Abstract:

Objective To investigate the effect of prolonged down ⁃ regulation protocols in different men⁃ strual phases on the clinical outcomes of in⁃vitro fertilizationand embryo transfer（IVF⁃ET）cycles. Methods A total of 324 couples who accepted IVF/ICSI⁃ET treatment between January 2019 and July 2020 were recruited in this retrospective study. They were divided into two groups according to the time the pituitary down⁃regulation started： group A（in luteal phase，n = 102）and group B（in follicular phase，n = 222）. The clinical characteristics and outcomes were compared. Results No significant difference was found between the two groups in stimulation days， total Gn dosage，serumLH level，progesterone level，estradiol level，and endometrial thickness on human chorionic gonadotropin（hCG）administration day（P > 0.05）. No significant difference was found in number of oocytes retrieved，mature oocyte rate，2PN fertilzation rate，number of embryos，highquality embryo rate and moderate⁃to⁃ severe ovarian hyperstimulation syndrome（OHSS）rate between the two groups（P > 0.05）. No significant differ⁃ encewas found in the implantationrate，clinical pregnancyrate，pregnancylossrateandlivebirth rate betweenthe two groups（P > 0.05）. Conclusion The clinical outcomes are similar in prolonged pituitary down⁃regulation protocols in luteal phase or follicular phase.

Key words:

prolonged pituitary down?regulation protocol, GnRH?a, IVF/ICSI?ET