From Today’s Parent, a Canadian site:
Is it safe to use weed while breastfeeding?
Yes, weed does gets into breastmilk, but there’s been little research on how marijuana may impact a baby. Here’s what we know so far.
Canada has legalized recreational pot. I’m sure we’ll have a definitive answer on the longterm health effects of marijuana and breastfeeding in a few years, when those kids arrive at school.