ObjectiveTo compare HR pattern of vigorous newborns during the first 180 s with early (≤60 s, ECC) or delayed (>60 s, DCC) cord clamping.Study designObservational study including dry-electrode ECG monitoring of 610 vaginally-born singleton term and late-preterm (≥34 weeks) who were vigorous after birth.Results198 received ECC while 412 received DCC with median cord clamping at 37 s and 94 s. Median HR remained stable from 30 to 180 s with DCC (172 and 170 bpm respectively) but increased with ECC (169 and 184 bpm). The proportion with bradycardia was higher among ECC than DCC at 30 s and fell faster in the DCC through 60 s. After adjusting for factors affecting timing of cord clamping, ECC had significant risk of bradycardia compared to DCC (aRR 1.51; 95% CI; 1.01–2.26).ConclusionEarly heart instability and higher risk of bradycardia with ECC as compared to DCC supports the recommended clinical practice of DCC.