. 2016 Oct 13;7:55. doi: 10.1186/s13293-016-0108-4

Table 2.

Fetal cardiovascular and circulation measures

	Fetal sex
	Female fetuses	Male fetuses
	n = 496	n = 532	p value
Preload
Ductus venosus PIV	ref	0.02 (0.01; 0.05)	<0.05
E wave tricuspid valve^a	ref	−1.02 (−1.81; −0.24)	<0.05
A wave tricuspid valve^a	ref	−0.49 (−1.55; 0.58)	NS
E/A ratio tricuspid valve^a	ref	−0.01 (−0.03; −0.00)	<0.05
E wave mitral valve^a	ref	−1.28 (−2.11; −0.46)	<0.05
A wave mitral valve^a	ref	−0.55 (−1.59; 0.50)	NS
E/A ratio mitral valve^a	ref	−0.02 (−0.03; −0.01)	<0.05
Afterload
Umbilical artery PI	ref	−0.03 (−0.05; −0.01)	<0.05
Middle cerebral artery PI	ref	−0.03 (−0.07; 0.01)	NS
Ascending aorta PSV (cm/s)^a	ref	−0.94 (−2.60; 0.71)	NS
Pulmonary artery PSV (cm/s)^a	ref	−1.33 (−2.63; −0.03)	<0.05
Fetal heart rate (beats/min)	ref	−1.71 (−2.90; −0.53)	<0.05
Combined cardiac output (ml/min)^a	ref	−21.8 (−71.00; 27.38)	NS

Results from multiple linear regression analyses. Values are regression coefficients (95 % confidence interval (CI)) and reflect differences in fetal cardiovascular and circulation measures of male fetuses compared with female fetuses (reference category) in the third trimester of pregnancy (median 30.4 weeks; range 27.4–35.1 weeks). All analyses were adjusted for gestational age and estimated fetal weight at the time of measurement

PI pulsatility index, PIV pulsatility index for veins, PSV peak systolic velocity, NS not significant

^aCardiac measurements were additionally adjusted for fetal heart rate