This study aims to examine the factors associated with preterm infant's intestinal microbiota depending on feeding type (breast milk or preterm formula)

The gut microbiome has been increasingly found to affect human health. Feeding plays an important role in determining the composition and diversity of the neonatal gut microbiome. Preterm infants are at a high risk of gut microbiota disruption and dysbiosis because of physiological immaturity and environmental factors. In preterm infants, breast milk has been associated with improved growth and cognitive development and a reduced risk of necrotizing enterocolitis and late onset sepsis.

The objective of study is to determine the impact of feeding type on gut microbiome of very preterm infants admitted in a neonatal intensive care unit (NICU). Meconium and the additional 2 fecal samples will be collected from preterm infants. Fecal samples will be collected every 14 days, during 28 days, from diapers into sterile tubes. DNA will be extracted from fecal samples and different bacterial genus and species will be analyzed.

The type of infant feeding (breast milk or preterm formula) is recorded daily to classify the type of infant feeding received during the 14 days prior to each fecal sample collection.

Inclusion Criteria:

- Very preterm infants (< 32 weeks gestational age) admitted in the NICU of CHA Bundang Medical Center within the first 24 hours after birth

Exclusion Criteria:

• Parents refuse to participate/sign informed consent
• Major congenital anomalies

Very preterm infants born before 32 gestational weeks and admitted to the NICU of CHA Bundang Medical Center