Anticonvulsant drugs in monotherapy. Effect on the fetus.

We describe a material of 577 infants born of epileptic women treated with anticonvulsants in monotherapy during early pregnancy and collected from France, Italy, and Sweden. The incidence of major malformations is increased compared with the general population but no definite difference in risk can be demonstrated between the various anticonvulsants, but valproic acid was associated with a doubling of the average risk. The increased risk for facial clefts and for cardiac malformations, described from most studies on epilepsy during pregnancy, cannot be seen in this material. Unusually many cases of penis abnormalities (micropenis, hypospadias) were noted. An effect on fetal growth can be demonstrated and is apparently more pronounced for carbamazepine than for the other drugs. It results in a reduced birth weight in spite of normal gestational length, reduced body length and head circumference. The possible biological significance of this finding is discussed.