Preconception Health and Folic Acid
Anything Else I Should Know?

Yes. As with all of science, our knowledge of congenital anomalies, including the prevention of NTDs, is continually evolving. New research findings may emerge that will require this resource document to be updated. For example, several initiatives are under way in Canada to assess the effect of food fortification with folic acid. In the United States, a recent study found that the birth prevalence of NTDs in that country dropped by 19% following the introduction of a fortification program similar to that in Canada. ⁵³

Researchers have looked at the relationship between use of folic acid supplements in the periconceptional period and the rate of multiple births. ^{54 55} At this time, the evidence for an association between increased periconceptional folic acid consumption and increased rate of twins is inconclusive. However, because of population differences in the frequency of twins, there remains the possibility that the twin rates in populations with higher existing rates of twinning, such as Afro-Americans, may be affected by folic acid consumption, as compared with populations such as the Chinese that have much lower rates of twinning. Keep in mind that NTDs occur more frequently in twin pregnancies, particularly monozygotic twins, than in singleton pregnancies, independent of folic acid use. ¹²

A recent initiative to improve population-based surveillance of congenital anomalies, including fetal anomalies, is the Canadian Congenital Anomalies Surveillance Network (CCASN). The network, led by an advisory group of experts in genetics, epidemiology and related fields, will lead the development of standards and guidelines for the collection of data on congenital anomalies in Canada.

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