Does Transfer of Embryos at the Blastocyst Stage Increase the Risk of Multiple Pregnancy?

Prolonged in vitro cultivation allows us to obtain better quality embryos and provides better intrauterine conditions for transfer. The aim of this study was to compare the results of in vitro fertilisation (IVF) procedures in which 1, 2 or 3 blastocysts (group 1) were transferred with the results of IVF procedures in which 1, 2 or 3 embryos at the stage of 8 cells to morula, achieved under the identical cultivation conditions, were transferred (group 2). The study period was from September 1997 to September 1998. Ovulation induction protocols including short or long GnRHa combined with gonadotrophins were used. Embryos were cultured in Medi-Cult IVF and M3 media. Maximally 3 embryos were transferred. In group 1, from a total of 377 cultured embryos, 129 reached the blastocyst stage (34.2 %) and 88 transfers of embryos resulted in 29 clinical pregnancies (33.0 % pregnancy rate). In 5 cases (17.3 %) multiple pregnancy was detected. In group 2, 274 embryo transfers were carried out and 56 pregnancies were achieved (20.4 % pregnancy rate), out of which 11 (19.6 %) were multiple pregnancies. Transfer of embryos at the blastocyst stage improved the outcomes of the assisted reproduction method in our Department; it did not result in any increase in multiple pregnancies and no triplet pregnancy occurred.