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Previous Volume 357:135-142 July 12, 2007 Number 2 Next

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ABSTRACT

Background In 1998, folic acid fortification of a large variety of cereal products became mandatory in Canada, a country where the prevalence of neural-tube defects was historically higher in the eastern provinces than in the western provinces. We assessed changes in the prevalence of neural-tube defects in Canada before and after food fortification with folic acid was implemented.

Methods The study population included live births, stillbirths, and terminations of pregnancies because of fetal anomalies among women residing in seven Canadian provinces from 1993 to 2002. On the basis of published results of testing of red-cell folate levels, the study period was divided into prefortification, partial-fortification, and full-fortification periods. We evaluated the relationship between baseline rates of neural-tube defects in each province and the magnitude of the decrease after fortification was implemented.

Results A total of 2446 subjects with neural-tube defects were recorded among 1.9 million births. The prevalence of neural-tube defects decreased from 1.58 per 1000 births before fortification to 0.86 per 1000 births during the full-fortification period, a 46% reduction (95% confidence interval, 40 to 51). The magnitude of the decrease was proportional to the prefortification baseline rate in each province, and geographical differences almost disappeared after fortification began. The observed reduction in rate was greater for spina bifida (a decrease of 53%) than for anencephaly and encephalocele (decreases of 38% and 31%, respectively).

Conclusions Food fortification with folic acid was associated with a significant reduction in the rate of neural-tube defects in Canada. The decrease was greatest in areas in which the baseline rate was high.

Source Information

From Laval University, Quebec, QC (P.D.W., F.T.); the University of British Columbia, Vancouver (M.I.V.A.); British Columbia Ministry of Health, Victoria (S.-H.U.); Alberta Health and Wellness, Calgary (R.B.L., B.S.); the University of Manitoba, Winnipeg (J.A.E.); Dalhousie University, Halifax, NS (M.C.V.H.); the IWK Health Centre, Halifax, NS (P.Z.); Health Science Centre, St. John's, NL (M.C., B.F.); Food Directorate, Health Canada, Ottawa (N.S.L.) — all in Canada; and Robert Stempel School of Public Health, Florida International University, Miami (T.N.).

Address reprint requests to Dr. De Wals at the Département de Médecine Sociale et Préventive, Université Laval, Pavillon de l'Est, Local 1110, 2180, Chemin Sainte-Foy, Quebec, QC G1K 7P4, Canada, or at philippe.dewals{at}msp.ulaval.ca.

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