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Background. Multiple pregnancy can be prevented by an elective single blastocyst transfer. The aim of this prospective study was to evaluate the effect of blastocyst development and morphology on the outcome of single blastocyst transfer. Methods. In this study 157 women with single blastocyst transfer were included; their mean age was 33.6 years, range 20–42. Embryos were cultured to the blastocyst stage and evaluated using the Gardner’s classification. An elective single blastocyst transfer was performed in 83 women although 2 or more blastocysts developed (Group 1) and in 74 with only one developed blastocyst (Group 2). Results. In Group 1 (2 or more blastocysts) the pregnancy rate was a significantly higher than in Group 2 (1 blastocyst only) (39.8 % vs. 23.0 %; P < 0.05). After the transfer of a single expanded blastocyst no statistical difference in the pregnancy rate between the two groups was observed (45.5 % vs. 44.6 %). A significantly higher pregnancy rate was found after the transfer of one expanded blastocyst with a good embryoblast and trophoblast morphology compared to the transfer of a single early blastocyst (45.6 % vs. 7.1 %, P < 0.05). Conclusions. After single blastocyst transfer, the likelihood of achieving a pregnancy is higher in women with 2 or more blastocysts developed. And also the likelihood of achieving a pregnancy is higher with an expanded blastocyst transferred with good embryoblast and trophoblast morphology. The blastocyst development is the main predictor of pregnancy, which may reflect the embryonic genetic status.

Background. Multiple pregnancy is in itself already a risk factor for the course and outcome of the pregnancy and birth. Its frequency in in-vitro fertilisation is approximately twenty fold in comparison to natural conception which is also why it is one of the main problem areas of pregnancy and birth after an IVF-ET procedure. The aim of our research is to determine whether the twins, born after an IVF-ET procedure are any different than twins, born after spontaneous conception.Methods. The research was retrospective in nature. It included 1511 twin pregnancy patients who gave birth to twins between April 1987 and May 1995 and between January 1997 and December 1999. Our research group consisted of 255 mothers and 510 twins, born after an IVF-ET procedure. The research was divided into a cohort and controlled study. In the cohort study the research group was compared to the entire Ljubljana cohort of 1256 mothers and 2512 twins resulting from spontaneous conception. In the controlled study 93 mothers and 186 twins from the research group were compared with 93 mothers and 186 newborns after spontaneous conception. In this group the mothers matched the research group in age, parity and birth year. The course of and complications during the pregnancy, and the course, complications and outcome of the birth as well as the characteristics of the newborns were compared.Results. Certain serious complications during the course of the pregnancy, including hypertension, gestation diabetes and threatened preterm labours, were no more frequent with the IVF group of mothers with twin pregnancy than with the control group. However more bleeding in the first trimester and less proteinuria were determined in comparison to the control group. During the course of birth and its outcome more premature labours were determined (62.3–68.8% vs. 51.4– 50.5%), a 6 to 7 days lower average gestation age, a coresponding birth weight, three times more elective and urgent caesarean sections were determined for the IVF group than for the control group and the differences were all statistically significant.Conclusions. Multiple pregnancies are a complication of an IVF-ET procedure. Women who conceive after an IVF-ET procedure and with a twin pregnancy outcome are not subject to any more danger than pregnant women after spontaneous conception. Children are born somewhat earlier and are therefore lighter, however the perinatal outcome of newborns is no different and the morbidity and mortality rates are similar to that of newborns after spontaneous conception.

Background. Slovene data on iatrogenic multiple pregnancy after IVF/ICSI procedures are presented. The influence of elective transfer of two high-quality embryos on the incidence of iatrogenic multiple pregnancy were evaluated.Methods. Retrospective analysis of the Slovene IVF/ICSI data in the period 1983–2000.Results. In 17436 IVF/ICSI cycles 3068 pregnancies were achieved. Of the 2308 deliveries 369 (16%) were twins and 49 (2%) triplets. Of the 2827 newborns 738 (26%) were twins and 148 (5%) triplets. With elective transfer of two high quality embryos in 1999 and 2000 in two of the three Slovene centres for assisted reproduction, the pregnancy rate per transfer increased (32%), triplet deliveries decreased to 2/492 deliveries (0.4%) (p < 0.000), and twin deliveries remained unchanged 111/492 deliveries (23%).Conclusions. After elective transfer of two high-quality embryos and cryopreservation of surplus high-quality embryos in two of the three Slovene centres in the years 1999 and 2000, the problem of iatrogenic triple and higher rate multiple pregnancies has been successfully resolved, but the twin delivery rate still remains too high. Only by elective transfer of a single high-quality embryo the high multiple pregnancy rate after IVF/ICSI procedures could be avoided.

Background. Twin pregnancy rates following the transfer of two embryos in in vitro fertilization (IVF) treatment are high. Therefore, the aim of this study was to evaluate twin pregnancy rates in regard to the developmental stage of the embryo, patient age, and cause of infertility.Methods. A retrospective analysis involved 1222 IVF procedures. Overall pregnancy rates and twin pregnancy rates following the transfer of two blastocysts or two cleavage-stage embryos were assessed. The blastocyst group was divided into four age subgroups, and into four subgroups by the cause of infertility.Results. After the transfer of two blastocysts or two cleavagestage embryos the overall pregnancy rates (45% vs. 9%) and the twin pregnancy rates (18% vs. 5%) were significantly higher in the blastocyst group. The effects of patient age and the transfer of two blastocysts on the overall pregnancy and twin pregnancy rates were significantly greater in the subgroups of patients aged ≤ 30 years (21%) and 31–34 years (20%) than in older patients (35–38 years = 15.7%; ≥ 39 years = 9%). In the blastocyst group the twin pregnancy rate was significantly higher in patients with tubal (21%) and endocrinological causes of infertility (24.5%) than in patients with endometriosis (7%) and uterine malformations (12.5%).Conclusions. After the transfer of two blastocysts twin pregnancy rates are significantly higher in patients with tubal factor or endocrinological causes of infertility younger than 34 years. In this population of women the risk of twin pregnancy can be avoided by the transfer of a single embryo – most developed blastocyst.

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 and > 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.