Lithium is a medication prescribed as a mood stabilizer for conditions like bipolar disorder. For individuals who are pregnant or considering pregnancy, concerns arise about continuing lithium treatment safely. This decision requires careful consideration of potential effects on the developing baby and the pregnant individual’s well-being. Healthcare providers, including psychiatrists and obstetricians, guide this process to determine the most appropriate course of action.
Effects on the Developing Baby
Historically, concerns about lithium use during pregnancy centered on congenital malformations. Early 1970s reports linked prenatal lithium exposure to cardiac anomalies, specifically Ebstein’s anomaly, a rare heart defect. While initial estimates suggested a significantly increased risk, recent studies indicate a much lower, though still present, risk of cardiac malformations.
Current data suggests the risk of any cardiac malformation in infants exposed to lithium during the first trimester is 2% to 2.5%, compared to a background rate of 1% in unexposed infants. While Ebstein’s anomaly was a focus in earlier research, subsequent studies have not consistently confirmed a direct association, or if a link exists, the effect is smaller than previously thought. However, an elevated risk remains for right ventricular outflow tract obstruction defects, at 0.6% in exposed infants compared to 0.18% in unexposed infants.
Beyond structural malformations, late-pregnancy lithium exposure can lead to temporary newborn effects, often called “floppy baby syndrome.” These transient effects include hypotonia (reduced muscle tone), lethargy, a poor suck reflex, respiratory distress, and cardiac arrhythmias. These symptoms resolve shortly after birth. Prenatal screening and monitoring, such as detailed ultrasound scans around 20 weeks, are recommended to check for fetal development and heart defects.
Managing Lithium Treatment During Pregnancy
Managing lithium treatment during pregnancy requires collaboration between the pregnant individual, their psychiatrist, and obstetrician. Physiological changes during pregnancy significantly impact how the body processes lithium. Increased renal clearance and fluid retention can substantially reduce lithium blood levels, particularly in the first and second trimesters, increasing the risk of mental health symptom return.
Due to fluctuating levels, frequent blood monitoring is necessary to maintain lithium within a therapeutic range and prevent levels from becoming too low or too high. Blood tests for lithium levels are recommended at least monthly throughout pregnancy, increasing to weekly from 36 weeks until delivery. Dosage adjustments are required to compensate for changes in lithium clearance, with doses often increased during pregnancy.
The decision to continue or adjust lithium treatment weighs risks to the baby against those of untreated maternal mental illness. Discontinuing lithium, especially abruptly, carries a high risk of relapse, with adverse consequences for the pregnant individual’s well-being and the pregnancy. If lithium is to be stopped, it is recommended to do so gradually over at least four weeks. During labor and delivery, fluid balance and lithium levels require careful monitoring to mitigate any potential complications.
Considerations After Delivery
The postpartum period brings adjustments to lithium therapy due to rapid fluid shifts and changes in renal function as the body returns to its pre-pregnancy state. Lithium levels, higher towards the end of pregnancy, can increase after birth. Frequent monitoring of lithium blood levels is recommended, often twice weekly for the first two weeks postpartum. A higher target therapeutic lithium level (e.g., 0.8-1.0 mmol/L) may be recommended in the immediate postpartum period to optimize relapse prevention, given the elevated risk of mood episodes.
Breastfeeding while on lithium is a significant consideration, as lithium passes into breast milk and to the infant. Infant serum lithium levels are about 25% of maternal levels. While some guidelines historically advised against breastfeeding with lithium, recent data suggests it can be acceptable for healthy infants with close monitoring.
If breastfeeding, infant monitoring may include checking serum lithium levels, as well as thyroid and kidney function (TSH, BUN, and creatinine). Some recommendations suggest monitoring at delivery, 48 hours postpartum, and 10 days postpartum, with further monitoring if the infant’s lithium level exceeds 0.3 mEq/L or if clinical signs of toxicity appear. Other approaches recommend testing during the immediate postpartum period and then every 8-12 weeks if initial results are normal. The increased risk of postpartum mood episodes underscores the ongoing importance of continued psychiatric care and support for the individual.