Association between catamenial epilepsy and seizure frequency during pregnancy

To compare seizure outcomes during pregnancy in women with epilepsy (WWE) by history of catamenial patterns.

Catamenial patterns are defined as increased seizure frequency during certain phases of the menstrual cycle (perimenstrual, peri-ovulatory, or luteal in anovulatory cycles). Animal studies suggest seizure improvement occurs with higher progesterone and allopregnanolone concentrations and lower estrogen concentrations. Prior human studies also reported that WWE with catamenial patterns were more likely to have improved seizure frequency during pregnancy, presumably due to higher sensitivity to fluctuations in sex steroid hormones.

Women with epilepsy (WWE), ages 18-40yo, were enrolled in a longitudinal, prospective cohort study at time of attempting conception to compare fertility outcomes to healthy controls. Once enrolled, WWE used a daily diary app for menstrual and seizure tracking from preconception through delivery. For this secondary analysis, participants were excluded if they chose to discontinue the study, if they did not become pregnant, were seizure free preconception, if their diary data was inadequate (defined as <80 % of the days tracked), or if they had <1 month of seizure data tracked prior to conception. Prospective diary data was used to determine if participants met criteria for observed catamenial patterns. Seizure frequency during pregnancy was compared to preconception frequency.

Among 89 participants, 13 became pregnant with seizure tracking; 6 (46 %) met criteria for catamenial epilepsy. Focal epilepsy was less common than generalized epilepsy in the catamenial group (33 %) vs the non-catamenial group (86 %, p = 0.10). No significant differences in seizure frequency change from preconception to pregnancy were observed between groups (p = 0.42). During pregnancy, 33 % of the catamenial group and 43 % of the non-catamenial group became seizure-free (p = 0.99). Seizure improvement or stability occurred in 67 % and 86 %, respectively (p = 0.56).

In patients who had preconception seizures, seizure control during pregnancy was generally favorable: many patients' seizure frequency improved or achieved seizure freedom. There was no clear evidence that a pre-conception catamenial pattern immediately before pregnancy altered prognosis. Further research is needed to guide counseling and treatment during pregnancy.