![Preconception Health and Folic Acid](/web/20061214091444im_/http://www.phac-aspc.gc.ca/fa-af/images/preconception.gif)
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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