Reduced Lung Function at Preschool Age in Survivors of Very Low Birth Weight Preterm Infants

Survivors of preterm birth are at risk of long-term respiratory consequences. The objective of this prospective study was to assess pulmonary function at preschool age of former very low birth weight (VLBW) preterm children. Lung function of children born preterm and term controls aged 5-6 years were assessed by spirometry. The results were converted to z-scores. A questionnaire regarding respiratory symptoms was completed. Associations to gestational age (GA), birth weight (BW), bronchopulmonary dysplasia (BPD), and perinatal factors were assessed. In total, 85 VLBW preterm children and 29 term controls were studied. Of the preterm children, the mean GA was 28.6 ± 2.6 weeks and the mean BW was 1,047 ± 273 gm. Preterm children had significantly lower z-scores of forced expiratory volume in 1 s (FEV), FEV/forced vital capacity (FVC) ratio, and forced expiratory flow rate between 25-75% of FVC (FEF), compared with term controls (-0.73 vs. 0.04, = 0.002; -0.22 vs. 0.39, = 0.003; -0.93 vs. 0.0, < 0.001; respectively). Further segregation of the preterm group revealed significantly impaired FEV, FEF in children at earlier gestation (≤ 28 weeks, = 45), lighter at birth (≤ 1,000 g, = 38), or with BPD ( = 55) compared with term controls ( < 0.05). There were significant negative relationships between the severity of BPD with FEV, FVC, and FEF ( < 0.05). However, no correlation between lung function measurements and respiratory symptoms was found. VLBW preterm infants have reduced lung function at preschool age, especially among those with younger GA, lower BW, and BPD. Additional long-term follow-up of respiratory outcomes are needed for this vulnerable population.