Heart beat rate in healthy full-term newborn infants across different historical periods: a systematic review

Aim: to systematically summarize published findings on reference (normative) heart rate (HR) magnitude in healthy term newborns during the first 7 days of life and to examine HR variability with respect to measurement method and age at assessment; additionally, to provide a historical bibliographic perspective on how neonatal HR norms evolved. Materials and Methods. We conducted a PRISMA-reported systematic review for the contemporary evidence base and a separate historical bibliographic component. Searches were performed in PubMed/MEDLINE, Cochrane Central, eLibrary, and CyberLeninka. After deduplication, 705 unique records were screened; 23 studies were included in the systematic component. Thirteen historical sources were additionally included (overall period covered 1710–2025). Data extraction followed a standardized form; methodological quality for the systematic component was appraised using the JBI checklist. All quantitative comparisons were performed at the study level and interpreted as exploratory. Results. Historical sources report a wide HR range predominantly obtained by clinical assessment (e.g., 72–172 bpm). Contemporary instrumental studies confirm substantial physiological variability in healthy term newborns, with reported HR values spanning from 55 bpm up to 240 bpm. Mean HR values appear broadly comparable across source groups (approximately 136–140 bpm). However, maximal HR values are lower in historical sources compared with contemporary instrumental data, and marked differences exist across groups in HR measurement methods. Conclusion. Reference HR values in healthy term newborns exhibit wide physiological variability, limiting the use of rigid thresholds without considering postnatal age, functional state, and measurement modality. While mean HR values remain broadly comparable across historical periods, extreme values (particularly maximal HR) and measurement approaches differ substantially.