The data for 15 years were divided into 3 stages and the ratio, mortality, major complication and the causes of death of VLBW were studied.

• 将15年均分成3个阶段,探讨各阶段极低体重儿的发生率、死亡率和高危因素,主要并发症和死亡原因,探讨治疗进展。