Can sex outside of fertile window still improve fertility?

Can sex outside of fertile window still improve fertility?

I just heard about a fascinating study and had to share. Fertility is an ever-evolving topic and I’m always learning new things. 

Check this out: it has been suggested that regular sex outside of one’s fertile window can actually improve fertility because of the influence that sex has on our immune system regulation. Wild, right? 

Here are the deets: 

First, a quick primer on the immune system. 

T helper cells are white blood cells that play an important role in the immune system. They are responsible for activating other immune cells to fight off infection or disease. The two main types of T helper cells, Th1 cells and Th2 cells, each have unique characteristics and functions.

The primary function of Th1 cells is to activate the cellular immune response. This usually involves recruiting macrophages and other cells to destroy malfunctioning cells. 

The primary function of Th2 cells is to activate the antibody-mediated immune response. This involves recruiting B cells to produce antibodies that can neutralize or eliminate pathogens. 

Th cells are activated by cytokines, which are signaling molecules that help activate other immune cells to fight off infections.

Th1 cytokines are pro-inflammatory and are involved in the immune response against intracellular pathogens such as viruses and bacteria. They activate macrophages to kill these pathogens and promote the development of cytotoxic T cells that can directly kill infected cells.

Th2 cytokines are anti-inflammatory and are involved in the immune response against extracellular pathogens such as parasites, as well as self-cell tolerance. They inhibit the activation of macrophages, promote the production of antibodies by B cells and activate eosinophils and other cells that can help to eliminate pathogens.

Ok, so now that we understand the role of T helper cells, we can see that this study suggests that sexually active women had higher TH2 cell levels in their luteal phase (after ovulation) and they had higher progesterone levels (which are necessary to support a pregnancy once implantation takes place). Both of these states mirror the states that occur in pregnancy. 

Pregnancy is considered a Th2 dominant phase. Higher levels of Th2 cytokines are expressed during pregnancy, because these cytokines facilitate embryo implantation and placental development. Th2 dominance is believed to help prevent the immune system from attacking the fetus (which might be considered a “foreign invader” if not for this shift). Th2 cells produce cytokines that help suppress inflammation and support the development of immune tolerance, which is important for maintaining pregnancy. 

Now that we understand Th1/Th2 dominance in pregnancy, back to the study: it says that “...the ratio of TH1/TH2-associated cytokines can be characterized as reflecting immune priorities: defending against viruses and bacteria (TH1 dominant) versus preparing for and/or tolerating the semiallogenic [partially genetically different] fetus (TH2 dominant).” They go on to say that “partnered sexual behavior may signal that conception is possible, and as such, downshift immune responses that may interfere with reproduction and/or up-regulate immune responses that may promote conception. Among women who are sexually abstinent, however, there would be no such signal and therefore, potentially, no significant shifts in the TH1-TH2 ratio…” Also, the study mentions another shift in a key marker of immune system regulation: “Increased frequency of partnered sexual activity is associated with lower levels of secretory immunoglobulin A, an antibody important for first-line immune defense.” Here’s the clincher: “...partnered sexual activity—even that which occurs outside the fertile window and thus can not directly lead to a conception—may promote fertility via priming the immune system to engage in shifts that promote reproduction.” Basically, with regular sex, the body anticipates conception and makes physiological shifts to prepare itself!

In addition, the study suggests that regular sex also decreases inflammation levels, which we also know can interfere with conception. 

The authors conclude that: “...sexual activity within a relationship—even that which does not result in conception—serves a variety of functions that affect reproductive health, from improving pair bonds…and improving relationship satisfaction across the lifespan… to engaging endocrine and immune responses… that may promote fertility.”

Basically, in addition to increasing intimacy, regular sexual activity may encourage certain types of immunity that support conception.

This was a small study, so there definitely needs to be more research here, but the concept makes sense - and besides, if you assume this is true, the only thing you’re going to be doing is having more sex, which is not the worst outcome 🙂

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