Many women who struggle to get pregnant also worry about early miscarriages or very early pregnancy losses. Research now shows that a hidden virus in the uterus—HHV-6A—may play a role in some of these cases.
HHV-6A can quietly live inside the cells of the uterine lining. When it becomes active, it can change the immune signals the uterus uses to support a new pregnancy. Some studies show that women with HHV-6A in their endometrium have higher levels of inflammatory signals and lower levels of the calming signals an embryo needs to stay attached.
Scientists have also found HHV-6 DNA in the placenta and fetal tissues in certain cases of miscarriage, showing that the virus may affect pregnancy very early on. While HHV-6A is not proven to cause every miscarriage, the research suggests it may make the uterus less stable and less supportive during the first few days or weeks after conception.
Because HHV-6A does not show up on normal fertility tests, many women never know it’s there. Testing the uterus lining—or the endometrial cells in menstrual fluid—can help uncover this hidden factor before trying again.
If HHV-6A can affect early pregnancy, the next question many women ask is:
“Why haven’t I heard about this before?”
Read this article next: “Why Haven’t I Heard of HHV-6A Before?”
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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Komaroff AL, Pellett PE. Human Herpesviruses 6 and 7. StatPearls; NCBI Bookshelf. 2021.
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Kaspersen MD, et al. HHV-6A/B binds to spermatozoa and is the most prevalent herpesvirus in semen from sperm donors. PLOS ONE. 2012.
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Several studies summarized in the HHV-6 Foundation’s reproductive health reviews.