Umbilical Cord Clamping

This randomized controlled trial aims to compare the effects of 30-second cord clamping and pulsation-based delayed cord clamping on neonatal metabolic adaptation in term newborns delivered vaginally. Eligible mother-newborn pairs will be randomly assigned in a 1:1 ratio to either 30-second cord clamping or pulsation-based delayed cord clamping. In the intervention group, the umbilical cord will be clamped after spontaneous cessation of cord pulsation, whereas in the control group, the cord will be clamped 30 seconds after birth. The primary outcome is umbilical arterial lactate level. Secondary outcomes include umbilical arterial pH, pCO2, pO2, HCO3-, base deficit, 1- and 5-minute Apgar scores, and maternal postpartum blood loss.

Congenital diaphragmatic hernia (CDH) is a malformation that affects 1 in every 3000 newborns. The diaphragm does not complete its closure during embryogenesis, which allows the abdominal organs to herniate into the thoracic cavity altering lung development. The lungs of patients with CDH are small, with a decreased surface area for gas exchange and developmental impair of the pulmonary vasculature, resulting in respiratory failure and pulmonary hypertension shortly after birth. When clamping the umbilical cord, a large part of the preload is abruptly excluded, generating an increase in vascular resistance, which in turn increase the afterload, resulting in a decrease in cardiac output. The output is restored by decreasing vascular resistance in pulmonary circuit after lung aeration upon receiving the preload of the right atrium, increasing pulmonary flow and thus sustaining the preload of the left ventricle. If pulmonary aeration occurs before clamping the umbilical cord, the pulmonary blood flow increases before placenta flow is lost, thus avoiding a decrease in cardiac output. This modality has been called physiological base cord clamping (PFC). The hypothesis is that PFC once ventilation has been established could prevent hypoxia and improve cardiac output in newborns with CDH and secondarily improve their hemodynamic parameters, stabilizing gas exchange and pulmonary hypertension during the first 24 hours of birth.