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Reproduction, Fertility and Development http://dx.doi.org/10.1071/RD13412

Elective single versus double embryo transfer: live birth outcome and patient acceptance in a prospective randomised trial* Nicola´s Prados A,B, Rocı´o Quiroga A, Cinzia Caligara A, Myriam Ruiz A, Vı´ctor Blasco A, Antonio Pellicer C,D and Manuel Ferna´ndez-Sa´nchez A,B,E A

Instituto Valenciano de Infertilidad (IVI) Sevilla, Avenida de la Repu´blica Argentina 58, PC 41011, Sevilla, Spain. B Universidad Pablo de Olavide, Carretera de Utrera km. 1, PC 41013, Sevilla, Spain. C Instituto Valenciano de Infertilidad (IVI), Parc Cientı´fic Universitat de Vale`ncia, Calle Catedra´tico Agustı´n Escardino 9, PC 46980, Paterna, Valencia, Spain. D Hospital Universitario y Polite´cnico La Fe, Bulevar Sur s/n, PC 46026, Valencia, Spain. E Corresponding author. Email: [email protected]

Abstract. The purpose of this study was to determine which strategy of embryo transfer has a better trade-off in live birth delivery rate versus multiple pregnancy considering patient acceptance: elective single embryo transfer (eSET) or elective double embryo transfer (eDET). In all, 199 women ,38 years of age undergoing their first IVF treatment in a private centre were included in a prospective open-label randomised controlled trial. Patients were randomised into four groups: (1) eSET on Day 3; (2) eSET on Day 5; (3) eDET on Day 3; and (4) eDET on Day 5. Per patient, main analysis included acceptance of assigned group, as well as multiple and live birth delivery rates of the fresh cycle. Secondary analysis included the rates of subsequent cryotransfers and the theoretical cumulative success rate. Of 98 patients selected for eSET, 40% refused and preferred eDET. The live birth delivery rate after eDET was significantly higher after eDET versus eSET (65% vs 42%, respectively; odds ratio ¼ 1.6, 95% confidence interval 1.1–2.1). No multiple births were observed after eSET, compared with 35% after eDET. Although live birth delivery is higher with eDET, the increased risk of multiple births is avoided with eSET. Nearly half the patients refused eSET even after having been well informed about its benefits. Additional keywords: delivery rate, multiple birth rate, multiple pregnancy. Received 2 December 2013, accepted 24 January 2014, published online 19 February 2014

Introduction Multiple pregnancies, even of twins, are associated with a substantial risk of low birthweight, perinatal and infant mortality, preterm delivery, and disability among survivors (Martin and Park 1999; The ESRHE Capri Workshop Group 2000). Although there is a trend to transfer fewer embryos, especially in Europe, the average rate of multiple births is still considerable. The introduction of single embryo transfer (SET) halved the multiple pregnancy rates while maintaining a high ongoing pregnancy rate (Gerris et al. 2002; Kresowik et al. 2011). This strategy appears to be the most effective for a reduction in the number of multiple births. However, infertile couples do not always perceive multiple pregnancies as an unwelcome side effect; they would rather assume the risk in order to achieve more pregnancy options. Elective (e) SET is associated is *

perceived by clinicians and patients to be associated with a much lower chance of live birth delivery than the transfer of two or more embryos (Thurin et al. 2004; Newton et al. 2007). Different studies have reported similar rates of live births among women with at least two good-quality embryos who underwent double fresh embryo transfer (ET) and women who underwent single fresh ET, which was followed, in unsuccessful cases, by the transfer of a single frozen–thawed embryo (Thurin et al. 2004; Pandian et al. 2009; Mullin et al. 2010). It has also been shown that with respect to the incremental costeffectiveness ratio, maternal and paediatric complications are greater in the double ET group (Kjellberg et al. 2006). To date, the benefit of the generalised application of blastocyst-stage ET remains a contentious issue. Some investigators believe that the extended embryo culture is a clear drawback for

This study has been registered with ClinicalTrials.gov (ID NCT00814398).

