FIGURE 1.

Flow chart of sample selection for the analyses of the current endometrial transcriptome study. In the short‐term analysis, we considered only the implantation outcome after the second fresh embryo transfer (ie the first fresh cycle following endometrial biopsy), whereas in the long‐term analysis, the outcome of all fresh and frozen embryo transfers within the 12‐month follow‐up period after enrollment were considered. Ongoing pregnancy was defined as a positive heartbeat on ultrasound at 10 weeks of gestational age, and no pregnancy as negative urinary or serum human chorionic gonadotropin levels 18 days after the ovum pickup. “Fertile” women were not fertile in the conventional sense but were infertile women who achieved a live birth through assisted reproductive technology after three or fewer embryos transferred. RIF was defined as no live birth after transfer of at least three good quality embryos as determined by morphology. Only the samples meeting these definitions were included in the respective analyses. ETs, embryo transfers; RCT, randomized controlled trial; RIF, recurrent implantation failure.^aEndometrial biopsies (n = 141) were obtained from women undergoing endometrial scratching (biopsy) in the SCRaTCH trial, a randomized controlled trial on endometrial scratching in women with a first failed IVF/ICSI cycle (van Hoogenhuijze et al. Hum Reprod 2020;36:87–98). ^bOf the 141 biopsies, 107 samples had sufficient RNA quality to be sequenced and were used for further analysis.