This study by Kerri Bertrand et al., reviewed self-reported cannabis use and cannabinoid concentrations in breast milk. Previous evidence on the matter was collected in the 1980’s – since which time we’ve seen an increase in cannabis potency and prevalence.
50 breast-feeding women provided 54 milk samples for the research repository, Mommy’s Milk. Concentrations of THC, 11-OH-THC, CBD, and CBN were measured using liquid chromatography mass spectrometry electrospray ionization. 80% of the samples were from full expression.
THC was detectable in 34 samples (63%) up to 6 days after last reported use. The median concentration was 9.47 ng/mL ranging from 1.01 to 323 ng/mL.
5 samples (8%) had detectable 11-OH-THC or CBD ranging from 1.33 to 12.8 ng/mL and 1.32-8.56 ng/mL, respectively. CBN was not detected in any samples
Number of hours since last use was a significant predictor, in addition to number of daily uses and time from collection to analysis.
11-OH-THC is less lipophilic than THC which may explain lower concentrations in samples.
While this study did not measure infant plasma concentrations, using previous evidence of 10 mg THC, we can extrapolate infant concentrations to be ~1,000 times lower than in adults.
The strengths of this study include guided recall by trained staff and collection of dose and timing. The doses used by mothers in this study are currently available and reflect the higher concentrations of THC found today.
While researchers continue to caution and advise against the use of cannabis while breastfeeding, it’s important research in the field continues for the benefit of both mom and baby.