Journal compilation Ó CSIRO 2014

www.publish.csiro.au/journals/rfd

B

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Excluded (n ⫽ 656)

Assessed for eligibility (n ⫽ 855)

Enrollment

Did not accept (n ⫽ 595)

Accepted to participate before start of stimulation (n ⫽ 260)

Not meeting inclusion criteria (n ⫽ 61) Randomised on day 3 of embryo culture (n ⫽ 199)

Allocated to 1d5 (n ⫽ 50)

Allocated to 2d3 (n ⫽ 49)

Allocated to 2d5 (n ⫽ 50)

Received allocated intervention (n ⫽ 29)

Received allocated intervention (n ⫽ 34)

Received allocated intervention (n ⫽ 47)

Received allocated intervention (n ⫽ 44)

Did not receive allocated intervention (n ⫽ 21):

Did not receive allocated intervention (n ⫽ 16):

Allocation

Allocated to 1d3 (n ⫽ 50)

- Preferred eDET

- Preferred eDET (n ⫽ 14)

Did not receive allocated intervention (n ⫽ 2): - Preferred eSET (n ⫽ 2)

- Transfer cancelled (n ⫽ 2): ~ risk of OHSS

Did not receive allocated intervention (n ⫽ 6): - Preferred eSET (n ⫽ 2) - Preferred cleavage eDET (n ⫽ 2)

Analysis

- Transfer cancelled (n ⫽ 2): ~ personal problems ~ inadequate endometrium

ITT analysed (n ⫽ 50)

ITT analysed (n ⫽ 50)

ITT analysed (n ⫽ 49)

ITT analysed (n ⫽ 50)

ESA analysed (n ⫽ 30)

ESA analysed (n ⫽ 37)

ESA analysed (n ⫽ 71)

ESA analysed (n ⫽ 57)

Fig. 1. CONSORT participant flow diagram. 1d3, cleavage stage elective single embryo transfer (eSET); 1d5, blastocyst stage eSET; 2d3, cleavage stage elective double embryo transfer (eDET); 2d5, blastocyst stage eDET; OHSS, ovarian hyperstimulation syndrome. No patient was lost to follow up. Intention-to-treat (ITT) and efficacy subset analysis (ESA) were performed.

embryo development because embryos are unable to reach the blastocyst stage properly, which increases the risk of cancelling the transfer (Tsirigotis 1998). The association of extended embryo culture with epigenetic defects (Jacob and Moley 2005) or monozygotic twinning (Behr et al. 2000; Milki et al. 2003; Papanikolaou et al. 2010) is not clear. In addition, many studies have shown significantly higher implantation, pregnancy and delivery rates after transfer of blastocysts compared with transfer of cleavage stage embryos (Papanikolaou et al. 2005; Blake et al. 2007; Zander-Fox et al. 2011). Ka¨lle´n et al. (2010) observed a small increase in the risk of preterm birth associated with blastocyst transfer. The main objective of a modern IVF program is to achieve a higher live birth delivery rate minimising any side effects, especially multiple births. We designed the present study with a global approach that takes into account the day of transfer, number of transferred embryos and patient acceptance to

determine the best combination to obtain the best results and to quantify patients’ reluctance for eSET in the daily practice of a private centre. Materials and methods The study was approved by the Instituto Universitario IVI Research Ethics Committee (Protocol no. 0901-E-056-MF-SV) and all patients provided written informed consent. Between December 2008 and September 2009, 199 women requesting infertility treatment were randomly assigned to one of four groups: (1) cleavage-stage eSET (Group 1d3); (2) blastocyststage eSET (Group 1d5); (3) cleavage-stage elective double ET (eDET; Group 2d3); or (4) blastocyst-stage eDET (Group 2d5; Fig. 1). The inclusion criteria were age ,38 years and first trial of IVF or intracytoplasmic sperm injection (ICSI). Patients who underwent preimplantation genetic diagnosis or oocyte donation treatments were excluded. Patients were also excluded

