Table 1 Baseline characteristics of patients

Gender

0.564

  Male

116 (52.3%)

69 (50.4%)

47 (55.3%)

  Female

106 (47.7%)

68 (49.6%)

38 (44.7%)

GA(weeks)

0.015

  < 30

62 (27.9%)

48 (35.0%)

14 (16.5%)

  30–34 + 6

94 (42.3%)

55 (40.1%)

39 (45.9%)

  35–36 + 6

38 (17.1%)

18 (13.1%)

20 (23.5%)

  ≥ 37

28 (12.6%)

16 (11.7%)

12 (14.1%)

BW (kilograms)

0.258

  < 1500

108 (48.6%)

72 (52.6%)

36 (42.4%)

  1500–2500

83 (37.4%)

49 (35.8%)

34 (40.0%)

  ≥ 2500

31 (14.0%)

16 (11.7%)

15 (17.6%)

Length

41.7 ± 5.31

41.0 ± 5.64

42.8 ± 4.52

0.009

HC

29.3 ± 2.69

28.9 ± 2.69

29.9 ± 2.59

0.010

UC

0.054

  No

129 (58.1%)

87 (63.5%)

42 (49.4%)

  Yes

93 (41.9%)

50 (36.5%)

43 (50.6%)

PROM

<0.001

  No

144 (64.9%)

109 (79.6%)

35 (41.2%)

  Yes

78 (35.1%)

28 (20.4%)

50 (58.8%)

Multiple births

0.005

  No

156 (70.3%)

106 (77.4%)

50 (58.8%)

  Yes

66 (29.7%)

31 (22.6%)

35 (41.2%)

Apgar score

0.525

  ＞7

135 (60.8%)

85 (62.0%)

50 (58.8%)

  4–7

76 (34.2%)

47 (34.3%)

29 (34.1%)

  ≤ 3

11 (4.95%)

5 (3.65%)

6 (7.06%)

PS dosage

0.002

  ＞100

189 (85.1%)

125 (91.2%)

64 (75.3%)

  ≤ 100

33 (14.9%)

12 (8.76%)

21 (24.7%)

PS

0.654

  No

172 (77.5%)

108 (78.8%)

64 (75.3%)

  Yes

50 (22.5%)

29 (21.2%)

21 (24.7%)

PH ¹

7.31 ± 0.08

7.34 ± 0.06

7.26 ± 0.07

<0.001

PaO ₂ ¹

76.6 ± 23.9

82.8 ± 23.5

66.7 ± 21.1

<0.001

PaCO ₂ ¹

38.6 ± 9.56

35.4 ± 8.14

43.7 ± 9.49

<0.001

BE ¹

-7.16 ± 2.96

-6.94 ± 2.98

-7.52 ± 2.91

0.157

PH ²

7.35 ± 0.10

7.36 ± 0.10

7.35 ± 0.09

0.469

PaO ₂ ²

83.7 ± 21.6

85.0 ± 20.7

81.6 ± 23.0

0.268

PaCO ₂ ²

36.9 ± 37.8

33.5 ± 11.0

42.3 ± 59.3

0.181

BE ²

-7.02 ± 3.30

-6.67 ± 3.21

-7.57 ± 3.37

0.050

Invasive ventilation

0.167

  No

111 (50.0%)

63 (46.0%)

48 (56.5%)

  Yes

111 (50.0%)

74 (54.0%)

37 (43.5%)