Fetal growth restriction is worse than extreme prematurity for the developing lung.

Background: Perinatal lung growth is highly vulnerable to inflammation and intrauterine growth restriction (IUGR), two major risk factors for chronic lung disease (CLD) in preterm neonates. However, the balance between extremely low gestational age (ELGA) and IUGR in very preterm infants as risk factors for CLD and co-morbidities remains poorly explored.

Objectives: This single-center study aims to compare neonatal morbidity (including CLD) and mortality among ELGA infants with normal birth weight (ELGA-AGA), very preterm infants with IUGR <3rd percentile (VLGA-IUGR) and very preterm infants with a birth weight appropriate for gestational age (VLGA-AGA), matched with VLGA-IUGR infants.

Methods: Selected characteristics of the perinatal and neonatal periods were recorded and retrospectively compared among the three groups. Infants with major congenital anomalies were excluded. The diagnosis of CLD was based on whether the infant was receiving supplemental oxygen and/or non-invasive ventilation at a postmenstrual age of 36 weeks.

Results: We found that, despite a median difference of 3 weeks in gestational age at birth between VLGA-IUGR and ELGA-AGA infants, neonatal mortality was 35% higher in neonates who had experienced fetal growth restriction, and that VLGA- IUGR was five times more predictive of CLD than was ELGA-AGA. These differences persisted after adjustment for confounding factors such as antenatal steroids, gender and respiratory distress syndrome.

Conclusions: This study reports that VLGA-IUGR infants are at higher risk of neonatal mortality and CLD than both ELGA-AGA and VLGA-AGA infants.