Objective: To reduce the number of multiple pregnancies after IVF/ICSI treatment by an elective single embryo transfer, without significant reduction of pregnancy rate (PR). Design: A pilot study. Setting: Department of Obstetrics and Gynecology, University Hospital, Olomouc. Methods: The patients were devided into the three groups according to number and quality of transferred embryos: elective Single EmbryoTransfer (eSET, n=14), Single EmbryoTransfer (SET, n=21), and Double EmbryoTransfer – control group (DET, n=85). After 3 days of cultivation the embryos were transferred. In all groups the following parameters were compared: age of the patient, number of oocytes obtained, fertilization rate, number of frozen embryos, pregnancy rate (PR), implantation rate (IR), abortions (AB) and the number of multiple pregnancy. Results: In eSET group PR and (or IR) was 42.8%, in SET group PR and (or IR) was 19%. There were no monozygotic twins in these groups. In DET group PR was 40.7% and IR 25.9%. Nine of these 33 pregnancies were twins (27%). Because of small number of the patients detailed statistical analyses were not performed. Conclusion: An elective transfer of one „TOP“ embryo can reduce the number of multiple pregnancies without significant decrease of pregnancy rate.

        Key words: in-vitro fertilization, multiple pregnancy, elective single embryo transfer, nuclear precursor body (NPB)