title: Maternal Folate Intake during Pregnancy and Childhood Asthma in a Population-based Cohort.
abstract: A potential adverse effect of high folate intake during pregnancy on children's asthma development remains controversial.
  
  
  
  To prospectively investigate folate intake from both food and supplements during pregnancy and asthma at age 7 years when the diagnosis is more reliable than at preschool age.
  
  
  
  This study included eligible children born 2002-2006 from the Norwegian Mother and Child Cohort Study, a population-based pregnancy cohort, linked to the Norwegian Prescription Database. Current asthma at age 7 was defined by asthma medications dispensed at least twice in the year (1,901 cases; n = 39,846) or by maternal questionnaire report (1,624 cases; n = 28,872). Maternal folate intake was assessed with a food frequency questionnaire validated against plasma folate. We used log-binomial and multinomial regression to calculate adjusted relative risks with 95% confidence intervals.
  
  
  
  Risk of asthma was increased in the highest versus lowest quintile of total folate intake with an adjusted relative risk of 1.23 (95% confidence interval, 1.06-1.44) that was similar for maternally reported asthma. Mothers in the highest quintile had a relatively high intake of food folate (median, 308; interquartile range, 241-366 μg/d) and nearly all took at least 400 μg/d of supplemental folic acid (median, 500; interquartile range, 400-600 μg/d).
  
  
  
  In this large prospective population-based cohort with essentially complete follow-up, pregnant women taking supplemental folic acid at or above the recommended dose, combined with a diet rich in folate, reach a total folate intake level associated with a slightly increased risk of asthma in children.
authors: 1 Department of Mental and Physical Health and.|2 Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina.
authors: Christine L
authors: 0000-0002-4690-0085
authors: CL
authors: Parr
authors: 1 Department of Mental and Physical Health and.|3 Medical Research Council Integrative Epidemiology Unit and.|4 School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
authors: Maria C
authors: MC
authors: Magnus
authors: 1 Department of Mental and Physical Health and.
authors: Øystein
authors: Ø
authors: Karlstad
authors: 5 Department of Exposure and Risk Assessment, Norwegian Institute of Public Health, Oslo, Norway.
authors: Margaretha
authors: M
authors: Haugen
authors: 6 Institute of Basic Medical Sciences, Department of Nutrition, and.
authors: Helga
authors: H
authors: Refsum
authors: 7 Department of Clinical Science, University of Bergen, Bergen, Norway.|8 Laboratory of Clinical Biochemistry, Haukeland University Hospital, Bergen, Norway; and.
authors: Per M
authors: PM
authors: Ueland
authors: 9 Bevital AS, Bergen, Norway.
authors: Adrian
authors: A
authors: McCann
authors: 1 Department of Mental and Physical Health and.|10 Department of Community Medicine, University of Oslo, Oslo, Norway.
authors: Per
authors: P
authors: Nafstad
authors: 1 Department of Mental and Physical Health and.
authors: Siri E
authors: SE
authors: Håberg
authors: 1 Department of Mental and Physical Health and.
authors: Wenche
authors: W
authors: Nystad
authors: 2 Epidemiology Branch, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina.
authors: Stephanie J
authors: SJ
authors: London
mesh_terms: D000328:Adult; D001249:Asthma / Q000453:epidemiology / Q000209:etiology*; D002648:Child; D019587:Dietary Supplements / Q000009:adverse effects*; D005260:Female; D005492:Folic Acid / Q000009:adverse effects*; D006801:Humans; D008297:Male; D009664:Norway / Q000453:epidemiology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology / Q000209:etiology*; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires
chemical_list: D005492:Folic Acid
keywords: birth cohort; children’s asthma development; epidemiology; folic acid; maternal diet