As of May 2021, 36 states and 4 territories allow for use of medical cannabis products (National Conference of State Legislators, 2021). A recent resource from the National Academies of Sciences, Engineering, and Medicine (NASEM, 2017) details evidence on potential therapeutic value of cannabinoid drugs, primarily tetrahydrocannabinol (THC), for pain relief, control of nausea and vomiting, and appetite stimulation. Psychological effects of cannabinoids, such as anxiety reduction, sedation, and euphoria may influence therapeutic value. Cannabinoids could be beneficial in some patients and situations and undesirable in other populations (NASEM). Some data suggest as many as 10% to 15% of lactating parents use cannabis products (Lactation Matters, 2021)

There are conflicting recommendations from professional organizations on marijuana during lactation. The Academy of Breastfeeding Medicine states "at this time, although the data are not strong enough to recommend not breastfeeding with any marijuana use, we urge caution" (Reece-Stremtan et al., 2015, p. 139). Per the American Academy of Pediatrics (AAP), "limited data reveal that TCH does transfer into human milk and there is no evidence for the safety or harm of marijuana use during lactation" (Ryan et al., 2018, p. 10). AAP recommends women be counseled about adverse effects of THC on brain development during early infancy (Ryan et al.).

Dr. Thomas Hale, a pharmacologist who is an expert on perinatal pharmacology in pregnancy and lactation, states that in low-to-moderate use, levels that pass into human milk are exceedingly small. For example, if an infant breastfed immediately after the parent smokes marijuana, the infant would get at very most 8.7% of the parent's dose but only absorb 1% of that (Lactation Matters, 2021). When marijuana is ingested orally, as an infant would while receiving human milk, approximately 1% to 5% is absorbed. The majority is absorbed by the liver and does not get into the plasma. Research by Hale and his team demonstrated that THC was transferred into human milk such that exclusively breastfeeding infants ingested a mean of 2.5% of maternal dose (Baker et al., 2018).

With conflicting professional recommendations, but known relatively low transfer rate of THC into human milk, how should health care providers proceed? As health professionals, we must have open and transparent conversations with families. There are clear risks associated with not breastfeeding. Lack of human milk can be the difference between life and death for preterm infants (Lactation Matters, 2021). Clinicians should look at the evidence, for example, how much THC is absorbed by the parent and how much gets into the breastmilk (Lactation Matters). It is important that parents are informed there are risks associated with marijuana and smoking. However, instead of hospitals implementing strict policies to prohibit breastfeeding and use of human milk in all cases of cannabis usage, a tailored approach based on the individual situation is more appropriate. Risks must be weighed carefully versus the benefits of human milk and the risks associated with formula feeding.

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