Neonatal mortality and morbidity among infants between 24 to 31 complete weeks: a multicenter survey in China from 2013 to 2014

Background: The outcome of preterm infants has been varied in different hospitals and regions in developing countries. Regular clinical monitor are needed to know the effects of health care. This study aimed to describe the survival and morbidity rates of extreme to very preterm infants in 15 neonatal-intensive care hospitals in China.

Methods: Data were collected from January 1, 2013 to December 31, 2014 for preterm neonates with gestational age (GA) between 24 and 31 complete weeks born in hospitals from our collaborative study group. The primary outcomes were survival and major morbidities prior to hospital discharge. Major morbidities included bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), retinopathy of prematurity (ROP), patent ductus arteriosus (PDA) and sepsis. Mutivariate logistic regression was used to analyze the risk factor influencing on the outcomes.

Results: The preterm birth rate was 9.9 % (13 701/138 240). The proportion of extreme to very preterm infants was 1.1 % and 11.8 % respectively. The survival rate prior to discharge was increased with increasing GA (0, 24 weeks; 28 %, 25 weeks; 84.8 %, 26 weeks; 83.5 %, 27 weeks; 87.4 %, 28 weeks; 90.7 %, 29 weeks; 93.9 %, 30 weeks; 96 %, 31 weeks). Rate of survival and without severe morbidity according to GA were 0 at 24 weeks, 8 % at 25 weeks, 60.6 % at 26 weeks; 53.2 % at 27 weeks; 62.3 % at 28 weeks; 67.9 % at 29 weeks; 79.1 % at 30 weeks, 85.8 % at 31 weeks respectively. Rate of antenatal steroid use was 56 %. The antenatal steroid use was lower in GA < 28 weeks infants than that in GA between 28 and 32 weeks (28-44.3 % vs 49.7-60.1 %, P < 0.05). Infants at the lowest GAs had a highest incidence of morbidities. Overall, 58.5 % had respiratory distress syndrome, 12.5 % bronchopulmonary dysplasia, 3.9 % necrotizing enterocolitis, 15.4 % intraventricular hemorrhage, 5.4 % retinopathy of prematurity, 28.4 % patent ductus arteriosus, and 9.7 % sepsis. Mortality and morbidity were influenced by gestational age (OR = 0.891, 95 % CI: 0.796-0.999, p = 0.0047 and OR = 0.666, 95 % CI: 0.645-0.688, p = 0.000 respectively), birth weight (OR = 0.520, 95 % CI: 0.420-0.643, p = 0.000 and OR = 0.921, 95 % CI: 0.851-0.997, p = 0.041 respectively), SGA (OR = 1.861, 95 % CI: 1.148-3.017, p = 0.012 and OR = 1.511, 95 % CI: 1.300-1.755, p = 0.000 respectively), Apgar score <7 at 5 min (OR = 1.947, 95 % CI: 1.269-2.987, p = 0.002 and OR = 2.262, 95 % CI: 1.950-2.624, p = 0.000 respectively). The survival rate was increased with more prenatal steroid use (OR = 1.615, 95 % CI: 1.233-1.901, p = 0.033).

Conclusion: Although most of the preterm infants with GAs ≥26 weeks survived, a high complication in survivors still can be observed. Rate of survival of GAs less than 26 weeks was still low, and quality improvement methods should be used to look into increasing the use of antenatal steroids in the very preterm births.