eSET vs eDET: live births and patient acceptance

from the study if the spermatozoa were not obtained from an ejaculate sample. There was a final cycle inclusion criterion, which was to have at least four good-quality embryos on Day 3 of embryo development. The study was designed as an equivalence randomised open-label trial (trial registration name ‘single vs double embryo transfer’; ClinicalTrials.gov: ID NCT00814398). The randomisation list was generated by one of the authors (NP) using Randomization.com [http://www. randomization.com, accessed 10 November 2008] with randomly permuted blocks of eight subjects per block. The list was kept in a locked drawer in the administration office, to which the clinical staff who enrolled the participants in the study had no access; group allocation was requested by telephone. Patients were informed on Day 3 of embryo culture of the group to which they had been assigned by their physician. Fifty patients were assigned to Group 1d3, 50 to Group 1d5, 49 to Group 2d3 and 50 to Group 2d5. Despite being a prospective randomised trial, the present study was designed as a open-label study. In case any patient changed her mind just before transfer, a switch to another group was considered acceptable to respect a patient’s autonomy. The number of embryos transferred on the following thawed embryo cycles was determined independently of the group the patient belonged to. Statistical analysis was performed according to both the intention-to-treat principle (ITT; original group assignment) and efficacy subset analysis (ESA; real treatment group; Lachin 2000). For descriptive statistics, data are presented as the mean  s.d. Three different comparisons were made: (1) the four groups were compared independently; (2) depending on the number of embryos transferred (eSET vs eDET; Groups 1d3 þ 1d5 vs Groups 2d3 þ 2d5); and (3) depending on embryo stage (cleavage vs blastocyst; Groups 1d3 þ 2d3 vs Groups 1d5 þ 2 d5). Each comparison generated a different P-value (P4, PN and PD, respectively). In all cases, P , 0.05 (two-sided) was considered significant. The x2-test was used for non-parametric analysis and the t-test for parametric analysis (two sided). We calculated a sample size of 412 patients taking into account a pregnancy rate of 60% for blastocyst DET and a 40% pregnancy rate for a SET with an a risk of 5% and power of 80%. The main outcome measures were patient acceptance and multiple and live birth rates of fresh ET. In addition to the standard parameters, we also defined a cumulative multiple live birth delivery rate as the number of patients with at least one multiple birth resulting from the cycle when fresh embryos were transferred and subsequent frozen–thawed ET cycles (cryotransfers). We followed up the birth data of patients by telephone up to 18 months after ET. The data on thawed ET was collected for this workup until December 2010. A long-protocol half-dose with gonadotrophin-releasing hormone (GnRH) agonists was used in all cases. A contraceptive pill containing 0.15 mg levonorgestrel plus 0.03 mg ethinyl oestradiol (Mycroginon; Bayer, Leverkusen, Germany) was administered the previous cycle. Leuprolide acetate (0.1 mL; Procrin; Abbott, Madrid, Spain) was injected daily from contraceptive pill number 15 up until the second day of menses. From then until the last day of stimulation, the dose was halved to 0.05 mL. Patients were given a single daily injection of 150 IU recombinant FSH (Gonal-F (Merck Serono,

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Geneva, Switzerland) or Puregon (MSD, Whitehouse Station, NJ, USA)) plus 75 IU of human menopausal gonadotropin (hMG; Menopur; Ferring Pharmaceuticals, Copenhagen, Denmark) or hMG Lepori (Angelini Farmace´utica, Barcelona, Spain)) if their body mass index (BMI) was between 18 and 25 kg m2 and the antral follicle count (AFC) was between 6 and 20. When the BMI was .25 kg m2, the doses administered were 225 IU FSH plus 75 IU hMG. When the AFC was .20, the doses administered 75 IU FSH plus 75 IU hMG. Ovulation was induced when at least two follicles reached an average diameter of 18 mm by injection of 0.25 mg human chorionic gonadotrophin (hCG; Ovitrelle, Merck Serono). Oocyte retrieval was performed 36 h after hCG injection and 200 mg micronised progesterone (Progeffik (Effik, Madrid, Spain) or Utrogestan (SEID, Barcelona, Spain)) was administered vaginally every 12 h from the day after oocyte retrieval. Progesterone was maintained until two weeks after a positive pregnancy test or suspended after a negative pregnancy test. Follicles were aspirated transvaginally under ultrasound guidance and corona–cumulus cell–oocyte complexes were isolated from the follicular fluid. All gametes and embryos were cultured with the appropriate sequential media (IVF, G1 or G2; Vitrolife, Go¨teborg, Sweden) according to the manufacturer’s instructions. Spermatozoa were prepared by density gradient separation (SpermGrad; Vitrolife). Standard insemination or ICSI, as necessary, was performed 4 h after retrieval. All embryos were cultured individually under oil (Ovoil; Vitrolife) in HeraCell 150 incubators (Thermo Fisher Scientific, Waltham, MA, USA) at 6% CO2 with atmospheric oxygen concentrations. Fertilisation was checked 18  1 h after insemination. Embryo quality on Days 2, 3 and 5 was assessed at 44  1 h, 68  1 h and 120  1 h (after insemination). We used the scoring system of the Spanish embryologist society (ASEBIR; Alpha Scientists in Reproductive Medicine and ESHRE Special Interest Group of Embryology 2011) to classify embryos based on their morphology into four groups: Grade A (top quality), Grade B (good quality), Grade C (average quality) and Grade D (poor quality). Grades A and B were considered good-quality embryos for the present study. Only good-quality supernumerary embryos were frozen on Day 3 or 5. A slow freezing method was used (Freeze/Thaw kit 1 and 2; Vitrolife) in a Planer controlled-rate freezer (Planer, Sunbury-on-Thames, UK). Transabdominal ultrasound-guided ET was performed with a 23-cm catheter (Wallace, Smiths, Kent, UK) on Day 3 or 5. For the cryotransfer, hormone therapy was performed with a 200-mg oestradiol transdermal patch (Estraderm matrix 100 mg; Novartis, Basel, Switzerland) every 3 days for 10–12 days, starting on the first or second day of the cycle, once the ovarian basal state was confirmed by transvaginal ultrasound. Depending on the developmental stage of the frozen embryo, 400 mg vaginal micronised progesterone (Progeffik (Effik) or Utrogestan (SEID)) was added every 12 h either 2 or 4 days before ET (in the case of cleavage and blastocyst stage embryos, respectively). No GnRH agonist was used during the preparation. One or two embryos were transferred the same day of thawing after confirming their survival (.50% live surviving cells). The number of embryos transferred depended on the patient’s decision and availability after thawing.

