Elective single embryo transfer (eSET) policy in the first three IVF/ICSI treatment cycles

Aafke P.A. van Montfoort1,3, John C.M. Dumoulin1, Jolande A. Land2, Edith Coonen1, Josien G. Derhaag1 and Johannes L.H. Evers2

1 Research Institute of Growth & Development (GROW), University of Maastricht and IVF-Laboratory and 2 Department of Obstetrics & Gynaecology, Academic Hospital Maastricht, Maastricht, The Netherlands

3 To whom correspondence should be addressed at: Research Institute of Growth & Development (GROW), University of Maastricht, Maastricht, The Netherlands. Email: avmn{at}sgyn.azm.nl


    Abstract
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
BACKGROUND: Elective single embryo transfer (eSET), applied in the first or second IVF cycle in young patients with good quality embryos, has been demonstrated to lower the twin pregnancy rate, while the overall pregnancy rate is not compromised. It is as yet unclear whether eSET could be the preferred transfer policy in all treatment cycles, or that it should be restricted to the first or first two cycles. METHODS: eSET policy (when two or more embryos were available, at least one of them being of good quality) was offered to patients younger than 38 years in the first three treatment cycles. Retrospectively, treatment cycle outcome was studied. RESULTS: In 326 patients, 586 treatment cycles were performed (326 first, 168 second and 92 third treatment cycles). In 65 cycles (11%), eSET could not be applied because there was either no fertilization, or only one embryo available. In the remaining 521 cycles, eSET was performed in 111 cycles (19%), while in 410 cycles, no good quality embryo was available resulting in the transfer of two embryos (double embryo transfer, DET). No significant differences in ongoing pregnancy rates after transfer of fresh embryos were observed between eSET and DET in the first (both 33%), second (36 and 23%, respectively) and third treatment cycles (20 and 24%, respectively). In significantly more eSET cycles compared to DET cycles, could embryos be frozen. This resulted in a significantly higher cumulative pregnancy rate after eSET compared to DET. CONCLUSIONS: In patients younger than 38 years with at least one top quality embryo, eSET can be the transfer policy of choice in at least the first three treatment cycles, since the pregnancy rates obtained in each treatment cycle are comparable to those after DET.

Key words: assisted reproductive technology/multiple pregnancy/single embryo transfer


    Introduction
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
Multiple pregnancy rates are high in assisted reproductive technology (ART) cycles. Recently, the European IVF-monitoring programme of the European Society of Human Reproduction and Embryology (ESHRE) reported a 26.3% multiple delivery rate in 258 460 IVF/ICSI treatment cycles initiated during 1999 in 22 countries (ESHRE, 2002Go). The majority of multiple deliveries after IVF and ICSI concern twins, representing 24.0% of all deliveries (ESHRE, 2002Go). Twin pregnancies must be regarded as a serious complication of ART cycles, with relatively high risks of health problems in the children (both during the pre- and perinatal period and later in life) and their mothers, social problems, and high economic costs (ESHRE Capri Workshop, 2000Go; Gerris et al., 2004Go).

The high twin pregnancy rate after IVF is the result of the current standard practice of transferring more than one embryo. The elective transfer of only a single embryo (eSET) has been shown to be an effective method to reduce the incidence of twin pregnancies in twin-prone IVF/ICSI patients without compromising the overall ongoing pregnancy rate (Vilska et al., 1999Go; ESHRE Campus Course Report, 2001Go; Gerris et al., 2001Go, 2002Go; Martikainen et al., 2001Go; Tiitinen et al., 2001Go, 2003Go; De Neubourg and Gerris, 2003Go).

It was recently recommended by the ESHRE consensus meeting on risks and complications in ART that eSET should be proposed in the first and second treatment cycles (Land and Evers, 2003Go). Since 2003 in Belgium, SET in the first, and eSET in the second treatment cycle is mandatory in patients younger than 36 years of age, to obtain maximal reimbursement of the costs of IVF treatment (Ombelet, 2004Go,). However, little information is available on eSET results to substantiate this proposal to limit eSET to the first two treatment cycles. In the present study we evaluate the results per treatment cycle number in a cohort of patients in whom eSET was offered as the standard transfer policy during the first three treatment cycles.


