Folic acid may have a role in the prevention of other birth defects, such as:

• oral clefts (cleft palate, cleft lip), and
• some congenital heart defects relating to cardiac outflow. 

Congenital defects in cardiac outflow result in conditions that are usually fatal if not surgically corrected: 

• transposition of the great arteries,

• double outlet right ventricle,

• truncus arteriosus,

• tetralogy of Fallot, and

• the rare abnormalities, such as double outlet left ventricle.[13] 

In one randomized trial [14] and several case-control studies,[15] [16] [17] researchers observed that among women who consumed vitamin supplements and folate-fortified food, fewer pregnancies resulted in oral clefts and congenital heart defects. 

Additionally, there is some evidence that folic acid supplementation may prevent other birth defects, such as limb reduction and urinary tract defects.[18]

More research is needed to determine if the effect observed in all of these studies was from folic acid or from a combination of vitamins, and to ensure that the findings are valid.[7]