Summary: Research on lithium exposure through breast milk is limited and often methodologically weak, according to a new systematic review. Until stronger evidence is available, decisions about continuing lithium during breastfeeding should be individualized, balancing risks to both mother and infant.
Source: Northwestern University
Women prescribed lithium for bipolar disorder frequently ask whether breastfeeding while taking the medication could harm their infants. A Northwestern Medicine systematic review finds that the existing evidence is sparse and inconsistent, leaving important questions unresolved.
The review appears in the International Review of Psychiatry.
Lithium remains a cornerstone treatment for bipolar disorder, used worldwide to prevent manic episodes and reduce the risk of postpartum psychosis. Because lithium passes into breast milk, clinicians and patients worry about potential toxicity in breastfed infants. The new review examined how well past studies have measured infant exposure and outcomes and whether they provide reliable guidance for breastfeeding mothers on lithium.
Studies published before 2000 were typically retrospective and lacked important design elements: many did not include control groups, rarely accounted for the health status of the mother or baby, and often omitted information about other medications taken concurrently. More recent research, published after 2000, shows improvements in design and suggests that lithium exposure via breast milk may pose a low risk for many infants. Nevertheless, the authors emphasize that the current evidence base remains limited and more rigorous research is needed.
“This is a controversial issue with varying expert opinions, but even in 2019 we still lack high-quality data to definitively resolve concerns about lithium and breastfeeding,” said Dr. Crystal Clark, assistant professor of psychiatry and behavioral sciences and obstetrics and gynecology at Northwestern University Feinberg School of Medicine and a practicing psychiatrist at Northwestern Medicine.
Decisions about continuing lithium during breastfeeding should be individualized. The review concludes that clinicians must weigh the potential risks of infant lithium exposure against the clear and well-documented risks of stopping lithium for the mother, such as relapse of bipolar symptoms or postpartum psychosis.
“There are few absolutes when it comes to managing illness while breastfeeding,” Clark said. “It’s not one size fits all.”
The authors recommend that clinicians discuss known potential signs of lithium exposure with breastfeeding parents, including infant lethargy, feeding difficulties, and restlessness, and that mothers and infants be monitored closely if breastfeeding is chosen while on lithium therapy.
Bipolar disorder commonly affects women during their reproductive years. Pregnancy and the postpartum period are times of heightened vulnerability, with increased risk of mood episodes and postpartum psychosis. Untreated bipolar disorder is associated with adverse outcomes such as preterm birth and small-for-gestational-age infants, in addition to an elevated risk of suicide, a major contributor to maternal mortality. These consequences underscore the importance of carefully balancing maternal mental health needs with potential infant exposure risks when considering breastfeeding while taking lithium.
Despite ongoing uncertainty about lithium levels in breast milk and the long-term developmental effects on infants, the authors note that for some women the benefits of breastfeeding and the psychiatric stability provided by lithium may justify continued use. Future research planned by Dr. Clark and colleagues aims to measure lithium concentrations in breast milk, quantify infant intake, and evaluate developmental outcomes in early childhood.
“I don’t see the same level of breastfeeding concern for women taking medications for other chronic conditions such as seizure disorder,” Clark added, noting that many drugs with limited study are nonetheless not routinely discouraged during breastfeeding. She suggested that stigma around mental illness may contribute to overly cautious or inconsistent messaging about lithium and breastfeeding.
The systematic review screened 441 publications, assessed 230 articles that met inclusion criteria, and ultimately selected 12 case-report articles comprising 37 mother-infant pairs for detailed analysis. All included studies reported at least one maternal serum or breast milk lithium concentration and one infant serum lithium concentration, following strict inclusion standards aligned with PRISMA guidelines.
Funding: The study received support from the National Institute of Child Health and Human Development grant K23 (1K23HD087529-01A1). Other Northwestern contributors to the review include Dr. Katherine Wisner, Rebecca Newmark, Dr. Mariana Isaac, and Jody Ciolino.
Source:
Northwestern University
Media Contacts:
Kristin Samuelson – Northwestern University
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Original Research: Closed access. Title: “Risk-Benefit assessment of infant exposure to lithium through breast milk: a systematic review of the literature.” Authors: Rebecca L. Newmark, Debra L. Bogen, Katherine L. Wisner, Mariana Isaac, Jody D. Ciolino & Crystal T. Clark. Published in International Review of Psychiatry. DOI: 10.1080/09540261.2019.1586657
Abstract
The systematic review assessed available evidence on lithium exposure through breast milk and the potential risks to breastfed infants. Multiple databases were searched through December 2018 for studies reporting matched maternal and infant lithium concentrations. Following PRISMA guidelines, 12 case-report articles were selected from 441 initially identified publications. Data remain limited, and it is difficult to isolate the effects of breastfeeding-related lithium exposure from other factors such as prenatal lithium exposure, infant health conditions, and concurrent maternal medications. The review concludes that decisions about continuing lithium while breastfeeding should be personalized to each mother-infant dyad and guided by careful monitoring.