Comparative study on the pregnancy outcomes of in vitro fertilization–embryo transfer between patients with different ovarian responses (a STROBE-compliant article)

There have been few studies on large-sample data of cleavage-stage embryo and blastocyst transfers. We compared the pregnancy outcomes of patients with different ovarian responses after the transfer of different numbers of embryos in different developmental stages. Patients were divided into 3 groups including low response group, medium response group, and high response group according to different ovarian responses. Patients in each group were further divided into 4 subgroups including group A: transfer of 1 D3 embryo, group B: transfer of 2 D3 embryos; group C: transfer of 1 D5 blastocyst; and group D: transfer of 2 D5 blastocysts. In low ovarian responders, the implantation rate, clinical pregnancy rate and live birth rate were significantly lower in the group A than in the groups B and C. In medium ovarian responders, the implantation rate was significantly higher, but the multiple pregnancy rate was significantly lower in the group C than in the group B. The multiple pregnancy rate was significantly higher in the group D than in the group C. In high ovarian responders, the implantation rate was significantly lower, but the multiple pregnancy rate was significantly higher in the group B than in group C. Based on the above results, the single blastocyst transfer is preferable for the patients with different ovarian responses.