Table 1 Clinical characteristic of three groups (WGE = week of gestational age)

Newborn with WGE 30^+ 0–32^+ 6

35

47

56

Mean gestational age

30,9

31

31,5

Newborn with WGE < 31 sett (30^+ 0–30^+ 6)

16/35 (45,7%)

18/47 (38,3%)

16/56 (28,57%)

P = 0.29

Newborn treated with PLV

27

2

56

P < 0,00001

Number of bronchiolitis

6/35 (17%)

12/47 (26%)

6/56 (10,7%)

P =0.048

Hospitalized for bronchiolitis

3/6 (50%)

6/12 (50%)

3^a/6 (50%)

P = 1

Absolute percentage of admissions

3/35 (8,6%)

6/47 (12,8%)

3/56 (5,3%)

P =0.184

Intubation at birth

3/3 (100%)

4/6 (66,7%)

0/3 (0%)

P = 0,16

Age at the admission (Months)

7

4.3

3^b

Intubation at admission

1/3 (33,3%)

2/6 (33,3%)

1^c/3 (33,3%)

P = 1