Table 1 Demographic and clinical characteristics

 Gestational age, mean ± SD, week

27⁺¹ ± 2⁺³

27⁺⁰ ± 2⁺¹

0.99

 Birth weight, mean ± SD, g

761 ± 153

775 ± 154

0.32

 Multiples

72 (45)

119 (45)

0.97

 Vaginal delivery

42 (26)

80 (30)

0.39

 Small for gestational age (<10 percentile)

69 (43)

112 (42)

0.85

 Antenatal steroid use

108 (72)

229 (87)

<0.001

 Antenatal antibiotic use

65 (41)

126 (48)

0.19

 Maternal chorioamnionitis

46 (31)

97 (37)

0.16

 Maternal preeclampsia

38 (24)

65 (25)

0.91

 Maternal diabetes

7 (5)

7 (3)

0.32

 Bronchopulmonary dysplasia

89 (60)

152 (63)

0.56

 Necrotizing enterocolitis (surgical)

16 (10)

23 (9)

0.63

 Intraventricular hemorrhage (≥ grade 2)

28 (18)

58 (22)

0.32

 Retinopathy of prematurity

70 (49)

134 (56)

0.23

 Invasive bacterial infection

47 (30)

82 (32)

0.67

 Full feeding reach (≥100 mL/kg/d), mean ± SD, day

31 ± 17

26 ± 16

0.001

 H2 blocker use

109 (69)

104 (39)

<0.001

 Oxygen therapy > 48 hours

150 (94)

230 (87)

0.02

 Intubation > 48 hours

127 (80)

198 (75)

0.28

 Umbilical lines at postnatal 3rd day

22 (14)

35 (13)

0.85

 Antibiotic duration, mean ± SD, day

28 ± 26

19 ± 20

<0.001

 3rd generation cephalosporin use

42 (26)

12 (5)

<0.001

 Vancomycin use

95 (60)

128 (49)

0.03