Weed smoking affecting sperm

My husband smokes to alleviate chronic pain, but after reading a study showing that weed affected the quality of sperm leading to a higher precedence of genetic material associated with autism, I convinced him to quit for three months (how long it takes for a sperm cycle). We tested positive on the pregnancy test yesterday, but today he is back to smoking weed (not around me). As I can’t be more than three weeks, I feel it’s a little early for him to start again since if I happen to miscarry since it’s so early on, we’ll have to wait another three months before trying again. Is this crazy? I’m 31 and we want to have 2-3 kids (don’t have any yet).