Hum. Reprod. Advance Access published online on June 18, 2008
Human Reproduction, doi:10.1093/humrep/den156
Why don't we perform elective single embryo transfer? A qualitative study among IVF patients and professionals
1 Department of Obstetrics and Gynaecology, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands 2 Centre for Quality Care Research (WOK), Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands 3 Department of Obstetrics and Gynaecology, Gelderse Vallei Ziekenhuis, Willy Brandtlaan 10, 6716 RP Ede, The Netherlands
4 Correspondence address. Tel: +31 243668665; Fax: +31 24 3668597; E-mail: arnovp{at}gmail.com
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Abstract |
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BACKGROUND: Elective single embryo transfer (eSET) enables the prevention of multiple pregnancies after in vitro fertilization (IVF). However, in Europe, the multiple pregnancy rate after IVF remains stable at
23%, with SET occurring in 15% of all IVF cycles. In most European clinics, the decision for the number of embryos transferred is established through a form of shared decision-making between patients and professionals. The aim of this study is to explore factors influencing this decision, in particular factors preventing eSET use. METHODS: We performed explorative, semi-structured, in-depth interviews, based on two theoretical models. The interviews were performed among 19 Dutch IVF professionals and 20 patients who had just undergone IVF or were on the waiting list for IVF. The interviews were fully transcribed and two researchers independently scored the factors according to the models.
RESULTS: We identified a wide variety of factors, potentially influencing eSET use: 37 with the professionals and 26 among the patients. Examples of factors mentioned by both patients and professionals were: uncertainty about the eSET technique, couples' lack of knowledge about essential eSET aspects, absence of a reimbursement system which favours eSET, inadequate options to select couples suitable for eSET and inferior cryopreservation success rates.
CONCLUSIONS: This study demonstrates that both IVF professionals and patients identify numerous factors preventing eSET use in clinical practice. To estimate the impact of these factors identified, a quantitative confirmation and assessment of the magnitude of the effect is necessary.
Key words: in vitro fertilization/single embryo transfer/shared decision-making/multiple pregnancy
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Introduction |
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About one-third of all twin pregnancies are the result of in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) (Bergh et al., 1999
). Multiple pregnancies are associated with increased morbidity and mortality for both mothers and neonates compared with singleton pregnancies (Koudstaal et al., 2000; Helmerhorst et al., 2004; Pinborg, 2005). The complications associated with multiple pregnancies also account for elevated costs (Wolner-Hanssen and Rydhstroem, 1998; Lukassen et al., 2004). Elective single embryo transfer (eSET) enables us to prevent multiple pregnancies after IVF (Martikainen et al., 2001; Thurin et al., 2004; Lukassen et al., 2005; Pandian et al., 2005; Karlström and Bergh, 2007). However, eSET may result in a lower pregnancy rate per cycle, especially in an unselected population (van Montfoort et al., 2006). For couples with a less favourable chance for pregnancy, twins may be seen as a success (Gleicher and Barad, 2006; van Wely et al., 2006). It is therefore not surprising that the implementation of eSET in daily practice is not yet overwhelming. The multiple pregnancy rate after IVF in Europe remains stable at 23%, with an SET proportion of 15% of all IVF cycles (Andersen et al., 2007). In Europe, no national legislation or compulsory protocols for eSET exist, with the exception of Sweden and Belgium. This means that in most IVF clinics, the decision for the number of embryos transferred is established through a form of shared decision-making involving both IVF patients and professionals. If we would want to reduce the multiple pregnancy rate in the future, it is essential to identify why the decision to perform eSET is so difficult.
Previous studies concerning the decision-making process focused mainly on the couples' desire for twins or their lack of knowledge on twin-related complications (Grobman et al., 2001; Kalra et al., 2003; Pinborg et al., 2003; Child et al., 2004; Ryan et al., 2004; Blennborn et al., 2005; Newton et al., 2007). However, these studies used quantitative questionnaires and did not explore all aspects of the decision. Furthermore, it is essential to realize that professionals are also involved in taking the decision. To obtain true insight in this decision-making process it is necessary to perform an exploratory investigation at both the level of IVF patients and professionals.
