Table 1 Baseline characteristics of the population: descriptive statistics and comparisons between early intervention and standard care groups

 Maternal age (years), mean ± SD

35.1 ± 6.1

33.1 ± 4.8

0.293^{^}

 Socio-economic status, mean ± SD

47.8 ± 15.8

51.3 ± 9.3

0.627*

 Maternal smoking before or during pregnancy, n (%)

2 (12%)

1 (6%)

0.591°

 Maternal alcohol abuse during pregnancy, n (%)

0 (0%)

0 (0%)

> 0.999°

 Maternal Body Mass Index, mean ± SD

20.9 ± 4.5

21.8 ± 2.1

0.473

 Clinical chorioamnionitis, n (%)

8 (50%)

5 (28%)

0.291°

 Gestational age at birth (weeks), mean ± SD

27.9 ± 1.1

28.1 ± 1.4

0.318*

 Birth weight (g), mean ± SD

1089 ± 347

1005 ± 296

0.453^{^}

 Male, n (%)

9 (56%)

9 (50%)

0.744°

 Singleton, n (%)

6 (38%)

8 (44%)

0.738°

 Small for gestational age, n (%)

3 (19%)

4 (22%)

> 0.999°

 Cesarean section, n (%)

14 (88%)

18 (100%)

0.214°

 Apgar score at 1′, median (range)

7 (2–8)

6 (4–8)

0.832*

 Apgar score at 5′, median (range)

8 (5–9)

8 (6–9)

0.409*

 Clinical Risk Index for Babies (CRIB) II score, mean ± SD

8.0 ± 2.5

8.1 ± 2.1

0.903*

 Days of hospitalization, mean ± SD

79.4 ± 30.7

83.9 ± 27.6

0.654^{^}

 Gestational age at discharge (weeks), mean ± SD

39.4 ± 3.7

40.1 ± 3.7

0.567^{^}

 Days in the incubator, mean ± SD

51.9 ± 21.9

55.7 ± 18.8

0.589^{^}

 Days of invasive mechanical ventilation, mean ± SD

4.2 ± 6.3

6.1 ± 8.8

0.914*

 Days of non-invasive ventilation (NCPAP + nHFT), mean ± SD

31.9 ± 20.4

49.1 ± 36.1

0.220*

 Sepsis, n (%)

5 (31%)

11 (61%)

0.101°

 Severe bronchopulmonary dysplasia, n (%)

2 (12%)

8 (44%)

0.063°

 Germinal matrix hemorrhage - intraventricular hemorrhage (GMH - IVH) 1–2, n (%)

2 (12%)

2 (11%)

> 0.999°

 Retinopathy of prematurity (ROP) any grade, n (%)

2 (12%)

2 (11%)

> 0.999°