Comparison of the developmental potential of the morphological good embryos between normal-responders with low and high rate of MG day 3 embryos formation

Background: To determine whether the morphological good (MG) day 3 embryos or blastocysts from normal responders with the low rate of MG day 3 embryos formation (LRTD3) and high rate of MG day 3 embryos formation (HRTD3) have similar developmental potential. Methods Oocyte retrieval cycles were ranked by the rate of MG day 3 embryos (MG day 3 embryos/ 2PN zygotes), cycles in the bottom25th percentile was defined as low potential group (L) while cycles in the top 25th percentile was defined as high potential group (H). The basic characteristics of patients and cycles, blastocyst formation rate, and clinical outcomes of transfer of the MG blastocysts or day 3 embryos were compared between the H and L groups. Results The overall characteristics of patients and cycles were grossly comparable between the H and L group in patients with MG day 3 embryo transfer or blastocysts transfer. In patients with transfer of MG day 3 embryos, patients with LRTD3 showed decreased rate of blastocyst formation and similar clinical outcomes of direct transfer of MG day 3 embryos, compared to patients with HRTD3. In patients with transfer of MG blastocysts, patients with LRTD3 showed decreased rate of blastocyst formation, as well as decreased rate of implantation and livebirth of transfer of MG blastocysts. compared to patients with HRTD3. Conclusion We concluded that the quality of MG day 3 embryos or MG blastocysts from patients with LRTD3 was reduced, compared to patients with HRTD3. However, it seems that direct transfer of MG day 3 embryos effectively avoid the flaws of poor quality of MG day 3 embryos from patients with LRTD3. Therefore, our study support the strategy of transfer of MG day 3 embryos rather than expended culture for patients with LRTD3.