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This paper was written up according to the updated guidelines for reporting parallel group randomised trials (CONSORT statement; Moher et al. 2010; Schulz et al. 2010). Results Patient acceptance Before the start of stimulation, 260 patients of 855 potential subjects who met the initial inclusion criteria agreed to participate in the study. Sixty-one of these patients were excluded because they did not meet the cycle inclusion criteria of having more than four good-quality embryos. Thus, 199 patients were randomly assigned to one of the four groups (i.e. Groups 1d3,

Table 1.

Patients’ acceptance of the group to which they were allocated Data show the number of patients in each group, with percentages in parentheses. Group 1d3, cleavage stage elective single embryo transfer (eSET); Group 1d5, blastocyst stage eSET; Group 2d3, cleavage stage elective double embryo transfer (eDET); Group 2d5, blastocyst stage eDET Allocated

Group 1d3 (n ¼ 50) Group 1d5 (n ¼ 48) Group 2d3 (n ¼ 49) Group 2d5 (n ¼ 48)

Actual Group 1d3

Group 1d5

Group 2d3

Group 2d5

29 (58%) – 1 (2%) –

– 34 (71%) 1 (2%) 2 (4%)

21 (42%) 1 (2%) 47 (96%) 2 (4%)

– 13 (27%) – 44 (92%)

1d5, 2d3 and 2d5; Fig. 1). After allocation, 41 of 199 patients refused their assigned group and decided to change the day of transfer or the number of embryos transferred. Most changes (35/98) were from patients allocated to eSET who decided to have eDET. Only four of 97 patients preferred eSET to the assigned eDET (Table 1). The transfer was cancelled in four patients on Day 5 for different reasons (Fig. 1). The trial was stopped after the recruitment of 199 patients (rather than the 412 calculated sample size) because of a change in the embryo cryopreservation program at IVI Sevilla. Specifically, a vitrification protocol (Cobo et al. 2008) was introduced that replaced the slow freezing protocol. We believed that this could alter survival and pregnancy rates and thus add a confounding factor to the study. There were no significant differences in the characteristics of the patients assigned to each group, such as female and male age, BMI, duration of infertility, cause of infertility, duration and dose of stimulation, fertilisation procedure, number of oocytes retrieved and fertilised and embryo quality (see Table S1, available as Supplementary Material to this paper). Efficacy subset analysis To study the impact of each treatment, an ESA was undertaken for each actual treatment independent of the initial allocated group (Table 2). Compared with the SET group, the transfer of two embryos (cleavage and blastocyst stage embryos) resulted in a higher percentage of clinical pregnancy (75.0% vs 55.2%; odds ratio (OR) 1.36; 95% confidence interval (CI) 1.071–1.72)

