Neonatal Respiratory Morbidity Risk and Mode of Delivery at Term: Influence of Timing of Elective Cesarean Delivery

Abstract

In view of the increasing rates of elective cesarean delivery in Western countries, occasioned chiefly by previous cesarean delivery or breech presentation, this study was designed to compare rates of respiratory distresssyndrome (RDS) and transient tachypnea of the newborn (TTN) in infants delivered electively at term during each week of gestation between 37 + 0 and 41 + 6 weeks gestation. Control women who delivered vaginally were matched with the study group for week of gestation. Elective cesarean deliveries at or after 37 + 0 weeks gestation totalled 1284, representing 13% of live births during the years 1998 to 2000. Previous section delivery accounted for approximately half the elective cesarean deliveries at term and breech presentation for approximately one fourth. The incidence of RDS after elective cesarean delivery at term and after vaginal delivery were, respectively, 22 and 4 per 1000; the incidence of TTN after elective cesarean delivery at term and after vaginal delivery were respectively 9 and 8.5 per 1000 deliveries. Compared with vaginal births, infants delivered by elective section had a significant and progressive reduction in neonatal RDS, but there were no significant differences in TTN related to mode of delivery. The odds ratio (OR) for total neonatal respiratory morbidity in the elective cesarean group, compared with the vaginal delivery group, was 2.6. The OR for TTN in the cesarean group was only 1.19, but the risk of RDS increased significantly (OR, 5.85) and peaked in weeks 37 + 0 to 38 + 6 (OR, 12.9). There was no significant difference in RDS risk beyond 39 + 0 weeks. There were no neonatal deaths in this study. In this population lacking prenatally identified risk factors, elective cesarean delivery at term was associated with more neonatal respiratory morbidity than was vaginal delivery. Less morbidity may be expected by waiting until week 39 + 0 before performing elective cesarean deliveries.