Therefore, the aim of this study is to explore factors related to the decision for the number of embryos transferred, in particular factors preventing the use of eSET, at the level of both IVF patients and professionals.
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Materials and Methods |
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Study design
We performed explorative semi-structured interviews among Dutch IVF professionals and patients who had just undergone IVF or were on the waiting list for IVF. To develop an interview guide for both IVF professionals and patients, we used two theoretical models for identification of influencing factors (Cabana et al., 1999
; Peters et al., 2003). These models had four similar domains: characteristics of the innovation itself (e.g. cost-effectiveness), professionals' characteristics (e.g. attitude towards eSET), patients' characteristics (e.g. desire for twins) and characteristics of the context in which the innovation has to be applied (e.g. legislation).
Setting
In the Netherlands, IVF and ICSI are performed in 13 licensed hospitals: eight university hospitals, four general hospitals and one private clinic. Hospitals without a licence can initiate and monitor the stimulation phase and refer to a licensed hospital for both oocyte retrieval and embryo transfer (satellite clinics) or for embryo transfer alone (transport clinics). The costs of the first three fresh IVF or ICSI cycles are currently reimbursed by the national healthcare system, but only if no more than two embryos are transferred. The choice for either one or two embryos is taken by both the couple and the professional and is discussed at the hospital where the treatment is initiated.
Interviews among IVF professionals
We performed the interviews at seven locations: three university centres, two general hospitals, one transport clinic and one satellite clinic. At each location, three professionals at different levels of expertise and with different roles in IVF were asked to participate by the local head of department: a consultant gynaecologist, a fertility doctor and an IVF nurse. The centres were randomly selected by a senior gynaecologist of our department. In total, 20 professionals (one clinic did not have IVF nurses) participated. We interviewed the IVF professionals individually, thus allowing them to discuss the issue in the absence of their direct colleagues. The structure of all interviews was identical; we started with explorative questions for possible factors related to the choice for eSET or DET. Subsequently, we asked questions about all factors potentially related to eSET use, suggested by the models. The interviews took 30 min and all were audiotaped and transcribed.
Patient focus-group interviews
We performed two focus-group interviews among patients of our own university IVF centre who were non-pregnant, living within 30 km of our centre and had no recent physical or psychosocial problems. We invited 28 couples (56 patients) on the IVF waiting list and 22 couples (44 patients) who had already experienced one or more IVF cycles. A group setting was chosen because we expected that this might lead to the identification of more relevant factors related to the choice for eSET or DET. Furthermore, previous research reported that patients preferred a group setting and demonstrated no differences in results obtained from individual and group interviews (Fuscaldo et al., 2007). In our study, both interviews were moderated by an independent gynaecologist not involved in IVF. The structure of the focus-group interviews was similar to the interviews at the professional level: after asking explorative questions, we specifically asked the participants to reflect on potential factors influencing the choice for eSET or DET. The interviews took 90 min each and were also audiotaped and transcribed.
Analysis
All interviews were independently analysed by two sets of two researchers (A.M.P., L.J. and A.M.P., W.L.D.M.N.). The factors identified were scored according to the two models (Cabana et al., 1999; Peters et al., 2003) and placed in the appropriate domains. Factors identified, but not present in the models, were added. The two sets of scores were compared and any discrepancies were discussed until consensus was achieved.
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Results |
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Our participants described a variety of factors which potentially influenced the choice for eSET or DET, in all four domains of the theoretical models. We identified 37 factors at the level of IVF professionals (Table I) and 26 among the IVF patients (Table II). We summarized in more detail the factors that were mentioned by at least two-thirds of the professionals or patients. We present the factors according to the four domains of the theoretical models: characteristics of eSET (Domain 1), characteristics of the professionals (Domain 2), characteristics of the patients (Domain 3) and characteristics of the context (Domain 4). For greater clarity, we will describe all found factors as potential barriers for eSET. Quotes are taken verbatim from the transcripts of the interviews and are presented in separate sections with italic text.
