Women & Epilepsy: Pregnancy & Contraception
The management of epilepsy in women of childbearing potential requires careful attention to the bidirectional interactions between antiseizure medications (ASMs) and reproductive hormones, the teratogenic risks of specific ASMs, and the pharmacokinetic changes of pregnancy. Approximately 1.5 million people with epilepsy of childbearing potential (PWECP) live in the United States, and roughly 24,000 give birth each year. In May 2024, the AAN, AES, and SMFM jointly published an updated practice guideline addressing teratogenesis, perinatal outcomes, and neurodevelopmental effects of in utero ASM exposure — the most comprehensive revision since 2009. This topic integrates these guidelines with data from major pregnancy registries (EURAP, NAAPR, MONEAD, NEAD) to provide an evidence-based framework for preconception counseling, pregnancy management, contraception, and breastfeeding in women with epilepsy.
Bottom Line
- Valproate is the highest-risk ASM in pregnancy: Dose-dependent major congenital malformation (MCM) rate of 10.3%, plus neurodevelopmental impairment including lower IQ and increased autism spectrum disorder risk — the AAN mandates avoidance in PWECP if clinically feasible
- Safest ASMs in pregnancy: Lamotrigine, levetiracetam, and oxcarbazepine have MCM rates ≤3% and favorable neurodevelopmental profiles
- Folic acid ≥0.4 mg/day is recommended for all PWECP from preconception through pregnancy; higher doses (4–5 mg/day) may be considered for those on valproate or carbamazepine
- Lamotrigine clearance increases 50–100% during pregnancy due to estrogen-driven glucuronidation — monthly level monitoring and proactive dose adjustments are essential
- Enzyme-inducing ASMs reduce hormonal contraceptive efficacy: IUDs (especially levonorgestrel-releasing) are the most reliable reversible contraception for women on enzyme-inducing ASMs
- Catamenial epilepsy affects ~40% of women with epilepsy; recognition of perimenstrual (C1), periovulatory (C2), and luteal (C3) patterns guides targeted hormonal therapy
- Breastfeeding is encouraged for women on most ASMs; infant monitoring for sedation is advised for phenobarbital, lamotrigine, and zonisamide
Preconception Counseling & Planning
Preconception counseling should begin at the first prescription of an ASM to any person of childbearing potential — ideally during adolescence as part of transition care. The AAN quality measures for epilepsy include counseling PWECP (age ≥12 years) on folic acid supplementation, ASM–contraceptive interactions, and teratogenic risks at every visit. Because 65% of pregnancies in women with epilepsy are unplanned, these conversations must be ongoing rather than deferred until pregnancy is actively planned.
Preconception Counseling Checklist
- Review current ASM regimen for teratogenic risk — transition off valproate, topiramate (if possible), and phenobarbital before conception
- Optimize seizure control on the lowest effective dose of a pregnancy-compatible ASM (lamotrigine, levetiracetam, or oxcarbazepine preferred)
- Achieve seizure freedom for ≥9 months before conception — associated with 84–92% chance of remaining seizure-free during pregnancy
- Start folic acid supplementation: minimum 0.4 mg/day (up to 4–5 mg/day if on valproate or carbamazepine)
- Obtain baseline ASM serum level to serve as reference target during pregnancy
- Discuss contraception: ensure current method is compatible with ASM regimen
- Assess bone health: DEXA scan if on long-term enzyme-inducing ASMs; supplement vitamin D
- Genetic counseling if familial epilepsy syndrome or known pathogenic variant
- Establish multidisciplinary care: neurology, maternal-fetal medicine, and anesthesia
ASM Teratogenicity
Major Congenital Malformation Risk
The EURAP registry (7,355 pregnancies exposed to monotherapy) and the North American Antiepileptic Drug Pregnancy Registry (NAAPR) provide the most robust data on ASM teratogenicity. The 2024 AAN/AES/SMFM guideline synthesizes these registry data alongside systematic reviews to generate actionable recommendations. Teratogenic risk is dose-dependent for valproate, carbamazepine, lamotrigine, and phenobarbital.
