Objective: To evaluate the history of pregnancies after IVF-ET, to define multiple pregnancy risk factors. Design: A retrospective analysis of the period of 1992-2000. Setting: Department of Gynecology and Obstetrics, University Hospital, Palacký University, Olomouc. Methods: 343 pregnancies were evaluated, divided into 4 groups according to the patients’ ages: <29 yrs. (n=150), 30-34 yrs. (n=122), 35-39 yrs. (n=66), >40 yrs. (n=5). The number of transferred embryos and frequency of pregnancies in relation to the patient’ ages were compared as well as the multiple pregnancy and spontaneous abortion rates. The dependence of pretermlabour rate, foetus weight and the incidence of operative delivery on the frequency of pregnancies were evaluated (n=276). The data were analysed using the
2 and Sheffe tests. Results: Three or four transferred embryos markedly increase the number of multiple pregnancies (P<0.01). No relation to the patient’s ages was found. An increased incidence of operative deliveries (P<0.01) as well as preterm deliveries (P<0.05) in multiple pregnancies was found. Conclusions: The number of transferred embryos is the most important risk factor for multiple pregnancy development. It is recommended to decrease the number of transferred embryos to two or one per ET.

        Key words: multiple pregnancy, IVF-ET, number of transferred embryos