Prenatal and postnatal factors affecting short-term survival of very low birth weight infants. Italian Collaborative Group on Preterm Delivery.

Factors affecting the survival of 175 preterm infants born with body weight less than 1500 g were examined. The still-birth and perinatal mortality rates were 143 and 446 per 1000 births respectively; neonatal death rate was 447 per 1000 live births. Survival improved progressively with increasing gestational age, and survival was better for infants born after 27 weeks of gestation. Neither maternal nor labour and delivery variables significantly affected survival. Male infants had half the survival rate of females. Birth asphyxia, hypercapnia and respiratory distress syndrome were the most common forms of morbidity, occurring in greater than 20% of the population. Infants with such pathology had significantly lower survival rates.