Breastfeeding and viral infections in preterm infants: a multicenter cohort study.

BACKGROUND: This study aimed to evaluate the effect of breastfeeding status up to 6 months of age on the incidence of viral infections during the first year of life in preterm infants. METHODS: Data were obtained from the Japanese National Hospital Organization Neonatal Intensive Care Unit Registry for the periods 2010-2014 and 2016-2018. Information on breastfeeding exposure and infection history was collected through parental questionnaires administered when the infants reached one year of age. A total of 3,368 preterm infants who completed follow-up at one year were analyzed. The risk ratio (RR) and 95% confidence intervals (CI) were estimated using a modified Poisson regression model to evaluate the association between breastfeeding and the risk of viral infections, including influenza virus, respiratory syncytial (RS) virus, rotavirus, and norovirus. RESULTS: Breastfeeding was associated with a lower risk of influenza infection (adjusted RR: 0.66, 95% CI: 0.48-0.89) and indicated a trend toward lower risk for other viral infections. CONCLUSION: Breastfeeding for up to 6 months may lower the risk of viral infections in preterm infants, suggesting that providing breastfeeding support could contribute to improved health outcomes. IMPACT: This study examined the association between breastfeeding up to 6 months and viral infections in preterm infants using data from a multicenter cohort. Breastfeeding was associated with a lower incidence of influenza and showed a possible protective association with other viral infections. These findings support the promotion of breastfeeding in preterm infants as part of infection prevention strategies. Given the vulnerability of preterm infants, further research is required to confirm these associations and to evaluate the long-term health implications of breastfeeding.