Outcome measures
Indicators of birth asphyxia were studied as outcome measures among liveborn infants. Our primary outcome was a low 5-minute Apgar score, defined as Apgar <7 and Apgar <4. Secondary outcomes were: NICU admission for 24 hours or more, low umbilical artery pH (pH <7.1 and pH <7.0), and neonatal mortality (within 7 and 28 days after birth). We limited NICU admissions to admissions for at least 24 hours to prevent misclassification of infants admitted for transient symptoms of fetal-to-neonatal transition.