A 28-year-old woman with generalized tonic-clonic seizures has been seizure-free on phenytoin monotherapy for 2 years. She now plans pregnancy and presents for preconception counselling. She is concerned about teratogenic effects of her current antiepileptic. What is the most appropriate next step in management?

Explanation

## Antiepileptic Drug Selection in Pregnancy **Key Point:** Pregnancy planning in women with epilepsy requires careful drug selection. Lamotrigine and levetiracetam are preferred over older agents like phenytoin, valproate, and carbamazepine due to lower teratogenic risk. ### Why Lamotrigine Is the Best Choice Here **High-Yield:** Lamotrigine has the lowest teratogenic risk profile among commonly used antiepileptics, with an estimated major malformation rate of 2–3%, comparable to the general population baseline. Phenytoin carries a 5–10% risk of fetal hydantoin syndrome (cleft palate, cardiac defects, growth restriction). **Clinical Pearl:** Lamotrigine undergoes increased hepatic glucuronidation during pregnancy, particularly in the third trimester. Dose escalation by 50–100% may be needed to maintain seizure control. This requires therapeutic drug monitoring and careful counseling. ### Comparative Risk Profile | Antiepileptic | Teratogenic Risk | Fetal Syndrome | Pregnancy Consideration | |---|---|---|---| | **Lamotrigine** | 2–3% (low) | Rare | Preferred; requires dose ↑ | | **Levetiracetam** | 1–2% (very low) | None established | Preferred alternative | | **Phenytoin** | 5–10% (high) | Fetal hydantoin syndrome | Avoid; switch preconception | | **Valproate** | 10–20% (very high) | Valproate syndrome | Contraindicated | | **Carbamazepine** | 4–5% (moderate) | Carbamazepine syndrome | Avoid if alternatives available | **Mnemonic:** **LAME** = **L**amotrigine, **A**cetazolamide (adjunct), **M**gSO₄ (seizure prophylaxis in eclampsia), **E**xchange transfusion (not AED, but context) — drugs relatively safe in pregnancy. ### Additional Management Points 1. **Folic acid supplementation:** 4–5 mg daily (higher than standard 400 μg) due to antiepileptic-induced folate depletion. 2. **Baseline and trimester-wise drug level monitoring:** Lamotrigine levels often fall by 40–60% by third trimester. 3. **Postpartum dose adjustment:** Return to prepregnancy doses after delivery, as glucuronidation normalizes. 4. **Seizure risk in pregnancy:** Approximately 25–30% of women experience increased seizure frequency; discontinuation is not recommended. [cite:Harrison 21e Ch 369]