Prevalence of bradycardia in 4876 newborns in the first minute after birth and association with positive pressure ventilation: a population-based cross-sectional study.

Objective: To determine the prevalence of bradycardia in the first minute after birth and association with positive pressure ventilation (PPV).

Method: A population-based cross-sectional study was conducted from June 2019 to December 2021 at Stavanger University Hospital, Norway. Parents consented to participation during pregnancy, and newborns ≥28 weeks' gestation were included at birth. Heart rate (HR) was captured immediately after birth and continuously for the first minute(s). Time of birth was registered on a tablet. Provision of PPV was captured using video.

Results: Of 4876 included newborns, 164 (3.4%) did not breathe (two-thirds) or breathed ineffectively (one-third) and received PPV at birth. HR in the first minute had a wide distribution. The prevalence of first measured HR <100 and <60 beats/minute at median 16 s was 16.3% and 0.6%, respectively. HR increased in most cases. At 60 s, 3.7% had HR <100 beats/minute, of which 82% did not require PPV. In total, 25% of newborns had some registered HR <100 beats/minute during the first minute, of which 95% did not require PPV. Among newborns who received PPV, 76% and 62% had HR ≥100 beats/minute at 60 s and at start PPV, respectively.

Conclusion: Bradycardia with HR <100 bpm in the first minute of life was frequent, but mostly self-resolved. Among the 4% of newborns that remained bradycardic at 60 s, only 20% received PPV. Two-thirds of resuscitated newborns had HR ≥100 beats/minute at start PPV. None of the ventilated newborns were breathing adequately at start PPV.

Trial registration number: NCT03849781.