Can One Bad Apple Spoil the Whole Bunch? A Retrospective Analysis of Pregnancy Rates as Impacted by Transferring Embryos of Poor Quality With Good Quality Embryos

Abstract

Guidelines have been published by the American Society for Reproductive Medicine (ASRM) for the number of embryos to transfer during an Assisted Reproductive Technology (ART) cycle. However, limited data exist on whether the presence of a lower quality embryo together with high quality ones in a transferred cohort affects the likelihood of a clinical pregnancy. In this study, we evaluate if transferring a grade 3 (fair) or 4 (poor) embryo with grade 1 (excellent) or 2 (good) embryos negatively affects pregnancy rate. A retrospective data analysis. Data were evaluated concerning 337 ART cycles from 251 patients who underwent a transfer, using ASRM guidelines, with two to four embryos. These patients ranged in age from 22 to 39 years of age, used their own embryos, had not exceeded 3 previous embryo transfers, and had embryos transferred on day 3. Before transfer, embryos were inspected for cell stage and grade. Clinical pregnancy was defined as the presence of a fetal sac and a heart beat at 6-7 weeks post transfer. Categorical variables were analyzed with the use of Pearson Chi-Square test, while continuous variables were compared through the use of the independent-samples t test. Whether or not lower quality embryos transferred with higher quality embryos affected clinical pregnancy was determined by the odds ratio (OR) and 95% confidence interval. The odds ratio was adjusted for variables that were significantly different between groups by using unconditional multiple logistic regression. Age had a significant effect on pregnancy rate (P = .03), as did the quality of embryos transferred (P = .002). However, age was not significantly related to the quality of the embryos at transfer (P = .44). Age was related to cell stage (P = .02), while cell stage was borderline related to clinical pregnancy (P = .06). Thus, age appeared to affect clinical pregnancy rate through cell stage, but not through the quality score of the embryos being transferred. Clinical pregnancy rate (%) differed for the four, embryo transfer cohort classifications (Grade 1 or 2 only; n = 149: 63%, Exactly one Grade 3 or 4 in with Grade 1 or 2; n = 84: 50%, More than one Grade 3 or 4 in with Grade 1 or 2; n = 75: 43%, Grade 3 or 4 only; n = 29: 31%; P < .05). A logistic regression analysis controlling for age and number of cycles indicated that having at least one lower quality embryo transferred together with high quality embryos reduced the odds of a clinical pregnancy[OR = 0.55 (0.34-0.89; P = .02)] when compared to the transfer of high quality embryos only. In fresh ART cycles, when a grade 3 or 4 embryo was added to a cohort of grade 1 or 2 embryos, pregnancy rates were decreased when compared to embryo transfers containing only excellent quality embryos.