    Materials and methods
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
Patients
All IVF/ICSI patients who started their first treatment cycle in the period from July 2000 until December 2001 in the academic hospital Maastricht were included in this study. A treatment cycle was defined as an ovarian s timulation cycle which resulted in an ovum pick-up. In the study period eSET was offered as our standard transfer policy (see below) to patients younger than 38 years at the time of transfer, irrespective of the rank of the cycle and of previous IVF results. Only patients who were 38 years or older, patients with a strong wish for the transfer of either one or two embryos, patients who had a medical or socio/psychological reason to prevent a twin pregnancy, and patients requesting preimplantation genetic diagnosis (PGD) were excluded from the standard eSET policy.

In the study period the costs of the first three IVF/ICSI treatment cycles were fully reimbursed in The Netherlands. For this reason the study has been limited to the first three treatment cycles, including the transfer of frozen embryos, if any.

Ovarian stimulation protocol
Patients were down-regulated with daily s.c. injections of triptorelin (Decapeptyl; Ferring B.V., Hoofddorp, The Netherlands) or nafarelin intranasally (Synarel; Searle BV, Maarssen, The Netherlands) according to the long protocol. To stimulate multiple follicular development, recombinant FSH (Puregon, Organon, Oss, The Netherlands) was used. Follicle growth was monitored by ultrasound and 5000 IU of hCG (Pregnyl, Organon, Oss, The Netherlands) was given as soon as at least three follicles were ≥18 mm. Ultrasound-guided oocyte retrieval was performed 36 h after hCG administration. The luteal phase was supported by progesterone (Progestan, Organon, Oss, The Netherlands) 600 mg daily intravaginally, starting at the day of ovum pick-up and continued for 14–16 days. In the case of pregnancy 600 mg Progestan was continued for three more weeks.

Laboratory and embryo transfer procedures
IVF and ICSI procedures used have been described in detail earlier (Dumoulin et al., 2001Go). Oocytes and embryos were cultured individually in 5 µl droplets covered by mineral oil in an atmosphere of 5% O2, 5% CO2 and 90% N2 in sequential culture media either from Vitrolife (Göteborg, Sweden) or from Cook (Eight Mile Plains, Queensland, Australia). Embryo transfer was routinely performed on day 2 or day 3 after ovum retrieval. Embryos were evaluated at 23–26 h post-injection (in the case of ICSI) or 25–28 h post-insemination (in the case of IVF), 41–45 h post-injection/insemination, and in the case of day 3 transfer, also at 65–69 h post-injection/insemination. For each embryo originating from a normally fertilized oocyte, an embryo score was calculated on the basis of morphological grade (1 to 4, with grade 4 being the best grade, using the grading system of Bolton et al., 1989Go), number of blastomeres and presence or absence of multinucleated blastomeres (MNBs). Embryos that had reached the 4- or 5-cell stage on day 2 or the 8-cell stage on day 3, in combination with having the best morphological grade (regular, even sized blastomeres with <20% fragmentation) and an absence of MNBs were classified as good quality embryos (Van Royen et al., 1999Go). When patients were eligible for standard eSET policy and if at least one good quality embryo was available, only a single embryo was transferred (eSET). In all other cases, two embryos, if available, were transferred (double embryo transfer, DET). Cryopreservation of supernumerary embryos was performed on the third day after ovum retrieval. Only embryos which had reached the 8-cell stage and which were considered to be of sufficient morphological quality (grades 3 or 4) were cryopreserved. After thawing, two embryos, if available, were transferred, also in cases in which in the fresh transfer eSET was applied.

Pregnancy
An hCG pregnancy test with a detection limit of 50 IU/l in urine was performed 14–16 days after embryo transfer and patients with a positive test had an ultrasound examination 3 weeks later. Patients were asked to report an abortion occuring after this ultrasound examination immediately. In this study an ongoing pregnancy was defined as the presence of at least one intrauterine gestational sac with fetal heartbeat on ultrasound at ~7/8 weeks gestation and no report of pregnancy loss before 12 weeks gestation.

