Retrospective Review of Postpartum Lithium Use Including During Lactation.

Introduction: Lithium remains a gold standard treatment for bipolar disorder including during peripartum. Historically, guidelines advised against breastfeeding while taking lithium though recent data suggest it is acceptable for a healthy infant. Lack of awareness of acceptability contributes to decreased patient and clinician comfort and low breastfeeding rates. We report current breastfeeding rates, monitoring practices, and infant outcomes with lithium exposure in breastmilk at our institution. Methods: A retrospective chart review was conducted at a single academic medical center using records from 2013 to 2023. Electronic medical records were queried to identify patients prescribed lithium postpartum. Data were collected on timing of lithium initiation, lithium dose and concentration, breastfeeding status, and infant outcomes. Results: A total of 18 cases of lithium use in the postpartum period were identified. A total of 39% (n = 7) of patients taking lithium postpartum breastfed. Most patients, 61% (n = 11), initiated lithium prior to pregnancy, 11% (n = 2) initiated during pregnancy and 27% (n = 5) started postpartum. Four infant charts were reviewed with no reports of adverse events. Of these infants, average maternal lithium dose was 750 mg daily, with an average maternal serum lithium concentration of 0.62 mmol/L and average infant serum lithium concentration of 0.16 mmol/L. Conclusion: Our data demonstrate most patients using lithium postpartum have been taking lithium long-term and are not breastfeeding. Lithium exposure in breastmilk appears to be tolerated by healthy infants. There is a need for ongoing research and education on acceptability and infant monitoring recommendations to support patients who would like to breastfeed while on lithium.