Introduction A postnatal cytomegalovirus (CMV) infection in very preterm infants may present with hyperbilirubinemia, hepatosplenomegaly, pneumonitis, and hematologic abnormalities. Central nervous system involvement is considered to be mild or absent.

Aim To evaluate the prevalence of hearing loss (HL) in postnatally acquired CMV infection in very preterm infants.

Methods In infants of gestational age <32 weeks who developed symptoms before term age a negative CMV status at birth (demonstrated by PCR from Guthrie card serum samples taken at day 3) and seroconversion and/or PCR CMV positive urine were considered proof of a postnatally acquired CMV infection. All infants underwent (automated) auditory brainstem response hearing screening. After a failed screening further audiologic diagnostics was performed.

Results From 2004–2007 early postnatal CMV infection was detected in 11/388 (median gestational age 26 weeks; range 25–30). In 6/11 (55%) CMV infants HL developed. CMV was detected in the breast milk of the mother in 3/6 cases. Mild cochlear HL occurred in 1 case and moderate cochlear HL in 2 cases. In 3 cases auditory neuropathy (AN) was detected. In 2/3 AN interferes with normal speech and language development. In 1/3 AN was transient, either as a result of maturation or as a result of treatment with valgancyclovir.

Conclusions Hearing loss may be a sign of early postnatally acquired CMV infection in very preterm newborns. Outcome of perinatal CMV infections may be more dependent on the developmental stage (i.e. gestational age) at the time of infection than on the mode of transmission.