory health.
abstract: BACKGROUND
  Folate supplementation is recommended for pregnant women to reduce the risk of congenital malformations. Maternal intake of folate supplements during pregnancy might also influence childhood immune phenotypes via epigenetic mechanisms.
  
  
  OBJECTIVE
  To investigate the relationship between folate supplements in pregnancy and risk of lower respiratory tract infections and wheeze in children up to 18 months of age.
  
  
  METHODS
  In the Norwegian Mother and Child Cohort Study, questionnaire data collected at several time points during pregnancy and after birth on 32,077 children born between 2000 and 2005 were used to assess the effects of folate supplements during pregnancy on respiratory outcomes up to 18 months of age, while accounting for other supplements in pregnancy and supplementation in infancy.
  
  
  RESULTS
  Folate supplements in the first trimester were associated with increased risk of wheeze and respiratory tract infections up to 18 months of age. Adjusting for exposure later in pregnancy and in infancy, the relative risk for wheeze for children exposed to folic acid supplements in the first trimester was 1.06 (95% CI 1.03 to 1.10), the relative risk for lower respiratory tract infections was 1.09 (95% CI 1.02 to 1.15) and the relative risk for hospitalisations for lower respiratory tract infections was 1.24 (95% CI 1.09 to 1.41).
  
  
  CONCLUSIONS
  Folic acid supplements in pregnancy were associated with a slightly increased risk of wheeze and lower respiratory tract infections up to 18 months of age. The results suggest that methyl donors in the maternal diet during pregnancy may influence respiratory health in children consistent with epigenetic mechanisms.
authors.affiliation: Division of Epidemiology, Norwegian Institute of Public Health, PO Box 4404, Nydalen, NO-0403 Oslo, Norway. siri.haberg@fhi.no
authors.forename: S E
authors.initials: SE
authors.lastname: Håberg
authors.forename: S J
authors.initials: SJ
authors.lastname: London
authors.forename: H
authors.initials: H
authors.lastname: Stigum
authors.forename: P
authors.initials: P
authors.lastname: Nafstad
authors.forename: W
authors.initials: W
authors.lastname: Nystad
mesh_terms: D019587:Dietary Supplements; D004812:Epidemiologic Methods; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007223:Infant; D008297:Male; D009664:Norway / Q000453:epidemiology; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011295:Prenatal Care / Q000379:methods*; D011297:Prenatal Exposure Delayed Effects; D039401:Prenatal Nutritional Physiological Phenomena; D012135:Respiratory Sounds / Q000209:etiology; D012141:Respiratory Tract Infections / Q000196:embryology* / Q000453:epidemiology
chemical_list: D005492:Folic Acid