Heart rate trends in healthy newborns >=35+0 weeks gestation after caesarean delivery with extrauterine placental transfusion and physiology-based cord clamping: a Norwegian observational study (INTACT-3)

Objective To describe the normal heart rate (HR) of healthy newborns ≥35+0 weeks' gestation in the first 10 min after caesarean delivery (CD) with extrauterine placental transfusion, using dry-electrode ECG (NeoBeat). Design Single-centre, prospective observational study.

Setting Norwegian County Hospital. Patients Newborns ≥35+0 weeks' gestation delivered by CD under regional anaesthesia were eligible for inclusion.

Newborns delivered by CD under general anaesthesia, or who needed medical intervention, were excluded. Interventions NeoBeat was attached to the newborn's chest immediately following delivery.

The placenta was delivered without cord clamping after 60 - 90 s and transferred with the newborn to a resuscitation table. Modified physiology-based cord clamping (PBCC) was performed.

Main outcome measures HR was recorded every second for 10 min. HR quartiles were calculated.

Events possibly influencing HR were annotated using Liveborn Observation App. Results 89 newborns with a mean (SD) gestational age of 39+3 weeks (10 days) and birth weight of 3649 (536) g were included.

Median (IQR) HR was 164 (117 - 176) and 169 (145 - 186) beats per minute at 20 s and 30 s, respectively, peaking at 169 (152 - 183) beats per minute at 4 min and then slowly decreasing to 157 (146 - 167) beats per minute at 10 min. HR was not significantly affected by intact-cord blood sampling (mean difference=5.4 (95% CI - 1.4 to 12.1)), placental delivery (mean difference=0.7 (95% CI - 3.5 to 4.9)) or cord clamping (mean difference = - 0.6 (95% CI - 2.1 to 0.9)).

Conclusions This report describes, for the first time, HR quartiles for healthy newborns ≥35 0 weeks' gestation from 15 s to 20 s and up to 10 min after CD with extrauterine placental transfusion and PBCC.