(Photo: Marina Agular)
Researchers at Indiana University found that women who have sexual intercourse even while they were not ovulating were more likely to become pregnant than women who had sex only while ovulating. Physiological changes resulting from non-fertile sexual congress increased the likelihood of conception. Eureka Alert quotes lead study author Tierney Lorenz:
"It's a common recommendation that partners trying to have a baby should engage in regular intercourse to increase the woman's changes of getting pregnant -- even during so-called 'non-fertile' periods -- although it's unclear how this works," Lorenz said. "This research is the first to show that the sexual activity may cause the body to promote types of immunity that support conception.
"It's a new answer to an old riddle: How does sex that doesn't happen during the fertile window still improve fertility?"
Women in the study who had regular non-procreative sex were preparing their immune systems to accept conception:
"We're actually seeing the immune system responding to a social behavior: sexual activity," Lorenz said. "The sexually active women's immune systems were preparing in advance to the mere possibility of pregnancy."
Both studies contribute to a growing body of evidence that the immune system isn't a passive system that waits to react to outside threats, but a highly proactive system that changes in response to external cues, such as the physical environment and social behavior.
-via Dave Barry