What is HHV-6A?

Most fertility tests look at your eggs, hormones, fallopian tubes, and your partner’s sperm.
But new research shows there can also be a “hidden” virus in the lining of the uterus that standard tests completely miss. That virus is called HHV-6A.

HHV-6A is a member of the herpes virus family (like the viruses that cause cold sores or chickenpox). Once a herpes virus enters your body, it can stay for life—usually sleeping quietly and causing no obvious symptoms. Scientists have learned that HHV-6A can hide inside certain tissues, including the cells that line the uterus (the endometrium).

In one important study, researchers looked at the uterine lining of women with unexplained infertility and compared it to women who had already had babies. They found HHV-6A in about 43% of women who couldn’t get pregnant, but in 0% of the fertile women. The virus showed up only in the tissue from the uterus, not in blood tests, which explains why it is so easy to miss with normal testing.

Other studies suggest that when HHV-6A is active in the uterine lining, it can change the local immune environment and make it harder for an embryo to implant and grow. In simple terms, the virus may quietly disturb the “welcome mat” your uterus needs to offer a tiny embryo.

Because this virus lives in the lining of the uterus, the most useful tests look directly at cells from that lining—either through a biopsy in a clinic or by analyzing endometrial cells that naturally come out in menstrual fluid with specialized testing.

Could this be one reason you haven’t been able to get pregnant yet?
Read this article next to find out: “Could a Silent Virus Be Blocking Your Pregnancy?”

References

  1. 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.

  2. Knox K, Doody K. Prospective evaluation of human herpesvirus 6 (HHV-6) in endometrial biopsies of women with repeat implantation failure. ASRM Poster. 2019.

  3. 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.

  4. Komaroff AL, Pellett PE. Human Herpesviruses 6 and 7. In: StatPearls; NCBI Bookshelf. 2021.

  5. Menstrual blood holds the key to better diagnostics. Drug Discovery News. 2022.