Folic acid food fortification is associated with a reduction in the birth prevalence of congenital heart defects, according to a study published in Circulation.

Shiliang Liu, MD, PhD, from the Surveillance and Epidemiology Division, CCDPC-Public Health Agency of Canada, and colleagues conducted a population-based cohort study (n=5,901,701) that included live births and stillbirths delivered at ≥20 weeks gestation in Canada from 1990 to 2011. A total of 72,591 congenital heart defects were diagnosed at birth and in infancy.

The researchers compared prevalence rates and temporal trends of congenital heart defect subtypes before and after 1998, which was the year that food fortification with folic acid was mandated in Canada. They used an ecological study lasting 22 years in 14 geographic areas to analyze the effect of folic acid food fortification on nonchromosomal subtypes of congenital heart defects (n=66,980). The analysis was controlled for changes in maternal age, pre-pregnancy diabetes, preterm preeclampsia, multiple births, and termination of pregnancy.

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The overall birth prevalence rate of congenital heart defects was 12.3 per 1000 total births. Most types of congenital heart defects decreased between 1990 and 2011, although atrial septal defects increased significantly.

Food fortification with folic acid was associated with lower rates of conotruncal defects (adjusted rate ratio [aRR], 0.73) coarctation of the aorta (aRR, 0.77) ventricular septal defects (aRR, 0.85), and atrial septal defects (aRR, 0.82). However, there was no observed reduction in severe nonconotruncal heart defects (aRR, 0.81) and other heart or circulatory system abnormalities (aRR, 0.98).

“The estimate of the effect of food fortification with folic acid on each specific subtype of CHDs [congenital heart defects] was similar in primary analyses involving all CHD cases and in secondary analyses restricted to isolated CHDs,” the study authors wrote.

“This concordance provides further assurance that the estimated effect of folic acid food fortification excluded the influence of temporal increases in pregnancy termination for prenatally diagnosed CHDs, given the assumption that termination of pregnancy might occur more often in those cases with multiple anomalies.”


  1. Liu S, Joseph KS, Luo W, et al. Effect of folic acid food fortification in Canada on congenital heart disease subtypes. Circulation. 2016;134(9):647-655. doi:10.1161/CIRCULATIONAHA.116.022126.