Men who’ve smoked pot in the past or currently smoke marijuana have higher concentrations of sperm than men haven’t smoked pot, say researchers at the Harvard T.H. Chan School of Public Health in Boston. These findings — which were unexpected, the researchers say — were published in Human Reproduction.
The researchers collected 1,143 semen samples from 662 men (average age 36) and obtained blood samples from 317 of the men to measure reproductive hormone levels, over a seven-year period. They used self-report questionnaires to assess the men’s past and current marijuana use and determined that 365 of the men (55 percent) had smoked pot — 44 percent in the past and 11 percent currently.
The semen and blood tests showed that:
- Men who had used marijuana had average sperm concentrations of 62.7 million per milliliter (ml) of ejaculate while men who had not had average concentrations of 45.4 million sperm per ml of ejaculate.
- Just 5 percent of marijuana smokers had sperm concentrations below 15 million/mL (the threshold for “normal” levels) compared with 12 percent of men who had never smoked.
- Among men who used marijuana, greater use was associated with higher blood levels of testosterone.
Sourced from: Human Reproduction