Risk Factors for Mortality and Neurodevelopmental Impairment among Neonates Born at 22-23 Weeks' Gestation

We aimed to evaluate the risk factors for mortality and neurodevelopmental impairment (NDI) among infants of 22-23 weeks' gestational age, which currently remain unclear.

This retrospective case-control study included 104 infants delivered at 22-23 weeks' gestation at Kagoshima City Hospital from 2006 to 2015. We compared 65 and 34 cases of survival to discharge and postnatal in-hospital death (5 excluded), respectively, and 26 and 35 cases with and without NDI, respectively, using maternal, prenatal, and postnatal records. A high rate of survivors' follow-up (61/65) was achieved in this study.

The survival rate was 75.0% (21/28) and 62.0% (44/71) among infants born at 22 and 23 weeks' gestation, respectively. Infants who died weighed less (525.5 vs. 578 g, p = 0.04) and their intrauterine growth retardation (IUGR) rate (<5th percentile) was higher (14.7 vs. 1.5%, p = 0.02). Mortality was associated with an increased incidence of bradycardia on fetal heart rate monitoring (11.8 vs. 1.5%, p = 0.046), periventricular hemorrhagic infarction (PVHI; 32.4 vs. 6.2%, p = 0.001), necrotizing enterocolitis (NEC, surgery or drain tube; 14.7 vs. 0.0%, p = 0.004), and tension pneumothorax (29.4 vs. 6.2%, p = 0.004). There were significant differences in the proportion of PVHI (15.4 vs. 0%, p = 0.03) between infants with and without NDI.

IUGR, bradycardia, PVHI, NEC, and tension pneumothorax were associated with neonatal mortality among infants born at 22-23 weeks' gestation. NDI at 36-42 months' chronological age was associated with PVHI.