Table 2. Efficacy subset analysis of cycle outcome Data show the number of patients in each group, with percentages in parentheses, or are given as mean values with 95% confidence intervals in parentheses, as appropriate. Group 1d3, cleavage stage elective single embryo transfer (eSET); Group 1d5, blastocyst stage eSET; Group 2d3, cleavage stage elective double embryo transfer (eDET); Group 2d5, blastocyst stage eDET; P4, P-value comparing the four study groups; PN, P-value comparing eSET (1d3 þ 1d5) with eDET (2d3 þ 2d5); PD, P-value comparing Day 3 (1d3 þ 2d3) with Day 5 (1d5 þ 2d5) Actual intervention Fresh cycle outcomes Pregnancy rateA Miscarriage rateB Live birth delivery rate Multiple birth rate Implantation rate Live born rate per embryo Frozen cycle outcomes per patient No. frozen embryos No. thawed cycles No. thawed embryos per cycle No. cryotransfers No. embryos transferred No. patients with frozen embryos Pregnancy rate Miscarriage rate Live birth delivery rate Multiple birth rate Implantation rate Live birth rate per embryo A

Group 1d3 (n ¼ 30)

Group 2d3 (n ¼ 71)

P4

PN

PD

Group 2d5 (n ¼ 57)

16 (53%) 5 (31%) 11 (37%) 0 (0%) 16 (53%) 11 (37%)

21 (57%) 4 (19%) 17 (46%) 0 (0%) 21 (57%) 17 (46%)

51 (72%) 3 (6%) 47 (67%) 20 (43%) 76 (54%) 67 (47%)

45 (79%) 9 (20%) 36 (63%) 11 (31%) 65 (57%) 47 (41%)

6.3 (4.4–7.3) 1.7 (1.2–2.2) 4.3 (2.9–5.7) 1.6 (1.1–2.1) 1.6 (1.4–1.8) 30 (100%) 10 (32%) 3 (30%) 7 (23%) 3 (43%) 13 (28%) 10 (22%)

2.1 (1.4–2.8) 1.2 (1.0–1.4) 2.6 (1.8–3.4) 1.1 (0.7–1.4) 1.5 (1.2–1.7) 26 (70%) 2 (11%) 0 (0%) 2 (11%) 0 (0%) 2 (8%) 2 (8%)

4.4 (4.8–5.9) 1.5 (1.3–1.8) 3.7 (3.0–4.4) 1.4 (1.2–1.7) 1.9 (1.7–2.0) 71 (100%) 16 (35%) 6 (43%) 10 (22%) 1 (13%) 21 (27%) 11 (14%)

1.5 (0.9–2.1) 1.3 (1.0–1.6) 2.0 (1.3–2.8) 1.2 (1.0–1.6) 1.4 (1.0–1.7) 26 (46%) 4 (29%) 1 (25%) 3 (21%) 0 (0%) 4 (24%) 3 (18%)

Clinical pregnancies. First and second trimester miscarriages.

B

Group 1d5 (n ¼ 37)

