The influence of timing of elective cesarean section on neonatal resuscitation risk

Objective: Cesarean section has negative effects on the physiologic responses to birth, including the development of lung volumes, pulmonary vascular resistance, and biochemical responses. The objective of this study was to examine the association between the timing of delivery between 37 and 42 wks gestation and neonatal resuscitation risk in elective cesarean section. Design: Observational, cohort study. Setting: Maternity Department of Padua University, Italy. Subjects: All pregnant women who delivered by elective cesarean section at term during a 3-yr period were identified from a perinatal database and compared retrospectively with pregnant women who delivered vaginally and matched for week of gestation. Interventions: None. Measurements and Main Results: Comparative neonatal resuscitation risk (odds ratio, OR; confidence interval, CI) was analyzed. During this time, 1,284 (13%) elective cesarean section deliveries occurred at or after 37 wks of gestation. Forty-four (3.4%) newborns delivered by elective cesarean section and 18 (1.4%) newborns vaginally delivered needed positive pressure ventilation resuscitation by laryngeal mask airway or tracheal tube. Positive pressure ventilation resuscitation risk was significantly higher in the infant group delivered by elective cesarean section compared with vaginal delivery (OR, 2.05; CI, 1.25-5.67; p < .01) and involved both laryngeal mask airway and tracheal tube resuscitation maneuvers (OR, 2.77 CI, 1.26 -5.8; p < .01 and OR, 2.9; CI, 1.02-7.81; p < .01, respectively). In the period of weeks 37+0 to 38+6, positive pressure ventilation resuscitation risk and single laryngeal mask airway and tracheal tube resuscitation maneuver risk were significantly greatly increased (OR, 4.25; CI, 1.46 -16.12; p < .01; OR, 2.25; CI, 1.46-6.12; p < .01; and OR, 11.3; CI, 2.15-16.0; p < .01, respectively). After 38+6 weeks, there was no significant difference in positive pressure ventilation resuscitation risk. Conclusions: Elective cesarean section at term, in an obstetric population without prenatally identified risk factors, remains associated with increased resuscitation risk with related implications for the neonate compared with vaginal delivery. A significant reduction in neonatal resuscitation risk would be obtained by waiting until week 39-0 before performing elective cesarean section. (Pediatr Crit Care Med 2004; 5:566 -570) Copyright © 2004 by the Society of Critical Care.