Q. Does smoking marijuana make men infertile?

A. With medical marijuana use on the rise, more researchers are studying the connection between cannabinoids, the active chemical components in marijuana, and the brain. Few have tackled the question of marijuana use and fertility.

Several studies have drawn a link between men who smoke marijuana and a higher prevalence of problems that could cause infertility, including lower testosterone levels, less vigorous sperm swimming patterns, and testicular cancer. Nevertheless, no studies have proven that marijuana use leads to male infertility, in animals or humans.

“More research is required to know exactly what are the effects of smoking marijuana,’’ said S.K. Dey, director of the reproductive sciences division at Cincinnati Children’s Hospital Medical Center. One study that Dey helped conduct (published in the March issue of the journal Cancer) showed that men who had smoked marijuana had a higher risk of testicular cancer, especially if they smoked before age 18. “What studies we have done suggest that the risk factors could be more if exposed at an earlier age.’’

Lani Burkman, a professor emerita of obstetrics and gynecology at the University of Buffalo School of Medicine, runs a business that gives fertility tests to men and women who have used drugs including marijuana. She advises couples who are trying to become pregnant that the man and woman should quit smoking marijuana for at least a year prior to when they want to conceive. Burkman said there are “no hard studies’’ that support that specific time frame, but it’s an estimate she bases on research that shows that marijuana chemicals get stored in the body’s fat tissue, which suggests it could take at least a year or two to “work its way out of your system.’’

Marijuana use by women during pregnancy, on the other hand, has been linked to a variety of problems in the children, including low birth weight and cognitive problems. Source.