Physiological Variation in Heart and Respiratory Rates of Healthy Term Neonates Following Delayed Cord Clamping

Background: Delayed cord clamping (DCC) at birth has been shown to improve cardiovascular stability in neonates. However, reference ranges for respiratory and heart rates (HRs) in term neonates following DCC have not been established. We describe respiratory and HR changes during the first 24 h in healthy term neonates following DCC. Methods: This study was conducted at a tertiary care hospital in Northern Rajasthan from January 2022 to July 2023. We included 200 full-term neonates delivered through uncomplicated vaginal delivery who underwent DCC of 60 s. Respiratory rate (RR) was measured by observation and by auscultation. HRs and RRs were recorded at 2, 4, 8, 12, 16, and 24 h after birth while in Prechtl’s behavioral states 1–4. Percentile curves were estimated using the generalized additive model for location, scale, and shape. Results: HR and RR data from 200 infants were recorded. Mean observed RR declined from 49.44 to 42.18 breaths/min between 2 and 24 h and mean auscultated RR declined from 50.18 to 43.20 breaths/min. Mean HR decreased from 145.80 to 128.94 beats/min over the same period. RRs were higher in neonates with meconium-stained amniotic fluid at all time points ( P < 0.001), no sex-based differences detected. Conclusions: The reference ranges and percentiles for respiratory and HR derived in this study support early postnatal assessment and help identify abnormal patterns warranting further evaluation.