Background: Recent evidence suggests that periconceptional folic acid use could not only prevent neural tube
defects but also other malformations. The objectives of this study were to assess trends in dispensed high dose
periconceptional folic acid (5 mg) and birth prevalence of major congenital malformations.
Methods: The Quebec Pregnancy Registry, an administrative database with information on periconceptional prescribed
medication and diagnostic codes was used to conduct this study.
All pregnant women insured by the Quebec public drug plan between January 1st 1998 and December 31st 2008 were
included. The exposure was defined as the use of high dose periconceptional folic acid 30 days before, and during the first
70 days of pregnancy. The outcome measured was the birth prevalence of major congenital malformations among live
Results: We identified 152,392 pregnancies and babies. The annual prevalence of high dose periconceptional folic acid
use increased from 0.17% to 0.80% (p<0.05) during the study period; birth prevalence of congenital malformations
increased by 15% (3.35% to 3.87%, p<0.05). More specifically, a 23% increase in the prevalence of cardiac malformation
and 23% increase in musculoskeletal defects were observed, whereas there was no change in the prevalence of
malformations of the nervous system.
Conclusions: Although there was an increase in the use of periconceptional high dose folic acid over the past decade,
there was no decrease in the prevalence of major congenital malformations. A limitation of this study is the absence of
data on low dose folic acid use, available over the counter, in our administrative database.