Background and aim Heart rate (HR) is the most important parameter for evaluation of infants at birth. Studies using pulse oximetry (PO) have shown that healthy (pre)term infants can be bradycardic at birth. While HRs measured with PO (HR_PO) and ECG (HR_ECG) have been compared, time after birth was not a factor in the analysis. We compared HR_ECG and HR_PO at specific time points after birth, hypothesising that a discrepancy may exist immediately after birth.

Methods ECG electrodes and a PO sensor were attached as soon as possible after birth in healthy pre (term) infants. PO data with Signal Identification and Quality <0.30 were excluded. HR_ECG and HR_PO were compared every 30 s from 1–10 min.

Results 755 data pairs of 53 patients were analysed. Median (range) gestational age was 36 (27–41) weeks. Data from ECG and PO were acquired from 82 (26) and 99 (33)s after birth. Median HR_PO was <100 bpm the first 2 min after which it rapidly increased. HR_ECG remained stable at 150–160 bpm (table).

Conclusion HR measured by PO is significantly lower compared to ECG, which has important implications for clinical care in the first minutes after birth.