A prospective study of maternal cytomegalovirus infection and its effect on the fetus.

In order to define the effects of maternal cytomegalovirus infection in pregnancy and to identify risk factors associated with delivery of a cytomegalovirus-infected infant, a cohort of 1089 adolescents were prospectively evaluated during pregnancy. One hundred twenty-four subjects (11.4%) manifested cytomegaloviruria during pregnancy. Primary cytomegalovirus infection, defined virologically and serologically, occurred in three subjects. Infants of 119 cytomegalovirus-excreting mothers were cultured at birth, with detection of 12 congenital infections (10%), including one infant delivered of a mother with a third-trimester primary infection. A high titer of urinary virus or a fourfold or greater increase in antibody during the third trimester was significantly associated with delivery of a congenitally infected infant. All maternal and infant infections were asymptomatic. None of the congenitally infected infants manifested adverse effects during the first year of life. Our data demonstrate that pregnant women with cytomegaloviruria are at increased risk of being delivered of congenitally infected infants, particularly if active infection occurs late in pregnancy. If the maternal infection represents reactivation, overall probability of a poor fetal outcome is low.