Table 1.

Fetal cardiac metrics during apnea and breathing.

	Exercise n = 15		Control n = 15
	[mean ± SD]		[mean ± SD]
	Apnea	Breathing	Apnea	Breathing
Epoch Duration (sec)	87.4 ±27.7	88.3 ±27.1	72.5 ±13.2	72.5 ±13.3
Parasympathic Metrics
Log HF	1.62 ± 0.52	3.02 ± 0.98	1.47 ± 0.60	2.21 ± 0.58
Log RSA	1.34 ± 0.67	2.51 ± 0.98	1.23 ± 0.69	1.87 ± 0.58
Metrics Summarizing Total HRV
Log RMSSD	1.70 ± 0.35	2.19 ± 0.51	1.58 ± 0.37	1.85 ± 0.29
Log HRV	5.67 ± 1.13	5.61 ± 1.01	5.45 ± 1.08	4.33 ± 0.73
Log Total Power	4.76 ± 1.06	5.10 ± 1.05	4.66 ± 1.06	4.04 ± 0.72
Other Frequency Domain Metrics
Log VLF	3.93 ± 1.18	3.93 ± 1.36	3.86 ± 1.17	2.68 ± 1.24
Log LF	2.95 ± 1.14	3.33 ± 1.22	2.52 ± 1.58	2.31 ± 0.98
Log INT	1.25 ± 1.12	2.30 ± 1.51	0.86 ± 1.04	1.08 ± 0.87
Metrics of Rate
IBI (msec)	428.9 ± 29.6	456.6 ± 29.4	405.9 ± 28.7	423 ± 27.8
HR(bpm)	140.9 ± 9.6	132.2 ± 8.8	148.8 ± 10.5	142.5 ± 9.6
Ratios Attributed to Sympatho-Vagal Balance
Log VLF/LF	0.98 ± 0.94	0.61 ±1.07	1.25 ± 1.23	0.37 ± 1.20
Log VLF/HF	2.31 ± 1.03	0.90 ± 1.26	2.42 ± 1.04	0.32 ± 1.63
Log LF/HF	1.33 ± 0.88	0.31 ± 0.88	1.17 ± 1.15	0.10 ± 1.12

Note: Measures of parasympathetically-controlled heart rate variability include Log RSA = natural Log of variance of filtered [0.4-1.7 Hz] IBI time-series and high frequency power (Log HF) [0.4-1.7 Hz]. Time and frequency domain measures of total heart rate variability include RMSSD = root mean square of differences between IBIs; Log HRV = natural log of variance of IBI time-series, and Log Total Power [0.02-1.7 Hz]. Other frequency domain measures of band specific power (integrals in msec²) include very low frequency (Log VLF) [0.02-0.08 Hz], low frequency (Log LF) [0.08-0.2 Hz], and intermediate frequency (Log INT) [0.2-0.4 Hz] and their ratios. Assessments of rate include IBI=mean interbeat interval; HR=mean heart rate. Time domain HRV metrics are in msec.