Perinatal Characteristics and Neonatal Outcomes of Singletons and Twins in Chinese Very Preterm Birth Infants: A Cohort Study

Background: The prevalence of preterm birth has been raising, and there is a paucity of nationwide data on the perinatal characteristics and neonatal outcomes of twin deliveries of very preterm infants (VPIs) in China. This study compared the perinatal characteristics and outcomes of singletons and twins admitted to neonatal intensive care units (NICUs) in China. Methods: : The study population comprised all infants born before 32 weeks in Chinese Neonatal Network (CHNN) between January 2019 and December 2019. Results: : During the study period, there were 6634 (71.2%) singletons and 2680 (28.8%) twins, with mean birth weight of 1333.70g and 1294.63g, respectively. Twins were significantly more likely to be delivered by cesarean section (p<0.01), to have antenatal steroid usage (p=0.048), to have received assisted reproductive technology (ART) (p<0.01), and have higher prevalence of maternal diabetes (p<0.01) and more were inborn (p<0.01) compared with singletons. In addition, twins had a lower prevalence of small for gestational age, maternal hypertension, primigravida compared to singletons (all p<0.01). After adjusting for the potential confounders, twins had higher mortality (adjusted odds ratio [AOR] 1.28, 95% confidence interval [CI] 1.10-1.49), short term composite outcome (AOR 1.28, 95% CI 1.09-1.50), respiratory distress syndrome (RDS) (AOR 1.30, 95% CI 1.12-1.50), bronchopulmonary dysplasia (BPD) (AOR 1.10, 95% CI 1.01-1.21), surfactant usage (AOR 1.22, 95% CI 1.05-1.41) and prolonged hospital stay (adjusted mean ratio 1.03, 95% CI 1.00-1.06), compared to the singletons. Conclusion: Our work suggest that twins have a greater risk of mortality, higher incidence of RDS and BPD, more surfactant usage, and longer NICU stay compared with singletons among VPIs in China.