Rates of survival and complications among extremely preterm infants and extremely low birth weight infants

Abstract

Objective To review the trends of the rates of survival and complications in extremely preterm infants and extremely low birth weight infants (ELBWI). Methods The clinical data of 259 extremely preterm infants (gestational age <28 weeks) and 239 ELBWI (birth weight <1 000 g) (163 cases with gestational age <28 weeks and birth weight <1 000 g), who were discharged between January 1, 2009 and December 31, 2015, from Neonatal Intensive Care Unit of Shenzhen Maternity & Child Healthcare Hospital, Southern Medical University, were collected and studied retrospectively. Grouped by gestational age and birth weight, the number of inpatients, and the rates of survival and complications were compared in pairs by trend Chi-square test. Results The median gestational age of extremely preterm infants was 27 weeks (22+6 to 27+6 weeks), and the median birth weight of ELBWI was 880 g (450-998 g). The survival rate of extremely preterm infants and ELBWI was 42.9% (9/21) in 2009, which increased to 85.3% (58/68) in 2015, with an ascending trend (χ2trend=21.643, P=0.001). The cure and survival rates of 259 extremely preterm infants were 64.1% (166/259) and 71.0% (184/259); the cure and survival rates of 239 ELBWI were 64.4% (154/239) and 70.7% (169/239); and the cure and survival rates of 163 extremely preterm ELBWI were 62.6% (102/163) and 69.9% (114/163), respectively. The survival rate in extremely preterm infants with gestational age <24 weeks was 1/7, increased to 81.4% (118/145) in those with gestational age≥27 to <28 weeks, showing an ascending trend with increased gestational age (χ2trend=36.037, P=0.000). The survival rate in ELBWI with birth weight <500 g was 0/2, increased to 80.7% (88/109) when birth weight was ≥900 to <1 000 g, with an ascending trend with increased birth weight (χ2trend=26.505, P=0.000). The major complications were neonatal respiratory distress syndrome [85.1%(285/335)], intraventricular hemorrhage [48.1%(161/335)], bronchopulmonary dysplasia [45.1%(151/335)], patent ductus arteriosus [40.9%(137/335)], retinopathy of prematurity [30.1%(101/335)], periventricular leukomalacia [4.2%(14/335)], hospital-acquired infection [3.0%(10/335)] and necrotizing enterocolitis ≥Ⅱa stage [2.1%(7/335)]. The incidence of complications, such as neonatal respiratory distress syndrome, patent ductus arteriosus,Ⅲ and Ⅳstages of intraventricular hemorrhage, moderate and severe bronchopulmonary dysplasia and hospital-acquired infection, decreased with increased gestational age in extremely preterm infants, while the incidence of neonatal respiratory distress syndrome, patent ductus arteriosus,Ⅲ andⅣstages of intraventricular hemorrhage decreased with the increase of birth weight in ELBWI (all P<0.05). Conclusions In recent years, the number of extremely preterm infants and ELBWI has increased obviously. The survival and cure rates have shown an increasing trend. With the increase of gestational age and birth weight, the survival rate has increased, and the rate of complications has decreased. Key words: Infant, extremely premature; Infant, extremely low birth weight; Survival rate; Mortality; Intensive care units, neonatal