4 Surprising Reasons to Have More Sex, According to Science

How sex helps: Regular sex—even outside of your fertile period—may trigger immune and inflammation changes that prep your body for pregnancy.
The science: Your immune system can help or hurt your chances of conceiving. For example, it can assist with uterine tissue changes that make implantation more likely, or it can identify sperm as a harmful invader and basically tell it to scram. Sexual activity, regardless of when it happens during your cycle, appears to signal that it's time to switch from protector mode to a more nurturing, time-to-get-pregnant state, found two recent studies, one in Fertility and Sterility and the other in Physiology & Behavior. The "how" isn't totally clear, but the fact that women using condoms experienced the same changes as women who weren't using them suggests that it's something about sex itself that causes the effect, says Tierney Lorenz, PhD, a visiting research scientist at the Kinsey Institute and lead author of both studies. What's more, another of Lorenz's studies (in Evolution, Medicine, and Public Health) found that sexually active women had lower inflammation levels around peak fertility, which helps with ovulation.