Many women are told their fertility tests are “normal,” yet they still struggle to get pregnant. If this sounds familiar, there may be another piece of the puzzle that routine testing doesn’t check for: a silent virus hidden in the uterus called HHV-6A.
HHV-6A doesn’t usually show up in blood tests because it prefers to live inside endometrial cells—the very cells that help an embryo implant. Researchers have discovered that in some women, this virus becomes active in the uterine lining and may interfere with early steps in pregnancy.
In a major study, HHV-6A was found in 43% of women with unexplained infertility, but in 0% of fertile women. Other findings show that active HHV-6A can disrupt the immune balance of the endometrium—making it harder for the embryo to “stick,” even when eggs, sperm, hormones, and tubes are perfectly healthy.
Because HHV-6A doesn’t cause noticeable symptoms, many women never know it’s there. Standard fertility workups don’t test for it. That’s why a targeted test that looks directly at endometrial cells—such as a menstrual-fluid–based HHV-6A test—can reveal a hidden cause of failed implantation that would otherwise go unnoticed.
If a virus in the uterus can quietly affect implantation, the next question many women ask is:
“What do I do if I test positive?”
Read this article next to learn the answer: “Is There Treatment for HHV-6A?”
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, Doody K. Prospective evaluation of human herpesvirus 6 (HHV-6) in endometrial biopsies of women with repeat implantation failure. ASRM Poster. 2019.
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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.
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Komaroff AL, Pellett PE. Human Herpesviruses 6 and 7. In: StatPearls; NCBI Bookshelf. 2021.