Perinatal morbidity and mortality for extremely low-birthweight infants: A population-based study of regionalized...

The aim of this study was to clarify the mortality and long-term outcomes of extremely low-birthweight infants according to the process of maternal or infant transport and indications for maternal transport.

We conducted a population-based study between 2005 and 2009. The collected data included the process and indications for maternal or neonatal transport, maternal and infant characteristics and the prognosis of extremely low-birthweight infants. Intergroup comparisons were made using the Mann-Whitney U-test, while multiple group comparisons were made using the Kruskal-Wallis test followed by the post-hoc paired t-test according to the Dunn procedure. Comparisons of the cumulative survival rates based on postnatal age according to the process of maternal or neonatal transport were performed using a Kaplan-Meier survival analysis and the log-rank test.

The study subjects included 195 infants from 189 mothers following 50,632 deliveries during the study period. Overall, 32 (16.4%) infants died and 33 (20.2%) infants had neurological impairments. The rates of mortality and handicaps among the infants in the maternal transport group were 15.2% and 23.2%, respectively, compared to 25% and 44%, respectively, in the neonatal transport group. There were no differences in the prognoses of the infants according to the process of maternal transport, although more premature neonates were managed in the tertiary center. There were no differences in the cumulative survival rates based on the institution that managed the neonate. The incidence of a poor prognosis was significantly higher among the infants born from mothers transported to the tertiary center due to bulging membranes (P = 0.047). All mothers with placental abruption were transported to the nearest secondary center.

The morbidity and mortality of extremely low-birthweight infants demonstrated a low incidence following the regionalization of high-risk pregnancies in our region. Further reductions in severe neonatal morbidities may depend on reducing the rate of neonatal transport.