Comparison of neonatal outcomes between multiples and singletons among very low birth weight infants: The Korean Neonatal Network Cohort Study

To compare neonatal outcomes between multiples and singletons among very low birth weight infants (VLBWIs), this was a prospective cohort study that was conducted by collecting data registered in the Korean Neonatal Network (KNN) database from January 2013 to December 2016. There were 8265 infants in the KNN database, and 2958 of them were from a multiple pregnancy (MP VLBWIs). Among them, 2636 infants were twins, 308 infants were triplets, and 14 infants were quadruplets. MP VLBWIs had a higher gestational age, birth weight, Apgar scores at 5 minutes, the rates of caesarean section and artificial reproductive technology (ART) but lower maternal hypertension, oligohydramnios, chorioamnionitis rates and CRIB scores than the singleton VLBWIs (SG VLBWIs). In univariate analysis, the MP VLBWIs had a lower incidence of respiratory distress syndrome, bronchopulmonary dysplasia, and sepsis, but the mortality rate was not significantly different for overall gestational ages except born at ≤ 26 weeks of gestation. In multivariate logistic analysis, the incidences of intraventricular haemorrhage (grade ≥ 3), and retinopathy of prematurity requiring treatment were significantly higher than the SG VLBWIs. A new strategy to improve the mortality of immature MP VLBWIs born at ≤ 26 weeks of gestation should be developed.