Early-term deliveries as an independent risk factor for long-term respiratory morbidity of the offspring

Objective: Newborns exhibit the lowest immediate respiratory morbidity rates when born following 39 completed weeks of gestation. We sought to determine whether early-term delivery (37–38 + 6 weeks’ gestation) impacts on long-term pediatric respiratory morbidity. Study design: In this population-based prospective cohort analysis, all term singleton deliveries occurring between 1991 and 2013 at a single tertiary medical center were included. Gestational age upon delivery was sub-divided into: early (37–38 + 6 weeks’ gestation), full (39–40 + 6 weeks’ gestation), late (41–41 + 6 weeks’ gestation), and post-term (>42 weeks) deliveries. The incidence of long-term hospitalizations (up to the age of 18 years) of the offspring due to a set of predefined respiratory morbidities was evaluated. Survival curves were used to compare cumulative morbidity incidence. A Cox hazards regression model was used to control for confounders. Results: During the study period, 229,142 term deliveries met the inclusion criteria. Of those, 24% (n = 55,202) occurred at early term. Hospitalizations up to the age of 18 years, as a result of complications in the respiratory system were significantly more common in the early-term group as compared with full and late-term delivery groups. In the Cox regression model, while controlling for multiple confounders, early-term delivery exhibited an independent association with long-term respiratory morbidity (adjusted HR = 1.24, CI 1.19–1.29, P < 0.001). Conclusion: Deliveries occurring at early term are associated with higher rates of pediatric respiratory hospitalizations compared with full and late-term deliveries. Pediatr Pulmonol. 2017;52:198–204.