Statistics
The {chi}2 test with Bonferroni correction was used to compare the pregnancy rates. Differences were considered significant at P<0.05.


    Results
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
In our IVF center, in the period of July 2000 until December 2001, 388 patients underwent their first IVF/ICSI treatment cycle. The results of 62 patients (16%) were not included in the present study for the following reasons: 15 patients applied for PGD, 43 patients had reached the age of 38 years at the time of their first or subsequent IVF treatment cycles and four patients had either a strong wish for the transfer of one or two embryos or had medical or socio/psychological reasons for single embryo transfer.

The results of the first treatment cycles (performed in the period July 2000 until December 2001) and of all eventual subsequent second or third treatment cycles or frozen embryo replacement cycles (performed in the period July 2000 until May 2004) of the 326 patients who accepted our standard eSET policy can be found in Table I. In these patients, after transfer of fresh embryos, 159 ongoing pregnancies were achieved (49%), of which 40 (25%) were twin pregnancies. In 175 patients (54%), an ongoing pregnancy was achieved, either after transfer of fresh embryos in the first, second or third treatment cycle, or after transfer of cryopreserved embryos.


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Table I. Results of 586 cycles in 326 patients who entered the standard eSET policy program at the university hospital Maastricht

 
The 326 patients eligible for eSET policy underwent 586 treatment cycles (1.8 cycles per patient). Total fertilization failure was found in 26 cycles (4%), while in 39 cycles (7%), only one embryo was obtained and transferred (compulsory SET, cSET). In 521 treatment cycles, more than one embryo was available. In 111 of these cycles (21%), at least one good-quality embryo was present and consequently only one embryo was transferred (eSET). In this group, 39 positive pregnancy tests (35%) were achieved, of which four ended in an early abortion (10%). In 410 cycles, two embryos were transferred (DET). In this group, 142 positive pregnancy tests (35%) were achieved, of which 23 ended in an early abortion (16%). The pregnancy rates after one, two or three cycles were respectively 33, 36 and 20% for eSET and 33, 23 and 24% for DET. The differences between the first, second and third eSET cycle and between the first, second and third DET cycles were not statistically significant. Neither are the differences between eSET and DET in each treatment cycle rank group.

In 112 cycles at least one surplus embryo of good morphology was available after transfer and subsequently frozen. After eSET significantly more often embryos could be cryopreserved as compared to after DET (53% and 13% of the treatment cycles, respectively). In Table I, pregnancy results are shown for 65 thaw cycles performed in patients who did not get pregnant in any of their transfers of fresh embryos. This resulted in 16 ongoing pregnancies (25%). In 12 patients, thawing has not yet been performed because of the patients' wishes. The cumulative ongoing pregnancy rates after fresh and frozen transfers were significantly different between eSET and cSET and between eSET and DET (13% cSET, 41% eSET and 30% DET). An additional 35 patients who became pregnant from fresh embryos, had embryos cryopreserved. In seven of these patients, embryos have been thawed, resulting in two pregnancies.

After the first cycle, 48 patients (30% of the patients not getting pregnant in the first cycle) dropped out because of medical reasons or patient wishes. After the second cycle the drop-out rate was 36% (27 patients). The Dutch health insurance system only reimburses three IVF/ICSI cycles. Therefore the drop-out rate after the third cycle increased to 75%.


    Discussion
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
After publication of the encouraging results from the first eSET studies (Gerris et al., 1999Go; Vilska et al., 1999Go) showing that acceptable pregnancy rates can be obtained when eSET is carried out in a subset of good prognosis patients, and after a brief pilot study in our own clinic, we felt confident in introducing eSET in the year 2000 as our standard clinical ET policy. eSET was offered to all patients younger than 38 years of age, who had at least one good quality embryo, irrespective whether it was their first, second or third treatment cycle.

