Effects of Delayed Umbilical Cord Clamping at Different Timings on Neonatal Hemoglobin and Maternal Blood Loss During Cesarean Delivery at Term: A Randomized Controlled Trial.

Abstract

To examine during cesarean delivery the effects of delayed umbilical cord clamping at different timings vs early clamping in regard to neonatal hemoglobin levels and maternal blood loss. In total, 359 pregnant women scheduled for term cesarean delivery at 2 hospitals were randomly assigned to 4 groups: early clamping (<15 seconds; control) or delayed by 30 seconds, 60 seconds, or 90 seconds. Primary outcomes were neonatal hemoglobin levels within 72 hours after delivery; and the change in maternal hemoglobin levels before and after delivery, an indicator of blood loss, with a prespecified noninferiority margin of -0.87 g/dL. The secondary and exploratory outcomes included neonatal hyperbilirubinemia and polycythemia. Overall adherence to the assigned interventions was 96.1%. Compared with controls, all delayed groups showed significantly higher neonatal hemoglobin levels, with mean differences (95% CI) of 1.17 (0.53-1.80), 0.89 (0.25-1.54), and 1.11 (0.47-1.76) g/dL in groups delayed for 30 seconds, 60 seconds, and 90 seconds, respectively. In regard to the change in maternal hemoglobin levels, lower limits of the 95% CIs for the differences between delayed groups and controls were all higher than the margin (-0.48, -0.11, and -0.37 g/dL, respectively). Secondary and exploratory outcomes did not show any substantial difference across groups. For term elective cesarean delivery, cord clamping delayed by 30 seconds, 60 seconds, or 90 seconds vs early clamping led to similar increases in neonatal hemoglobin, and was not worse in terms of maternal blood loss. ClinicalTrials.gov (NCT05492214; https://clinicaltrials.gov/).