Intra-uterine transmission of cytomegalovirus in women known to be immune before conception.

A prospective study identified 785 pregnant women who had been shown to possess complement fixing antibodies against cytomegalovirus (CMV) during a previous pregnancy. As these women were thus known to have been immune prior to their subsequent conception, their neonates were examined for evidence of congenital CMV infection. Specimens were obtained from 725 (92%) of the neonates and congenital infection was found in only one (0.14%). The elder sister of the infected child was also shown, by retrospective testing of her stored cord serum for specific IgM antibodies, to have been infected in utero. Thus, one woman was identified who had delivered consecutive siblings congenitally infected with CMV. We conclude that some women have a propensity for intra-uterine transmission of CMV, despite being immune prior to conception, and speculate that such women may have acquired their infections perinatally.