Concerns and Implications of Marijuana Use During Breastfeeding

By Kelly Bonyata, IBCLC

The Academy of Breastfeeding Medicine's revised Clinical Protocol #21 emphasizes the importance of counseling breastfeeding mothers on reducing or ceasing marijuana use. This recommendation stems from concerns about the potential long-term neurobehavioral effects on infants exposed to marijuana through breastmilk.

Marijuana's impact on breastfeeding is not a new concern. It was highlighted in the American Academy of Pediatrics’ 2001 list of substances with adverse effects reported during breastfeeding. While initial literature suggested limited impact with only one documented case, the evolving understanding of marijuana's active components necessitates cautious guidance.

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More than the chemical effects of marijuana on infants, there's the risk that it may impair a mother's ability to care for her child. Maternal judgment could be compromised, leading to less optimal caregiving.

Exposure to secondhand marijuana smoke only exacerbates the situation, potentially increasing the drug levels that infants receive. The composition of street marijuana can also be unpredictable, raising concerns over harmful additives.

Active Ingredients and Breastmilk

THC, the primary active ingredient in marijuana, accumulates in a mother's fat tissues over time, leading to prolonged presence in the body. Studies indicate that THC is measurable in breastmilk and can be concentrated at levels significantly higher than in maternal plasma. For example, research has found that chronic heavy users could have milk concentrations of THC up to eight times that of their blood plasma, although this may not always translate into significant side effects for infants. However, some absorption by infants has been documented, and the long-term implications of such exposure remain uncertain.

Potential Effects on Infants

Notably, infants exposed to marijuana could experience increased sleepiness, which might impede weight gain and overall development. Additionally, secondhand smoke exposure from cannabis is linked to a heightened risk of Sudden Infant Death Syndrome (SIDS).

There’s also evidence suggesting that THC can suppress prolactin production, possibly impacting milk supply. In animal studies, THC has been shown to affect milk production directly, which poses additional risks for breastfeeding mothers.

The early months of life are critical for brain development, and marijuana exposure through breastmilk could disrupt neurodevelopmental processes. Studies on animals indicate that THC in maternal milk might interfere with DNA and RNA metabolism, potentially compromising the proteins essential for healthy growth.

Detecting Exposure

Post-consumption, THC can be found in an infant's urine and stool, sometimes for extended periods. Some studies suggest that infants exposed to THC through breastfeeding might test positive on urine screenings for several weeks.

One longitudinal study from the early 1990s suggested that infants exposed to marijuana in their first month showed signs of decreased motor development by one year of age. However, in a follow-up study involving 27 infants who had been exposed via breastmilk, researchers found no significant differences in growth or developmental milestones when compared to non-exposed infants.

Recent research has examined THC levels in breastmilk from mothers who use cannabis regularly. One study highlighted that infants could receive about 2.5% of the maternal dose of THC. This finding emphasizes the uncertainty surrounding the long-term neurobehavioral impacts of THC exposure during critical developmental phases.

Further Reading and Resources

For those seeking more information on the subject, references include:

• Cannabis from the Drug and Lactation Database (LactMed).
• Marijuana Use During Breastfeeding by Susan Condon, IBCLC.
• Social Drugs and Breastfeeding: Handling an issue that isn’t black and white by Denise Fisher, BN, RN, RM, IBCLC, covering substances including marijuana.
• Marijuana from the National Institute on Drug Abuse (NIDA).

References

[most recent references listed first]

• Transfer of Inhaled Cannabis Into Human Breast Milk. Baker T, Datta P, et al. Obstetrics & Gynecology. April 2018.
• Hale’s Medications & Mothers’ Milk 2025-2026. Hale TW, Rowe HE. 21st Edition. New York, New York: Springer Publishing Company; 2025-2026.
• Prenatal substance abuse: short- and long-term effects on the exposed fetus. Behnke M, Smith VC. Pediatrics. 2013;131(3):e1009-24.
• Breastfeeding Answers Made Simple. Mohrbacher N. Hale Publishing, 2010.
• Cannabis and breastfeeding. Garry A, et al. J Toxicol. 2009.
• Marijuana use and breastfeeding. Djulus J, et al. Can Fam Physician. 2005.
• Breastfeeding and the use of recreational drugs. Liston J. Breastfeed Rev. 1998.