Gestational age-dependent effects of intrauterine inflammation, delivery mode, and fetal growth on respiratory morbidity in preterm neonates.

Introduction: Respiratory morbidity in preterm neonates is influenced by both lung immaturity and antenatal environmental exposures. Because lung maturation continue throughout late gestation, the effects of these factors may vary according to gestational age. As most preterm neonates are born after 28 weeks, a better understanding of respiratory morbidty in this population is clinically important. We aimed to evaluate the gestational age-specific effects between intrauterine inflammation, other perinatal factors, and respiratory morbidity in neonates born between 28 and 36 weeks of gestation. Methods: We retrospectively analyzed the data of 912 neonates born between 28 and 36 weeks of gestation from March 2013 to December 2018 at Nagoya City University West Medical Center. Respiratory morbidity was defined as the need for invasive ventilation or continuous positive airway pressure for ≥24 h. Logistic regression analyses, including interaction terms with gestational age, were used to assess gestational age-specific associations. Results: Respiratory morbidity occurred in 275 neonates (30.2%) and was associated with lower gestational age, cesarean delivery, chorioamnionitis, funisitis, and low umbilical cord pH. At earlier gestational ages (33.4 weeks; 1 SD below the mean), intrauterine inflammation and higher birth-weight Conclusion: The effects of intrauterine inflammation, fetal growth, and cesarean delivery on respiratory morbidity differed according to gestational age. These findings suggest that gestational age-specific assessment of perinatal factors may improve the prediction and management of respiratory morbidity in preterm neonates. However, because only gestational age was adjusted for, residual confounding by other factors cannot be excluded, and these findings should be interpreted with caution.