Endometrial injection of embryo culture supernatant may adversely affect assisted reproductive technology outcomes in frozen-thawed embryo transfer cycles: A retrospective case-control study

Abstract

Abstract Purpose This study aimed to determine the effects of endometrial injection of embryo culture supernatants on assisted reproductive technology (ART) outcomes in frozen-thawed embryo transfer (FET) cycles. Methods We included hormone replacement therapy cycles, with the transfer of embryos reaching the blastocyst on day 5 after fertilization. To mitigate any potential bias, we excluded cycles that possibly affected implantation. We included 118 cycles in the stimulation of endometrial embryo transfer (SEET) group (participants received an endometrial injection of the embryo culture supernatant) and 878 cycles in the blastocyst transfer (BT) group (participants did not receive the embryo culture supernatant). Results Maternal age was significantly higher in the SEET group than in the BT group (p < 0.05). The implantation rate (p < 0.05), ongoing pregnancy rate (p < 0.05), and live birth rate (p < 0.05) were significantly lower in the SEET group than in the BT group. There was no significant difference in the clinical pregnancy and miscarriage rates between the groups. The age-adjusted odds ratios (ORs) for implantation and miscarriage were 0.70 and 1.52, respectively, in the SEET group. The age-adjusted OR for implantation was 1.0 and 0.29 for good-quality blastocysts (GQBs) and non-GQBs, respectively, in the SEET group compared to the BT group. The age-adjusted OR for miscarriage was 0.81 and 2.2 for participants aged < 37 and ≥ 37 years, respectively, in the SEET group compared to the BT group. Conclusions Endometrial injection of the embryo culture supernatant may adversely affect ART outcomes in FET cycles, especially in non-GQB embryo transfers and mothers aged ≥ 37 years.