Participants
This retrospective study was carried out from January 2016 to December 2019 at the Center for Reproductive Medicine of Mali Hospital, Haikou, China and the Hospital of Shenzhen Immigration Inspection, Shenzhen, China. This study included the first frozen-thawed blastocyst transfer cycle of woman who underwent IVF cycle with or without ICSI (Intracytoplasmic Sperm Injection) with an indication of tubal, male, or unexplained infertility. Women with a diagnosis of a congenital or acquired uterine abnormality, such as a uterine malformation, adenomyosis, submucous myoma, uterine fibroids or intrauterine adhesions were excluded from this study.