Current marijuana use was linked to worse sperm morphology but better motility

Current marijuana use was associated with 2.15 times higher odds of abnormal strict morphology and 2.76 times higher odds of low semen volume. However, current users had 0.47 times the odds of abnormal motility (meaning better motility). Past users also showed higher rates of abnormal morphology (53.4%) compared to never-users (33.1%). 43% of men in the infertility clinic reported ever using marijuana.

Prospective study of 409 men presenting for infertility evaluation at one institution (July 2017-April 2018). Semen analysis performed per WHO 5th Edition criteria. Marijuana use assessed via reproductive health questionnaire. Multivariate logistic regression controlled for confounders.

With 43% of infertility patients reporting marijuana use, understanding its effects on semen quality is clinically relevant. The mixed findings (worse morphology and volume, better motility) complicate simple messaging about marijuana and fertility.

The motility finding is counterintuitive and has been seen in other studies. One hypothesis involves the endocannabinoid system role in sperm function, where THC may mimic endocannabinoids that regulate sperm movement. The morphology finding is more concerning for fertility outcomes.

Infertility clinic population may not represent general population. Self-reported marijuana use. Cannot determine dose-response. Retrospective questionnaire for past use. Confounders like other substance use not fully controlled.