Objective To study risk factors and cranial ultrasound (cUS) findings in a large cohort of preterm infants, admitted to a neonatal intensive care unit and diagnosed with postnatally acquired cytomegalovirus (CMV) infection.

Study design This prospective, observational study was performed from April 2007 until June 2009 among 315 infants born <32 weeks of gestation. Postnatal CMV infection was diagnosed by CMV PCR on urine collected at term-equivalent age. In CMV-positive infants, congenital infection was excluded. The authors compared the clinical and demographic data, feeding pattern and cUS results of infected and non-infected patients. Logistic regression analysis was performed.

Results In 39 of 315 infants, the diagnosis of postnatal CMV infection has been made. The majority of CMV-infected infants (33/39.85%) did not develop any symptoms of CMV infection. The most important, independent risk factors of postnatal CMV infection were non-native Dutch maternal origin (OR 9.6 (95% CI 4.3 to 21.5)) and breast milk (OR 13.2 (95% CI 1.7 to 104.5)). The risk of infection significantly increased in infants with lower gestational age (GA) (OR 0.7 (95% CI 0.5 to 0.9)). Lenticulostriate vasculopathy (LSV) was significantly more often present in infants with CMV infection (OR 4.1 (95% CI 1.9 to 8.8)).

Conclusions Postnatal CMV infection is an asymptomatic infection among preterm infants. Infants with lower GA are at greatest risk of postnatal CMV infection, especially when fed with fresh breast milk from their non-native Dutch mother. LSV not present at birth but confirmed at term-equivalent age can suggest a postnatal CMV infection.