Seizure Frequency in Pregnant Women with Epilepsy
Approximately one-third of pregnant women with known epilepsy will experience increased seizure frequency during pregnancy. 1, 2
Expected Seizure Patterns During Pregnancy
The evidence consistently demonstrates that seizure control varies predictably across the pregnant epilepsy population:
- Most women (approximately 70%) maintain their baseline seizure control throughout pregnancy, experiencing no significant change in seizure frequency 3, 4
- 25-33% of women experience worsening seizures with increased frequency during pregnancy 1, 2, 5
- 15-30% may experience an increase in seizures according to some studies, though the higher estimate of one-third is most commonly cited in guidelines 3, 5
- A small minority may actually experience improvement in seizure control during pregnancy 6
Why Seizure Frequency Changes
The primary mechanisms driving increased seizure activity during pregnancy include:
- Declining antiepileptic drug (AED) plasma concentrations as pregnancy progresses, largely due to marked alterations in plasma protein binding and increased hepatic metabolism 3, 5
- Medication non-compliance is a significant contributing factor, often driven by maternal fears about fetal medication exposure 3
- Hormonal changes affecting seizure threshold 6
- Metabolic disturbances during labor (hypoglycemia, electrolyte imbalances, hypoxia) can precipitate breakthrough seizures 2
Critical Management Implications
Never discontinue or reduce AEDs during pregnancy due to concerns about fetal effects—breakthrough seizures carry catastrophic risks that far outweigh medication risks. 7, 2
The clinical approach should prioritize:
- Maintaining therapeutic AED levels through close monitoring and dose adjustments as pregnancy progresses 4, 5
- If seizure control worsens, increase AED doses rather than switching medications during pregnancy 7
- Status epilepticus occurs in only 1-2% of pregnancies but requires immediate aggressive treatment 3
Common Clinical Pitfall
The most dangerous error is attempting to taper or discontinue AEDs during pregnancy when seizures are controlled, as uncontrolled seizures pose greater risks to both mother and fetus than AED exposure. 7, 2 Medication optimization should occur before conception, not during pregnancy. 7, 8