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Factors related to the choice for eSET or DET according to IVF professionals (table I)
Because one professional was on sick leave, we interviewed 19 IVF professionals (response rate 95%). Characteristics of the professionals are shown in Supplementary Table S1 (available online). The following factors were suggested by two-thirds of the professionals.
Domain 1: Characteristics of eSET itself
Uncertainty about eSET technique
Every respondent mentioned the potential disadvantages of performing eSET: a lower pregnancy rate per cycle and the potential burden of necessary extra cycles to achieve pregnancy.
...and because of this decrease [in pregnancy rate] per cycle, you give people an extra burden. Because every treatment is an additional burden.
Lack of prognostic models for eSET
Additional knowledge on prognostic factors is felt to be necessary before eSET can be implemented. The professionals described their difficulty in discriminating between couples eligible for eSET and couples with a less favourable profile. They told us that they often choose the ‘safe option’; DET instead of eSET.
I think that eSET use will increase in the future, but I hope that we will know even better in which patient categories and to what extent we can apply this.
Inferior cryopreservation success rates
All professionals mentioned the necessity for improvement of cryopreservation success rates before the use of eSET can be increased. Without this improvement, they feel that they are wasting embryos and that the burden of an IVF cycle is too high to transfer only one embryo.
They [Finland] freeze more frequently than we do and they freeze one by one, which we don't ... That has to reach a higher level in this country before you can implement something like that[eSET].
Domain 2: Characteristics of the professionals
Negative attitude towards eSET
Not all professionals wanted to prevent twins in all cases; not everyone defined twins as a complication of IVF.
In the Netherlands, we focus too much on the pregnancy itself, and you should actually focus on when the family is complete. Most people don't want only one child. And if you take away their chance to form a complete family, by always transferring just one embryo ... I think that this is not always the right thing to do.
I think a twin is not always a drama, for some people it is a blessing!
Necessity for sufficient communicating skills
To make a thorough decision, couples must comprehend the complex facts concerning eSET. A good explanation and clear information about the chances for a (twin) pregnancy and the consequences of eSET and DET ensures that patients are better prepared to make a good decision. Our participants stated that clinicians who are unable to provide thorough and accurate information about eSET and DET will adversely influence eSET implementation. Moreover, whether information is provided objectively or through directive counselling may also impact on the use of eSET.
I think that at the moment you inform your patients in a better way and you can bring it all into perspective, it would be favourable for the patient, because they would feel more secure, as in: ‘it will be alright, I'm in good hands’.
I think, the more directive you counsel, the easier your patients will be compliant.
Lack of negative experience with twins
If a professional has experienced a negative incident with twin pregnancies, this could strongly influence the use of eSET. Our participants suggested that professionals working only with subfertile couples, and not with obstetrical complications, would be less inclined to regard twins as a complication instead of a success. Furthermore, personal experiences with multiple pregnancies, either positive or negative could also have impact.
Look what happens [in the hospital] at night time! One immature twin after the other, always a mess with twins on the ward.
I myself am the mother of a triplet. Patients don't know that about me, and that is not up for discussion, but that also determines what you say of course.
Professional level
The participants suggested that the level of profession may also influence the attitude towards eSET. A gynaecologist has more obstetric experience than an IVF doctor or nurse and might therefore be more aware of the disadvantages of twin pregnancies. Consequently, if an IVF cycle is mostly monitored by IVF doctors and nurses, as is often the case in the Netherlands, this could impede the eSET use.
Maybe a gynaecologist is more aware of the misery you can have with a twin, and is also more confronted with the large amount of twin pregnancies, compared to the IVF doctors and nurses.