The pregnancy rates obtained in the first two treatment cycles in our study are comparable to those reported by other studies in which eSET was performed in either only the first (Gerris et al., 1999Go; Vilska et al., 1999Go) or in the first two treatment cycles (Martikainen et al., 2001Go; De Neubourg and Gerris, 2003Go). It is concluded in several publications that eSET should be limited to the first two cycles (Martikainen et al., 2001Go; De Neubourg and Gerris, 2003Go; Land and Evers, 2003Go). However, our results show that pregnancy rates of eSET compared to DET are not significantly different up to and including the third treatment cycle, although it must be noted that the group of patients that received a third treatment cycle is relatively small (four pregnancies in 20 patients receiving only a single embryo). Yet, the pregnancy rates in the third treatment cycle in both the eSET and the DET groups are decreased compared with the previous treatment cycles. These decreasing pregnancy rates in successive IVF cycles were already reported by others (Tan et al., 1992Go; Templeton et al., 1996Go).

Our results confirm earlier publications showing that cryopreservation clearly improves the cumulative pregnancy rate after eSET (Martikainen et al., 2001Go; Tiitinen et al., 2001Go). In our study, in significantly more eSET cycles could embryos be cryopreserved compared to DET cycles (53 and 13%, respectively). After thawing, two embryos, if available, were transferred. The reason for this was that cryopreserved embryos have a lower potential for implantation and therefore were not considered to be ‘good quality’ embryos, which is a necessary condition for eSET (Levran et al., 1990Go; Edgar et al., 2000aGo,bGo). At present, almost all embryos from patients who did not became pregnant from fresh embryos have been thawed. A significantly higher cumulative pregnancy rate in the eSET group can be seen, caused by the additive effect of frozen embryo transfers.

In order to improve the results after eSET, effort is taken to improve the embryo selection criteria. In addition, to further reduce the risk of twins, the proportion of eSET transfers needs to be enlarged. Tiitinen et al. (2003)Go reported an increase over the years in the proportion of eSET in their IVF/ICSI programme from 10% to 56%, while maintaining comparable pregnancy rates. The same applies for Gerris et al., who reported an increase of eSET from 9.8% in 1998 to 23.6% in the year 2001 (Gerris et al., 2002Go). This increase was achieved by liberalization of the criteria for application of eSET. However, the twin pregnancy rate in both clinics (ranging from 7.5% to 13.5%) (Tiitinen et al., 2003Go; Gerris et al., 2004Go) remained above the twin pregnancy rate after a spontaneous pregnancy (ranging from 1% to 1.5%) (Ghai and Vidyasagar, 1988Go; Dhont, 2001Go). In the present study, 19% of the patients eligible for the eSET policy received one embryo. In the DET group however, a high twin pregnancy rate (23%) was found in spite of ‘suboptimal’ quality embryos. Apparently our embryo selection criteria for eSET are still too strict. Instead of gradually liberating the criteria for eSET, we decided to start a prospective randomized study in which consenting patients will be allocated by lot for the transfer of either one or two embryos, irrespective of the presence or absence of a top quality embryo. This study will provide more insight into whether we should perform SET in every patient, or how the selection of the embryos and the patients suitable for SET can be improved.

In conclusion, eSET in a selected group of patients (younger than 38 years, with at least one good quality embryo) can be performed not only in the first two treatment cycles, but also in the third cycle while maintaining a pregnancy rate comparable to DET. In this way the proportion of eSET in the total IVF programme can be increased, which will result in a further decline in the twin pregnancy rate.


    Acknowledgements
 Top
 Abstract
 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
This study was supported by a research grant (number 945-12-014) from the Dutch Organization for Health Research and Development (ZonMw) and the Dutch Health Insurance Board (CvZ) in a joint research program on health technology assessment of infertility.


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 Introduction
 Materials and methods
 Results
 Discussion
 Acknowledgements
 References
 
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Submitted on October 20, 2003; resubmitted on September 2, 2004; accepted on October 22, 2004.