Relationship between embryo morphology and implantation rate after in vitro fertilization treatment in conception cycles

Objective: To investigate the relationship between the embryo number and morphology in conception cycles and the incidence of multiple pregnancies. Design: The study is based on information received from a computerized data base. Setting: In Vitro Fertilization Unit, Sapir Medical Center, Kfar Saba, Israel. Patients: A total of 117 consecutive pregnancies resulted from replacement of fresh embryos in our IVF-ET program. Main Outcome Measures: The impact of embryo quality, as assessed by morphological parameters, on the multiple pregnancy rate (PR). Results: Implantation rates positively correlated with the number and the quality of transferred embryos. However, no multiple pregnancies occurred when only two embryos were replaced. There were no multiple pregnancies when only embryos of low quality (grades 1 and 2) were transferred. Furthermore, there was no correlation between the number of replaced embryos of poor quality and the rate of implantation. The multiple PR increased from 10% when a mixture of high and low quality embryos were transferred to 30.76% when only embryos of highest quality were transferred. Conclusion: The implantation rate of transferred embryos is directly correlated with the morphological scoring. The results of the study suggest that the number of embryos transferred should be balanced against their morphological quality to reduce the rate of multiple pregnancies.