Blood pressure and cerebral oxygenation with physiologically-based cord clamping: sub-study of the BabyDUCC trial

Cord-clamping strategies may modify blood pressure (BP) and cerebral tissue oxygen saturation (rStO₂) immediately after birth.

We conducted a sub-study nested within the Baby-Directed Umbilical Cord-Clamping trial. Infants ≥32⁺⁰ weeks' gestation assessed as requiring resuscitation were randomly allocated to either physiologically-based cord clamping (PBCC), where resuscitation commenced prior to umbilical cord clamping, or standard care where cord clamping occurred early (ECC). In this single-site sub-study, we obtained additional measurements of pre-ductal BP and rStO₂. In a separate observational arm, non-randomised vigorous infants received 2 min of deferred cord clamping (DCC) and contributed data for reference percentiles.

Among 161 included infants, n = 55 were randomly allocated to PBCC (n = 30) or ECC (n = 25). The mean (SD) BP at 3-4 min after birth (primary outcome) in the PBCC group was 64 (10) mmHg compared to 62 (10) mmHg in the ECC group, mean difference 2 mmHg (95% confidence interval -3-8 mmHg, p = 0.42). BP and rStO₂ were similar across both randomised arms and the observational arm (n = 106).

We found no difference in BP or rStO₂ with the different cord clamping strategies. We report reference ranges for BP and rStO₂ for late-preterm and full-term infants receiving DCC.

Among late-preterm and full-term infants receiving varying levels of resuscitation, blood pressure (BP, at 3-4 minutes and 6 min) and cerebral tissue oxygen saturation (rStO₂) are not influenced by timing of cord clamping in relation to establishment of ventilation. Infants in this study did not require advanced resuscitation, where cord clamping strategies may yet influence BP and rStO₂. The reference ranges for BP and rStO₂ represent the first, to our knowledge, for vigorous late-preterm and full-term infants receiving deferred cord clamping. rStO₂ > 90% (~90^th percentile) may be used to define cerebral hyperoxia, for instance when studying oxygen supplementation after birth.