Aim: Detailed mortality and morbidity data for preterm infants treated in Chinese NICUs are needed to profile the current status of outcomes, to provide baseline data for epidemiological or quality improvement studies, and to serve as a reference for neonatologists and parents in China. The aim of this study was to describe the mortality, morbidities and center variations for infants born less than 34 weeks’ gestation from 25 Chinese NICUs in 2015. 

Methods: This cohort study included all infants born less than 34 weeks’ gestation and admitted to participating NICUs within 7 days of life from May 1^st, 2015 and April 30^th, 2016. Twenty-five tertiary hospitals from 19 provinces of China participated in this study. A customized database collecting clinical information of preterm infants was developed. All data collection followed a standard manual of operations and definitions. 

Results: A total of 8065 preterm infants were eligible. Overall, 97 (1.2%), 941 (11.7%), 3080 (38.2%) and 3947 (48.9%) infants were of gestational age <26⁺⁰ weeks, 26⁺⁰-28⁺⁶ weeks, 29⁺⁰-31⁺⁶weeks and 32⁺⁰-33⁺⁶ weeks, respectively. A total of 446 (5.5%) infants were of extremely low birth weight, and 2956 (36.7%) infants were of very low birth weight. Overall 6852 (85%) of enrolled infants received active care in NICUs. Among infants who received active care, the in-hospital mortality was 3.6% (248/6852). The predicted mortality of DAMA infants was 65% (788/1213). The overall mortality, combining in-hospital deaths and predicted deaths among DAMA infants, was 12.9% (1036/8065) for infants born less than 34 weeks’ gestation. The overall mortality rates of infants with gestational age <26 weeks, 26⁺⁰-28⁺⁶weeks, 29⁺⁰-31⁺⁶weeks and 32⁺⁰-33⁺⁶weeks were 68.0% (66/97), 34.9% (328/941), 13.7% (422/3080) and 5.6% (220/3947), respectively. Sepsis, BPD and severe IVH or PVL were the most common morbidities among all preterm infants born at less than 34 weeks’ gestation. Overall 26.7% of infants actively care in NICUs died or had at least one morbidity. In-hospital mortality or any morbidity of infants with gestational age <26 weeks, 26⁺⁰-28⁺⁶weeks, 29⁺⁰-31⁺⁶weeks and 32⁺⁰-33⁺⁶weeks were 88.1% (52/59), 60.7% (408/672), 32.7% (842/2574) and 14.8% (525/3547), respectively. 

Conclusions: Our study provided a completed and detailed picture of outcomes for infants born <34 weeks’ gestation and admitted to Chinese NICUs. Mortality and incidences of morbidities of preterm infants remained high in Chinese NICUs. A number of preterm infants, especially VPIs, did not received active care in Chinese NICUs. Further studies and efforts are needed to both provide more infants with appropriate care and reduce the mortality and morbidities of preterm infants in Chinese NICUs.