Improved Postnatal Growth in Preterm Very Low Birth Weight Infants: A Population Based Study

Aims: To assess whether postnatal growth of preterm VLBW infants, as determined by measures of postnatal growth failure (PNGF), improved during the period 1995-2010 and to evaluate postnatal growth by gestational age (GA) and intrauterine growth groups.
Methods: The study was based on the Israel national VLBW infant database and composed 13,531 VLBW infants of 24-32 weeks GA, discharged at a postmenstrual age of ≤40 weeks. Z-scores were determined for weight at birth and discharge. Severe and mild PNGF was defined as a decrease >2 and 1-2 z-scores respectively. Three time periods were considered: 1995-2000, 2001-2005 and 2006-2010. Multinomial logistic regression was used to assess the independent effect of time period PNGF.
Results: Severe PNGF rates decreased from 11.7% in 1995-2000 to 7.2% in 2001-2005 and 5.2% in 2006-2010. Infants born in 2006-2010 had a 6-fold lower odds for severe PNGF than babies born in 1995-2000 [adjusted odds ratio (aOR) 0.17; 95% confidence interval (CI) 0.14-0.21)] and >2-fold lower odds for mild PNGF [aOR 0.42; 95% CI 0.39-0.48].
Conclusion: We demonstrated a marked decline in PNGF among preterm VLBW infants from 1995-2000 to 2006-2010. This decline was present even in extremely premature infants.