Two of the participants had a low but measurable concentration of delta-9-tetrahydrocannabinol at zero time (the samples collected just before smoking), suggesting some residual accumulation of it from prior heavy use or use close to the start of breast milk collection.
“Although the transfer of delta-9-tetrahydrocannabinol into the plasma compartment is almost instantaneous, the transfer of delta-9-tetrahydrocannabinol into breast milk in our study appears to be slightly slower than the transfer into the plasma compartment,” the authors wrote.
The women in the study were all 2-5 months postpartum. The authors noted that in these women who were exclusively breastfeeding, the breast milk compartment, along with drug entry and exit, “remains fairly consistent.”
The researchers also noted that the lack of corresponding plasma samples was a major limitation of the study, but because of the nature of the study, anonymity was important.
No conflicts of interest were declared.
SOURCE: Baker T et al. Obstet Gynecol. 2018;131:783-8.