3 Clinical psychopharmacology3.4 Therapeutics
3.4.5.5 Pregnancy
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Written by Resident Doctor Committee · Published
Review before conception
Review treatment before conception, or promptly after an unplanned pregnancy, covering diagnosis, previous perinatal episodes, relapse after stopping, effective treatments and current exposures.
Sustained wellness may reflect effective medication, not a low relapse risk.
Weighing fetal against maternal risk
Set fetal risk against the risks of untreated illness: relapse, self-harm and poor nutrition.
Use absolute numbers: raising a 2% risk by half gives 3%, not 50%.
Window | What exposure affects |
|---|---|
Weeks 3 to 8 after conception (organogenesis) | Structure; the neural tube closes around day 28 after conception (about 6 gestational weeks) |
Second and third trimesters | Growth, functional maturation and neurodevelopment |
Near delivery | Neonatal toxicity, withdrawal or adaptation |
Stopping after a positive test does not reverse earlier exposure.
Choosing treatment
Use an effective drug at an effective dose and avoid unnecessary combinations.
Switching adds exposure and can destabilise illness, so plan it before conception if a high-risk drug must go.
Pharmacokinetics
Lamotrigine clearance rises substantially in pregnancy and falls after birth, so check levels against the patient's baseline and review the dose postpartum.
Lithium levels shift with renal function, fluid balance and delivery-related illness.
Antipsychotics
Continuing is often the better balance when relapse risk is high; monitor weight and gestational diabetes risk.
A depot may suit a patient whose oral non-adherence caused relapse.
Antidepressants
Drug or exposure | What follows |
|---|---|
Sertraline | Common option with substantial experience |
Paroxetine | Possible small association with cardiac malformations |
Late selective serotonin reuptake inhibitor exposure | Usually transient neonatal jitteriness, feeding or breathing problems; small risk of persistent pulmonary hypertension |
Exposure in the month before delivery | Small rise in postpartum haemorrhage |
Stopping routinely in late pregnancy is not automatically beneficial, because of maternal withdrawal and relapse.
Mood stabilisers
Drug | Reproductive risk | Prescribing |
|---|---|---|
Valproate | Major malformations in about 1 in 9 to 10 pregnancies; developmental problems in up to 30 to 40% of children | Contraindicated for psychiatric use in pregnancy; Pregnancy Prevention Programme |
Carbamazepine | Malformations, including neural tube defects | Generally avoid |
Topiramate | Malformation, growth and possible neurodevelopmental risks | Pregnancy prevention and indication-specific restrictions |
Lamotrigine | Lower than valproate, but not zero | Frequent level and clinical review |
Lithium | Small dose-related rise in cardiac malformations | Levels every 4 weeks, weekly from 36 weeks |
Starting valproate under age 55 needs two specialists to document independently that no other effective or tolerated treatment exists, or that compelling reasons make the reproductive risks inapplicable.
Pregnancy on valproate needs urgent specialist review, without unsupervised abrupt withdrawal.
The National Institute for Health and Care Excellence advises stopping lithium in labour and checking the level 12 hours after the last dose.
Historical estimates overstated lithium's teratogenic risk.
Benzodiazepines
Sustained or late exposure can cause neonatal sedation, hypotonia, breathing problems or withdrawal.
Established dependence needs a supervised plan, not abrupt cessation.
Delivery and after
Before delivery, document medicines, neonatal observation, hydration and lithium level plans, and postpartum dose changes.
Falling clearance, broken sleep and a substantial postpartum relapse risk make early postnatal follow-up important.