title: Supplemental folic acid in pregnancy and childhood cancer risk.
abstract: BACKGROUND
  We investigated the association between supplemental folic acid in pregnancy and childhood cancer in a nation-wide study of 687 406 live births in Norway, 1999-2010, and 799 children diagnosed later with cancer.
  
  
  METHODS
  Adjusted hazard ratios (HRs) compared cancer risk in children by approximated periconceptional folic acid levels (folic acid tablets and multivitamins (0.6 mg), only folic acid (0.4 mg), only multivitamins (0.2 mg)) and cancer risk in unexposed.
  
  
  RESULTS
  Any folic acid levels were not associated with leukemia (e.g., high-level folic acid HR 1.25; 95% CI 0.89-1.76, PTrend 0.20), lymphoma (HR 0.96; 95% CI 0.42-2.21, PTrend 0.51), central nervous system tumours (HR 0.68; 95% CI 0.42-1.10, PTrend 0.32), neuroblastoma (HR 1.05; 95% CI 0.53-2.06, PTrend 0.85), Wilms' tumour (HR 1.16; 95% CI 0.52-2.58, PTrend 0.76), or soft-tissue tumours (HR 0.77; 95% CI 0.34-1.75, PTrend 0.90).
  
  
  CONCLUSIONS
  Folic acid supplementation was not associated with risk of major childhood cancers.
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Kalfarveien 31, Bergen N-5018, Norway.|Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Jan Helge Seglem
authors.initials: JH
authors.lastname: Mortensen
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Kalfarveien 31, Bergen N-5018, Norway.|Center for Medical Genetics and Molecular Medicine, Haukeland University Hospital, Bergen, Norway.
authors.forename: Nina
authors.initials: N
authors.lastname: Øyen
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Kalfarveien 31, Bergen N-5018, Norway.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Fomina
authors.affiliation: Department of Epidemiology Research, National Health Surveillance and Research, Statens Serum Institut, Copenhagen, Denmark.|Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark.|Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Mads
authors.initials: M
authors.lastname: Melbye
authors.affiliation: Cancer Registry of Norway, Oslo, Norway.
authors.forename: Steinar
authors.initials: S
authors.lastname: Tretli
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Kalfarveien 31, Bergen N-5018, Norway.|Norwegian Institute of Public Health, Oslo, Norway.
authors.forename: Stein Emil
authors.initials: SE
authors.lastname: Vollset
authors.affiliation: Department of Global Public Health and Primary Care, University of Bergen, Kalfarveien 31, Bergen N-5018, Norway.|Cancer Registry of Norway, Oslo, Norway.
authors.forename: Tone
authors.initials: T
authors.lastname: Bjørge
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D006801:Humans; D008875:Middle Aged; D009369:Neoplasms / Q000209:etiology*; D011247:Pregnancy; D012306:Risk
chemical_list: D005492:Folic Acid