At the International Congress of Immunology held in Australia this year, Sarah Robertson, from the University of Adelaide, presented the results of her recent study that found semen to be valuable in boosting the health of pregnancy and improving in vitro fertilization (IVF) success rate. Frequent sex with a familiar partner seems to ensure the healthiest pregnancy, even while IVF is in progress.
Robertson’s study indicates semen is much more than a transport vessel for sperm. She described it as “a Trojan horse that activates the immune cells to get things ready for conception.”
Of Mice and T-Cells
In a study of mice, Robertson discovered that each time a female mouse mates, certain immune cells (regulatory T-cells) are released, perhaps to minimize inflammation throughout the body. The primary purpose of the immune system is to attack and destroy any DNA that enters the body that does not match the person’s. This battle of the immune system usually produces inflammation.
Attack and destroy is desired when the invader is a virus, bacterium, or other organism that can cause disease. It’s not good at all when the foreign DNA is sperm or a fertilized egg.
Signals from the Cervix
When Robertson explored the possibility of the immune system’s response to semen in humans, she found evidence that semen passing through the cervix causes it to release immune-signaling molecules. Robertson theorizes this immune-system activity triggers the release of regulatory T-cells.
T-Cells and Pregnancy
The release of T-cells during sex may relax the immune system enough to allow a fertilized egg to implant successfully in the uterine lining. The egg shares some genetic materials with the mother but it also contains foreign DNA supplied by the father. Without a boost from the immune system, the woman’s body might be more inclined to reject the fertilized egg and/or the fetus that develops from it.
“In humans, it seems that at least three months of sexual cohabitation is required to give you the priming that you need (for conception),” according to Robertson. She suggests this delay in conception may be related to the influence of a regular sex partner’s sperm on the female immune system. Frequent exposure to the same man’s semen over a period of time may cause the woman’s immune system to become familiar with his DNA and relax its guard against it.
T-Cells and Pregnancy Complications
Robertson noted that some reproductive issues and pregnancy complications are associated with low regulatory T-cell count. Some medical issues she mentioned specifically include unexplained infertility, miscarriage, pre-eclampsia, and pre-term labor.
T-Cells and IVF
A number of recent studies have found that the embryo implantation success rate is approximately 23% higher when couples engage in frequent intercourse even as the IVF process is under way. Robertson suggests the actual process of fertilization may be taking place in the lab but exposure to semen at home may make the uterus more immunologically receptive to implantation.
“Our results suggest that the first-line approach to treating infertility should be to tell people to go home and practise,” Robertson says. “But if that doesn’t work, tackling regulatory T-cells may be the way to go.”
Every case of infertility is different, however, so a complete evaluation by a fertility specialist should always the first-line approach. Some fertility specialists advise abstinence during IVF to decrease the risk of any infection that may prevent success. If the risk of infection is found to be low and your fertility specialist says intercourse poses no risk, Robertson’s advice to “go home and practise” may be what it takes to set the stage for a whole new life.
Sources:
Robertson, SA, and DJ Sharkey. "Seminal fluid and fertility in women." PubMed. Fertility and Sterility / American Society for Reproductive Medicine, July 2016. US National Library of Medicine / National Institutes of Health. Web. 26 Aug. 2016.
"When to Work on Your Sex Life." babyMed. BabyMed.com, n.d. Web. 26 Aug. 2016.
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By Sandy Hemphill, Contributing Writer, BabyMed