Means and standard errors of the group-by-condition interactions for fetal heart rate variability (HRV) and heart rate (HR) metrics used in the analysis. Asterisks denote significant interactions between maternal exercise and fetal breathing (p ≤ 0.05). Abbreviations: RMSSD = root mean square of successive difference, RSA = respiratory sinus arrhythmia. Frequency domain HRV measures: Total Power (log Total Power), [0.02-1.7 Hz].very low frequency (log VLF) [0.02-0.08 Hz], low frequency (log LF) [0.08-0.2 Hz], intermediate (log INT) [0.2-0.4 Hz], high frequency (log HF) [0.4-1.7 Hz].