Impact of delayed cord clamping on respiratory distress in late preterm and early term infants in elective cesarean section: a single centre, phase Ⅲ, randomised controlled trial.

Abstract

Background: Delayed cord clamping (DCC) has the potential to alleviate respiratory distress by augmenting blood volume and oxygenation, although there is currently a lack of direct evidence to support this. Late preterm and early term infants born via elective cesarean section (CS) are known to be more vulnerable to the neonatal respiratory distress (NRD). This study was designed to examine the effect of DCC on NRD of these infants.

Methods: Conducted from January 1, 2019 to January 31, 2024 at Shanghai First Maternity and Infant Hospital, this single-centre, phase Ⅲ, open-label randomised controlled trial included newborns delivered via elective CS between 34⁺⁰ and 38⁺⁶ weeks of gestation. Participants were excluded if fetus had suspected or confirmed congenital malformations, metabolic diseases, intrauterine growth restriction, late fetal heart rate deceleration or fetal distress. Pregnant women and their infants were randomised into immediate cord clamping (ICC) within 10 s of birth or DCC for 60 s and stratified by late preterm or early term. The primary outcome was the incidence of NRD which was defined as requiring oxygen or airway pressure support within the first 24 h of life. This study was approved from the Ethics Committee of Shanghai First Maternity and Infant Hospital, School of Medicine, Tongji University (KS 18126, KS1947). Chinese Clinical Trial Registry (ChiCTR1800017865), registered on August 18th, 2018.

Findings: Of 2610 randomised women, 1418 neonates were included in the DCC group and 1419 in the ICC group. The mean maternal age for both groups was 33 (4) years, and all mothers were of Han ethnicity. The mean gestational age of the neonates was 37.9 (0.9) weeks in both groups. NRD occurred in 119 (8.4%) in DCC versus 135 (9.5%) in ICC (Adjusted Relative Risk [aRR] 0.93, 95% CI 0.75-1.14). There were no significant differences in infant and maternal adverse events such as low Apgar score (aRR 0.74, 95% CI 0.25-2.19), hypothermia (aRR 1.00, 95% CI 0.89-1.12), hypoglycemia (aRR 1.04, 95% CI 0.77-1.38), maternal intrapartum massive bleeding (aRR 0.96, 95% CI 0.76-1.19), or the requirement for transfusion (aRR 0.34, 95% CI 0.10-1.15).

Interpretation: Delayed cord clamping was safe for both mothers and infants in late preterm and early term delivered by elective cesarean section, while it did not reduce the risk of early respiratory diseases.

Funding: This trial was funded by Shanghai Municipal Health Commission, China in 2019 (201940140) and National Natural Science Foundation of China in 2022 (82204047).