A new study investigates how marijuana smoking can affect the quality of sperm. Its findings contradict the researchers' initial hypothesis.
Cannabis and Male Fertility: A Systematic Review. Research supports a role for cannabis in reducing sperm count and concentration.
Men who smoke marijuana frequently have significantly less seminal fluid, a lower total sperm count and their sperm behave abnormally.
In subjects, each taking the same moderate dose of marijuana daily over only several weeks, their sperm quality plummeted. Sperm motility.
Some studies have found that men who smoke marijuana have a higher sperm count. Other research has found they have a lower sperm count.