Up until 2001, the American Academy of Pediatrics (AAP) recommended that methadone was compatible with breastfeeding in women taking less than 20 mg per day. Because most women on methadone maintenance therapy typically require 50 to 15o mg of methadone per day during pregnancy, this meant that most women on methadone were not able to breastfeed. However, the dose restriction for methadone was eliminated in 2001, a decision driven by several studies indicating that the levels of methadone secreted into human breast milk were relatively low.
Published information regarding the exposure of infants to methadone through breast milk is sparse. In a recent update from Motherisk, the authors note that the concentrations of methadone in the breast milk tend to be low and remain stable over time. Maternal methadone doses of 25 to 180 mg per day produce concentrations in breast milk ranging from 27 to 260 ng/ mL, leading to an average daily methadone ingestion of 0.05 mg (based on an infant’s estimated milk intake of approximately 500 mL/d). This ingested amount would be equal, in a 5-kg baby, to the ingestion of less than 1% of the maternal weight–adjusted dose (typical adult dose is 40 to 180 mg/day).
While breastfeeding provides many benefits for any newborn, there may be other benefits specific to this population. About half of all infants born to mothers treated with methadone may experience withdrawal symptoms or neonatal abstinence syndrome (NAS). Several studies indicate that neonatal abstinence syndrome may be less frequent or less severe in women who breseastfeed. A retrospective study from New Zealand reviewed 121 infants of women on methadone maintenance over a 7-year period, and found that infants who were treated for NAS and who were breastfed in the hospital went home an average of 8 days earlier than infants who were formula-fed. It is not clear if this due to the beneficial effects of breastfeeding itself or if the low concentrations of methadone in the breast milk prevent or minimize withdrawal.
Breastfeeding rates among opioid-dependent women tend to be low, with one study indicating that three-quarters of women elected not to breastfeed. Among the women who did choose to breastfeed, more than half stopped within one week. Given there are clear benefits of breastfeeding for both the mother and the child, efforts must be made to support breastfeeding among methadone-treated women.
Ruta Nonacs, MD PhD
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