Table 3.

Day: night differences in fetal heart rate (FHR) parameters with respect to sex

	Male (n = 30)	Female (n = 24)	P value
Change in bFHR (bpm)	−7.3 [−3.3, −14.0]	−5.7 [+1.0, −15.6]	>0.4
Change in STV (ms)	1.2 [3.1, 0.2]	0.6 [1.6, −1.1]	0.076
Change in LTV (ms)	7.7 [17.6, 5.0]	3.5 [7.5, −5.6]	0.010
Change in RMSSD (ms)	0.0 [1.3 -1.3]	−0.31 [0.4, −1.5]	>0.2

Data are shown as mean median [IQR]

The day: night change in all measures of FHR variability was greater in male than female fetuses; this difference was significant with respect to long-term variation (LTV)

bFHR basal fetal heart rate, STV short term variation, LTV long term variation, RMSSD root mean square of successive differences