BACKGROUNDEndometrial scratching (with the use of a pipelle biopsy) is a technique proposed to facilitate embryo implantation and increase the probability of pregnancy in women undergoing in vitro fertilization (IVF). METHODSWe conducted a pragmatic, multicenter, open-label, randomized, controlled trial. Eligible women were undergoing IVF (fresh-embryo or frozen-embryo transfer), with no recent exposure to disruptive intrauterine instrumentation (e.g., hysteroscopy). Participants were randomly assigned in a 1:1 ratio to either endometrial scratching (by pipelle biopsy between day 3 of the cycle preceding the embryotransfer cycle and day 3 of the embryo-transfer cycle) or no intervention. The primary outcome was live birth. RESULTSA total of 1364 women underwent randomization. The frequency of live birth was 180 of 690 women (26.1%) in the endometrial-scratch group and 176 of 674 women (26.1%) in the control group (adjusted odds ratio, 1.00; 95% confidence interval, 0.78 to 1.27). There were no significant between-group differences in the rates of ongoing pregnancy, clinical pregnancy, multiple pregnancy, ectopic pregnancy, or miscarriage. The median score for pain from endometrial scratching (on a scale of 0 to 10, with higher scores indicating worse pain) was 3.5 (interquartile range, 1.9 to 6.0). CONCLUSIONSEndometrial scratching did not result in a higher rate of live birth than no intervention among women undergoing IVF.

DNA methyltransferases (DNMTs) and ten-eleven translocation proteins (TETs) facilitate methylation and hydroxymethylation of DNA, respectively. DNMTs are widely studied with conflicting results on their regulation in the endometrium. While the role of TETs in the endometrium remains relatively unexplored. Deregulated expression of TETs and DNMTs are associated with endometrial pathologies. The aim of this study is to characterize the temporal TET expression in endometrium and to determine the hormonal regulation of TETs in comparison to DNMTs. mRNA expressions were quantified by real-time PCR in endometrial tissues from cycling women and localization was determined by immunohistochemistry. Hormonal regulation was investigated in endometrial epithelial and stromal cell lines following a 24 and 48 h treatment cycle. TET1 and 3 mRNA expressions were significantly upregulated in the mid-secretory phase. TET protein expression was ubiquitous in endometrial epithelium throughout the menstrual cycle except during the late-secretory phase, while stromal staining was scattered. TET1 mRNA was significantly upregulated in response to estrogen in stromal cells. Transcriptions of all three TETs were induced in response to progesterone treatment in epithelial cells. Only DNMT3b in epithelial cells and DNMT1 in stromal cells were significantly upregulated upon 24-h estrogen exposure following a significant decrease of DNMT1 when treated with 24 h of estrogen and progesterone. This study suggests that TETs are expressed in a cell-specific, dynamic manner in the endometrium and are responsive to steroid hormones. Investigating the role of TETs individually and with respect to DNMTs, will help to elucidate gene regulatory mechanisms in endometrial biology and pathologies.