Domain 3: Characteristics of the patient
Lack of knowledge of patients about essential eSET aspects (as perceived by the professionals)
Patients' lack of knowledge about essential aspects of eSET was often mentioned as a factor influencing eSET use. According to the professionals, patients have insufficient knowledge about twin-related risks and pregnancy rates after eSET to make an objective decision. They may have problems in interpreting information provided by professionals. A better understanding of essential information could facilitate the implementation of eSET.
They don't always have the knowledge to take the right decision.
...because patients just cannot make an objective decision about this. Instinctively, two gives a higher chance than this in fact does. They just think: two is possible, so they want two... They don't know the risks related to that and they cannot judge this for themselves I think.
Domain 4: Characteristics of the context
Impeding reimbursement system
Many respondents were dissatisfied with the organization of the Dutch reimbursement system and mentioned it as a barrier for the implementation of eSET. The professionals felt that adjustment of the system, towards the reimbursement of more IVF cycles, will help to implement eSET. Many participants mentioned the Belgian system, where the costs of six cycles are reimbursed, and the number of embryos transferred varies with age and number of cycles, as an ideal way to implement eSET.
Health Insurance companies reimburse differently. The clinician will act according to this.
eSET is a good method for the prevention of a twin pregnancy, but it shouldn't be applied on a large scale until the moment that more cycles are reimbursed.
Variation between hospitals
Professionals often mentioned variation between clinics in opinions about eSET and twins in the Netherlands and felt that the lack of consensus might hinder the implementation of eSET.
I talk to a lot of colleagues around the country, and I know that some clinicians care a lot more about the prevention of twins than others.
Absence of protocol
A protocol that defines when to perform eSET could improve its implementation. If the decision is made according to clinical parameters only, clearly described in a protocol, this rules out other options for the couple or professional. Furthermore, even if such a protocol merely suggests certain options, it will enhance eSET implementation.
The protocol is something to hold on to.
Look, it is easier to hide behind something [protocol].
Factors related to the choice for eSET or DET according to patients (table II)
For the first focus-group eight couples (n = 14, two women participated without their partner) from the waiting list for IVF consented to participate, giving a response rate of 29%. The second focus-group session consisted of three couples (n = 6) with IVF experience (response rate 14%). Characteristics of the participating patients are outlined in Supplementary Table S2 (available online). The factors discussed by at least two-thirds of the patients are located in three of the four domains of the theoretical models: characteristics of eSET, the patients themselves and the context of the IVF treatment.
Domain 1: Characteristics of eSET itself
Uncertainty about eSET technique
For many participants, it was clear that the use of eSET also had disadvantages. The decision between eSET and DET was described as a difficult balance between optimal chance of pregnancy and the lowest possible risk of complications.
I think having two babies at once would be an advantage, however with twins you have the medical risks involved.
Domain 3: Characteristics of the patients themselves
Lack of knowledge of patients about essential eSET aspects
Patients felt themselves inadequate to make a decision about the number of embryos transferred. Even patients with IVF experience were not satisfied with their level of knowledge. Lack of, or inadequate, information inhibits the use of eSET.
We don't think that we have received enough general information to make the decision on the number of embryos transferred.
We did not receive any information on twin risks, no details, nothing. At our first outpatient visit this was not discussed.
Liberty of choice
Our participants mentioned their need to be part of the decision-making process for the number of embryos transferred. It is difficult to say if this freedom of choice actually impedes or facilitates the use of eSET.
I will make that decision myself. This should be done by the patient, not the doctor.
The couple eventually makes the decision for eSET or DET, but of course after consulting the professional.
Focus only on chance for pregnancy
For subfertile couples, becoming pregnant is the main priority with the chance of twins seen as of secondary importance.
When I compare it with the lottery two tickets gives more chance for success compared to only one.
It is important to feel that you have tried everything to become pregnant.
