Vertically transmitted cytomegalovirus infection in newborn preterm infants

To determine the epidemiology of congenital and acquired cytomegalovirus (CMV) infections in preterm infants and to analyze the efficacy of breast milk freezing in decreasing the vertical transmission rate of CMV.

During 2013 and 2014, preterm newborns who weighed ≤1500 g and were admitted to 22 Spanish neonatal units were included and screened for CMV infection according to the Spanish Neonatology Society recommendations. Each hospital treated the breast milk according to its own protocols.

Among the 1236 preterm neonates included, 10 had a congenital infection (0.8%) and 49 had an acquired infection (4.0%) (82% demonstrated positive PCR-CMV in breast milk). The neonates who received only frozen milk presented less frequently with acquired infection (1.2%) than those fed fresh milk (5.5%) (RR=0.22; 95% CI 0.05-0.90; P=0.017). The newborns who received bank milk followed by frozen or fresh breast milk more frequently had an acquired infection (2.1% or 2.2%, respectively) than those fed only frozen breast milk.

The incidence of congenital CMV infection in our sample is low, as described in the literature. To reduce acquired CMV infection, freezing breast milk might be an advisable procedure for preterm neonates born from seropositive mothers, either from the beginning of lactation or after a period of bank milk administration.