Morbidity and mortality trends in very-very low birth weight premature infants in light of recent changes in obstetric care

Objective: In this study, we describe trends in morbidity and mortality of preterm infants with less than 500mg birth weight in the changing landscape of obstetric and neonatal care.

Study design: During a ten year study period between 2006 and 2016 we assessed outcome data for all neonates with less than 500mg birth weight born at our Neonatal Intensive Care Unit. We divided study subjects into two groups based on whether their birth date fell in the first half (2006-2010; n=39) versus the second half (2011-2015; n=27) of the study period comparing clinical outcomes in the two groups. We also assessed several clinical parameters for association with postnatal survival by comparing relative frequencies for each clinical parameter among surviving infants versus mortality cases.

Results: Survival rate for preterm neonates with less than 500mg birth weight born between 2006 and 2010 was 30.8%. This survival rate rose to 70.4% in the second half of the study period between 2011 and 2015 (p<0.05). Among surviving babies premature birth was found to be predominantly associated with maternal hypertension or intrauterine growth restriction while in those who died premature birth due to premature rupture of membranes and spontaneous preterm labor were significantly more common. All surviving infants with less than 500mg birth weight were born via cesarean section whereas among those who died cesarean section had been performed in only 80% and vaginal delivery in 20% representing a significant difference between the groups (p<0.05). The majority (90.3%) of surviving infants with less than 500mg birth weight had received surfactant therapy while the proportion of neonates receiving surfactant therapy among mortality cases was significantly lower (65.2%; p<0.05).

Discussion: Our findings suggest that among premature neonates with less than 500mg birth weight preterm delivery due to premature rupture of membranes and intrauterine infections represents the worse mortality risk. Steroid prophylaxis and measures to prevent and treat intrauterine infections with appropriate use of antibiotics can markedly improve survival in these cases. In premature neonates with less than 500mg birth weight survival is more favorable after cesarean section compared to vaginal delivery.