Evaluation of placental function in women on antiepileptic drugs.

Placental function in the presence of antiepileptic drugs was assessed in 144 unselected late pregnancies of women with epilepsy. The most common drugs of the mothers were phenytoin (104 pregnancies), carbamazepine (42) and phenobarbitone (26). 144 control parturients matched for maternal age, parity, fetal sex and social class were also studied. No significant associations between the types or the serum concentrations of the mother's antiepileptic drugs and her serum HPL, 24-hour total urinary estriol excretion, placental weight or her child's birth weight were observed. However, since the serum levels of antiepileptic drugs were usually within or below the therapeutic ranges the study does not exclude the possibility that very high drug concentrations might have some effects. The incidences of common pregnancy complications did not differ between epileptics and controls. Serum HPL and urinary estriol values in epileptic women agreed well with the references for normal. It is concluded that the long-term use of antiepileptic drugs during pregnancy has no clinically important effects on placental function or on its biochemical tests in spite of the enzyme induction properties of these drugs. Values of serum HPL and 24-hour total urinary estriol excretion can thus be interpreted in the usual manner in women who are on antiepileptic medication.