Plasma vitamin values and antiepileptic therapy: case reports of pregnancy outcomes affected by a neural tube defect.

Background: Folic acid supplementation reduces the occurrence of neural tube defects (NTDs); however, it is not clear whether it protects against teratogenic effects of antiepileptic drugs.

Methods: We report the cases of four pregnant women receiving valproic acid therapy, who all had NTD-affected offspring, despite periconceptional 5 mg/day of folic acid supplementation (cases), and investigated homocysteine metabolism, linked with folate metabolism. Their plasma homocysteine, folates, and vitamin B6 and B12 results were compared with values of two other women, who were also receiving valproic acid and folic acid complement, but who had normal pregnancies (valproic acid controls), and values of 40 pregnant women who had normal pregnancies and were not receiving any therapy (controls without therapy).