Objective:To investigate the effect of dydrogesterone (DYD) on the ultrastructure of the endometrium in the window of implantation.Methods:We prospectively studied endometrium tissues of patients who underwent in vitro fertilization and embryo transfer (IVF-ET) from July 2020 to July 2022 at the Center for Reproductive Medicine of Zhejiang Provincial People's Hospital. The ultrastructure of mid-luteal endometrium was examined by scanning electron microscopy and transmission electron microscopy. Firstly, we used self-control study to compare the ultrastructure of endometrium between the natural cycle group and the DYD 40 mg/d group in 20 patients with male factor infertility. Secondly, we used self-control study to compare the ultrastructure of the endometrium between the DYD 40 mg/d group and the DYD 80 mg/d group in 43 patients with recurrent implantation failure (RIF). Results:There were no significant differences in endometrial thickness, ultrasound grading, positivity rate of nucleolar channel system (NCS), pinopode score and secretor status score, in addition to number and morphology score of mitochondria, between the natural cycle group and the DYD 40 mg/d group (all P>0.05). In RIF patients, the DYD 80 mg/d group rendered significantly higher pinopode score (-46.26±19.97), NCS positivity rate [65.12% (28/43)] and mitochondrial morphology score [0 (0, 1)] than those in the DYD 40 mg/d group [-67.62±15.94, P<0.001; 39.53% (17/43), P=0.043; 0 (0, 0), P=0.023], while other characteristics were not significantly different between the two groups (all P>0.05). Conclusion:The ultrastructure of endometrium in DYD supplementation cycle was similar to that in the natural cycle. Increasing the dosage of DYD significantly improved pinopode maturity, NCS positivity rate and mitochondrial morphology of the endometrium in RIF patients.

Objective:To investigate the effect of dydrogesterone (DYD) on the ultrastructure of the endometrium in the window of implantation.Methods:We prospectively studied endometrium tissues of patients who underwent in vitro fertilization and embryo transfer (IVF-ET) from July 2020 to July 2022 at the Center for Reproductive Medicine of Zhejiang Provincial People's Hospital. The ultrastructure of mid-luteal endometrium was examined by scanning electron microscopy and transmission electron microscopy. Firstly, we used self-control study to compare the ultrastructure of endometrium between the natural cycle group and the DYD 40 mg/d group in 20 patients with male factor infertility. Secondly, we used self-control study to compare the ultrastructure of the endometrium between the DYD 40 mg/d group and the DYD 80 mg/d group in 43 patients with recurrent implantation failure (RIF). Results:There were no significant differences in endometrial thickness, ultrasound grading, positivity rate of nucleolar channel system (NCS), pinopode score and secretor status score, in addition to number and morphology score of mitochondria, between the natural cycle group and the DYD 40 mg/d group (all P>0.05). In RIF patients, the DYD 80 mg/d group rendered significantly higher pinopode score (-46.26±19.97), NCS positivity rate [65.12% (28/43)] and mitochondrial morphology score [0 (0, 1)] than those in the DYD 40 mg/d group [-67.62±15.94, P<0.001; 39.53% (17/43), P=0.043; 0 (0, 0), P=0.023], while other characteristics were not significantly different between the two groups (all P>0.05). Conclusion:The ultrastructure of endometrium in DYD supplementation cycle was similar to that in the natural cycle. Increasing the dosage of DYD significantly improved pinopode maturity, NCS positivity rate and mitochondrial morphology of the endometrium in RIF patients.