To investigate the correlation of fetal aortic pulse wave velocity (PWV) with gestational age and cardiac annulus diameters in the second and third trimesters of pregnancy, and to explore the specific characteristics of fetal intrauterine growth and development.

This prospective study included normal fetuses (gestational age: 18 weeks to 39⁺⁶ weeks) undergoing fetal ultrasound at the Second Xiangya Hospital from October 2024 to March 2025. Dual-gate Doppler ultrasound successfully acquired valid measurements for ascending aortic PWV in 149 cases and descending aortic PWV in 201 cases. PWV was compared between the ascending and descending aorta, and the correlation of ascending and descending aortic PWV with gestational age and diameters of cardiac annuli, including the mitral valve annulus (MV), tricuspid valve annulus (TV), aortic valve annulus (AV), and pulmonary valve annulus (PAV), were analyzed. Multiple regression models were constructed to determine the optimal curve fitting.

Both ascending and descending aortic PWV showed a significant positive correlation with gestational age (r=0.30 and 0.38, respectively, both P＜0.01), with a Sigmoid curve showing the best goodness of fit. Descending aortic PWV was significantly higher than ascending aortic PWV in both the second and third trimesters [second trimester: (2.22±0.44) m/s vs (1.03±0.42) m/s, P＜0.01; third trimester: 2.48 (2.32, 2.66) m/s vs 1.31 (1.10, 1.47) m/s, P＜0.01] Additionally, there was a positive correlation between ascending and descending aortic PWV and each cardiac annulus diameter in normal second and third trimester fetuses (MV: r=0.26 and 0.34; TV: r=0.24 and 0.36; AV: r=0.28 and 0.33; PAV: r=0.28 and 0.39; all P＜0.01).

This study adopted the dual-pulse Doppler technique and demonstrated that fetal aortic PWV increases with gestational age, while also revealing segmental distribution differences in fetal aortic PWV. These findings facilitate further investigation of fetal aortic function and provide a novel reference indicator for the clinical quantitative assessment of fetal aortic elasticity.