Update on the prevention, diagnosis and management of cytomegalovirus infection during pregnancy

Human cytomegalovirus (CMV) is the leading cause of congenital infection, with morbidity and mortality at birth and sequelae. Each year approximately 1-7% (Rev Med Virol 2010; 20: 311) of pregnant women acquire a primary CMV infection. Of these, about 30-40% transmit infection to their fetuses. The risk of serious fetal injury is greatest when maternal infection develops in the first trimester or early in the second trimester. Between 10 and 15% of congenitally infected infants are acutely symptomatic at birth and most of the survivors have serious long-term complications. Until a few years ago, laboratory testing was not possible to precisely define the maternal immune status, the recent development of advanced serological tests (IgG avidity test, IgM immunoblot and neutralizing antibody testing) allow us to identify, among pregnant women with suspected CMV, those with primary infection who are therefore at high risk of transmitting CMV to the fetus. This is done with the use of a screening test. As most maternal infections are asymptomatic, the only way to disclose primary infection is to implement specific serological testing as early in pregnancy as possible (before week 12-16 of gestation). Given the high risk of mother-fetus transmission and fetal damage, prenatal diagnosis is recommended to women with primary CMV infection contracted in the first half of pregnancy and in case of fetal abnormalities suggestive of infection. The correct interpretation of serological and virological tests followed by appropriate counselling by an expert physician is an effective tool to reduce the number of unnecessary pregnancy terminations by over 70%.