The "love hormone" oxytocin may help keep straight men in relationships faithful by prompting them to steer clear of hot women.

New German research finds that oxytocin may play a role in keeping men in relationships faithful.

Researchers from the University of Bonn in Germany found that when men in monogamous relationships were given a dose of oxytocin nasal spray, they kept a larger physical distance -- about four to six inches (or 10-15 centimeters) -- from attractive women they didn't know compared to men who received a placebo.

However for single men, the oxytocin spray had no effect on the distance they kept between themselves and the attractive women. The study involved 57 heterosexual men.

"Because oxytocin is known to increase trust in people, we expected men under the influence of the hormone to allow the female experimenter to come even closer, but the direct opposite happened," says researcher Dr. René Hurlemann.

In humans, oxytocin has been found to promote bonding between parents and their children and also reduce conflict between couples. MyHealthNewsDaily also cites a recent study that found that couples with higher levels of oxytocin in the beginning of their relationship were more likely to stick together than couples with lower levels of the hormone.

The study is set to be published Wednesday in The Journal of Neuroscience.