Endometrial peristalsis may influence embryo implantation and pregnancy outcomes, but its role during hormone replacement therapy (HRT)-prepared frozen embryo transfer (FET) cycles remains unclear. This prospective observational study will assess endometrial peristalsis at predefined time points during HRT-prepared FET cycles using transvaginal ultrasonography and evaluate its association with pregnancy outcomes. The study aims to clarify the clinical significance of endometrial peristalsis in HRT-prepared FET cycles and to provide evidence supporting endometrial assessment in assisted reproductive technology.
Women aged 18 - 42 years old
Scheduled for frozen embryo transfer cycles using hormone replacement therapy protocol
Transferred no more than two cleavage embryos or one good-quality blastocyst or no more than two poor-quality blastocysts
Provision of written informed consent to participate
Having an allergy and contraindications for exogenous hormone administration (e.g., breast cancer, thromboembolic disease)
Cycles with preimplantation genetic testing, oocyte donation, or in vitro maturation
Having untreated uterine or adnexal abnormalities (e.g., intrauterine adhesions, unicornuate/ bicornuate/ arcuate uterus, endometrial polyp, large leiomyoma ≥5 cm in diameter, hydrosalpinx, endometrial hyperplasia)
Use of uterine relaxants or intralipid infusion during the embryo transfer process