Comparison of Fetal Cardiac Function in Structurally Normal Fetuses Conceived Via IVF and Spontaneous Pregnancy: a Prospective Case-Control Study

Objective To compare fetal cardiac function and cardiac cycle characteristics between pregnancies conceived via frozen embryo transfer in in vitro fertilization (IVF) and those conceived spontaneously. Methods This prospective case–control study included 30 IVF and 102 spontaneous pregnancies at 18–24 weeks’ gestation. Pregnancies with malformations or chromosomal abnormalities were excluded. Fetal cardiac function was assessed using two-dimensional ultrasound plus pulsed-wave and color Doppler. Parameters included left and right myocardial performance index (MPI), mitral and tricuspid E/A ratios, cardiac cycle intervals, and peak systolic velocities of the aortic and pulmonary valves. The IVF group was stratified by endometrial protocol: hormone replacement therapy (HRT), natural cycle (NC), and mild ovarian stimulation (m-OS). Results IVF-conceived fetuses showed deviations in diastolic cardiac function compared with spontaneous controls, with the most pronounced changes in the hormone replacement therapy (HRT) subgroup. The tricuspid E/A ratio was significantly higher and systolic cycle duration shorter in the HRT group. In the IVF group, mitral E-wave duration was shorter and A-wave velocity lower, while E-wave velocity showed no significant difference. MPI values were preserved with similar results between groups. Subgroup analyses were also performed for each IVF protocol. Conclusion This study suggests that IVF pregnancies, particularly those using HRT protocols, may exhibit alterations in fetal cardiac function as early as the second trimester. Further studies are needed to clarify their clinical relevance and to assess long-term outcomes and underlying mechanisms.