The presence of a sponsoring embryo in a batch of poor quality thawed embryos significantly increases pregnancy and implantation rate

Objective: To evaluate quantitatively the effect of one good-quality (sponsoring) embryo in a batch of low-quality thawed embryos on the implantation and pregnancy rates (PR). Design: Retrospective analysis of data. Setting: Tertiary care center IVF clinic affiliated with a university medical school. Patient(s): Between March 1988 and April 1995, 392 IVF patients underwent a total of 440 thawing and ET cycles of 1,436 multicellular embryos. Main Outcome Measure(s): Implantation, clinical pregnancy, and multiple pregnancy rates. Result(s): In the absence of sponsoring embryos in the thawed batch of embryos, a PR of 9.8% with an implantation rate of 3.1% was achieved. In the presence of a single sponsoring embryo, the PR nearly doubled (18.2%), with a significantly higher implantation rate of 7.0%. Only singleton pregnancies were achieved in the absence of sponsoring embryos compared with 21.7% multiple pregnancies in the single sponsoring embryo group. Conclusion(s): The presence of a sponsoring embryo in a batch of poor quality thawed embryos is an important factor that significantly increases pregnancy and implantation rates. The optimal strategy for planning batches of multicellular frozen embryos is to include at least one sponsoring embryo in each batch when possible. We speculate that the sponsoring embryo may favorably influence the chances of low-quality embryos to undergo successful implantation.