Table 2 Explanatory variables divided by experimental group and control group participants

 Birth weight (g)

 Gestational age (weeks)

 Apgar 1 min (1–10)

 Apgar 5 min (1–10)

 Gender

  Male (%)

  Female (%)

 Age when NIRS monitoring started (h)^a

N/A

 Stopping NIRS monitoring before end of monitoring period (%)^a

N/A

 Parents discontinuing trial participation (%)

 Changes in treatment due to cerebral hypoxia (%)^a

N/A

 Registered cardiovascular support treatment (%)^a

N/A

 Type of NIRS device used^a

  INVOS (%)

  NIRO (%)

  Fore-Sight (%)

  Sensmart (%)

  O3 (%)

  Egos (%)

  Oxyprem (%)

  Other (%)

N/A

 Cerebral NIRS monitoring despite being in control group (%)^b

N/A

 Surfactant therapy (%)

 Severe adverse reactions (%)

 Major congenital anomaly (%)

 Mechanical ventilation (%)

 Time with mechanical ventilation (days)

 Patent ductus arteriosus (%)

 Weight (g)

 Early cranial ultrasound scan (%)

 Late cranial ultrasound scan (%)