When you are trying to get pregnant, your uterus is more than just a “space” for the embryo. It is a living environment made up of cells, blood vessels, hormones, and immune signals. All of this together is called the uterus micro-environment.
For implantation to work, this environment has to be “just right.” The lining of the uterus (the endometrium) needs to be soft, rich in blood flow, and calm on the immune side—ready to welcome an embryo instead of attacking it. Special immune cells (like natural killer cells, or NK cells) and “messenger” proteins called cytokines help decide if the uterus feels safe for an embryo to attach.
Researchers have found that when HHV-6A is active in the uterine lining, this micro-environment can change in harmful ways. In one study, women with HHV-6A in their endometrium had different immune patterns than women without the virus: fewer of the normal NK cells and a shift in important cytokines. These changes can make the lining less friendly for an embryo to stick and grow, even if the embryo itself is healthy.
In simple terms, HHV-6A can quietly disturb the “welcome mat” in your uterus—changing the signals that tell your body, “It’s safe to let this baby grow here.”
Because these changes happen inside the uterine lining, they don’t show up on normal blood tests or standard fertility labs. They only show up when someone looks directly at endometrial cells—through a biopsy or a menstrual-fluid test designed to capture cells from the uterus.
Once you understand how the uterus micro-environment can fail, the next question is often:
“How can I test this in a simple, non-invasive way?”
Read this article next to find out: “What Makes Covee Different?”
References
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Marci R, Gentili V, Bortolotti D, et al. Presence of HHV-6A in endometrial epithelial cells from women with primary unexplained infertility. PLOS ONE. 2016.
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Knox K. Human Herpesvirus 6 and Unexplained Infertility. Coppe Laboratories Educational Slide Deck.
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Liu Z, Chen F, Li Y, Pratt P, Knox K. HHV-6 infection is correlated with uterine polyp and endometrial adhesion in infertile women. SRI Abstract. 2020.