| ASM (Monotherapy) | MCM Rate | Key Malformations | Dose-Dependence |
|---|---|---|---|
| Valproate | 10.3% | Neural tube defects (1–2%), cardiac defects, hypospadias, cleft palate | Strong — risk increases above 600–700 mg/day |
| Phenobarbital | 6.5% | Cardiac defects, cleft lip/palate | Yes |
| Phenytoin | 6.4% | Cardiac defects, cleft lip/palate, fetal hydantoin syndrome | Moderate |
| Carbamazepine | 5.5% | Neural tube defects (0.5–1%), cardiac defects | Yes — risk increases above 400 mg/day |
| Topiramate | 3.9% | Cleft lip/palate (OR 5.4), SGA (18.5%) | Moderate |
| Oxcarbazepine | ≤3% | No specific pattern identified | Limited data |
| Lamotrigine | 2.3–2.9% | No specific pattern; risk increases above 300 mg/day | Weak |
| Levetiracetam | 2.4–2.8% | No specific pattern identified | Not demonstrated |
Neurodevelopmental Outcomes
Beyond structural malformations, in utero ASM exposure can affect neurodevelopment. The NEAD study demonstrated that children exposed to valproate had significantly lower IQ scores at ages 3, 4.5, and 6, with a dose-dependent relationship. These children also experienced impaired learning, memory, and adaptive functioning. The MONEAD study, however, showed that adaptive functioning of children exposed to commonly used ASMs (excluding valproate) did not significantly differ from controls. Folic acid supplementation during periconception and pregnancy is associated with improved cognitive and behavioral outcomes, including reduced risk of autism spectrum disorder.
Valproate in Pregnancy — 2024 AAN Mandate
- Clinicians must avoid valproic acid in PWECP to minimize the risk of MCMs, neural tube defects, and offspring born small for gestational age
- Clinicians must avoid valproic acid in PWECP to reduce the risk of poor neurodevelopmental outcomes including autism spectrum disorder and lower IQ
- If valproate is the only effective ASM, use the lowest effective dose (<600 mg/day if possible) with high-dose folic acid (4–5 mg/day)
- Exercise caution when attempting to remove or replace a well-controlling ASM if the patient is already pregnant — breakthrough convulsive seizures pose immediate risk
Pharmacokinetic Changes in Pregnancy
Pregnancy profoundly alters ASM pharmacokinetics through multiple mechanisms: increased plasma volume and total body water (expanded volume of distribution), enhanced hepatic metabolism (particularly glucuronidation driven by rising estrogen), increased renal clearance, decreased protein binding, and altered gastrointestinal absorption. The MONEAD study demonstrated significant gestational decreases in serum concentrations of lamotrigine, levetiracetam, lacosamide, oxcarbazepine, topiramate, and zonisamide. By contrast, carbamazepine and valproic acid concentrations remain relatively stable throughout pregnancy.
| ASM | Clearance Change in Pregnancy | Mechanism | Monitoring Recommendation |
|---|---|---|---|
| Lamotrigine | ↑ 50–100% | Estrogen-induced glucuronidation | Monthly levels; preemptive dose increase; target ≥65% of preconception level |
| Levetiracetam | ↑ 40–60% | Increased renal clearance | Levels each trimester; dose adjustment as needed |
| Oxcarbazepine (MHD) | ↑ 30–50% | Glucuronidation and renal clearance | Levels each trimester |
| Lacosamide | ↑ 25–40% | CYP2C19 induction, renal clearance | Levels each trimester |
| Topiramate | ↑ 30–40% | Renal clearance | Levels each trimester |
| Zonisamide | ↑ 25–35% | CYP3A4 induction, renal clearance | Levels each trimester |
| Carbamazepine | Minimal change | Autoinduction already maximal | Check if clinical change; no routine increase needed |
| Valproic acid | Minimal change (total); free fraction ↑ | Decreased protein binding | Free levels preferred; total levels may be misleading |
Practical ASM Monitoring During Pregnancy
- Obtain a preconception baseline serum level when the patient is seizure-free and on a stable dose
- For lamotrigine: check levels monthly; proactively increase dose when level drops ≥25% from baseline or if level falls below 65% of target
- For levetiracetam, lacosamide, and oxcarbazepine: check levels at least once per trimester and after any seizure
- Postpartum: rapidly taper dose increases over 2–3 weeks after delivery to prevent supratherapeutic levels (especially lamotrigine — toxicity risk within days of delivery)
- The ILAE Task Force on Women and Pregnancy recommends early and frequent therapeutic drug monitoring beginning in the first trimester
Seizure Risk During Pregnancy & Labor
The MONEAD study (N = 351 pregnant women with epilepsy) found no significant difference in seizure frequency between pregnant and nonpregnant women with epilepsy, challenging earlier assumptions. ASM doses were changed at least once in 74% of pregnant patients compared with 31% of nonpregnant controls. Seizure freedom for ≥9 months before conception predicts an 84–92% likelihood of remaining seizure-free throughout pregnancy. Tonic-clonic seizures during pregnancy carry risks of fetal hypoxia, placental abruption, and trauma — making seizure control a paramount priority.
