THC, the main psychoactive compound present in cannabis, was detected in breast milk even after mothers had abstained from the plant for 12 hours, a recent study by researchers from the University of Washington has found.
The team analyzed milk samples from 20 breastfeeding mothers, all of whom had babies under six months old and provided detailed accounts of their cannabis consumption. The mothers took their milk samples at various intervals, starting at least 12 hours after their last consumption of the plant.
The analysis confirmed that THC levels in the milk were low, and it was estimated that the babies consumed around 0.07 mg per day - a much lower dose compared to a typical low-dose edible, which contains 2mg of THC.
However, the implications of this for babies are not yet known.
"Breastfeeding parents should be aware that if they consume cannabis, it is likely that their children are consuming cannabinoids through the milk they produce, and we don't know if this has any effect on the baby's development," stresses Courtney Meehan, biological anthropologist and leader of the project.
The study, published in the journal Breastfeeding Medicine on May 2, also observed variability in the concentration of THC among the participants, with different peaks in concentration being observed depending on the frequency of cannabis consumption.
"Human milk has compounds called lipids and cannabinoids are lipophilic, which means they dissolve in these lipids. This could mean that cannabinoids like THC tend to accumulate in milk - and potentially in the babies who drink it," adds Meehan.
Another facet of the research, qualitative, indicated that many breastfeeding mothers consume cannabis for therapeutic reasons, namely to manage anxiety, mental health problems or chronic pain. They prefer to smoke rather than ingest other medicines because of the perception of safety.
However, there is still no concrete evidence to confirm whether cannabis is safer or more harmful compared to other drugs for breastfeeding mothers.
The results reveal a significant gap in the scientific understanding and clinical guidelines given to breastfeeding mothers who consume marijuana. Unlike alcohol, for which guidelines suggest waiting at least two hours before breastfeeding after consumption, there are no similar guidelines for cannabis consumption - the popularity of which is increasing not only among new mothers, but among the general population.
"This is an area that needs substantial and rigorous research so that mothers know what's best," points out study co-author Shelley McGuire, who studies maternal and child nutrition.
