Physiological-based cord clamping in very preterm infants: the Aeration, Breathing, Clamping 3 (ABC3) trial-study protocol for a multicentre randomised controlled trial

Trials. 2022 Oct 1;23(1):838. doi: 10.1186/s13063-022-06789-6.


Background: International guidelines recommend delayed umbilical cord clamping (DCC) up to 1 min in preterm infants, unless the condition of the infant requires immediate resuscitation. However, clamping the cord prior to lung aeration may severely limit circulatory adaptation resulting in a reduction in cardiac output and hypoxia. Delaying cord clamping until lung aeration and ventilation have been established (physiological-based cord clamping, PBCC) allows for an adequately established pulmonary circulation and results in a more stable circulatory transition. The decline in cardiac output following time-based delayed cord clamping (TBCC) may thus be avoided. We hypothesise that PBCC, compared to TBCC, results in a more stable transition in very preterm infants, leading to improved clinical outcomes. The primary objective is to compare the effect of PBCC on intact survival with TBCC.

Methods: The Aeriation, Breathing, Clamping 3 (ABC3) trial is a multicentre randomised controlled clinical trial. In the interventional PBCC group, the umbilical cord is clamped after the infant is stabilised, defined as reaching heart rate > 100 bpm and SpO2 > 85% while using supplemental oxygen < 40%. In the control TBCC group, cord clamping is time based at 30-60 s. The primary outcome is survival without major cerebral and/or intestinal injury. Preterm infants born before 30 weeks of gestation are included after prenatal parental informed consent. The required sample size is 660 infants.

Discussion: The findings of this trial will provide evidence for future clinical guidelines on optimal cord clamping management in very preterm infants at birth.

Trial registration: NCT03808051. First registered on January 17, 2019.

Keywords: Cord clamping; Physiological-based cord clamping; Preterm infants; Randomised clinical trial; Study protocol.

Publication types

  • Clinical Trial Protocol

MeSH terms

  • Constriction
  • Female
  • Fetal Growth Retardation
  • Humans
  • Infant
  • Infant, Newborn
  • Infant, Premature*
  • Infant, Very Low Birth Weight*
  • Multicenter Studies as Topic
  • Oxygen
  • Pregnancy
  • Randomized Controlled Trials as Topic
  • Umbilical Cord / surgery


  • Oxygen

Associated data