“Women should definitely be counseled that it’s not a good idea to use marijuana while pregnant. If you’re breastfeeding, we would encourage you to cut back or quit,” said Seth Ammerman, a co-author of the report and professor of pediatrics at Stanford.
If a breastfeeding mother does not stop using, however, “the benefits of breastfeeding would outweigh the potential exposure to the infant,” he added.
A second study, also published in Pediatrics, found that THC, the molecule that gives marijuana most of its psychoactive effects, accumulates in breast milk, even up to six days after the mother’s last use.
I feel like this should be obvious, but pregnant women and breastfeeding mothers probably should stay with anything that has potentially brain-altering effects.