0.03 0.06 0.02 n/a 0.94 0.65

,0.01 0.09 ,0.01 n/a 0.98 0.69

0.56 0.22 0.88 0.11 0.53 0.59

,0.01 0.16 0.11 0.22 ,0.01 ,0.01 0.26 0.63 0.73 0.28 0.23 0.45

0.35 0.97 0.62 0.99 0.07 0.35 0.28 0.43 0.63 0.18 0.46 0.68

,0.01 0.03 ,0.01 0.05 ,0.01 ,0.01 0.09 0.33 0.41 0.20 0.09 0.45

eSET vs eDET: live births and patient acceptance

Reproduction, Fertility and Development

and live birth delivery rate (64.8% vs 41.8%; OR 1.55; 95% CI 1.14–2.12). No multiple births were reported in the SET groups (i.e. Groups 1d3 and 1d5). There were differences comparing all Day 3 transfers (Group 1d3 þ 2d3) with all Day 5 transfers (Group 1d5 þ 2d5). No significant differences were found between any group and any of their combinations in implantation rate or in live birth rate per transferred embryo. An ectopic pregnancy was reported in Group 2d3 and two stillbirths occurred in Group 2d5 (patients who underwent a double blastocyst stage embryo transfer). Curiously, in both cases the stillbirths occurred in twin pregnancies, with only one of the transferred embryos resulting in a healthy live born baby, with the other suffering placental thrombosis. These two live births were included in the clinical pregnancy and live birth delivery rates. No monozygotic twinning was found. There were significantly fewer available embryos for freezing on Day 5 (1.73) than on Day 3 (5.65), with a difference of 3.92 (95% CI [3.27–4.57], PD , 0.01). All patients who underwent a cleavage stage ET (Groups 1d3 and 2d3) froze supernumerary embryos, whereas 45% of the blastocyst transfer group did not freeze any embryo. Only one of the patients who did not achieve pregnancy in the fresh cycle decided not to perform a cryotransfer for personal reasons. The differences in the number of transferred embryos average per cryotransfer were significant. No significant differences were obtained for the remaining pregnancy outcomes analysed from cryotransfers. The cumulative live birth delivery rate did not differ among the four groups (P4 ¼ 0.08), although it was significantly higher for the eDET compared with eSET group (70.3 vs 53.7, respectively; OR 1.31; 95% CI 1.02–1.70). A higher percentage cumulative multiple live birth delivery rate was found in the eDET compared with eSET group (35.6 vs 8.3, respectively; OR 4.27; 95% CI 1.39–13.06), despite allowing the transfer of two embryos in the cryotransfers in the eSET group. No significant Table 3. Efficacy subset analysis of cumulative cycle outcome (fresh plus cryo-transfers) and theoretical cumulative rates of elective single embryo transfer (1 1 1) versus elective double embryo transfer (2 1 0) Data show the number of patients in each group, with percentages in parentheses. Group 1d3, cleavage stage elective single embryo transfer (eSET); Group 1d5, blastocyst stage eSET; Group 2d3, cleavage stage elective double embryo transfer (eDET); Group 2d5, blastocyst stage eDET; P4, P-value comparing the four study groups; PN, P-value comparing eSET (1d3 þ 1d5) with eDET (2d3 þ 2d5); PD, P-value comparing Day 3 (1d3 þ 2d3) with Day 5 (1d5 þ 2d5)

Group 1d3 (n ¼ 30) Group 1d5 (n ¼ 37) Group 2d3 (n ¼ 71) Group 2d5 (n ¼ 57) P4 PN PD eSET þ 1 cryo eSET (n ¼ 67) eDET (n ¼ 128) P-value

Cumulative live birth rate

Cumulative multiple live birth delivery rate

17 (57%) 19 (52%) 53 (75%) 37 (65%) 0.08 0.02 0.16 42 (63%) 83 (65%) 0.77

3 (18%) 0 (0%) 21 (40%) 11 (30%) ,0.01 ,0.01 0.07 0 (0%) 31 (24%) ,0.01

E

differences depending on day of transfer were found in these cumulative rates (Table 3). With these rates, we compared two theoretical subgroups, similarly to the work of Thurin et al. (2004): patients with a fresh eSET plus a following single embryo cryotransfer (1 þ 1) versus patients with fresh eDET (2 þ 0). The difference in cumulative live birth was not significant, but the cumulative multiple live birth delivery rate was significantly higher in the eDET groups (Table 3). Analysis per ITT To analyse the real impact on multiple pregnancy rates of proposing eSET to the patients of an actual IVF program, we calculated the pregnancy outcomes according to the ITT. The live birth delivery rate per fresh cycle was significantly higher in the eDET groups. The difference in the cumulative live birth delivery rate (fresh plus frozen cycles) according to the ITT between the eSET and eDET groups was also significant (73.2 vs 56.1, respectively; OR 1.3; 95% CI 1.055–1.613). Interestingly, although there was no difference in the cumulative multiple live birth delivery rate between the eSET and eDET groups, this difference was significantly higher on Day 3 versus Day 5 of culture (Tables S2–S4). Discussion We wanted to determine which ET strategy had a better trade-off in live birth delivery rate versus multiple pregnancy rate considering patient acceptance, namely eSET versus eDET of cleavage (Day 3 of embryo culture) or blastocyst (Day 5) stage embryos. Our results show that multiple live birth is avoided with eSET although lower pregnancy rates are achieved with this protocol. We found no difference in cycle outcome between transferring cleavage and blastocyst stage embryos. Obviously, SET with single cryotransfers results in a near null rate of multiple pregnancies. It must be noted that, even when SET is performed, multiple pregnancy is not completely avoided due to the risk of zygotic splitting (Blickstein et al. 2003). According to the day of embryo development, the live birth results after transfer of blastocyst stage embryos were similar to those after the transfer of cleavage stage embryos (Day 3). Unlike other groups (Papanikolaou et al. 2005; Elgindy et al. 2011), we did not find any significant advantage with the transfer of blastocyst stage embryos. In our case, it is possible to transfer single cleavage stage embryos with the same pregnancy results as seen following the transfer of blastocyst stage embryos. This strategy is easier to propose to the patient owing to the fact that most will have embryos to be frozen. We did not find differences in the cumulative live birth delivery rate with respect to the day of ET, but further thorough studies should be performed to confirm these findings. Most of the women included in the present study preferred DET, even though they were informed of the benefits of undergoing eSET. In the present study, 20.6% of patients did not accept the group to which they had been allocated and they were allowed to change. This is due to the fact that the trial design was open label, and the main concern was the perception that the success of the cycle would be lower. The ITT analysis showed limited impact of proposing eSET in the cumulative multiple live birth rate because many patients refused it.

