[Effect of sequential embryo transfer on pregnancy following in vitro fertilization]

In this study, the influence of sequential embryo transfers in an in-vitro fertilisation programme was examined. After in-vitro fertilisation, a maximum of 6 fertilised oocytes were cultured. In cases with more than 6 fertilised oocytes, the rest was cryopreserved in the pronucleus stage. At day 2 after an oocytes retrieval, three embryos with the best morphological appearance were replaced and the remaining embryos (1-3) were cultured for further 3 days. At day 5 after oocytes collection, second a embryo transfer was performed, if one of these embryos had reached the blastocyst stage. In a total of 106 patients, 40 pregnancies (38%) could be observed. No statistical difference in the pregnancy rate could be seen between the group with a second embryo transfer (n = 38; 42%) and the group without second transfer (n = 68; 35%). The incidence of multiple pregnancy was not statistically different between both group and no high-rank multiple pregnancy (greater than Triplete) were observed. Out of 300 cultured embryos, only 59 embryos (17%) reached the blastocyst stage. In the group, in which a second embryo transfer was performed, 22 patients received one blastocyst and 13 patients two blastocysts during the second transfer. The second transfer did not have a significant effect on the pregnancy rate in this series. The most important factor for the induction of pregnancy seems to be the quality of the embryos transferred on day 2 following oocyte retrieval.