Anxiety for experiences of the first treatment cycle
For patients it is very important how they will cope with the experience of the first IVF cycle. If this experience turns out to be negative, they might decide to perform DET instead of eSET, since an eSET regime might require more cycles.
You can read all about it, but you will not know how you will react on the hormones, how you will cope with the daily injections and how you will experience the time period before and after the oocyte aspiration.
If the first attempt is very tough, I do not want to endure this again. In that case I really want to have two embryos transferred.
Domain 4: Characteristics of the context
Impeding reimbursement system
Reimbursement of the costs of IVF has impact on the choice for the number of embryos transferred only when the patient experiences direct negative effects of the rules. Patients with sufficient insurance policy have no problem with higher medical costs. However, lack of reimbursement may hinder eSET use, because patients will then aim for the maximal chance for pregnancy.
I won't think about medical costs. I have a good insurance policy. They will pay for my treatment.
Aren't insurances supposed to take care of this? There is a double standard: they do not reimburse our IVF, but they do pay for the multiple pregnancies after an IVF treatment with many embryos abroad.
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Discussion |
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This study describes the numerous factors that influence Dutch IVF professionals and patients regarding the use of eSET. We identified three important potential barriers for eSET that both patients and professionals find important. First, there is uncertainty about the advantages of performing eSET. It prevents twin pregnancies (Pandian et al., 2005
), but may also mean a lower success rate per cycle (Lukassen et al., 2005; van Montfoort et al., 2006). Therefore, the choice for eSET is not easily taken. Second, couples undergoing IVF often have insufficient knowledge to make an informed decision for eSET or DET. They may not acknowledge the twin-related risks or decide for DET simply because they think this could double their chances of pregnancy. Previous research demonstrated that, if patients understood the complications associated with twins, this might result in a change of attitude in favour of eSET (Newton et al., 2007; Ryan et al., 2007). Moreover, it is vital that patients realize that if they accept possible extra cycles, the pregnancy rates for eSET and DET are similar (Thurin et al., 2004; Lukassen et al., 2005). Third, eSET implementation requires a cost reimbursement system that favours eSET and not DET. If no reimbursement system exists or when the cost of only a fixed number of cycles are reimbursed, this may act as a financial incentive for DET (Jain et al., 2002).
During the interviews, the professionals stated their feelings that eSET is not ready for full implementation. They suggest that some clinical aspects of eSET need to be improved before it can be commonly used in clinical practice. An improved prognostic model to enable professionals to select appropriate couples for eSET would be helpful and may minimize the lower success rate reported with eSET in an unselected population (van Montfoort et al., 2006). New prediction models have recently been published (Hunault et al., 2007; van der Steeg et al., 2007), but none of them are as yet translated to daily practice. The same situation applies to embryo selection. Better identification of the most suitable embryos will allow professionals to identify the couples with good prospects for pregnancy who are therefore suitable for eSET. New embryo selection methods have been suggested (Gerris et al., 1999; Holte et al., 2007), but their value remains uncertain for other settings, because they have not been broadly adapted. Another important factor is cryopreservation. The Dutch professionals are not content with the local success rates with frozen-thawed embryos and without exception mention the much better results in other European countries (Thurin et al., 2004; Veleva et al., 2006). Therefore, it will be difficult to implement eSET in the Netherlands without improvements in couple and embryo selection and without improvement of cryopreservation succes rates.
Noteworthy is that not all professionals felt the need to prevent twin pregnancies. This is in agreement with previous publications (Porter and Bhattacharya, 2005; Gleicher and Barad, 2006; van Wely et al., 2006; Iaconelli Junior et al., 2007), although a recent study has presented a different view (Bergh et al., 2007). Since the professional has an important say in the decision-making process, a doctor who does not feel the need for twin prevention will probably be reserved in advising eSET. This study cannot explain why some professionals do not regard twins as a complication of IVF. However, it is important to consider that for some couples with a less favourable prognosis, for instance where the female has an elevated level of follicle-stimulating hormone, a multiple pregnancy should probably be regarded as a success instead of a complication. More research on this topic is necessary.
