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Poster Session 2

Category: Medical/Surgical/Diseases/Complications

Poster Session 2

(414) Antiseizure medication use in pregnancy and risk of seizure in patients with epilepsy

Wednesday, February 11, 2026

3:30 PM - 5:00 PM

Submitting Author and Presenting Author(s)

Amelie Pham, MD (she/her/hers)

Assistant Professor
Vanderbilt University Medical Center
Nashville, Tennessee, United States

Coauthor(s)

CY

Chaochen You, MA, MD

Senior Database Administrator
Vanderbilt University Medical Center
Vanderbilt University Medical Center, Tennessee, United States
AW

Andrew D. Wiese, MPH, PhD

Assistant Professor
Vanderbilt University Medical Center
Vanderbilt University Medical Center, Tennessee, United States
AS

Andrew J. Spieker, PhD

Assistant Professor of Biostatistics
Vanderbilt University Medical Center
Vanderbilt University Medical Center, Tennessee, United States
AL

Ashley A. Leech, MS, PhD

Vanderbilt University Medical Center
Vanderbilt University Medical Center, Tennessee, United States
Margaret A. Adgent, MSPH, PhD (she/her/hers)

Research Associate Professor
Vanderbilt University Medical Center
Vanderbilt University Medical Center, Tennessee, United States
AS

Alexandra Sundermann, MD, PhD

Vanderbilt University Medical Center
Vanderbilt University Medical Center, Tennessee, United States
CG

Carlos G. Grijalva, MD, MPH

Professor
Vanderbilt University Medical Center
Vanderbilt University Medical Center, Tennessee, United States
Sarah S. Osmundson, MD, MS

Associate Professor
Vanderbilt University Medical Center
Vanderbilt University Medical Center, Tennessee, United States

Objective:
Antiseizure medications (ASM) are the primary method for epileptic seizure control in pregnancy. We examined the association between ASM adherence and the risk of seizure in pregnant individuals with epilepsy.

Study Design:
This nested case-control study examined a retrospective cohort of pregnant individuals continuously enrolled in Tennessee Medicaid (2007–2019). Linked maternal-infant data included healthcare claims and discharge data, prescription fills, and birth certificates. Pregnancies with ≥ 20 weeks’ gestation among individuals aged 15–44 with epilepsy diagnosis prior to conception and ASM exposure were included. Seizures during pregnancy were identified using ICD 9/10 and CPT code algorithms (Table 1). Each case was matched to up to 10 controls with replacement by gestational age at first seizure (index date, ±2 days). ASM adherence was measured as the proportion of days covered during a 60-day window before the index date. We used conditional logistic regression to estimate the association between ASM adherence prior to seizure onset and seizure risk in pregnancy, adjusting for a-priori selected confounders and using cluster-robust standard errors.

Results:
Among 1,491 eligible pregnancies, we examined 354 cases (24%) and 1,468 matched controls (Table 1). Most seizures occurred in the first trimester (47%, 168/354). Mean ASM adherence was low in both cases and controls. Each 10% increase in ASM adherence was associated with 5.5% higher odds of seizure (95% CI: 1.30%–9.87%, Table 2). Findings were similar when excluding cases of index seizure date within 60 days of conception.

Conclusion:
Among pregnant patients with epilepsy, ASM adherence was low, and seizures were common. Preliminary analysis noted that a small increase in ASM adherence was associated with higher odds for seizure events. Further analyses should examine whether pre-pregnancy epilepsy severity impacts ASM adherence and seizure control during pregnancy.