A total of 1,215 young Danish men aged 18-28 years were recruited between 2008 and 2012 when they attended a compulsory medical examination to determine their fitness for military service.
"Association Between Use of Marijuana and Male Reproductive Hormones and Semen Quality: A Study Among 1,215 Healthy Young Men," American Journal of Epidemiology, 2015 September 15
The participants delivered a semen sample, had a blood sample drawn, and underwent a physical examination.
They responded to questionnaires including information on marijuana and recreational drug use during the past 3 months (no use, use once per week or less, or use more than once per week).
A total of 45% had smoked marijuana within the last 3 months.
[style=font-weight:bold;]Regular marijuana smoking more than once per week was associated with a 28% lower sperm concentration and a 29% lower total sperm count after adjustment for confounders[/style].
[style=font-weight:bold;]The combined use of marijuana more than once per week and other recreational drugs reduced the sperm concentration by 52% (95% CI: -68, -27) and total sperm count by 55%.[/style]
"Association Between Use of Marijuana and Male Reproductive Hormones and Semen Quality: A Study Among 1,215 Healthy Young Men," American Journal of Epidemiology, 2015 September 15
