Primary prevention of birth defects by periconceptional care, including multivitamin supplementation.

Periconceptional care can significantly reduce untoward pregnancy outcomes and birth defects. The avoidance of alcohol, rubella vaccination and special care for certain maternal disorders can prevent some CAs. Periconceptional multivitamin supplementation, including a physiological dose of folic acid, has been shown to reduce the occurrence of NTDs and some other major CAs. The preventable proportion of the latter group is three times higher than the incidence of NTDs. Thus, periconceptional care that includes such supplementation increases the proportion of preventable defects and improves the efficacy of primary prevention.