The effect of delayed umbilical cord clamping on cord blood gas analysis in vaginal and caesarean-delivered term newborns without fetal distress: a prospective observational study.

Abstract

Objective: To determine variations in cord blood gas (CBG) parameters after 3-minute delayed cord clamping (DCC) in vaginal deliveries (VDs) and caesarean deliveries (CDs) at term without fetal distress.

Design: Prospective observational study.

Setting: University hospital.

Sample: CBG from 97 VDs and 124 CDs without fetal distress.

Methods: Comparison of paired arterial-venous CBG parameters drawn at birth from the unclamped cord and after 3-minutes DCC for VDs and CDs.

Main outcome measures: Base excess, bicarbonate, haematocrit and haemoglobin from both arterial and venous cord blood, lactate, neonatal outcomes, partial pressure of oxygen (pO₂ ), partial pressure of carbon dioxide (pCO₂ ), pH, and postpartum haemorrhage.

Results: Arterial cord blood pH, bicarbonate ( ${\text{HCO}}_3^{-}$ , mmol/l), and base excess (BE, mmol/l) decreased significantly after 3-minute DCC both in VDs (pH = 7.23 versus 7.27; P < 0.001; ${\text{HCO}}_3^{-}$  = 23.3 versus 24.3; P = 0.004; BE = -5.1 versus -2.9; P < 0.001) and CDs (pH = 7.28 versus 7.34; P < 0.001; ${\text{HCO}}_3^{-}$  = 26.2 versus 27.2; P < 0.001; BE = -1.5 versus 0.7; P < 0.001). After 3-minute DCC, pCO₂ increased in CDs only (57 versus 51; P < 0.001), whereas lactate increased more in CDs compared with VDs (lactate, +1.1 [0.9, 1.45] versus +0.5 [-0.65, 2.35]; P = 0.01). Postpartum maternal haemorrhage, neonatal maximum bilirubin concentration, and need for phototherapy were similar between the two groups. Newborns born by CD more frequently required postnatal clinical monitoring or admission to a neonatal intensive care unit.

Conclusions: After 3-minute DCC, the acid-base status shifted towards mixed acidosis in CDs and prevalent metabolic acidosis in VDs. CDs were associated with a more pronounced increase in arterial lactate, compared with VDs.

Tweetable abstract: By 3-minute DCC, acid-base status shifts towards mixed and metabolic acidosis in caesarean and vaginal delivery, respectively.