Table 3.

Maternal and fetal heart rate variability measures by sleep position, time of the night and fetal behavioral state.

Maternal HRV measures by sleep position and time of the night
	Position	Mean heart rate	SDNN	RMSSD
First 2 hours	Left	78.2±9.9	30.6±8.7	22.8±9.4
	Right	85.4±7.0	26.3±7.2	20.9±8.7
	Supine	84.8±13.7	33.4±11.4	17.7±5.8
Last 2 hours	Left	75.9±11.0	29.1±7.0	26.4±13.5
	Right	81.7± 8.1	27.8±8.3	19.0±6.1
	Supine	80.3±13.3	36.1±15.3	21.4±8.6
Fetal HRV measures by sleep position and sleep state
Sleep state	Position	Mean heart rate	SDNN	RMSSD
1F a	Left	135.3±5.5	7.6±1.3	8.5±1.7
	Right	131.5±5.6	9.4±1.7	9.5±2.4
	Supine	n/a	n/a	n/a
2F b	Left	136.9±5.5	14.9±2.1	9.7±2.2
	Right	136.7±5.1	15.2±1.8	9.5±1.1
	Supine	139.6±5.7	15.1±2.6	8.8±1.1

Abbreviations: HRV, heart rate variability; RMSSD, root mean square of successive differences of RR intervals; SDNN, standard deviation of normal-to-normal RR intervals.

Values given as mean ± SD unless indicated otherwise.

^aQuiet sleep.

^bREM sleep.