During labor and delivery, 1–2% of women with epilepsy experience a seizure. Epilepsy alone is not an indication for cesarean delivery unless consciousness is impaired during labor. Seizures during labor are managed with IV benzodiazepines (lorazepam preferred) followed by IV levetiracetam or phenytoin for sustained seizure activity. Magnesium sulfate for eclampsia prophylaxis is safe in women with epilepsy (unlike in myasthenia gravis) but has limited antiseizure efficacy for epileptic seizures.
Contraception in Women with Epilepsy
The interaction between ASMs and hormonal contraceptives is bidirectional: enzyme-inducing ASMs reduce contraceptive efficacy by accelerating estrogen and progestin metabolism, while estrogen-containing contraceptives reduce lamotrigine levels by enhancing glucuronidation. Data from the Epilepsy Birth Control Registry show that 78.9% of women with epilepsy reported at least one unintended pregnancy, underscoring the urgency of effective contraceptive counseling.
| ASM Category | Specific ASMs | Effect on Hormonal Contraception | Recommended Contraceptive |
|---|---|---|---|
| Strong enzyme inducers | Carbamazepine, phenytoin, phenobarbital, primidone | Significantly reduce estrogen & progestin levels | Levonorgestrel IUD, copper IUD, or depot medroxyprogesterone |
| Moderate enzyme inducers | Topiramate (≥200 mg/d), oxcarbazepine (≥1500 mg/d), eslicarbazepine, clobazam, felbamate, rufinamide | Reduce estrogen & progestin levels (dose-dependent) | Levonorgestrel IUD, copper IUD; avoid oral contraceptives |
| Progestin level reducers | Perampanel (≥8 mg/d), cenobamate | Reduce progestin levels | IUD preferred; supplement barrier method if using oral pills |
| Non-enzyme-inducing ASMs | Lamotrigine, levetiracetam, lacosamide, valproate, gabapentin, pregabalin, zonisamide, brivaracetam | No significant effect on hormonal contraception | Any method; note: estrogen-containing OCP lowers lamotrigine levels by 40–60% |
Key Contraception Principles
- The levonorgestrel-releasing IUD (Mirena, Liletta) is the most reliable reversible contraceptive for women on enzyme-inducing ASMs — local progestin action is not affected by hepatic enzyme induction
- The copper IUD is equally effective and avoids all hormonal interactions
- If combined oral contraceptives are used with lamotrigine: expect lamotrigine levels to drop 40–60% during the active pill weeks and rebound during the placebo week — adjust lamotrigine dose accordingly and consider continuous-cycle OCP to avoid fluctuations
- Emergency contraception with levonorgestrel (Plan B) may have reduced efficacy in women on enzyme-inducing ASMs — the copper IUD is the most effective emergency contraceptive regardless of ASM status
- Depot medroxyprogesterone (Depo-Provera) retains efficacy with enzyme-inducing ASMs when given at standard doses
Catamenial Epilepsy
Catamenial epilepsy describes seizure exacerbation linked to the menstrual cycle, affecting approximately 40% of women with epilepsy. The diagnosis requires demonstration of a ≥twofold increase in seizure frequency during a specific cycle phase over 2–3 consecutive cycles. Three patterns are recognized based on the hormonal milieu:
| Pattern | Cycle Phase | Days | Hormonal Mechanism | Treatment Strategy |
|---|---|---|---|---|
| C1 — Perimenstrual | Late luteal to menstruation | Day −3 to day +3 | Rapid progesterone withdrawal (proconvulsant shift) | Intermittent clobazam or acetazolamide perimenstrually; cyclic progesterone supplementation |
| C2 — Periovulatory | Ovulation | Day 10 to day −13 | Midcycle estrogen surge (proconvulsant) | Intermittent clobazam or acetazolamide around ovulation |
| C3 — Luteal | Entire second half of cycle | Day 10 to day +3 (anovulatory) | Inadequate luteal progesterone in anovulatory cycles | Cyclic progesterone (natural progesterone lozenges 200 mg TID, days 14–28 with taper); consider medroxyprogesterone |
The NIH Progesterone Treatment Trial confirmed that cyclic natural progesterone was superior to placebo specifically in women with robust perimenstrual (C1) seizure exacerbation (≥threefold increase in frequency). For C2 patterns, intermittent benzodiazepine prophylaxis (clobazam 10–20 mg/day for 3–4 days around ovulation) is commonly used. Acetazolamide (250–500 mg/day) is an alternative intermittent strategy with diuretic and mild carbonic anhydrase inhibitory effects that may reduce seizure susceptibility.
