Men who have smoked marijuana at some point in their life had significantly higher concentrations of sperm when compared with men who have never smoked marijuana, according to new research led by Harvard T.H. Chan School of Public Health. The study, conducted in the Fertility Clinic at Massachusetts General Hospital, also found that there was no significant difference in sperm concentrations between current and former marijuana smokers.

These unexpected findings highlight how little we know about the reproductive health effects of marijuana, and in fact of the health effects of marijuana in general.

📝Analysis of the semen samples showed that men who had smoked marijuana had average sperm concentrations of 62.7 million sperm per milliliter of ejaculate while men who had never smoked marijuana had average concentrations of 45.4 million sperm per milliliter of ejaculate. Only 5 percent of marijuana smokers had sperm concentrations below 15 million sperm per milliliter (the World Health Organization’s threshold for “normal” levels) compared with 12 percent of men who had never smoked marijuana.

❗️Unfortunately, science doesn’t always have the conclusive answers we crave — but given what the medical community does know, for the time being, choosing❌ not to smoke weed if you’re trying to get pregnant is the safest approach to avoid possible health effects on conception and the fetus down the line.