Cytomegalovirus Infection and Neonatal Outcome in Extremely Preterm Infants After Freezing of Maternal Milk

Background: Cytomegalovirus (CMV) infection acquired from breast milk can cause serious illness in extremely preterm (EPT) infants (<28 weeks). Some neonatal centers freeze maternal milk (MM) to prevent CMV transmission; however, this practice is controversial. In this study, we assessed the CMV transmission rate and neonatal outcome in EPT infants after routine freezing of all MM. Methods: EPT infants (n = 140) and their mothers were randomized to the intervention group (only freeze-thawed MM) or the control group (combined fresh and freeze-thawed MM). Freeze-thawed MM was frozen at -20 degrees C for >= 3 days before thawing. Mothers had serological tests for CMV, and MM was analyzed for CMV by polymerase chain reaction and CMV culture. Infants underwent CMV screening with urine analysis by CMV-polymerase chain reaction and CMV culture until 12 weeks of age. Results: Congenital CMV infection was detected in 2% of screened infants. The CMV transmission rate in infants fed with CMV-DNA positive milk was 8% (3 of 37) in the intervention group and 6% (2 of 33) in controls. All infants infected by CMV were asymptomatic. The final per-protocol analysis included 56 infants in the intervention group and 65 controls. Neonatal mortality was comparable between the groups (7% vs. 6%). Neonatal morbidity was similar, except for late onset Candida sepsis, which was more frequent in the controls (12% vs. 0%). Conclusions: Routine freezing of all MM did not affect the rate of CMV transmission but may help to prevent fungal sepsis in EPT infants. This observation merits further investigation.