Table 1 Description of Maturity Category Cohorts

Subjects (n)

155

192

1031

na

Observations (n)

2603

2501

21,058

na

0bservations/subject (n)

12 (4–22)

9 (4–17)

11 (4–29)

< 0.01

GA (weeks)

26 (24–28)

34 (33–35)

38 (37–39)

< 0.001

PMA (weeks)

28 (26–31)

35 (34–36)

40 (39–43)

< 0.001

Postnatal age (weeks)

2.1 (1.0–3.7)

1.1 (0.4–2.3)

2.0 (1.0–6.3)

< 0.001

FiO₂ (%)

45 (30–70)

50 (35–83)

45 (35–70)

< 0.001

SpO₂ (%)

93 (86–97)

96 (91–100)

97 (87–100)

< 0.001

PaO₂ (mmHg)

55 (45–71)

69 (50–100)

75 (47–112)

< 0.001

PaO₂ ≤ 40 (%)

15%

12%

15%

< 0.001*

PaO₂ 50–80 (%)

43%

33%

24%

< 0.001*

PaO₂ ≥ 100 (%)

10%

25%

32%

< 0.001*

PaO₂/FiO₂

130 (81–192)

161 (90–240)

167 (93–263)

< 0.001

PaCO₂ (mmHg)

45 (39–52)

45 (39–53)

45 (40–52)

ns

pH

7.34 (7.28–7.40)

7.36 (7.30–7.41)

7.39 (7.34–7.43)

< 0.001