Desire for children: sex makes you fertile

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Couples who do not want to have children should have sex more often. And not only during the woman's fertile days, but also in between. The reason: If the woman has cohabitation frequently, the woman's immune system tolerates male sperm better.

“It has long been recommended that couples who wish to have a child should have sex as often as possible outside of the fertile days. Why this works has not yet been clear, ”says Tierney Lopez of Indiana University in Bloomington. "Our work shows for the first time that sexual activity influences the immune system in such a way that it supports conception."

Transformed defense

For the body's own defenses, sperm are primarily one thing: strangers. And as such, many immune cells also treat the little swimmers: they fought them. But with frequent sexual contact, this attitude apparently changes. Then the immune system even supports the sperm.

One of the reasons for this is a changed composition of the T helper cells. This type of immune cell controls the immune system by activating other immune cells, which in turn eliminate germs.

However, the different T helper cell types are differently aggressive: Type 1 helper cells are indiscriminately mobile against all strangers - also against sperm, and even against the embryo itself, which is also genetically different from the mother. The type 2 helper cells are different: They promote the implantation of the fertilized egg cell and even protect sperm and embryo.

In women who often have sex, fewer T-helper cells of type 1 swarm out, instead more of type 2. This has a major impact on the chances of having a baby.

Helpful antibodies

The antibodies also change with frequent sexual intercourse: sexually active women have more immunoglobulin G than immunoglobulin A in the blood and in the vaginal and uterine mucus. This also supports the sperm's chances of success in reaching the egg cell.

For their study, scientists examined the immune systems of 30 women who were either very sexually active or who lived abstinently. The researchers determined both the number of different T cells and the amount of antibodies in the blood of the participants and in the mucus of the vagina and uterus.

Changes before ovulation

Interestingly, the immunological changes in the sexually active participants were limited to just a few days before ovulation. This makes sense insofar as the type 1 helper cells are important for the immune system. These cycle-related changes did not occur in women who did not have sexual intercourse.

“The female body is in a tricky dilemma: In order to protect itself, it builds up defenses against intruders. But if he proceeds with the same logic against sperm and fetuses, pregnancy is impossible, ”said study leader Lopez, explaining the problem. The solution could lie in the observed temporary adaptation of the immune system.

The body's own defense does not seem to be as fixed as previously assumed: It does not react according to a fixed pattern, but adapts to external circumstances - this makes it a highly potent protective mechanism.

Unintentionally childless

Unintentional childlessness is not uncommon: According to the Allensbach Institute for Demoscopy, one in five couples who want a child does not become pregnant. This even applies to parents who already have one child and want another. In total, the institute reckons with 1.4 million Germans who are involuntarily childless. In around 30 percent of the cases it is the woman, in another 30 percent the man and another 30 percent on both partners. In ten percent of the cases it cannot be medically clarified why it does not work.

Since people in Germany decide later and later to have children and the chances of conception decrease with increasing age, the number of couples affected is steadily increasing. (cf)

Sources:

Tierney K. Lorenz et al .: Sexual activity modulates shifts in TH1 / TH2 cytokine profile across the menstrual cycle: an observational study: Fertility and Sterility; 16 September 2015; doi: 10.1016 / j.fertnstert.2015.09.001

Tierney K. Lorenz et al .: Interaction of menstrual cycle phase and sexual activity predicts mucosal and systemic humoral immunity in healthy women; Physiology & Behavior; doi: 10.1016 / j.physbeh.2015.09.018

Tags:  healthy feet prevention unfulfilled wish to have children