Impact of metabolic acidemia at birth on neonatal outcomes in infants born before 34 weeks’ gestation

Purpose: To examine prematurity-associated neonatal outcomes in early preterm infants with metabolic acidemia compared to those without such acidemia. Methods: We performed a retrospective cohort analysis to assess the impact of metabolic acidemia on prematurity-associated complications in a large cohort of singleton live-born infants with complete umbilical cord gas analyses delivered between 24 0/7 and 33 6/7 weeks. Metabolic acidemia was defined as an umbilical artery pH less than 7.0 plus a base deficit of 12 mmol/L or greater. Outcomes were adjusted for gestational age using logistic regression. Results: Between 1 January 1988 and 31 December 2014, 6970 singleton early preterm infants were delivered at our hospital, of which 126 (1.8%) had metabolic acidemia. Neonatal mortality as well as prematurity-associated morbidities were significantly increased in the presence of metabolic acidemia. Included were ventilator requirement (73% versus 36%, p < 0.001), grade 3/4 intraventricular hemorrhage (10% versus 4%, p < 0.001), periventricular leukomalacia (5% versus 2%, p = 0.036), and neonatal death (13% versus 4%, p < 0.001). These significant findings persisted after adjustment for gestational age. Conclusion: Metabolic acidemia significantly increases the risks related to prematurity in infants delivered prior to 34 weeks’ gestation.