Our exploration among couples revealed that most couples did not really desire twins but focused on their chance to become pregnant. Although most patients agreed that a healthy singleton is the goal of IVF, they would accept a twin pregnancy if that was necessary to become pregnant. This finding may offer an opportunity for the design of an intervention to increase the use of eSET, especially if couples are informed that eSET combined with cryopreserved embryos equals the success of DET (Thurin et al., 2004). Our finding is in contrast with other studies reporting a high desire for twins (Grobman et al., 2001; Kalra et al., 2003; Pinborg et al., 2003; Child et al., 2004; Ryan et al., 2004). This discrepancy may be explained by our qualitative approach. During our interviews, the participants were able to explain that they only desire a twin in specific situations. Possibly the participants of the previous quantitative questionnaire studies lacked this opportunity. Patients also reported that they want to decide for the number of embryos transferred after experiencing the hormonal ovarian stimulation and oocyte aspiration. It is difficult to predict what the effect on eSET use would be, if this was allowed.
This study was designed to explore influencing factors regarding the choice for the number of embryos transferred with a qualitative approach. It enabled us to explore all potential factors related to the choice for eSET or DET, which is very difficult if not impossible with a quantitative approach (Peddie and Teijlingen, 2005). Our approach might enable clinicians in the field of IVF to select the relevant factors applicable to their own setting and use them to improve the use of eSET.
There are obviously some limitations to our study. First, interpretation of interviews is vulnerable to bias. For this reason, we decided to analyse all transcriptions on the basis of two theoretical models and with two independent researchers who took no part in the IVF procedure. Second, it is impossible to estimate the impact of each factor upon the choice between eSET and DET. This would require quantitative confirmation and assessment of the magnitude for the factors. Such confirmation would also enable the effects of different cultural, religious or locational settings to be analysed. Third, couples had a low participation rate which is difficult to explain. However, this is unlikely to have adversely affected the factors identified. A last limitation of our study is the Dutch setting. Other countries operate in a different context (e.g. reimbursement system) and Dutch IVF professionals may have a different opinion about eSET use, compared with others. However, many of the factors identified are not specifically related to the Dutch setting, so that the results of this study may be relevant to other countries. Therefore, despite its limitations, we believe our work provides necessary insight into the complex process behind the decision for eSET or DET.
In conclusion, our study identified several relevant factors influencing the decision-making process concerning the number of embryos transferred, at both the level of the IVF patients and professionals. However, to estimate the impact of the identified factors, a quantitative confirmation and assessment of the magnitude of the effect is necessary.
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Supplementary data |
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Supplementary data are available at http://humrep.oxfordjournals.org/
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Funding |
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The Netherlands Organisation for Health Research and Development (ZonMw) funded this project (Grant no. 945-16-105).
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Acknowledgements |
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The authors thank Dr Lenno Dukel for moderating the two focus group sessions and the patients and IVF professionals who generously participated with our interviews.
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References |
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Andersen AN, Goossens V, Gianaroli L, Felberbaum R, de Mouzon J, Nygren KG. Assisted reproductive technology in Europe, 2003. Results generated from European registers by ESHRE. Hum Reprod (2007) 22:1513–1525.
Bergh T, Ericson A, Hillensjo T, Nygren KG, Wennerholm UB. Deliveries and children born after in-vitro fertilisation in Sweden 1982-95: a retrospective cohort study. Lancet (1999) 354:1579–1585.[CrossRef][Web of Science][Medline]
Bergh C, Söderström-Anttila V, Selbing A, Aittomaki K, Hazekamp J, Loft A, Nygren KG, Wennerholm UB. Attitudes towards and management of single embryo transfer among Nordic IVF doctors. Acta Obstetricia et Gynecologica Scandinavica (2007) 86:1222–1230.[CrossRef][Web of Science]
Blennborn M, Nilsson S, Hillervik C, Hellberg D. The couple's decision-making in IVF: one or two embryos at transfer? Hum Reprod (2005) 20:1292–1297.
