THE PRESENCE OF A SPONSORING EMBRYO IN A BATCH OF POOR QUALITY THAWEDEMBRYOS 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 imp lantation and pregnancy rates (PR). Design: Retrospective analysis of data. Setting: Tertiary care center IVF clinic affiliated with a unive rsity medical school. Patient(s): Between March 1988 and April 1995, 3 92 IVF patients underwent a total of 440 thawing and ET cycles of 1,43 6 multicellular embryos. Main Outcome Measure(s): Implantation, clinic al pregnancy, and multiple pregnancy rates. Result(s): In the absence of sponsoring embryos in the thawed batch of embryos, a PR of 9.8% wit h an implantation rate of 3.1% was achieved. In the presence of a sing le sponsoring embryo, the PR nearly doubled (18.2%), with a significan tly higher implantation rate of 7.0%. Only singleton pregnancies were achieved in the absence of sponsoring embryos compared with 21.7% mult iple 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 emb ryo in each batch when possible. We speculate that the sponsoring embr yo may favorably influence the chances of low-quality embryos to under go successful implantation. (C) 1997 by American Society for Reproduct ive Medicine.