Non primary versus primary cytomegalovirus infection during pregnancy.

BACKGROUND: Cytomegalovirus (CMV) is the most common cause of intrauterine infection, occurring in 0.3% to 2% of all newborns. Each year approximately 1-4% of pregnant women acquire a primary CMV infection and vertical transmission occurs in a mean rate of 40%. Up to 15% of intrauterine CMV infections result in symptomatic congenital disease at birth, mainly with central nervous system and multiple organ involvement, and 8-15% of infected newborns without symptoms at birth develop long-term sequelae, mainly neurological or auditory damages. Unlike rubella or toxoplasmosis, preconceptional immunity against CMV provides only a partial protection and intrauterine transmission of CMV has been reported in women with pre-existing seroimmunity in 0.5% to 2.2 % of cases. Considering that 70–80% of pregnant mothers are seropositive prior to conception, we should conclude that over half of the children infected with CMV in utero are born from mothers with preconceptional immunity. Therefore, during pregnancy, both primary and non-primary maternal infection can lead to CMV crossing the placenta and infecting the fetus, resulting in congenital CMV infection. It is generally accepted that symptomatic congenital infection and permanent neurologic deficits are rare in the infants from women with preconceptional immunity. However, in recent years there is an increasing evidence that non primary maternal infection may be a significant cause of severe congenital CMV disease. OBJECTIVE: The objective of the study was to evaluate the pregnancy outcomes of non-primary CMV maternal infections versus primary infections. STUDY DESIGN: This is a retrospective study of 1496 consecutive pregnant women with confirmed active CMV infection, referred to our units for diagnostic evaluation and management in a 15 years period (1994- 2009). Patients with available follow-up were divided into 2 groups according to the results of confirmatory serologic testing (avidity test, immunoblotting): women with a CMV serologic profile consistent with non-primary infection and women with a CMV serologic profile suggestive of primary infection. We evaluated and compared the vertical transmission rate of non-primary and primary maternal infections and the percentage of symptomatic infections (at birth and/or long term sequelae) into the two groups. RESULTS: Long term follow-up was available in 1270 cases: 326 non-primary infections and 944 primary maternal infections. Congenital infections were diagnosed in 8 (2.5%) fetuses/neonates from pregnant women with non-primary infection, and in 258 (27.3%) fetuses/neonates from pregnant women with primary infection (p