Background: Cytomegalovirus (CMV) is the most frequent cause of congenital infections in humans. Prematurity occurs in as many as 34% of infants with symptomatic congenital CMV infection.

Objective: To determine the clinical presentation and frequency of congenital CMV infection among preterm infants and full-term infants from a population with a high seroprevalence rate.

Design/methods: A total of 289 preterm infants (median gestational age, 34 weeks; median birth weight, 1,757 g) and 163 term infants (median gestational age, 39 weeks; median birth weight, 3,150 g) sequentially born were included in the study. Serum IgG antibodies to CMV were measured in all mothers. One urine sample was collected within the first 7 days of age from all newborns. Virus isolation in urine samples was performed by tissue culture, and viral DNA was detected by a multiplex PCR. CMV infection was diagnosed in infants with virus excretion detected by both methods on at least two occasions within the first 3 weeks of life.

Results: Maternal CMV seropositivity rate was 95.7%. Congenital CMV infection was detected in 6 of 289 (2.1%) (95% confidence interval, 0.84 to 4.68) preterm infants and in 3 of 163 term infants (1.8%) (95% confidence interval, 0.48 to 5.74) (P > 0.05). Four of 6 preterm infants with congenital CMV infection were symptomatic, but none of the term infants was symptomatic (P = 0.16).

Conclusion: The frequency of congenital CMV infection in preterm newborn infants from mothers with a high seropositive rate was similar to that found in term infants. No significant difference was found between the proportion of symptomatic infants among preterm and term infants. Our finding of symptomatic congenital CMV infection underscores the need of further evaluation of correlates of congenital symptomatic infection in highly immune populations.