title: Maternal Folic Acid Supplementation During Pregnancy and Early Childhood Asthma.
abstract: BACKGROUND
  Asthma is one of the most common chronic childhood diseases. While folic acid supplementation around conception helps prevent neural tube defects, an animal model suggests that it may be a risk factor for respiratory diseases, although epidemiologic studies have had conflicting results. We investigated the timing of folic acid-containing prescription filling during pregnancy and child asthma.
  
  
  METHODS
  In a retrospective cohort study of 104,428 children, born 1996-2005, and their mothers enrolled in Tennessee Medicaid, we investigated the association of filling folic acid-containing prescriptions during pregnancy and childhood asthma at ages 4.5-6 years. We categorized women into exposure groups based on prescription filling centered around the first trimester: no folic acid prescription exposure, exposure in first trimester only, exposure after first trimester, and exposure in first trimester and beyond. We defined asthma using asthma-specific healthcare visits and medication fills. Using logistic regression models, we investigated the relationship adjusting for potential confounders.
  
  
  RESULTS
  Overall 15% of children had asthma. Compared with children born to women with no folic acid prescription exposure, children born to women with exposures in the first trimester only or first trimester and later had increased relative odds of asthma (adjusted odds ratios = 1.2, 95% confidence interval = 1.1, 1.3, and 1.2, 95% confidence interval = 1.2, 1.3); no association was seen in children born to women exposed after the first trimester.
  
  
  CONCLUSIONS
  Timing of folic acid-containing prescription filling during pregnancy was associated with childhood asthma. Our findings contribute to understanding of the role of prenatal nutritional supplements on child respiratory health.
authors.affiliation: From the Divisions of aGeneral Pediatrics, bPediatric Allergy, Immunology, and Pulmonary Medicine, cAllergy, Pulmonary and Critical Care Medicine, dCenter for Asthma and Environmental Sciences Research, eDepartments of Pediatrics, fMedicine, gHealth Policy, hBiostatistics, Vanderbilt University School of Medicine, Nashville, TN; iDepartment of Preventive Medicine, University of Tennessee Health Science Center, Memphis, TN; and jDepartment of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA.
authors.forename: Sreenivas P
authors.initials: SP
authors.lastname: Veeranki
authors.forename: Tebeb
authors.initials: T
authors.lastname: Gebretsadik
authors.forename: Edward F
authors.initials: EF
authors.lastname: Mitchel
authors.forename: Frances A
authors.initials: FA
authors.lastname: Tylavsky
authors.forename: Tina V
authors.initials: TV
authors.lastname: Hartert
authors.forename: William O
authors.initials: WO
authors.lastname: Cooper
authors.forename: William D
authors.initials: WD
authors.lastname: Dupont
authors.forename: Stacy L
authors.initials: SL
authors.lastname: Dorris
authors.forename: Terryl J
authors.initials: TJ
authors.lastname: Hartman
authors.forename: Kecia N
authors.initials: KN
authors.lastname: Carroll
mesh_terms: D000328:Adult; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D019587:Dietary Supplements / Q000706:statistics & numerical data*; D005260:Female; D005492:Folic Acid / Q000627:therapeutic use*; D006801:Humans; D016015:Logistic Models; D008297:Male; D009436:Neural Tube Defects / Q000517:prevention & control; D011247:Pregnancy; D011295:Prenatal Care; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D005492:Folic Acid