title: Spina bifida before and after folic acid fortification in Canada.
abstract: BACKGROUND
  In 1998, fortification of a large variety of cereal products with folic acid became mandatory in Canada. A multicentric study was carried out to assess the impact of this policy on the frequency of NTDs. The present analysis focused on spina bifida.
  
  
  METHODS
  The study population included approximately 2 million livebirths, stillbirths, and terminations of pregnancies because of fetal anomalies among women residing in seven Canadian provinces, from 1993 to 2002. Spina bifida cases were divided according to the upper limit of the defect: upper (cranial, cervical, or thoracic) and lower (lumbar or sacral) defects. Based on published results of red blood cell folate tests, the study period was divided into prefortification, partial fortification, and full fortification periods.
  
  
  RESULTS
  A total of 1,286 spina bifida cases were identified: 51% livebirths, 3% stillbirths, and 46% terminations. Prevalence decreased from 0.86/1,000 in the prefortification to 0.40 in the full fortification period, while the proportion of upper defects decreased from 32% to 13%. Following fortification, regional variations in the prevalence and distribution of sites almost disappeared.
  
  
  CONCLUSIONS
  Results confirmed the etiologic heterogeneity of spina bifida and the more pronounced effect of folic acid in decreasing the risk of the more severe clinical presentations.
authors.affiliation: Department of Social and Preventive Medicine, Laval University, Quebec City, QC, Canada. Philippe.Dewals@msp.ulaval.ca
authors.forename: Philippe
authors.initials: P
authors.lastname: De Wals
authors.forename: Fassiatou
authors.initials: F
authors.lastname: Tairou
authors.forename: Margot I
authors.initials: MI
authors.lastname: Van Allen
authors.forename: R Brian
authors.initials: RB
authors.lastname: Lowry
authors.forename: Jane A
authors.initials: JA
authors.lastname: Evans
authors.forename: Michiel C
authors.initials: MC
authors.lastname: Van den Hof
authors.forename: Marian
authors.initials: M
authors.lastname: Crowley
authors.forename: Soo-Hong
authors.initials: SH
authors.lastname: Uh
authors.forename: Pamela
authors.initials: P
authors.lastname: Zimmer
authors.forename: Barbara
authors.initials: B
authors.lastname: Sibbald
authors.forename: Bridget
authors.initials: B
authors.lastname: Fernandez
authors.forename: Nora S
authors.initials: NS
authors.lastname: Lee
authors.forename: Theophile
authors.initials: T
authors.lastname: Niyonsenga
mesh_terms: D002170:Canada / Q000453:epidemiology; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage* / Q000502:physiology*; D005527:Food, Fortified; D006801:Humans; D008297:Male; D011247:Pregnancy; D015995:Prevalence; D012189:Retrospective Studies; D016135:Spinal Dysraphism / Q000453:epidemiology* / Q000378:metabolism / Q000517:prevention & control
chemical_list: D005492:Folic Acid