Cabana MD, Rand CS, Powe NR, Wu AW, Wilson MH, Abboud PA, Rubin HR. Why don't physicians follow clinical practice guidelines? A framework for improvement. JAMA (1999) 282:1458–1465.
Child TJ, Henderson AM, Tan SL. The desire for multiple pregnancy in male and female infertility patients. Hum Reprod (2004) 19:558–561.
Fuscaldo G, Russell S, Gillam L. How to facilitate decisions about surplus embryos: patients' views. Hum Reprod (2007) 22:3129–3138.
Gerris J, De Neubourg D, Mangelschots K, Van Royen E, Van de Meersche M, Valkenburg M. Prevention of twin pregnancy after in-vitro fertilization or intracytoplasmic sperm injection based on strict embryo criteria: a prospective randomized clinical trial. Hum Reprod (1999) 14:2581–2587.
Gleicher N, Barad D. The relative myth of elective single embryo transfer. Hum Reprod (2006) 21:1337–1344.
Grobman WA, Milad MP, Stout J, Klock SC. Patient perceptions of multiple gestations: an assessment of knowledge and risk aversion. Am J Obstet Gynecol (2001) 185:920–924.[CrossRef][Web of Science][Medline]
Helmerhorst FM, Perquin DA, Donker D, Keirse MJ. Perinatal outcome of singletons and twins after assisted conception: a systematic review of controlled studies. BMJ (2004) 328:261–265.
Holte J, Berglund L, Milton K, Garello C, Gennarelli G, Revelli A, Bergh T. Construction of an evidence-based integrated morphology cleavage embryo score for implantation potential of embryos scored and transferred on day 2 after oocyte retrieval. Hum Reprod (2007) 22:548–557.
Hunault CC, te Velde ER, Weima SM, Macklon NS, Eijkemans MJ, Klinkert ER, Habbema JD. A case study of the applicability of a prediction model for the selection of patients undergoing in vitro fertilization for single embryo transfer in another center. Fertil Steril (2007) 87:1314–1321.[CrossRef][Web of Science][Medline]
Iaconelli Junior A, Bonetti TCS, Melamed RMM, Braga DPAF, Madaschi C, Borges E Jr. The ART professional attitudes in their own IVF cycles and infertility concerns. Hum Reprod (2007) 22(Suppl. 1):i222–i223. 2007 Abstracts book.
Jain T, Harlow BL, Hornstein MD. Insurance coverage and outcomes of in vitro fertilization. N Engl J Med (2002) 347:661–666.
Kalra SK, Milad MP, Klock SC, Grobman WA. Infertility patients and their partners: differences in the desire for twin gestations. Obstet Gynecol (2003) 102:152–155.[CrossRef][Web of Science][Medline]
Karlström PO, Bergh C. Reducing the number of embryos transferred in Sweden-impact on delivery and multiple birth rates. Hum Reprod (2007) 22:2202–2207.
Koudstaal J, Bruinse HW, Helmerhorst FM, Vermeiden JP, Willemsen WN, Visser GH. Obstetric outcome of twin pregnancies after in-vitro fertilization: a matched control study in four Dutch university hospitals. Hum Reprod (2000) 15:935–940.
Lukassen HG, Schonbeck Y, Adang EM, Braat DD, Zielhuis GA, Kremer JA. Cost analysis of singleton versus twin pregnancies after in vitro fertilization. Fertil Steril (2004) 81:1240–1246.[CrossRef][Web of Science][Medline]
Lukassen HG, Braat DD, Wetzels AM, Zielhuis GA, Adang EM, Scheenjes E, Kremer JA. Two cycles with single embryo transfer versus one cycle with double embryo transfer: a randomized controlled trial. Hum Reprod (2005) 20:702–708.
