Hepatic hemodynamics and fetal growth: a relationship of interest for further research

It is well known that hepatic hemodynamics is an important physiologic mechanism in the regulation of cardiac output (CO). It has been reported that maternal cardiac output relates to neonatal weight at birth. In this study, we assessed the correlation between maternal hepatic vein Doppler flow parameters, cardiac output and neonatal birth weight. Healthy women with uncomplicated second or third trimester pregnancy attending the outpatient antenatal clinic of Ziekenhuis Oost-Limburg in Genk (Belgium), had a standardized combined electrocardiogram-Doppler ultrasound with Impedance Cardiography, for measurement of Hepatic Vein Impedance Index (HVI = [maximum velocity - minimum velocity]/maximum velocity), venous pulse transit time (VPTT = time interval between corresponding ECG and Doppler wave characteristics) and cardiac output (heart rate x stroke volume). After delivery, a population-specific birth weight chart, established from a cohort of 27000 neonates born in the index hospital, was used to define customized birth weight percentiles (BW%). Correlations between HVI, VPTT, CO and BW% were calculated using Spearman's ρ, linear regression analysis and R2 goodness of fit in SPSS 22.0. A total of 73 women were included. There was a negative correlation between HVI and VPTT (ρ = -0.719, p < 0.001). Both HVI and VPTT correlated with CO (ρ = -0.403, p < 0.001 and ρ = 0.332, p < 0.004 resp.) and with BW% (ρ = -0.341, p < 0.003 and ρ = 0.296, p < 0.011 resp.). Our data illustrate that the known contribution of hepatic hemodynamics in the regulation of cardiac output is also true for women with uncomplicated pregnancies. Our study is the first to illustrate a potential link between maternal hepatic hemodynamics and neonatal birth weight. Whether this link is purely associative or whether hepatic vascular physiology has a direct impact on fetal growth is to be evaluated in more extensive clinical and experimental research.