Table 1 Demographic and clinical variables

Gestational age at birth (weeks, preterm/full-term, mean ± SD)

28.83 ± 3.37/39.72 ± 1

Gestational age at birth (23–25/26–27/28–29/30–31/32–33/34–35 weeks/full-term, N)

25/22/11/11/18/8/25

Birth Weight (Kg, preterm/full-term, mean ± SD)

1.29 ± 0.57/3.6 ± 0.45

Sex (male/female, N)

59/61

Race (Caucasian/AA/Asian/Other, N)^a

76/29/1/14

Ethnicity (Hispanic or Latino Y/N/unnkown, N)

13/103/4

Delivery method (C-section/vaginal, N)

60/60

Necrotizing enterocolitis diagnosis (medical, surgical, N)^b

11

Received antimicrobials (any, ≥ 7 days, N)^c

82 / 63

Received diuretics (any, N)^c

54

Received postnatal corticosteroids (any, N)^c

22

Received proton pump inhibitors (any, N)^c

7

Received H₂ receptor antagonist (any, N)^c

13

Received motility agents (any, N)^c

24