Previous research suggests that having sex at the right moment is everything. However, two new studies suggest that having sex any time can boost a woman’s immunity and chances of getting pregnant.
Both studies were lead by a visiting research scientist at Kinsey Institute of Research in Sex, Gender and Reproduction at Indiana University, Tierney Lorenz, according to Huffington Post.
“It’s a common recommendation that partners trying to have a baby should engage in regular intercourse to increase the woman’s chances of getting pregnant–even during so called ‘non-fertile’ periods–although it’s unclear how this works,” Lorenz said. She added that this is the first research that has illustrated how sexual activity “may cause the body to promote types of immunity that support conception.”
The study’s results were published Tuesday in two papers, one in the journal Physiology and Behavior and another in the journal Fertility and Sterility. The papers suggest that having sex during points that aren’t of fertility in a woman’s cycle could still raise her chance of getting pregnant, according to Newsweek.
Researchers from Indiana University collected data from 30 women who participated in the Kinsey Institute’s Women, Immunity and Sexual Health Study. Nearly half of the women were sexually active and the others were not. In the paper published in Fertility and Sterility, they looked at saliva samples of all of the women during the four phases of the women’s cycle: menstrual, follicular, ovulatory and luteal phases.
The researchers found higher levels of type 2 helper T cells, which help the body deal with changes associated with pregnancy, during the luteal phase of the menstrual cycle, according to Huffington Post. They also discovered that higher levels of type 1 helper T cells, which work to defend diseases, in the same women during the follicular phase of the menstrual cycle.
This means that the immune system is “responding to a social behavior: sexual activity,” Lorenz said in a press release. “The sexually active women’s immune systems were preparing in advance to the mere possibility of pregnancy.”
In second paper, published in Physiology and Behavior, Lorenz and her research team collected saliva from 32 premenopausal women. Fifteen of them were sexually active and the other 17 were not. Again, the sexually active women had more changes to helper T cells and proteins that tell the body it’s ready for pregnancy.
Lorenz said that their findings could impact what doctors recommend to couples looking to conceive, according to Fox. “It’s a new answer to an old riddle,” Lorenz said.