A patient with bipolar I disorder has been stable on lithium for 3 years. She becomes pregnant. The neonatologist is concerned about which lithium-associated fetal risk, and which management strategy is most evidence-based in early pregnancy?

• A Neural tube defects; switch to valproate after counselling
• B Ebstein's anomaly; discuss risk–benefit; lithium may be continued with fetal echocardiography at 18–20 weeks if risk of relapse is high ✓
• C Limb reduction defects; mandatory discontinuation in trimester 1
• D Ventricular septal defects; replace lithium with lamotrigine without dose adjustment

Explanation

Lithium carries a small absolute risk of Ebstein's anomaly (tricuspid valve malformation), estimated at 1–2 per 1000 exposures vs 1 per 20,000 in unexposed, representing a roughly 2-fold relative risk. Current guidelines favour shared decision-making: if the risk of bipolar relapse is high, lithium may be continued with monitoring (fetal echocardiography). Abrupt discontinuation sharply increases relapse risk. Valproate is teratogenic (neural tube defects, cognitive effects) and is contraindicated in women of childbearing potential. Lamotrigine requires dose increase during pregnancy due to enhanced clearance.

Reference: Kaplan & Sadock's Synopsis of Psychiatry, 11th ed.

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