Does the Transfer of a Poor-Quality Embryo alongside a Good-Quality Embryo at the Cleavage or Blastocyst Stage Affect Pregnancy Rates? A Retrospective Cohort Study

Background: Embryo quality is a critical determinant of success in assisted reproductive technology (ART). A strong and positive correlation between embryo quality and clinical pregnancy rate (CPR) has been reported. The aim of this study was to evaluate the effect of transferring one good-quality embryo (GQE) alongside one poor-quality embryo (PQE) on CPR and live birth rate (LBR) in fresh ART cycles. Methods: This retrospective cohort study included a total of 1631 women who underwent an in vitro fertilization–intracytoplasmic sperm injection (IVF-ICSI) cycle. The study was conducted at T.C. Ministry of Health, Zeynep Kamil Women’s and Children’s Diseases Training and Research Hospital, İstanbul, Türkiye. Patient data were obtained from medical records. Patients were assigned to 5 different groups according to the number and quality of embryos transferred: Group 1 for 1 GQE transferred; Group 2 for 2 GQEs transferred; Group 3 for 2 embryos transferred with 1 GQE along with 1 PQE; Group 4 for 1 PQE transferred; and Group 5 for 2 PQEs transferred. Age, number of retrieved oocytes, number of captured metaphase II (MII) oocytes, number of formed embryos, number of transferred embryos, and number of GQEs were assessed. Results: In 891 cases in which a single GQE was transferred, the LBR was 26.3%, whereas in 126 cases in which a GQE with a PQE was transferred, the LBR was 16.7% (p < 0.001). Statistically significant differences were observed for age (p < 0.001), number of oocytes retrieved (p < 0.001), total number of embryos obtained (p < 0.001), number of MII oocyte numbers (p < 0.001), CPR (p < 0.01), and LBR (p < 0.001) between groups classified according to the number and quality of the transferred embryos. The study group was also analyzed as two separate age groupings: <35 years and ≥35 years. Using a regression analysis, day 5 embryo transfer (ET) was found to improve CPRs in both age groups [relative risk (RR), 95% confidence interval (CI): 1.875, 1.267–2.775, p = 0.002 and RR, 95% CI: 2.973 1.277–6.918, p = 0.011]. Day 5 ET improved LBR only in <35 years age group (RR, 95% CI: 1.760, 1.174–2.639, p = 0.006). 2 GQE ETs were found to be more effective than other transfer options in both age groups, when considering CPRs (RR, 95% CI: 2.962, 1.463–6.000, p = 0.003; and RR, 95% CI: 2.001, 1.062–3.773, p = 0.032). Conclusions: This study indicated that the transfer of an additional PQE alongside a top-quality embryo does not have a favorable effect on clinical pregnancy and LBR. On the contrary, the transfer of an additional PQE negatively affects LBR.