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Elective SET on Day 5 was more accepted than on Day 3. Therefore, blastocyst transfer was significantly associated with a lower multiple birth rate. This is in accordance with previous published works that have explored attitudes of patients and clinicians towards a multiple birth and SET (Murray et al. 2004; Porter and Bhattacharya 2005; Newton et al. 2007). The occurrence of few previous cycles of IVF (Rai et al. 2011) and younger age (Gleicher et al. 1995; Grobman et al. 2001) have been associated with a greater acceptability of eSET. Our results show that the impact of eSET on lowering multiple pregnancy rates is very limited if it is just left in the patients’ hands. Stronger and more persuasive advice towards eSET or more restrictive policies may be required, as has been shown recently (Ryan et al. 2007; Hope and Rombauts 2010; van den Akker and Purewal 2011). This study was prematurely halted because of a methodological change, and so statistical power is limited. The theoretical cumulative live birth rates of eSET versus eDET were difficult to calculate because of the possibility of transferring one or two embryos in the cryotransfers. The study was designed this way because our experience with thawed blastocysts from the slow-freezing method was not completely satisfactory and, taking into consideration the principles of good clinical practice, as always the patient’s benefit and well being prevail over a theoretical better trial model. This is also one of the reasons why a new vitrification method was introduced in our setting, which made us decide to stop the trial. However, the results are consistent with the extra effort a clinical setting must take to successfully introduce an eSET program: good embryo quality and education of patient and clinicians. In general, clinicians tend to inform patients about pregnancy rates following a single attempt, initiated cycle or transfer. We should insist that patients are informed about accumulated pregnancy rates as well, which include the subsequent cryotransfers of the same cycle. This evidence should help patients to realise the benefits of a (1 þ 1) strategy versus a (2 þ 0) strategy. In addition, the live birth rate clearly should replace pregnancy rates. Regarding costs, these are increased when eSET is performed due to the necessity of a subsequent frozen–thawed cycle when pregnancy is not achieved at the first attempt. However, in the long-term, the cost may increase considerably per extra delivery when eDET is performed and the result is a multiple pregnancy. Kjellberg et al. (2006) performed a study in Scandinavian clinics and calculated an increase of h91 702 per extra delivery. In conclusion, multiple births are markedly diminished with eSET and the live birth delivery rate is the same as that of eDET if the frozen–thawed embryo is subsequently transferred. In our setting, Day 3 transfer can achieve the same good results as blastocyst transfer. The fact that nearly half the patients refuse eSET must be taken into account when establishing an eSET policy in an IVF program. eSET should be incorporated as a crucial strategy in assisted reproductive centres. Acknowledgements The authors thank all the patients for participating in the study. The authors also thank all the staff at IVI Sevilla (Seville, Spain) for their contribution to this work.

N. Prados et al.

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Elective single versus double embryo transfer: live birth outcome and patient acceptance in a prospective randomised trial.

The purpose of this study was to determine which strategy of embryo transfer has a better trade-off in live birth delivery rate versus multiple pregna...
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