# Mood Stabiliser Teratogenicity > Mood stabiliser teratogenicity for FMGE Pharmacology: valproate 10% malformation risk, lithium Ebstein anomaly, lamotrigine safest and folic acid 5 mg. - Canonical URL: https://prepelephant.com/topics/fmge/pharmacology/mood-stabiliser-teratogenicity-fmge - Exam / course: FMGE · Subject: Pharmacology - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Mood Stabiliser Teratogenicity", PrepElephant, https://prepelephant.com/topics/fmge/pharmacology/mood-stabiliser-teratogenicity-fmge ## Direct answer Valproate sits at the top of the teratogenic league among mood stabilisers: roughly one in ten exposed pregnancies results in a major malformation — neural tube defects, cardiac, renal and limb anomalies — plus neurodevelopmental impairment in a further proportion, which is why it is contraindicated in pregnancy and in women who can become pregnant unless no alternative exists and a pregnancy-prevention conversation is documented; Indian product labels now carry this warning in line with international action. Carbamazepine roughly doubles baseline malformation risk with neural tube defects of its own; lithium's classic association is Ebstein anomaly, though in absolute terms the risk is about 1 in 1000, and continuation with level monitoring is often safer for both mother and baby than relapse. Lamotrigine is the safest antiepileptic-type option at around 3% malformation risk. Every woman of childbearing age on these drugs receives folic acid 5 mg daily before conception, and severe episodes in pregnancy are managed with olanzapine or quetiapine, with ECT for the most dangerous presentations. ## What you must remember - **Valproate:** major malformation risk of about 10% (dose-related, highest above 1000 mg/day) and neurodevelopmental delay; contraindicated in pregnancy unless no alternative — effective contraception mandatory, and Indian labels now warn accordingly. - **Carbamazepine:** risk roughly 5%, neural tube defects and (in Asian populations) the separate HLA-B*15:02 Stevens-Johnson risk. - **Lithium:** Ebstein anomaly of the tricuspid valve, absolute risk roughly 1 in 1000; if continued in pregnancy, monitor levels each trimester (target lower therapeutic), at delivery, and in the neonate. - **Lamotrigine:** about 3% malformation risk — relatively safest of the antiepileptics — but pregnancy doubles its clearance, so levels and dose need review each trimester. - **Topiramate:** oral clefts — not a mood option in women planning pregnancy. - **Folic acid 5 mg daily** before conception and through the first trimester for every woman on an antiepileptic mood stabiliser; enzyme-inducing drugs additionally call for neonatal vitamin K. - **Acute mania in pregnancy:** olanzapine or quetiapine are the usual antipsychotics; severe life-threatening illness justifies ECT, which is safe in pregnancy. - **Postpartum:** relapse risk is at its lifetime peak — restart prophylaxis early, and breastfeeding is compatible with lamotrigine, valproate and most atypicals with infant monitoring. ## A preconception consultation A 26-year-old woman with bipolar I disorder, stable for two years on valproate 1000 mg daily, announces she is planning pregnancy. The correct sequence is deliberate: confirm that she is truly stable; begin folic acid 5 mg; switch the valproate — cross to lamotrigine started low and titrated slowly over six weeks, or to an antipsychotic such as quetiapine — and maintain contraception until the switch is proven tolerable, because a relapse into mania during the change endangers the pregnancy as surely as any drug. If she conceives unexpectedly on valproate, the drug is stopped or minimised at once, a detailed anomaly scan at 18-20 weeks with fetal echocardiography follows, and the couple is counselled honestly about the 10% figure rather than reassured vaguely. Contrast lithium: a first-trimester exposure does not mandate termination; it mandates a fetal echocardiogram and a shared decision, because untreated maternal mania carries its own fetal risk from dehydration, impulsivity and medication chaos. The different tone of the two consultations — valproate avoided, lithium monitored — is the distinction examiners probe. ## Where students slip The predictable slip is ranking: asked which mood stabiliser is most teratogenic, candidates hesitate between carbamazepine and valproate — valproate is unambiguously the worst, and "10%" is the quotable number. The second is overreacting to lithium: Ebstein anomaly is the association, but the absolute risk is low, and the modern answer for a pregnant lithium user is monitored continuation, not automatic discontinuation — stopping abruptly stacks postpartum relapse on top of fetal exposure. Third, the folate dose: 5 mg daily is the preconception prescription for women on antiepileptics, an order of magnitude above routine antenatal 400 micrograms, and stems test exactly that digit. ## Frequently asked questions ### Which mood stabiliser carries the highest teratogenic risk? Valproate, with about a 10% major malformation rate plus neurodevelopmental impairment — it is contraindicated in women who can become pregnant unless no alternative exists and pregnancy prevention is assured. ### What is Ebstein anomaly and which drug causes it? A downward-displaced tricuspid valve producing atrialisation of the right ventricle, classically associated with first-trimester lithium at an absolute risk of roughly 1 in 1000. ### Which mood stabiliser is safest in pregnancy? Lamotrigine, with a malformation rate around 3% — still above baseline, and its clearance doubles in pregnancy so dose review is required each trimester. ### What dose of folic acid is given before conception with antiepileptics? 5 mg daily, continued through the first trimester, compared with 400 micrograms in routine antenatal use. ### How is severe mania treated in pregnancy? With an antipsychotic such as olanzapine or quetiapine at the lowest effective dose, reserving ECT for life-threatening illness — it is safe and often faster than any drug.