Is breastfeeding safe while taking lithium (lithium carbonate)?

From the Guidelines

Breastfeeding while taking lithium is not recommended due to the significant risks of lithium toxicity to the infant. Although the provided evidence primarily discusses the use of lithium in treating Kleine-Levin syndrome 1, it highlights the importance of monitoring serum lithium concentrations to avoid toxicity, which is crucial when considering breastfeeding. The evidence notes that lithium may cause fetal harm based on animal studies, and human studies suggest fetal harm but are insufficient to determine risk 1. This, combined with the knowledge that lithium passes freely into breast milk at concentrations similar to maternal blood levels, poses a significant risk to the nursing infant.

Key Considerations

• Lithium exposure through breast milk can lead to serious complications in infants, including lithium toxicity, hypotonia, lethargy, poor feeding, cyanosis, cardiac arrhythmias, and changes in thyroid function.
• Infants have immature kidney function, making them unable to efficiently eliminate lithium from their bodies, thus increasing the risk of toxicity.
• Close monitoring of the infant would be necessary if a mother on lithium were to breastfeed, including regular blood tests for lithium levels, thyroid function, and kidney function, as well as observation for signs of toxicity.

Alternative Considerations

• In cases where lithium treatment is crucial for maternal mental health, healthcare providers might consider alternative mood stabilizers that are safer during breastfeeding, such as certain antipsychotics or anticonvulsants 1.
• The decision to breastfeed while on lithium should involve a careful discussion between the mother and healthcare providers, weighing the benefits of breastfeeding against the risks of lithium exposure to the infant.

Given the potential for significant harm to the infant, the primary concern should be minimizing exposure to lithium through breast milk, thus, avoiding breastfeeding while on lithium treatment is the recommended course of action 1.

From the FDA Drug Label

Nursing mothers: Lithium is excreted in human milk. Nursing should not be undertaken during lithium therapy except in rare and unusual circumstances where, in the view of the physician, the potential benefits to the mother outweigh possible hazards to the child

• Breastfeeding is not recommended during lithium therapy, as lithium is excreted in human milk.
• The decision to breastfeed should be made on a case-by-case basis, weighing the potential benefits to the mother against the possible hazards to the child 2.

From the Research

Breastfeeding on Lithium: Key Findings

• A retrospective review of postpartum lithium use, including during lactation, found that 39% of patients taking lithium postpartum breastfed, with no reports of adverse events in the infant charts reviewed 3.
• Lithium exposure in breastmilk appears to be tolerated by healthy infants, with average infant serum lithium concentrations of 0.16 mmol/L 3.
• A study using a rat model found that lithium from breastmilk inhibits thyroid iodine uptake and hormone production, which can be remedied by maternal iodine supplementation 4.
• A systematic review of the literature found that data are limited on the safety of lithium continuation while breastfeeding, and recommendations must be personalized to the individual woman and her infant 5.

Infant Exposure to Lithium through Breast Milk

• A study of 10 mother-infant pairs found that serum lithium levels in nursing infants were low and well tolerated, with no serious adverse events observed 6.
• Another study found that lithium transfers to breastmilk and can be detected in infants' serum, and regular monitoring of infants' renal clearance, thyroid function, and lithium levels is warranted when breastfeeding under lithium exposure 7.
• A case series of three bipolar mothers treated with lithium during pregnancy and breastfeeding found that therapeutic drug monitoring is important due to fluctuating plasma levels during pregnancy and after birth, and reported the birth and development of three healthy infants despite lithium medication during pregnancy and breastfeeding 7.

Clinical Implications

• The current evidence suggests that lithium can be used during breastfeeding, but close clinical monitoring of nursing infants is necessary to minimize potential risks 3, 6, 7.
• Maternal iodine supplementation may be beneficial in preventing thyroid dysfunction in infants exposed to lithium through breastmilk 4.
• Healthcare providers should personalize recommendations for lithium use during breastfeeding based on individual patient circumstances and monitor infants for potential adverse effects 5, 7.