摘要：Objective: To compare duration of ventilation to mortality and adverse neurode velopmental outcomes among extremely low birth weight (ElBW; 501-1000 g) infant s. Study design: Retrospective analysis of prospectively collected data from 536 4 infants with a birthweight of 501 to 1000 g born at National Institute of Chil d Health and Human Development (NICHD)-Neonatal Research Network centers from 1 995 to 1998. The main outcome measures were: survival, duration of mechanical ve ntilation, and neurodevelopmental outcome. Results: Overall survival was 71%. T he median duration of ventilation for survivors was 23 days; 75%were free of me chanical ventilation by 39 days, and 7%were ventilated for ≥60 days. Of those ventilated for ≥60 days, 24%survived without impairment. Of those ventilated f or ≥90 days, only 7%survived without impairment. Of those ventilated ≥120 day s, all survivors were impaired. Conclusions: The prognosis for ElBW with protrac ted ventilation remains grim. The cohort who remain intubated have diminished su rvival.a.d high rates of impairment. Parents of these infants should be informed of changes in prognosis as the time of ventilation increases.