Figure 1.

Proposed scheme for cytomegalovirus (CMV) infection in pregnancy. Women are often exposed to toddlers excreting CMV. Both seronegative and seropositive women can be exposed, particularly the latter if they live in countries where children are often infected. The CMV infection in both cases rapidly becomes intracellular, although first infections in seronegative women are likely to include cell-free virus in the plasma. In both types of women, CMV spreads to multiple organs. In seronegative women, spread to the placenta cells and on to the fetus is likely, whereas in seropositive women who are repeatedly infected, the placenta usually but not always remains virus free. Thus, seropositivity is a relative protective factor. (Source: Jackson and Sparer [23].)