Menopause & Epilepsy
Perimenopause (lasting up to 5.5 years) is characterized by hormonal fluctuations that may exacerbate seizures, particularly in women with a history of catamenial epilepsy. Women with epilepsy may experience early onset of perimenopausal symptoms. After menopause (defined as 12 months without menses), women who had catamenial patterns often experience seizure improvement. Hormone replacement therapy (HRT) can be considered in consultation with gynecology but requires monitoring for seizure exacerbation. Estrogen-only HRT carries a higher theoretical risk of increased seizures than combined estrogen-progesterone HRT. Nonestrogen-based therapies should be considered first-line for vasomotor symptoms in women with epilepsy who experienced catamenial seizure patterns.
Breastfeeding
The American Academy of Pediatrics recommends exclusive breastfeeding for at least 6 months. The ILAE Women Task Force systematic review concluded that breastfeeding should be encouraged in women with epilepsy, as the amount of ASM transferred via breast milk is substantially lower than in utero placental transfer. The MONEAD study found that breastfeeding rates were lower in women with epilepsy compared to controls, but this difference was not significant after adjusting for maternal education and IQ.
| ASM | Milk:Plasma Ratio | Breastfeeding Safety | Monitoring |
|---|---|---|---|
| Lamotrigine | 0.6–1.0 | Compatible; moderate milk transfer | Monitor infant for rash; observe for sedation |
| Levetiracetam | 1.0 | Compatible; minimal clinical effect on infant | Routine observation |
| Valproate | 0.01–0.10 | Compatible; very low milk transfer | Routine observation |
| Carbamazepine | 0.4–0.6 | Compatible; moderate transfer | Monitor for sedation, hepatic function |
| Oxcarbazepine | 0.5 | Compatible | Routine observation |
| Phenobarbital | 0.4–0.6 | Compatible with caution; extensive transfer | Monitor for sedation, poor feeding; infant drug levels if symptomatic |
| Zonisamide | 0.9–1.0 | Compatible with monitoring; extensive transfer | Monitor for sedation and poor feeding |
| Topiramate | 0.7–0.9 | Compatible with monitoring | Monitor for sedation, diarrhea |
Bone Health & ASMs
The impact of ASMs on bone health is a particularly important consideration in women, who face cumulative bone loss from multiple sources: enzyme-inducing ASMs, pregnancy and lactation, and postmenopausal estrogen decline. Enzyme-inducing ASMs (carbamazepine, phenytoin, phenobarbital) accelerate vitamin D catabolism via CYP450 induction, leading to reduced calcium absorption, secondary hyperparathyroidism, and decreased bone mineral density. Valproate also adversely affects bone health through non-CYP mechanisms, including direct osteoblast inhibition and increased bone resorption markers.
Women with epilepsy on long-term enzyme-inducing ASMs have a 2–6-fold increased fracture risk compared to the general population. The risk is compounded by repeated falls during seizures, postictal confusion, and ASM-related ataxia. Baseline DEXA screening is recommended for women on enzyme-inducing ASMs for >5 years, postmenopausal women with epilepsy, and any patient with fragility fracture. Vitamin D supplementation (1,000–2,000 IU/day) and calcium (1,000–1,200 mg/day) should be prescribed for all women on enzyme-inducing ASMs, with 25-OH vitamin D levels monitored at least annually (target ≥30 ng/mL). Weight-bearing exercise is recommended to maintain bone density, and bisphosphonate therapy should follow standard osteoporosis guidelines for women with documented low bone mineral density.
