Abstract
INTRODUCTION: Women characterised by diminished ovarian reserve are considered to have poor ovarian response (POR) according to Patient-Oriented Strategies Encompassing IndividualizeD Oocyte Number (POSEIDON) criteria. Patients in this population often have a poor prognosis for treatment with assisted reproductive technology. In previous studies, oestrogen pretreatment before ovarian stimulation has been shown to have a beneficial effect. However, recent studies presented conflicting conclusions. This study aims to evaluate the effectiveness of oestrogen pretreatment in patients with expected POR (POSEIDON groups 3 and 4) undergoing gonadotrophin releasing hormone antagonist (GnRH-ant) protocol. METHODS AND ANALYSIS: A prospective superiority randomised parallel controlled trial will be conducted at a tertiary university-affiliated hospital. A total of 316 patients will be randomly divided into two groups at a ratio of 1:1. In the intervention group, oral oestrogen pretreatment will be administered from day 7 after ovulation until day 2 of the next menstrual cycle. Afterwards, a flexible GnRH-ant protocol will be initiated. The control group will receive no additional intervention beyond routine ovarian stimulation. The primary outcome is the number of oocytes retrieved. Secondary outcomes include the total number of retrieved metaphase II oocytes, average daily dose of gonadotropin, total gonadotropin dose and duration of ovarian stimulation, cycle cancellation rate, top quality embryos rate, blastocyst formation rate, embryo implantation rate, clinical pregnancy rate, early miscarriage rate and endometrial thickness on trigger day. All data will be analysed according to the intention-to-treat and per-protocol principles. ETHICS AND DISSEMINATION: The ethical approval has been confirmed by the reproductive ethics committee of the affiliated hospital of Shandong University of Traditional Chinese Medicine (SDUTCM/2022.9.20). In addition, written informed consent will be obtained from all the participants before the study. The results will be disseminated via publications. TRIAL REGISTRATION NUMBER: ChiCTR2200064812.