Table 2 Neonatal characteristics of patients included in the analyses separated for the severity of BPD

Weeks

30 [29, 30]

27 [26, 28]*

25 [24, 27]*^,†

 < 0.001

Birth weight [g]

1390 [1140, 1475]

885 [800, 970]*

695 [575, 879]*^,†

 < 0.001

z-score birth weight

− 0.15 [− 0.56, 0.01]

− 0.58 [− 0.88, − 0.23]

− 0.90 [− 1.25, − 0.42]^*

0.0094

z-score weight at 36 weeks gestational age

− 0.80 [− 1.11, − 0.46]

(na = 1)

− 1.02 [− 1.36, − 0.62]

(na = 1)

− 1.32 [− 1.55, − 1.09]*

0.025

Δz-score (weight 36 weeks gestational age–birth)

− 0.49 [− 0.94, 0.04]

(na = 1)

− 0.50 [− 0.75, − 0.30]

(na = 1)

− 0.41 [− 0.74, − 0.25]

0.99

Small for gestational age

3 (10%)

2 (8%)

3 (21%)

0.49

Female

13 (42%)

13 (52%)

6 (43%)

0.78

Caesarean section

30 (97%)

24 (96%)

13 (93%)

0.79

Singleton

17 (55%)

14 (56%)

10 (71%)

0.57

APGAR 5'

9 [8, 9]

9 [8, 9]

9 [8, 9]

0.76

APGAR 10'

10 [9, 10]

10 [9, 10]

10 [9, 10]

0.50

Maternal age

33 [29, 34]

33 [25, 37]

33 [26, 36]

0.90

Maternal BMI at birth

29 [28, 37]

29 [26, 32]

(na = 1)

29 [25, 32]

0.54

Nicotine

5 (16%)

(na = 1)

3 (12%)

1 (7%)

0.73

Antibiotics before birth

9 (29%)

5 (20%)

(na = 1)

6 (43%)

0.35

Histological chorioamnionitis

7 (23%)

4 (16%)

5 (36%)

(na = 1)

0.30

Cause for premature birth

0.82

 AIS

16 (52%)

9 (36%)

7 (50%)

 HELLP/preeclampsia

4 (13%)

7 (28%)

2 (14%)

 IUGR

6 (19%)

4 (16%)

2 (14%)

 Other

5 (16%)

5 (20%)

3 (21%)

ANCS

0.073

 None/ < 24 h

10 (32%)

5 (20%)

2 (14%)

 ANCS 24 h – 7 d

10 (32%)

13 (52%)

11 (79%)

 ANCS > 7 d

11 (35%)

7 (28%)

1 (7%)

ROP

3(10%)

10 (40%)*

10 (71%)*

 < 0.001

ROP treatment

0 (0%)

0 (0%)

4 (29%)

0.25

PVL

0 (0%)

0 (0%)

0 (0%)

1

IVH

1 (3%)

1 (4%)

2 (14%)

0.33

Pneumothorax

1 (3%)

0 (0%)

0 (0%)

0.60

Nosocomial infection

0 (0%)

1 (4%)

6 (42%)*^,†

 < 0.001

Duration invasive ventilation [d]

0 [0, 0]

0 [0,2]*

0 [0, 22]*

0.0076

Duration non-invasive ventilation [d]

8 [5, 22]

42 [32, 49]*

67 [49, 97]*^,†

 < 0.001

Oxygen supplementation at discharge

0 (0%)

0 (0%)

2 (14%)

0.033

Max. FiO₂ (24 h)

0.30 [0.24, 0.38]

0.34 [0.30, 0.42]

0.39 [0.33, 0.54]

0.060

Intubation within 24 h

3 (10%)

6 (24%)

6 (42%)

0.042

Max. invasive PIP (24 h) [cmH₂0]

16 [15, 18]

(na = 27)

15 [15, 17]

(na = 18)

16 [8, 16]

(na = 9)

0.81

Max. invasive PEEP (24 h) [cmH₂O]

6 [6, 7]

(na = 27)

6 [6, 7]

(na = 18)

6 [6]

(na = 9)

0.63

Max. invasive MAP (24 h) [cmH₂O]

9 [9, 10]

(na = 28)

9 [8, 9]

(na = 19)

9 [8, 9]

(na = 9)

0.86

Max. FiO₂ (72 h)

30 [24, 38]

36 [30, 50]*

40 [36, 54]*

0.022

Intubation within 72 h

3 (10%)

9 (36%)

6 (42%)

0.017

Max. invasive PIP (72 h) [cmH₂0]

18 [16, 21]

(na = 27)

16 [15, 17]

(na = 16)

17 [16, 18]

(na = 9)

0.35

Max. invasive PEEP (72 h) [cmH₂O]

6 [6, 7]

(na = 27)

6 [6]

(na = 16)

6 [6]

(na = 9)

0.34

Max. invasive MAP (72 h) [cmH₂O]

9 [9, 10]

(na = 28)

9 [8, 10]

(na = 17)

9 [8, 10]

(na = 9)

0.79

Surfactant

10 (32%)

19 (76%)*

11 (79%)*

 < 0.001

Surfactant doses (72 h)

0 [0, 1]

1 [1]*

1 [1]*

 < 0.001

Postnatal corticosteroids

0 (0%)

1 (4%)

2 (14%)

0.048