Folic acid is a recognized environmental factor associated with the occurrence of cleft lip and palate. Multiple studies have evaluated the relationship between maternal folic acid supplementation and the occurrence of clefts using epidemiological designs. However, the effects of folic acid on cleft lip and palate cited in studies remain generally inconsistent. This paper briefly reviews the epidemiological studies on the effect of maternal folic acid supplementation on cleft lip and palate to provide a reference for further understanding of this relationship.
