A prospective study of congenital cytomegalovirus infection in Japan.

A prospective study on congenital cytomegalovirus (CMV) infection was carried out in Sapporo, Japan. Only 77 (6.2%) of 1233 pregnant women were seronegative in the first trimester. In such a highly immune population, 11 (0.5%) of 2070 newborn infants were found to have congenital CMV infection. None of them showed any clinical abnormalities during the period of observation (3-24 months), except for a cyst of septum pellucidum in one case. The incidence of congenital CMV infection in the first pregnancies was 1.1% (9/816) and in subsequent pregnancies 0.2% (2/1254). The difference was statistically significant. Three mothers of infants with congenital CMV infection were already seropositive in the first trimester. 26/30 (86.7%) infants, born to mothers with active CMV infection during pregnancy, had started to excrete CMV with urine before the age of 12 months. In contrast, none of the 4 infants born to seronegative mothers excreted CMV.