Some doctors are concerned that frequent marijuana use may cause sexual problems. But pot smokers in a recent Stanford study weren't concerned at all. Quite the opposite.

The study of over 50,000 people spanned more than a decade and found that daily marijuana smokers had sex about 20 percent more often than non-smokers did. People who smoked it less frequently also had more sex than non-smokers did. This relationship was dose-dependent: more frequent marijuana use meant more frequent sex.

In general, pot users are having about 20 percent more sex than pot abstainers.

This trend was true for men and women, as well as for people of all races, ages, education levels, income groups, religions and health status. It also held whether a person was married or single and whether or not they had children.

Nevertheless, the study shouldn’t be misinterpreted as having proven a causal link. “It doesn’t say if you smoke more marijuana, you’ll have more sex,” the study’s senior author, Michael Eisenberg, assistant professor of urology at Stanford, noted.

The study looked at about 28,000 women and 23,000 men. Women in the study who said they hadn't smoked marijuana in the past year had sex on average 6.0 times during the previous four weeks, while that number was 7.1 for daily pot users. Among men, these numbers were 5.6 for nonusers and 6.9 for daily users. The average age of those in the study was 29 years old.

These figures come from the National Survey of Family Growth which explicitly asks respondents how many times they’ve had intercourse with a member of the opposite sex in the past four weeks and how frequently they’ve smoked marijuana over the past 12 months.

Nearly a quarter of the men and 14.5 percent of the women reported marijuana use. All figures in the study were self-reported. People's sexual frequency isn't a topic that lends itself to close laboratory scrutiny, so researchers typically have to settle for self-reported information.

The relationship between marijuana and sex has returned mixed results in previous research. Some researchers report erectile dysfunction in heavy users, while other studies have found reduced sperm counts in men who smoke it.

At the same time, experiments on both animals and humans show that marijuana stimulates activity in brain regions involved in sexual arousal and activity.

The current study's researchers decided to take a closer look and found regular marijuana use linked to more sex. The trend — more marijuana, more frequent sex — remained even after accounting for people's use of other drugs, suggesting that the study findings aren't merely a reflection of less inhibited people being more inclined both to use drugs and to have sex.

The authors do caution that their findings aren't the last word on this topic, but call their results reassuring.

The study appears in the Journal of Sexual Medicine.