Risk of Transient Tachypnea of the Newborn following Elective Cesarean Section Increases at a Gestational Age of 37 Weeks Compared to That at ≥ 38 Weeks Despite the Exclusion of Pre-Existing Risk Factors for Neonatal Respiratory Disorders.

Background: Elective cesarean sections (ECSs) for early-term pregnancies at 37 weeks of gestational age (GA) aim to reduce the risk of emergency cesarean sections due to the onset of labor or rupture of membranes. However, resultant increases in neonatal respiratory disorders, including transient tachypnea of the newborn (TTN) have been observed. However, few studies have elucidated the associated risk factors. Consequently, we aimed to determine whether differences existed in the clinical outcomes between neonates delivered via ECS at 37 weeks and those delivered at ≥ 38 weeks of GA.

Methods: A retrospective analysis was conducted on 259 neonates born via ECS at Tottori University Hospital, between January 2013 and December 2019, with birthweights ≥ 2500 g and GAs > 37 weeks. The neonates were categorized into two cohorts: births at 37 and at ≥ 38 weeks of GA (37-week and 38-week cohorts). The principal clinical outcomes included the appearance, pulse, grimace, activity, and respiration (Apgar) scores, need for positive-pressure ventilation, incidence of TTN, and length of hospital stay.

Results: No statistically significant differences were observed in the indications for ECS, sex, or birthweight between the two cohorts. The 37-week cohort exhibited a lower 1-min Apgar score than did the 38-week cohort, with no statistically significant differences between the two cohorts, at 5 min. Statistically significant differences were not observed in the need for positive-pressure ventilation during initial resuscitation or length of hospital stay for patients with TTN between the two cohorts. Notably, the 37-week cohort exhibited a significantly higher incidence of TTN than did the 38-week cohort.

Conclusion: ECSs at 37 weeks of GA exhibited an increased risk of TTN than ECSs at ≥ 38 weeks of GA. Strategic neonatal care and adequate preparation can mitigate this risk without affecting the length of hospital stay.