title: Trend in prevalence of neural tube defects in Quebec.
abstract: BACKGROUND
  In Canada, the first recommendations on the use of folic acid (FA) supplements by women planning a pregnancy or capable of becoming pregnant were issued in 1993. In 1998, fortification of flour with FA became mandatory. The objective of this study was to assess the impact of these measures on the prevalence of neural tube defects (NTDs) in the province of Quebec.
  
  
  METHODS
  The study population included stillbirths, live births, and elective terminations for fetal malformations that were reported in 1992-2000 for women residing in the province of Quebec. NTD cases were identified from stillbirth certificates and hospital discharge summaries.
  
  
  RESULTS
  There was a marked decrease in the total NTD rate after 1997. The average NTD rate was 1.89 per 1000 total births during the period of 1992-1997, and 1.28 per 1000 in 1998-2000, a 32% reduction (p < 0.001).
  
  
  CONCLUSIONS
  Fortification of flour, which began in early 1997 and gradually became widespread, is a very plausible explanation for the timing, shape, and magnitude of the decrease in NTD prevalence observed in Quebec and other Canadian provinces. An increase in FA supplement use may have played only a minor role. Birth Defects Research (Part A) 67:000-000, 2003.
authors.affiliation: Département de Médecine Sociale et Préventive, Université Laval, Québec, Canada. Philippe.De.Wals@ssss.gouv.qc.ca
authors.forename: Philippe
authors.initials: P
authors.lastname: De Wals
authors.forename: Ira David
authors.initials: ID
authors.lastname: Rusen
authors.forename: Nora S
authors.initials: NS
authors.lastname: Lee
authors.forename: Pascale
authors.initials: P
authors.lastname: Morin
authors.forename: Théophile
authors.initials: T
authors.lastname: Niyonsenga
mesh_terms: D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000627:therapeutic use; D005527:Food, Fortified; D006801:Humans; D008297:Male; D009436:Neural Tube Defects / Q000453:epidemiology*; D011247:Pregnancy; D011256:Pregnancy Outcome; D015995:Prevalence; D011792:Quebec; D013997:Time Factors; D014815:Vitamins
chemical_list: D014815:Vitamins; D005492:Folic Acid