Outcome of very preterm infants delivered outside tertiary perinatal centers in China: a multi-center cohort study

BACKGROUND: To describe the incidence of outborns among very preterm infants (VPIs, <32 weeks of gestation) in Chinese perinatal centers and to examine the association of outborn status with adverse outcomes. METHODS: A cohort study enrolling all VPIs admitted to 18 perinatal centers in China from May 1st, 2015 to April 30th, 2018. Neonatal outcomes including rates of discharge against medical advice (DAMA), in-hospital mortality, overall mortality, severe intraventricular hemorrhage (IVH) or periventricular leukomalacia (PVL), sepsis, bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC) and severe retinopathy of prematurity (ROP) were compared between outborn and inborn infants. A multivariate logistic regression model was used to estimate the independent association of outborn status with neonatal outcomes. RESULTS: Among 12,014 VPIs, 1,991 (16.6%) infants were outborn. Outborn infants had lower Apgar scores and higher illness severity score on admission. Mothers of outborn infants were less likely to receive antenatal steroids, prenatal care and caesarean section. The incidence of DAMA (18.0% vs. 12.5%, P<0.001), overall mortality (19.9% vs. 15.8%, P<0.001) and severe brain injury (10.8% vs. 9.1%, P=0.024) of outborn infants were significantly higher than inborn infants. Outborn status was independently associated with increased risks of DAMA (aOR, 1.6; 95% CI: 1.4–1.8), overall-hospital mortality (aOR, 1.3; 95% CI: 1.1–1.5) and severe IVH/PVL (aOR, 1.2; 95% CI: 1.0–1.5). CONCLUSIONS: The incidence of outborn VPIs was high in China. Outborn infants were more likely to be delivered in an uncontrolled situation and were at significantly higher risk of neonatal mortality and severe brain injury compared with inborn infants. Quality improvement efforts are needed to facilitate in-utero transfer of high-risk pregnancies to tertiary centers.