From the FDA Drug Label
WARNINGS Lithium may cause fetal harm when administered to a pregnant woman. There have been reports of lithium having adverse effects on nidations in rats, embryo viability in mice, and metabolism in-vitro of rat testis and human spermatozoa have been attributed to lithium, as have teratogenicity in submammalian species and cleft palates in mice Studies in rats, rabbits and monkeys have shown no evidence of lithium-induced teratology. Data from lithium birth registries suggest an increase in cardiac and other anomalies, especially Ebstein’s anomaly. If the patient becomes pregnant while taking lithium, she should be apprised of the potential risk to the fetus If possible, lithium should be withdrawn for at least the first trimester unless it is determined that this would seriously endanger the mother. Pregnancy Teratogenic Effects - Pregnancy Category D: See WARNINGS section
The risks and considerations of lithium use during pregnancy include:
- Fetal harm: Lithium may cause harm to the fetus, particularly during the first trimester.
- Teratogenic effects: There is an increased risk of cardiac and other anomalies, especially Ebstein's anomaly.
- Withdrawal of lithium: If possible, lithium should be withdrawn for at least the first trimester unless it would seriously endanger the mother. Key considerations for pre-counseling purposes:
- Patients should be apprised of the potential risk to the fetus if they become pregnant while taking lithium.
- The decision to continue or withdraw lithium therapy during pregnancy should be made on a case-by-case basis, taking into account the potential risks and benefits to both the mother and the fetus 1, 1.
From the Research
Lithium use during pregnancy requires careful consideration due to potential risks to the developing fetus, and I recommend close collaboration between psychiatric and obstetric care providers to develop an individualized treatment plan. For precounseling a pregnant woman on lithium, it is essential to discuss the potential risks and benefits of lithium treatment during pregnancy. Lithium crosses the placenta and is associated with a small increased risk of cardiac malformations (particularly Ebstein's anomaly) when used in the first trimester, with an absolute risk of approximately 1-2 per 1000 births 2.
The most recent and highest quality study on this topic, published in 2022, found that lithium treatment during pregnancy was not associated with significant differences in obstetric complications, neonatal complications, or congenital anomalies, except for lower Apgar scores in newborns of lithium-treated women 2. Another recent study, published in 2021, reported the birth and development of three healthy infants despite lithium medication during pregnancy and breastfeeding, highlighting the importance of therapeutic drug monitoring due to fluctuating plasma levels during pregnancy and after birth 3.
Throughout pregnancy, regular monitoring of lithium levels is essential, typically every 4 weeks until 36 weeks, then weekly until delivery, with target serum levels of 0.6-0.8 mEq/L 4. Dosage adjustments are often necessary as pregnancy progresses due to increased renal clearance. During labor, maintain hydration and continue lithium at a reduced dose to prevent toxicity. After delivery, lithium levels should be checked within 24 hours as postpartum renal function changes can lead to elevated levels.
Breastfeeding while on lithium is generally not recommended due to infant exposure, though some experts support it with careful infant monitoring 3. The decision to continue lithium during pregnancy must balance the risk of untreated maternal bipolar disorder (which carries its own risks of relapse, self-harm, and impaired maternal functioning) against potential fetal risks. For women with severe bipolar disorder or history of postpartum psychosis, continuing lithium may represent the safest option despite the risks 5.
Key considerations for lithium use during pregnancy include:
- Regular monitoring of lithium levels and adjustment of dosage as needed
- Close collaboration between psychiatric and obstetric care providers
- Discussion of potential risks and benefits of lithium treatment during pregnancy
- Consideration of alternative treatments, if possible
- Planning for delivery in a specialized hospital with psychiatric and obstetric care available
- Monitoring of newborns for potential complications, such as low Apgar scores.