Postnatal CMV Infection in Extremely Premature Newborns: A Single-Center Exploratory Study

Background/Objectives: The impact of postnatal CMV infection in extremely premature newborns is poorly characterized. We aimed to determine the impact and outcomes of postnatal CMV infection in a population of extremely premature newborns of gestational age of less than 29 weeks hospitalized in the Department of Perinatology, Division of Gynecology, University Medical Center Ljubljana. Methods: We included all extremely premature newborns of gestational age of less than 29 weeks treated in the Department of Perinatology between December 2022 and December 2024. Newborns were screened for CMV infection at set timepoints and congenital infection was excluded with PCR testing. Additional PCR testing for CMV was performed if newborns developed clinical features suspect for postnatal CMV infection. Clinical characteristics and treatment outcomes of newborns were noted. Mothers of infected newborns had their CMV serostatus determined. Results: In total, 63 extremely premature newborns were included, and 14 newborns had confirmed postnatal CMV infection. Postnatal CMV infection was associated with hepatosplenomegaly and lower platelet and leukocyte counts compared to controls. We found no association between postnatal CMV infection and other neonatal comorbidities. Conclusions: In our study, postnatal CMV infection was associated with a more severe and prolonged clinical course of extremely premature newborns compared to uninfected controls; however, in multivariable analysis, the association with a prolonged length of stay was no longer statistically significant. The results suggest that preventing postnatal CMV infection in this population is important.