In addition to preventing neural tube defects, taking  folic acid during the month before, and during the first  2 months of pregnancy reduces the risk of fetal cleft lip with or without cleft palate by about one third, but has no apparent effect on the risk of cleft palate alone.  

Researchers performed a national population-based case–control study involving infants born in Norway between 1996 and 2001. After adjusting for usage of multivitamins, smoking, and other confounding factors, they found that 400 μg/d folic acid before and early in pregnancy was associated with an adjusted odds ratio (OR) for isolated cleft lip with or without cleft palate of 0.61 (95% CI, 0.39–0.96).  

Independent of supplements, a diet rich in fruits, vegetables, and other high-folate containing foods was associated with about a 25% reduction in risk (adjusted OR 0.75, 0.50–1.11). Women who had folate-rich diets and who took folic acid and multivitamin supplements had the lowest risk (0.36, 0.17–0.77).  