Study design
This retrospective study was performed at the Reproductive Medical Center of Anhui Provincial Hospital, involving women with thin endometrium who undergoing their FET cycles during the period from January 2016 till February 2019.
In our center, thin endometrium is diagnosed when the maximal endometrial thickness(EMT) is ˂7 mm, dominant follicle are 18 mm in diameter in nature cycle(NC), or after 12 to 16 days of estradiol (E2) replacement(4–6 mg, Progynova; Bayer Schering Pharma, Roubaix, France). Infertile women who met these criteria in their 1-2 previously FET cycles were included in this study. All these women failed pregnancy despite the treatment with oral and/or vaginal estrogen, sildenafil or aspirin. Exclusion criteria were: uterine or endometrial abnormalities other than thin endometrium; patients with repeated implantation failures;<20 or >40 years of age at oocyte retrieval; patients with multiple types of FET protocol following the same fresh IVF/ICSI cycle. As there isn’t any consensus as to the ideal method of endometrium preparation in patients with thin endometrium, endometrium was prepared with TAM or HRT at the discretion of physicians and/or patients’ preference. The study was approved by the institutional ethics committee of Anhui Provincial Hospital.