Peigné M, Devouche E, Ferraretto X, et al. - Researchers sought to determine the endometrial preparation supporting better ongoing pregnancy rates and live birth rate (LBR) following frozen-thawed embryo transfer (FET) between mild gonadotropin ovarian stimulation (OS) and artificial cycles (AC). They conducted a retrospective follow-up study including 1,021 FETs performed from 2013 to 2016 in one fertility center. Of these, 35% underwent OS preparation and 65% had an AC. Outcomes revealed significantly higher LBR with mild OS than with the AC preparation, despite a similar CPR; this was observed even after adjusting for potential confounders. These results emphasize considering OS as the first-line endometrial preparation instead of an AC. In view of the possible existence of a potential defect of the luteal phase in an AC, optimization of treatment could be undertaken to avoid pregnancy losses.