FIG 1.

Congenital HCMV transmission rates in CMV-seronegative and -seropositive women. (A) Primary HCMV infection occurs infrequently (rate, 1% to 3%) in HCMV-seronegative pregnant women, but rates of cCMV transmission (30% to 40%) and infant disease (25%) are known to be high following primary maternal infection (1, 97). (B) The rate of systemic maternal HCMV reactivation in chronically infected women is not known; nor is the rate of cCMV infection in the setting of maternal reactivation known. (C) HCMV reinfection rates, identified by detection of a serologic response against a new strain of HCMV, have suggested that nearly 1 of 3 CMV seropositive women become reinfected during pregnancy (24, 39), and yet the cCMV transmission rate is up to 10-fold lower than that in primary maternal infection (3.4%) (23) and the disease rates have been reported as 10% or less (24, 29, 33, 34). Thus, similar numbers of cCMV-infected and -impaired infants occur in HCMV-seronegative and -seropositive pregnant women populations (1). *, data points where more studies are needed to further advance our understanding of the partial protective nature of preexisting HCMV immunity.