Annual trends in use of periconceptional folic acid and birth prevalence of major congenital malformations.

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 1(st) 1998 and December 31(st) 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 births.

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.