Monitoring Fetal Heart Rate during Pregnancy: Contributions from Advanced Signal Processing and Wearable Technology

Table 3

Results of fetal HRV analysis by parameters in time domain, in frequency domain, by nonlinear indices and PRSA derived indices. Usefulness in separating populations is confirmed by 𝑡-test results.

Parameter	Healthy	IUGR	𝑡-test	𝑃 value
	(mean ± std)	(mean ± std)
Time parameters
STV (ms)	6.7 ± 2.24	4.29 ± 1.62	***	1.22𝑒−09
Interval index	0.87 ± 0.07	0.86 ± 0.06		0.37
LTI (ms)	21.46 ± 6.53	17.17 ± 5.37	***	1.5𝑒−11
Frequency domain
LF (Low Frequency power)	82.92 ± 5.29	81.39 ± 6.13		0.17
MF (Movement Frequency power)	6.7 ± 2.24	11.61 ± 3.50		0.63
HF (High Frequency power)	5.45 ± 3.18	6.65 ± 3.97		0.08
LF/HF + MF	5.36 ± 1.78	4.89 ± 1.76		0.16
Nonlinear parameters
ApEn(1, 0.1)	1.33 ± 0.13	1.21 ± 0.11	**	5.14𝑒−7
Lempel Ziv complexity (2, 0)	1.00 ± 0.08	0.94 ± 0.09	*	0.00078
SampEn(1, 0.1)	1.3 ± 0.19	1.13 ± 0.15	**	2.08𝑒−7
PRSA parameters
APRS	0.17 ± 0.041	0.12 ± 0.042	***	7.76𝑒−12
DPRS	−0.18 ± 0.046	−0.12 ± 0.042	***	1.08𝑒−13