Days after birth

F-value

p-value

Day 1

Day 2

Day 3

Mean Heart rate (beats/min)

77.3 ± 8.6

81.0 ± 9.1

77.9 ± 7.2

0.801

0.482

Parasympathetic nervous activity indicator HF (msec²)

2.80 ± 0.64

2.29 ± 0.25

2.60 ± 0.71

0.730

0.511

Sympathetic nervous activity indicator LF/HF (msec²)

2.54 ± 0.63

3.11 ± 1.65

3.01 ± 1.23

0.649

0.548