The findings, published online in the Journal of Sexual Medicine, negate concerns among physicians and scientists that frequent marijuana use may impair sexual desire or performance.
"Frequent marijuana use doesn't seem to impair sexual motivation or performance. If anything, it's associated with increased coital frequency," said the study's senior author Michael Eisenberg, Assistant Professor of Urology at Stanford University School of Medicine in the US.
"The overall trend we saw applied to people of both sexes and all races, ages, education levels, income groups and religions, every health status, whether they were married or single and whether or not they had kids," Eisenberg added.
To arrive at an accurate determination of marijuana's effect on intercourse frequency, the researchers turned to the US National Survey of Family Growth, sponsored by the federal Centers for Disease Control and Prevention (CDC).
The survey explicitly queries respondents on how many times they have had intercourse with a member of the opposite sex in the past four weeks, and how frequently they have smoked marijuana over the past 12 months.
The investigators compiled answers to those questions for all years since 2002, when the survey first began collecting data on men as well as women.
They included data from respondents between ages 25-45.
Some 24.5 per cent of men and 14.5 per cent of women in the analysis reported having used marijuana, and there was a positive association between the frequency of marijuana use and the frequency of sexual intercourse.
This relationship applied to both sexes: Women denying marijuana use in the past year, for example, had sex on average six times during the previous four weeks, whereas that number was 7.1 for daily pot users.
Among men, the corresponding figure was 5.6 for non-users and 6.9 for daily users.
In other words, pot users are having about 20 percent more sex than pot abstainers, Eisenberg noted.
In addition, coital frequency rose steadily with increasing marijuana use, a dose-dependent relationship supporting a possible active role for marijuana in fostering sexual activity, the study said.