ABSTRACT
Objective:To analyze the distribution of ages at the interhospital transfer of outborn very preterm infants in China and to compare their perinatal characteristics and outcomes at discharge and neonatal intensive care unit (NICU) treatment.Methods:A total of 3 405 outborn very premature infants with a gestational age of 24-31 +6 weeks who were transferred to the NICUs of the Chinese Neonatal Network (CHNN) in 2019 were included in this retrospective study. According to the age at transfer, they were divided into three groups: early transfer (≤1 d), delayed transfer (>1-7 d) and late transfer (>7 d) groups. Analysis of variance, t-test, Chi-square test (Bonferroni correction), Kruskal-Wallis test and Wilcoxon rank-sum test were used to compare the general clinical condition, treatment, and outcomes at discharge among the three groups. Results:The median gestational age was 29.7 weeks (28.3-31.0 weeks) and the average birth weight was (1 321.0 ± 316.5) g for these 3 405 infants. There were 2 031 patients (59.6%) in the early transfer group, 406 (11.9%) in the delayed transfer group and 968 (28.4%) in the late transfer group. Infants who received continuous positive airway pressure ventilation and tracheal intubation in the delivery room accounted for 8.4% (237/2 806) and 32.9% (924/2 805), respectively. A total of 62.7% (1 569/2 504) of the mothers received antenatal glucocorticoid therapy and the ratio in the early transfer group was 68.7% (1 121/1 631), which was higher than that in the delayed transfer group [56.1% (152/271), χ2=16.78, P<0.017] and the late transfer group [49.2% (296/602), χ2=72.56, P<0.017]. The total mortality rate of very premature infants was 12.7% (431/3 405), and the mortality rates in the early, delayed and late transfer groups were 12.4% (252/2 031), 16.3% (66/406) and 11.7% (113/968), respectively ( χ2=5.72, P=0.057). The incidences of severe intraventricular hemorrhage, late-onset sepsis, necrotizing enterocolitis, and bronchopulmonary dysplasia at the corrected gestational age of 36 weeks or discharge were all higher in the delayed and late transfer groups than in the early transfer group, respectively. The incidences of retinopathy of prematurity, retinopathy of prematurity requiring treatment and bronchopulmonary dysplasia at the corrected gestational age of 36 weeks or discharge in the late transfer group were significantly higher than that in the delayed transfer group (Bonferroni correction, all P<0.017). In the late transfer group, the median age of very premature infants at discharge was 66.0 d (51.0-86.0 d), and the corrected gestational age at discharge was 38.9 weeks (37.1-41.2 weeks), and both were greater than those in the early transfer [48.0 d (37.0-64.0 d), Z=260.83; 36.9 weeks (35.7-38.3 weeks), Z=294.32] and delayed transfer groups [52.0 d (41.0-64.0 d), Z=81.49; 37.4 weeks (36.1-38.7 weeks), Z=75.97] (all P<0.017). Conclusions:Many very premature infants need to be transferred to higher-level hospitals after birth. The later the very premature infants are transferred, the higher the incidence of complications will be. It is suggested that intrauterine or early postnatal transport may improve the prognosis of very premature infants.