Perinatal Factors and Postnatal Growth Trajectories as Determinants of School-Age Pulmonary Function in Preterm Infants

Purpose: This study investigated the associations between early-life perinatal risk factors, postnatal weight-growth trajectories, and pulmonary function at early school age in children born very preterm.Methods: This longitudinal cohort study included 72 children born before 30 weeks of gestation or with a birth weight below 1,250 g who completed spirometry at 6–7 years of age. Multiple linear and logistic regression analyses (n=69) were performed to examine the associations of gestational age, sex, birth weight z-score, antenatal corticosteroid exposure, Jensen 2019 bronchopulmonary dysplasia severity grade as an adjustment covariate, and two postnatal weight z-score change variables (birth to 36 weeks postmenstrual age [PMA], and 36 weeks PMA to the time of pulmonary function test [PFT]) with forced expiratory volume in 1 second (FEV₁) z-score and FEV₁/forced vital capacity (FVC) z-score.Results: Lower gestational age (β=0.18, P=0.026), male sex (β=−0.57, P=0.038), lower birth weight z-score (β=0.48, P<0.001), and smaller post-discharge weight gain (β= 0.19, P=0.048) were independently associated with lower FEV₁ z-score. For FEV₁/FVC z-score, higher birth weight z-score (β=−0.47, P=0.005), greater in-hospital weight gain PMA (β=−0.63, P=0.009), and higher Jensen BPD grade (β=−0.52, P=0.036) were inversely associated with FEV₁/FVC in multiple linear regression. In logistic regression, higher birth weight z-score (odds ratio [OR], 2.39, P=0.007) and greater in-hospital weight gain (OR, 3.97, P=0.002) were associated with higher odds of FEV₁/FVC.Conclusion: Lower gestational age, male sex, lower birth weight z-score, and smaller post-discharge weight gain were independently associated with lower school-age FEV₁. In contrast, higher birth weight z-score and greater early postnatal weight gain from birth to 36 weeks PMA were associated with lower FEV₁/FVC, consistent with a dysanaptic growth pattern.