Impact of asymptomatic congenital cytomegalovirus infection on size at birth and gestational duration.

Cytomegalovirus (CMV) is the most common viral agent causing congenital infection in humans, affecting 0.2 to 2.4% of all live births. Symptomatic congenital CMV infection has previously been shown to cause low birth weight and prematurity. Whether or not asymptomatic congenital CMV infection, which represents the majority of cases (90 to 95%), affects intrauterine growth or gestational duration is unknown. Using a population of 146 infants with asymptomatic congenital CMV infection and 1419 controls from two socioeconomically diverse populations (biracial low income and white mid- to upper income), determinants of body size (birth weight and crown-heel length) were investigated using multiple regression techniques. We found that congenital infection following the transmission of maternal primary and "unknown" CMV infection resulted in a significant mean birth weight deficit of 163 g (P less than 0.04) for the low income term infants (blacks and whites), but not in the mid- to upper income white infants. Newborns with congenital infection following the transmission of maternal reactivated (recurrent) CMV infection were significantly shorter by a mean of 1 cm (P less than 0.03) than controls, a finding that was consistent regardless of socioeconomic status or race.