Mothers with inherited chromosomally integrated human herpesvirus 6 (iciHHV-6) have a higher risk of spontaneous abortion, according to a study published in The Journal of Infectious Diseases.

Previous studies have associated iciHHV-6 with encephalitis, cognitive dysfunction, and fatigue, although they have not demonstrated any gender difference among index cases with iciHHV-6 even though many cases were of paternal origin. This study examined the origin of the HHV-6 genome and the pregnancy histories of mothers in families with iciHHV-6 to determine if paternal origin is more common than maternal origin, and evaluated the association between iciHHV-6 and spontaneous abortion.

Of the 23 iciHHV-6 index pregnant women included in this study, 8 of the mothers had iciHHV-6 with a history of 8 spontaneous abortions in 29 pregnancies, and 15 mothers without/fathers with iciHHV-6 had a history of 3 spontaneous abortions in 29 pregnancies. For the control group, 285 mothers in families without iciHHV-6 were included and had a history of 589 spontaneous abortions. High viral DNA copy numbers in whole blood and somatic cells confirmed iciHHV-6 and examined the original maternal or paternal viral genome.

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Results suggest that iciHHV-6 in mothers is a risk factor for spontaneous abortion. In total, 27.6% (8/29) of mothers with iciHHV-6 had a spontaneous abortion, compared to 10.3% (3/29) of mothers without/fathers with iciHHV-6, and 14.8% (87/589) mothers in families without iciHHV-6 (P =.012). Recurrent pregnancy loss, defined as at least 2 spontaneous abortions, occurred in 37.5% (3/8) of mothers with iciHHV-6, 0% (0/15) of mothers without/fathers with iciHHV-6, and 6.3% (18/285) of mothers in the control group (P =.002). Multivariable analyses showed that mothers with iciHHV-6 (odds ratio [OR], 6.41; 95% CI, 1.10-37.4; P =.001) and maternal age of 40 years or older at the most recent pregnancy (OR, 3.91; 95% CI 1.30-11.8; P =.016) were significantly associated with recurrent pregnancy loss.

“[A]lthough there is no gender difference among iciHHV-6 index cases, the frequency of iciHHV-6 inherited from the mother was lower than expected in this study,” authors concluded, noting that “careful management may be required for pregnant women with iciHHV-6, who may be predisposed to spontaneous abortion.”


Miura H, Kawamura Y, Ohye T, et al. Inherited chromosomally integrated human herpesvirus 6 is a risk factor for spontaneous abortion. J Infect Dis. Published online September 28, 2020. doi:10.1093/infdis/jiaa606/5912305

This article originally appeared on Infectious Disease Advisor