Clinical and Experimental Obstetrics & Gynecology (CEOG) is published by IMR Press from Volume 47 Issue 1 (2020). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with S.O.G.
Objective: To explore whether differential endometrial injury (EI) timing prior to a frozen-thawed embryo transfer (FET) cycle yields similar improvements in pregnancy outcomes. Materials and Methods: A total of 688 women underwent consecutive FET cycles. Based on their desire to undergo differentially timed EI or not, patients were divided into four groups: on the 3 rd-5 th day of the menstrual phase of the FET cycle (n = 308), on the 3 rd-5 th day of the menstrual phase preceding the FET cycle (n = 78), during the luteal phase of the cycle preceding the FET cycle (n = 83), and no intervention (n = 219). Results: The pregnancy outcomes in the four groups were significantly different. The chemical pregnancy, clinical pregnancy, implantation, and live birth rates of patients who underwent EI on the 3 rd-5 thday of the menstrual phase preceding the FET cycle were the highest, followed by those who underwent EI on the 3 rd-5 th day of the menstrual phase of the FET cycle. The lowest rates were those during the luteal phase of the cycle preceding the FET cycle and patients who had no interventions, which were similar. Conclusions: Differential EI timing resulted in differential improvement of pregnancy outcomes for FET.