title: Vitamin D intake in mid-pregnancy and child allergic disease - a prospective study in 44,825 Danish mother-child pairs.
abstract: BACKGROUND
  Past studies suggest that maternal vitamin D intake during pregnancy may protect against child wheeze but studies on asthma are limited. Our objective was to examine the relation between intake of vitamin D in mid-pregnancy and child asthma and allergic rhinitis at 18 months and 7 years.
  
  
  METHODS
  We examined data from 44,825 women enrolled during pregnancy in the longitudinal Danish National Birth Cohort (1996-2002). We estimated vitamin D intake from diet and supplements based on information from a validated food frequency questionnaire completed in gestational week 25. At 18 months, we evaluated child asthma using data from phone interviews. We assessed asthma and allergic rhinitis by self-report at age 7 and asthma by using records from national registries. Current asthma at age 7 was defined as lifetime asthma diagnosis and wheeze in the past 12 months. We calculated multivariable risk ratios with 95% CIs comparing highest vs. lowest quintile of vitamin D intake in relation to child allergic disease outcomes.
  
  
  RESULTS
  The median (5%-95%ile) intake of total vitamin D was 11.7(3.0-19.4) μg/day (68% from supplements). In multivariable analysis, mothers in the highest (vs. lowest) quintile of total vitamin D intake were less likely to have children classified with current asthma at 7 years (Q5 vs. Q1: 0.74, 95% CI: 0.56, 0.96, P = 0.02) and they were less likely to have children admitted to the hospital due to asthma (Q5 vs. Q1: 0.80, 95% CI: 0.64, 1.00, P = 0.05). We found no associations with child asthma at 18 months or with allergic rhinitis at 7 years.
  
  
  CONCLUSIONS
  Our findings suggest a weak inverse relationship between high total vitamin D and asthma outcomes in later, but not early, childhood. The data did not suggest a clear threshold of vitamin D intake above which risk of asthma was reduced.
authors.affiliation: Centre for Fetal Programming, Department of Epidemiology Research, Statens Serum Institut, Artillerivej 5, 2300 Copenhagen, Denmark. kmv@ssi.dk.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Maslova
authors.forename: Susanne
authors.initials: S
authors.lastname: Hansen
authors.forename: Camilla B
authors.initials: CB
authors.lastname: Jensen
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Thorne-Lyman
authors.forename: Marin
authors.initials: M
authors.lastname: Strøm
authors.forename: Sjurdur F
authors.initials: SF
authors.lastname: Olsen
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000453:epidemiology*; D002648:Child; D003718:Denmark / Q000453:epidemiology; D004032:Diet; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology*; D015995:Prevalence; D011446:Prospective Studies; D012042:Registries; D065631:Rhinitis, Allergic; D012221:Rhinitis, Allergic, Perennial / Q000453:epidemiology*; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000008:administration & dosage*; D014815:Vitamins / Q000008:administration & dosage*; D055815:Young Adult
chemical_list: D014815:Vitamins; D014807:Vitamin D