POSSIBLILTIES FOR A SINGLE EMBRYO TRANSFER IN AN IN VITRO FERTILIZATION PROGRAMME

Background. Since in in vitro fertilization two embryos – blastocysts are routinely transferred, the twin pregnancy rates are higher than in the general population. The aim of our study was to evaluate the clinical results after elective single-blastocyst transfer. Methods. Retrospectively we analysed clinical results of 696 in vitro fertilization cycles. The cycles were divided into 37 cycles, in which an elective single blastocyst transfer was performed (group 1), and in 659 cycles, in which an elective double blastocyst transfer was performed (group 2). The pregnancy rates, twin pregnancy rates, and spontaneous abortion rates were compared between the two groups. Additionally we evaluated the effect of the method of in vitro fertilization (classical IVF and ICSI) and female age ( 38 years) on the clinical results after a single or double blastocyst transfer. Results. After an elective single or double blastocyst transfer, there was no statistically significant difference in pregnancy rates (30% vs. 46%); after a single blastocyst transfer there were no twin pregnancies, whereas after a double blastocyst transfer the pregnancy rate was 18%. After a double blastocyst transfer, the method of in vitro fertilization did not affect the twin pregnancy rate, whereas in women younger than 38 years, the twin pregnancy rate was significantly higher than in women aged > 38 years (19% vs. 6%; p < 0,05). Conclusions. Clinical results obtained after an elective single and double blastocyst transfer are comparable. By the transfer of one blastocyst twin pregnancies are avoided. Elective single blastocyst transfer is recommended in women, younger than 38 years.