Pregnancy Registries & Key Studies
| Registry/Study | Full Name | Design | Key Contributions |
|---|---|---|---|
| EURAP | European & International Registry of Antiepileptic Drugs in Pregnancy | Prospective observational; 7,355+ monotherapy pregnancies | Comparative MCM rates across 8 ASMs; dose-dependence of risk; topiramate SGA risk |
| NAAPR | North American Antiepileptic Drug Pregnancy Registry | Prospective enrollment; Harvard-based | Specific MCM rates for individual ASMs; topiramate cleft palate signal |
| MONEAD | Maternal Outcomes and Neurodevelopmental Effects of Antiepileptic Drugs | NIH-funded prospective cohort | Seizure frequency in pregnancy; ASM pharmacokinetics; breastfeeding outcomes; child adaptive functioning |
| NEAD | Neurodevelopmental Effects of Antiepileptic Drugs | Prospective observational | Valproate cognitive effects at ages 3, 4.5, and 6; dose-dependent IQ reduction; folic acid protection |
Folic Acid Supplementation
Periconceptional folic acid reduces neural tube defect risk and improves neurodevelopmental outcomes. The 2024 AAN guideline recommends at least 0.4 mg/day for all PWECP on ASMs, from preconception through pregnancy. Higher doses (4–5 mg/day) are historically recommended for those on valproate or carbamazepine, which specifically interfere with folate metabolism. Valproate targets folate receptors, decreasing brain and placental uptake of folic acid metabolites.
The evidence supporting folic acid supplementation is robust. In the NEAD study, periconceptional folic acid supplementation was associated with higher IQ scores in children at age 6, particularly those exposed to valproate in utero. A Norwegian prospective cohort study found that folic acid supplementation in pregnancy was associated with reduced risk of autistic traits in children exposed to ASMs. The Norwegian Mother, Father and Child Cohort Study demonstrated that folic acid was associated with better verbal abilities at ages 5 and 8 in children of mothers with epilepsy.
A 2022 observational study raised concerns about an association between high-dose folic acid (≥1 mg/day) in pregnancy and childhood cancer risk, but multiple experts have identified significant methodologic flaws, concluding the study demonstrated only association rather than causation. The consensus remains strongly in favor of folic acid supplementation. Because half of pregnancies are unplanned, folic acid should be prescribed to all PWECP from menarche through menopause, not just when pregnancy is planned.
Folic Acid Dosing Recommendations
- All PWECP on any ASM: ≥0.4 mg/day (2024 AAN guideline)
- PWECP on valproate, carbamazepine, phenytoin, or phenobarbital: Consider 4–5 mg/day (folate-interfering ASMs)
- Timing: Begin at least 1–3 months before conception; continue throughout pregnancy and postpartum
- Prescription vs. over-the-counter: Standard prenatal vitamins contain 0.8–1.0 mg folic acid; prescription folic acid (1 mg or 4 mg tablets) may be needed for higher doses
- MTHFR variants: L-methylfolate (active form) may be considered in patients with known MTHFR polymorphisms, though clinical benefit over standard folic acid is unproven
Neurostimulation & Dietary Therapy in Pregnancy
For women with drug-resistant epilepsy on neurostimulation or dietary therapies, pregnancy planning requires additional consideration. Limited data from small case series suggest that vagus nerve stimulation (VNS) is safe during pregnancy, with a tendency toward increased obstetric complications (mostly cesarean deliveries). A single case report found deep brain stimulation (DBS) safe without adverse pregnancy outcomes. Responsive neurostimulation (RNS) data are limited but early case series showed no major congenital malformations. The effect of ketogenic diets on fetal development is uncertain — ketones cross the placenta, and elevated maternal ketone levels have been associated with decreased childhood IQ, oligohydramnios, and fetal heart rate irregularities. Ketogenic diets are generally not recommended during pregnancy, and the NAAPR is collecting data on outcomes.
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