Influence of perinatal factors on limit of viability in extremely low birth weight infants

This retrospective study investigated the influence of perinatal factors on the limit of viability in extremely low birth weight (ELBW) infants. From January 1997 to May 1998, all infants weighing less than 1000 gm admitted to NICU of China Medical College Hospital were enrolled in this study. Still-born infants and infants with congenital anomaly were excluded. The end outcome was survival of the infants (defined as alive at discharge). Eighty-four infants were included in this study. Their mean gestational age (GA) was 25.8 +/- 1.76 weeks, mean birth weight (BW) was 772 +/- 114 gm, and overall survival rate was 48.8%. The smallest intact survival was a female infant of GA 23 weeks and BW 530 gm. Early neonatal mortality rate (< 7 days) was 26.2% (23/84). The cut off levels, below which mortality significantly increased, were GA < 24 weeks and BW < 700 gm (odds ratio, 6.11, confidence interval, 2.01 to 18.63 for GA; odds ratio, 2.65, confidence interval, 1.09 to 6.39 for BW). The two most significant factors which independently affected neonatal survival were GA < 24 weeks and early neonatal dexamethasone treatment for the prevention of chronic lung disease (odds ratio, 9.24, confidence interval, 2.53 to 33.76 for GA; odds ratio, 35.83, confidence interval, 7.03 to 183 for dexamethasone treatment). We conclude that in order to further reduce neonatal mortality, efforts should be made in the areas of prenatal care and women's health to prevent extreme prematurity and low birth weight infants. In the case of an impending delivery of an ELBW infant, an active plan of management for all gestations > or = 24 weeks seems appropriate. Finally, unless it is proven to be safe, early neonatal dexamethasone treatment for prevention of chronic lung disease should not be routinely used in ELBW infants.