Abstract
OBJECTIVE: This study aims to explore the relationship between different endometrial preparations and pregnancy outcomes among patients with regular ovulatory cycles in order to find the best endometrial preparation methods in the freeze-thaw embryo transfer (FET) cycle. MATERIALS AND METHODS: This is a retrospective study to investigate FET pregnancy outcomes in women who had a regular menstrual cycle, were younger than 35 years old, and underwent a modified natural cycle (mNC), ovulation induction (OI), or a hormone replacement treatment (HRT) cycle. A total of 1071 frozen cycles were included for analysis. RESULTS: The implantation rate and live birth rate (LBR) in the OI group show a significant difference when compared to the mNC and HRT groups (P < 0.01). After adjusting for confounding factors, the logistic regression analysis revealed that the number of embryos transferred, the embryo stage, and quality were significantly associated with clinical pregnancy rate and LBR. The LBR was additionally affected by the mode of the endometrial preparation; the OI cycle could increase LBR. CONCLUSIONS: Endometrial preparation methods affect the LBR in women with a regular menstrual cycle. The OI cycle had an advantage in the LBR of FET.