This study evaluates the relationship between anemia and stool microbiota in premature infants. It also evaluates the relationship between blood transfusion and stool microbiota.

Necrotizing enterocolitis (NEC) is a leading cause of death in preterm infants, yet the disease mechanism is not well understood. Among the factors that have been studied are the change in stool microbiota (dysbiosis), severe anemia, and transfusion. Studies suggest that dysbiosis occurs in neonates with NEC. Large studies and meta-analyses have shown a predominance of Gammaproteobacteria, a decrease in Firmicutes, and decreased bacterial diversity in stool from infants with NEC. Studies do not support a relationship between transfusions and NEC since there are conflicting findings on this topic. There is a suggestion, however, that severe anemia may be associated with NEC though this requires further study.

No studies have been done evaluating the relationship between anemia and change in stool microbiota, or blood transfusion and change in stool microbiota. This study aims to primarily evaluate the relationship between anemia and stool microbiota, and secondarily evaluate the relationship between transfusion and stool microbiota.

Inclusion Criteria:

• Preterm infants less than 32 weeks gestation at birth
• Age at enrollment between 7 days and less than/equal to 30 days
• Minimum 100 mL/kg/day enteral feeds

Exclusion Criteria:

• Development of necrotizing enterocolitis (NEC) prior to enrollment
• Prior surgery
• Major congenital anomalies
• Oxygen requirement with FiO2 (fraction of inspired oxygen) >50% (at time of enrollment)

The study will enroll preterm infants that are less than 32 weeks gestational age at birth. At time of enrollment, these infants must be between 7 days of age up to (and including) 30 days of age. They must also be on enteral feeds of at least 100mL/kg/day. The investigators will exclude infants who have developed NEC prior to enrollment, who have had surgery prior to enrollment, who have major congenital anomalies, or who are requiring FiO2 >50% at time of enrollment.