Elective Caesarean Section at 38 Weeks Versus 39 Weeks

Abstract

British and American obstetric societies recommend that elective cesarean section (ECS) be scheduled after 39 weeks’ gestation to reduce the incidence of neonatal death or adverse events. This multicenter, open-label, randomized controlled trial was undertaken at 7 Danish hospitals to investigate the risk of neonatal intensive care unit (NICU) admission associated with ECS scheduled before versus after 39+0 weeks’ gestation. Participants with a singleton pregnancy were randomly assigned to an ECS scheduled 11 days before the estimated due date (38+3 weeks; 38-week group) or to an ECS scheduled 4 days before the estimated due date (39+3 weeks; 39-week group). Neonatal outcomes were assessed 30 days after delivery or at final discharge. Maternal outcomes were assessed 30 days postpartum. The primary outcome was admission to the NICU, regardless of cause, within 48 hours of birth. Secondary short-term neonatal outcomes were admission to the NICU within 7 days of birth, NICU length of stay, type and duration of treatment, Apgar score, and umbilical artery pH and standard base excess values. A composite maternal outcome included at least 1 of these adverse outcomes: maternal death, hysterectomy, pulmonary embolism or deep venous thrombosis, uterine incision lateral tear, injury to bowel or bladder, procedural or anesthesia complications, rupture or dehiscence, bleeding requiring treatment, additional operations, or antibiotic treatment within 30 days of delivery. The Fisher exact, Wilcoxon rank sum, and Student t tests were used for statistical analyses. All analyses were performed using the statistical software program STATA version 11. A total of 1274 pregnant women were enrolled, with 119 to 329 participants at each site. At trial entry, the 2 intervention groups were similar in baseline characteristics. A total of 571 women in the 38-week group and 526 in the 39-week group had an ECS, and 59 and 97, respectively, had an unscheduled CS. Five women in the 38-week and 16 in the 39-week group delivered vaginally. The median difference in gestational age at delivery was 6 days (38+3; IQR 38+1 to 38+5 vs 39+2; IQR 38+6 to 39+5). Eighty-eight (13.9%) of 635 neonates in the 38-week group were admitted to the NICU compared with 76 of 637 neonates (11.9%) in the 39-week group. The relative risk (RR) of NICU admission was 0.86 (95% CI, 0.65–1.15) for ECS at 39 weeks compared with 38 weeks, and the risk difference was −1.9% (95% CI, −5.6 to 1.8). Treatment with continuous oxygen for more than 1 day was significantly less frequent in the 39-week group, with an RR of 0.31 (95% CI, 0.10–0.94) and a risk difference of −1.4% (95% CI, −2.7 to −0.2). No significant differences were seen in the frequency of NICU admission within 7 days of birth, respiratory morbidity, or treatment with intravenous antibiotics. The 2 groups were similar for NICU length of stay of 2 or more days. No cases of maternal death, hysterectomy, or serious thromboembolic events occurred. The risk of maternal bleeding greater than 500 mL was 17.1% in the 39-week group and 21.7% in the 38-week group (RR, 0.79; 95% CI, 0.63–0.99). The risk of the composite maternal outcome was 10.3% and 9.4% in the 39- and 38-week groups, respectively (RR, 1.1; 95% CI, 0.79–1.53). Scheduling ECS at 39+3 weeks compared with 38+3 weeks did not significantly decrease neonatal NICU admissions within 2 days of birth, and no secondary neonatal or maternal outcomes improved significantly with late scheduling. Any long-term consequences to the neonate or mother of ECS timing at term are uncertain and require additional investigations.