Objective:To investigate the variation of reference ranges of hemodynamic parameters in normal pregnancy and their relation to maternal basic characteristics.Methods:A total of 598 healthy pregnant women who underwent regular prenatal examination at the Third Affiliated Hospital of Guangzhou Medical University from January to December 2023 were prospectively enrolled, and noninvasive hemodynamic monitors were used to detect changes in hemodynamic parameters of the pregnant women with the week of gestation, including cardiac output (CO), stroke volume (SV), thoracic fluid content (TFC), systemic vascular resistance (SVR), mean arterial pressure (MAP), and heart rate (HR). Relationships between hemodynamic parameters and maternal basic characteristics, including age, height, and weight, were analyzed using restricted cubic spline.Results:(1) CO ( r=0.155, P<0.001), TFC ( r=0.338, P<0.001), MAP ( r=0.204, P<0.001), and HR ( r=0.352, P<0.001) were positively correlated with the week of gestation, and SV was negatively correlated with the week of gestation ( r=-0.158, P<0.001). There was no significant correlation between SVR and gestational age ( r=-0.051, P=0.258). (2) CO exhibited a positive correlation with maternal height and weight (all P<0.001). The taller and heavier of pregnant women, the higher their CO. A linear relationship was observed between maternal weight and SV, MAP and HR (all P<0.01). As maternal weight increased, SV, MAP and HR showed an upward trend. Furthermore, there was an inverse association between maternal age and SVR ( P<0.001). (3) There was a significant nonlinear association observed between TFC and body mass index during pregnancy ( P<0.05). Additionally, a nonlinear relationship was found between SVR and MAP in relation to maternal age (all P<0.05). Notably, when the age exceeded 31 years old, there was an evident upward trend observed in both SVR and MAP. Conclusions:The hemodynamic parameters of normal pregnant women are influenced by their height, body weight, and age. It is advisable to maintain a reasonable weight during pregnancy and give birth at an appropriate age.