Association Between Use of Marijuana and Male Reproductive Hormones and Semen Quality

A Study Among 1,215 Healthy Young Men

Tina Djernis Gundersen; Niels Jørgensen; Anna-Maria Andersson; Anne Kirstine Bang; Loa Nordkap; Niels E. Skakkebæk; Lærke Priskorn; Anders Juul; Tina Kold Jensen


Am J Epidemiol. 2015;182(6):473-481. 

In This Article


A total of 1,215 of the 1,221 men responded to the questions on marijuana use. Their mean age was 19.1 years, and 8% had been responsible for a pregnancy. Among the 1,215 men, 45.4% had smoked marijuana within the last 3 months, and 61% of these smoked less than once per week. A total of 10.9% had used recreational drugs other than marijuana (93.9% of these for less than once per week), and. 9.6% had used both marijuana and other recreational drugs within the last 3 months (data not shown).

Men who had used marijuana during the last 3 months had a higher alcohol and caffeine intake, were more often smokers and had been exposed to their mothers' tobacco smoking in utero, had a higher stress and sleep score, were less often born with cryptorchidism, had a higher prevalence of sexually transmitted diseases, and had a higher use of recreational drugs (Table 1).

Sperm concentration, total sperm count, percentage of motile sperm, and percentage of morphologically normal forms were all lower among men smoking marijuana more than once per week (Table 2). In addition, use of both marijuana and recreational drugs was associated with a further decrease in semen quality. Men using marijuana more than once a week had a 28% (95% confidence interval (CI): −48, −1) and 29% (95% CI: −46, −1) lower sperm concentration and total sperm count, respectively, compared with nonmarijuana smokers after adjustment for hours of abstinence, tobacco smoking, alcohol intake, sexually transmitted diseases, and other recreational drugs (Table 3). Combined use of both marijuana more than once per week and other recreational drugs significantly reduced the sperm concentration by 52% (95% CI: −68, −27), total sperm count by 55% (95% CI: −71, −31), and sperm motility by 5.8 percentage points (CI: −10.6, −1.0) (Table 3). Semen volume was not associated with marijuana or recreational drug use.

A negative association with sperm concentration and total sperm count was found; however, trends were not significant (P = 0.12 and P = 0.17), indicating that the adverse association was found at a threshold with regular use of marijuana more than once per week. When the sperm concentration was categorized according to World Health Organization reference values, the adjusted odds ratios of having a concentration below 15 and 20 million/mL when using marijuana more than once per week were, respectively, 1.07 (95% CI: 0.62, 1.87) and 1.14 (95% CI: 0.69, 1.89). Serum testosterone, free testosterone, and sex hormone-binding globulin were higher among marijuana users than nonusers (Table 4). However, after adjustment for BMI, tobacco smoking, and time of day of blood draw, only testosterone was higher in marijuana users with a level of 7% (95% CI: 0, 14) (Table 5).

We repeated the analyses among smokers and nonsmokers and among men with high and normal BMI separately, which did not significantly change our findings. Moreover, adjustment for maternal education did not affect the findings. Men with a low weekly alcohol intake (1–5 units) using marijuana more than once per week had a reduction of 42% (95% CI: −73, 21) and 39% (95% CI: −72, 34) in sperm concentration and total sperm count, respectively, compared with nonmarijuana smokers after adjustment, whereas the association was attenuated among men with a higher alcohol intake (>5 units per week).