The first study to focus on the swimming patterns of sperm in men who regularly smoke marijuana found that sperm lose stamina and burn out - which may prevent conception. Researchers, who presented the findings at the recent conference of the American Society of Reproductive Medicine, learned that men who smoke marijuana have fewer sperm due to lower quantities of seminal fluid, compared with men who do not smoke. The speed, volume, shape, density, movement, and count of sperm were evaluated in both groups of men.
An ingredient of marijuana, tetrahydrocannabinol (THC), is the psychoactive chemical that results in people feeling "high." "We don't know exactly what is happening to change sperm functioning," said lead author Lani Burkman, PhD, "but we think it is 1 of 2 things:THC may be causing improper timing of sperm function by direct stimulation, or it may be bypassing natural inhibition mechanisms. Whatever the cause, the sperm are swimming too fast too early."