Outcomes
The primary outcome was a composite of perinatal morbidity, with any of the following: neonatal death, 5-minute Apgar score of <4, respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD), sepsis, periventricular leukomalacia (PVL), intraventricular hemorrhage (IVH) and necrotizing enterocolitis (NE). 5-minute Apgar score of < 7 was registered as well.
Like other authors[23], we did not use pH at birth as a primary outcome, as we found a significant interaction with 5-minute Apgar score of <4.
Secondary outcome included neurodevelopmental impairment (NDI) at 2 years of corrected age. Thus, we performed a standardized neurological examination on children at a corrected age of 2 years. For this purpose, we used the revised Brunet-Lézine scale to identify NDI. This scale includes four domains of psychomotor development: language, sociability, as well as gross and fine motor function. Infants were classified as having NDI if they had a global developmental quotient (DQ) on the revised Brunet–Lézine scale of < 85, or level 3 cerebral palsy (CP), and severe NDI was defined with a DQ of < 60.