To investigate the impact of pregnancy on human herpesvirus 8 (HHV-8) reactivation in human immunodeficiency virus type 1 (HIV-1)-infected women, the HHV-8 DNA presence and load were analyzed in peripheral blood mononuclear cells (PBMCs) and cervicovaginal secretions (CVSs) from 15 pregnant women coinfected with HIV-1 and HHV-8. HHV-8 detection was analyzed in relation to anti-HHV-8 antibodies and HIV-1-related parameters. Nucleotide sequence analysis of an ORFK1 hypervariable region of the HHV-8 strains was performed. HHV-8 was detected in maternal PBMCs (5/15 women) from the second trimester and in CVSs (5/15 women) mainly from the third trimester. The HHV-8 load significantly increased late in pregnancy in both maternal compartments and was associated with a significant increase in HIV-1 shedding in the genital tract. Antilytic antibodies were significantly more common in HHV-8 DNA-positive women. An elevated HHV-8 load was found in the PBMCs of an infant born to a mother with large amounts of HHV-8 in both compartments at delivery. Different ORFK1 subtypes were found in maternal samples, whereas the same subtype was identified in the mother-child pair. These data suggest that pregnancy may induce HHV-8 replication in HIV-1-infected women. An augmented HHV-8 load may, in turn, influence mother-to-child transmission, since one of the HIV-1-infected mothers with HHV-8 reactivation transmitted her ORFK1 subtype to the infant, who showed a high level of HHV-8 viremia indicative of a primary infection. This finding documents for the first time the perinatal transmission of a specific HHV-8 subtype. Vertical transmission may thus play a role in HHV-8 spread also in areas of subendemicity among HIV-1-infected women.