Factors affecting survival in infants weighing 750 g or less

To assess which factors independently affect survival in infants weighing 750g or less.

We reviewed the obstetric, neonatal, and placental pathology information of all non-malformed neonates with birth weight of 750g or less from January 1998 to December 2002. Logistic regression analysis was used to control for the effect of confounding variables. A P<0.05 was considered significant.

Fifty nine neonates fulfilled the inclusion criteria; 30 (51%) survived the perinatal period. Surviving neonates were more frequently born after steroid administration (P=0.03) and from indicated delivery (P=0.01), had greater birth weight (P=0.001), gestational age at delivery (P<0.001), and 5-min Apgar scores of 7 or more (P=0.04) than those who died. There were no significant differences in placental pathology between survivors and neonates who died. Stepwise logistic regression analysis showed that gestational age (P=0.01), birth weight (P=0.004), female sex (P=0.03), 5-min Apgar score (0.026), and steroid administration (P=0.04) were independent predictors of survival. Cumulatively these five predictors explained 69% of neonatal survival.

The predictors of survival among micropremies are the same as those reported for older preterm neonates. The type of preterm delivery (spontaneous versus indicated) and placental pathology do not independently affect survival.