Primary generalized epilepsy: a risk factor for seizures in labor and delivery?

PURPOSE Women in the United States who have epilepsy give birth to about 20000 newborns every year. Because seizures during late gestation and delivery may seriously affect the fetus, and because primary generalized tonic-clonic (GTC) seizures may occur during labor and delivery in 1-2% of women with epilepsy, we attempted to define the rate, risks, and causes of seizures during labor and delivery. METHODS To characterize seizures during labor and delivery, we retrospectively analyzed 89 consecutive pregnancies of women with epilepsy on antiepileptic drugs (AEDs). Six epileptologists in our group had treated these patients. We confirmed data and acquired new information by telephone for 83.1% of the pregnancies, and categorized the women as having primary generalized or partial epilepsy. Most of the patients (78%) were on monotherapy during pregnancy; 20% took two AEDs, and 3% took three AEDs during that period. RESULTS Seizures during labor and delivery occurred in 4/32 (12.5%) patients with primary generalized epilepsy, but in none of the 57 women with partial epilepsy (P<0.05). None of the 38 patients with therapeutic AED levels before labor and delivery had seizures, compared to 3/37 (8.1%) of the subtherapeutic group. However, drug levels were taken at variable times in relation to delivery, limiting their value. Also, the levels sampled were both total and free levels; the latter would be more helpful to determine the adequacy of AED drug coverage. CONCLUSIONS Maintaining therapeutic AED levels during the last trimester may help prevent seizures during labor and delivery, especially in women with generalized epilepsy. Women with epilepsy who had subtherapeutic AED levels and had been seizure-free may be at-risk for seizures during labor and delivery. Our sample was small, and a random sampling bias may have affected the results.