CONCISE COMMUNICATIONS Reactivation of Human Herpesvirus 6 during Pregnancy

Reactivation of human herpesvirus 6 (HHV-6) and cytomegalovirus (CMV) during preg-nancy and transmission of the viruses to the fetus were investigated by polymerase chain reaction (PCR) and serology. In all, 104 blood samples were obtained 3 times during pregnancy and once at delivery. In another 107 women, samples were obtained only at delivery. Cord blood samples were obtained from both groups of women. HHV-6 DNA was detected in 41%±44 % of the samples during months 3±8 of pregnancy, in 25 % at delivery, and in 24 % of age-matched controls. HHV-6 DNA was found in 1.0 % of the cord blood samples. CMV DNA was detected in 1.7 % of leukocytes from 104 pregnant women but in no cord blood sample. IgG antibodies to HHV-6 were found in 96 % and CMV IgG in 62.5 % of the women. HHV-6 IgG titers were signi®cantly higher in HHV-6 PCR-positive women. Thus, HHV-6 reactivation seems common during pregnancy, and transfer of HHV-6 to the fetus may occur in »1 % of pregnancies. Human herpesvirus 6 (HHV-6) is a ubiquitous virus [1], and infection with HHV-6 is commonplace in infancy or early child-hood [2]. Several studies indicate that primary HHV-6 infec