Martikainen H, Tiitinen A, Tomas C, Tapanainen J, Orava M, Tuomivaara L, Vilska S, Hyden-Granskog C, Hovatta O. One versus two embryo transfer after IVF and ICSI: a randomized study. Hum Reprod (2001) 16:1900–1903.
Newton CR, McBride J, Feyles V, Tekpetey F, Power S. Factors affecting patients' attitudes toward single- and multiple-embryo transfer. Fertil Steril (2007) 87:269–278.[CrossRef][Web of Science][Medline]
Pandian Z, Templeton A, Serour G, Bhattacharya S. Number of embryos for transfer after IVF and ICSI: a Cochrane review. Hum Reprod (2005) 20:2681–2687.
Peddie VL, Teijlingen EV. Qualitative research in fertility and reproduction: does it have any value? Hum Fertil (Camb) (2005) 8:263–267.[Medline]
Peters MAJ, Harmsen M, Laurant MGH, Wensing M. Ruimte voor verandering? (in Dutch) (2003) Nijmegen: Centre for Quality Care Research (WOK) Radboud University Medical Centre.
Pinborg A. IVF/ICSI twin pregnancies: risks and prevention. Hum Reprod Update (2005) 11:575–593.
Pinborg A, Loft A, Schmidt L, Andersen AN. Attitudes of IVF/ICSI-twin mothers towards twins and single embryo transfer. Hum Reprod (2003) 18:621–627.
Porter M, Bhattacharya S. Investigation of staff and patients' opinions of a proposed trial of elective single embryo transfer. Hum Reprod (2005) 20:2523–2530.
Ryan GL, Zhang SH, Dokras A, Syrop CH, Van Voorhis BJ. The desire of infertile patients for multiple births. Fertil Steril (2004) 81:500–504.[CrossRef][Web of Science][Medline]
Ryan GL, Sparks AE, Sipe CS, Syrop CH, Dokras A, Van Voorhis BJ. A mandatory single blastocyst transfer policy with educational campaign in a United States IVF program reduces multiple gestation rates without sacrificing pregnancy rates. Fertil Steril (2007) 88:354–360.[CrossRef][Web of Science][Medline]
Thurin A, Hausken J, Hillensjo T, Jablonowska B, Pinborg A, Strandell A, Bergh C. Elective single-embryo transfer versus double-embryo transfer in in vitro fertilization. N Engl J Med (2004) 351:2392–2402.
van der Steeg JW, Steures P, Eijkemans MJ, Habbema JD, Hompes PG, Broekmans FJ, van Dessel HJ, Bossuyt PM, van der Veen F, Mol BW. Pregnancy is predictable: a large-scale prospective external validation of the prediction of spontaneous pregnancy in subfertile couples. Hum Reprod (2007) 22:536–542.
van Montfoort AP, Fiddelers AA, Janssen JM, Derhaag JG, Dirksen CD, Dunselman GA, Land JA, Geraedts JP, Evers JL, Dumoulin JC. In unselected patients, elective single embryo transfer prevents all multiples, but results in significantly lower pregnancy rates compared with double embryo transfer: a randomized controlled trial. Hum Reprod (2006) 21:338–343.
van Wely M, Twisk M, Mol BW, van de Veen F. Is twin pregnancy necessarily an adverse outcome of assisted reproductive technologies? Hum Reprod (2006) 21:2736–2738.
Veleva Z, Vilska S, Hyden-Granskog C, Tiitinen A, Tapanainen JS, Martikainen H. Elective single embryo transfer in women aged 36–39 years. Hum Reprod (2006) 21:2098–2102.
Wolner-Hanssen P, Rydhstroem H. Cost-effectiveness analysis of in-vitro fertilization: estimated costs per successful pregnancy after transfer of one or two embryos. Hum Reprod (1998) 13:88–94.
Submitted on January 17, 2008; resubmitted on March 20, 2008; accepted on April 8, 2008.
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