Impact of endometriosis on embryo quality and endometrial receptivity in women undergoing assisted reproductive technology

ART is an important treatment method for infertile patients with endometriosis. However, the effects of endometriosis on embryo quality and endometrial receptivity remain unclear. Thus, we aimed to simultaneously investigate the impact of endometriosis and its stage on embryo quality and endometrial receptivity in women undergoing ART. We retrospectively analyzed the data from patients with and without endometriosis who underwent oocyte retrieval and/or high-quality embryos transfer between July 2015 and December 2020, including 1312 IVF cycles and 608 IVF or frozen-thawed embryo transfer (FET) cycles, respectively. The endometriosis group had a lower percentage of good cleavage-stage embryos and fertilization rates than those in the control group (p = 0.038 and 0.008, respectively). The number of retrieved oocytes, MII oocytes, cleavage, blastocysts, and blastulation rates was comparable between two groups. We found no significant difference in clinical pregnancy, implantation, live birth, miscarriage, or multiple pregnancy rates between the two groups among patients who transferred high-quality embryos. Stratification analysis showed that patients with stage III-IV endometriosis had fewer retrieved oocytes than those with stage I-II endometriosis (p = 0.012) and marginally fewer retrieved oocytes than the control group (p = 0.051). The stage I-II group had the lowest percentage of good cleavage-stage embryos, which was significantly lower than that of the control group (p = 0.043). In FET cycles, patients with stage III-IV endometriosis had a higher miscarriage rate than those in the control group (p = 0.023). Our results suggest that endometriosis does not alter endometrial receptivity but affects embryo quality, oocyte fertilization ability, and ovarian response.