Guidance on the limits to the number of embryos to transfer: a committee opinion.

On the basis of American Society for Reproductive Medicine and Society for Assisted Reproductive Technology data, the American Society for Reproductive Medicine's guidelines for the limits on the number of embryos to be transferred during in vitro fertilization cycles have been further refined in continuing efforts to promote singleton gestation and reduce the number of multiple pregnancies. This version replaces the document titled "Criteria for number of embryos to transfer: a committee opinion" that was published most recently in August of 2017 (Fertil Steril 2017;107:901-3).

Avoiding multiple pregnancies in assisted reproductive technologies: transferring one embryo at a time should be the norm.

Multiple pregnancies following fertility treatments typically occur in 30% of women in whom more than one embryo is transferred. Worldwide, fewer than 20 countries have fully funded public fertility treatments, and many women utilizing assisted reproduction technologies are transferring more than one embryo for financial reasons because they consider it will be cheaper to have two embryos transferred in the one procedure. Yet, there is a large body of evidence for the poorer health, economic, and social outcomes for mother and baby from multiple pregnancies. Some countries have reduced the multiple pregnancy rate to less than 5% by linking the funding of ART to policies where the large majority of transfers are single embryos.

Does the transfer of a poor quality embryo with a good quality embryo benefit poor prognosis patients?

BACKGROUND: While single embryo transfer (SET) is widely advocated, double embryo transfer (DET) remains preferable in clinical practice to improve IVF success rate, especially in poor prognosis patients with only poor quality embryos (PQEs) available in addition to one or no good quality embryos (GQEs). Furthermore, previous studies suggest PQE might adversely affect the implantation of a GQE when transferred together. This study aims to evaluate the effect of transferring an additional PQE with a GQE on the outcomes in poor prognosis patients. METHODS: A total of 5037 frozen-thawed blastocyst transfer (FBT) cycles between January 2012 and May 2019 were included. Propensity score matching was applied to control for potential confounders, and we used generalized estimating equations (GEE) models to identify the association between the effect of an additional PQE and the outcomes. RESULTS: Overall, transferring a PQE with GQE (Group GP) achieved significantly higher pregnancy rate (PR), live birth rate (LBR) and multiple pregnancy rate (MPR) than GQE only (group G). The addition of a PQE increased LBR in patients aged 35 and over and in patients who received over 3 cycles of embryo transfer (ET) (48.1% vs 27.2%, OR:2.56, 95% CI: 1.3-5.03 and 46.6% vs 35.4%, OR:1.6, 95% CI: 1.09-2.35), but not in women under 35 and in women who received less than 3 cycles of ET (48.7% vs 43.9%, OR:1.22, 95% CI: 0.93-1.59 and 48.3% vs 41.4%, OR:1.33, 95% CI: 0.96-1.85). Group GP resulted in significantly higher MPR than group G irrespective of age and the number of previous IVF cycles. CONCLUSIONS: An additional PQE does not negatively affect the implantation potential of the co-transferred GQE. Nevertheless, the addition of a PQE contributes to both live birth and multiple birth in poor prognosis patients. Physicians should still balance the benefits and risks of DET.

Fine-tuning blastocyst selection based on morphology: a multicentre analysis of 2461 single blastocyst transfers.

RESEARCH QUESTION: Which blastocyst morphology parameter is associated with live birth after controlling for female age and endometrial receptivity? DESIGN: Retrospective study including fresh single blastocyst transfers (n = 2461) where the value of serum progesterone on day of human chorionic gonadotrophin trigger (PdHCG) was available. Generalized estimating equation regression models evaluated the independent effects of developmental stage (DevSt), inner cell mass (ICM) and trophectoderm grade on live birth rates while controlling for the confounding effects of female age and PdHCG. RESULTS: DevSt was strongly associated with the probability of live birth (P < 0.0001) independently of female age (odds ratio [OR] 0.89, 95% confidence interval [CI] 0.87-0.91) and PdHCG (OR 0.80, 95% CI 0.74-0.87). For full blastocysts, expanded blastocysts and hatching blastocysts, addition of ICM and trophectoderm grading in the multivariable analysis suggested that besides female age (OR 0.92, 95% CI 0.90-0.94) and PdHCG (OR 0.80, 95% CI 0.73-0.87), only DevSt (P = 0.001) and trophectoderm quality (P = 0.004) were independent predictors of live birth, while the predictive capacity of ICM was no longer significant. The mean probability of live birth was highest for AA blastocysts (35.0%), followed by BA blastocysts (31.2%) and AB blastocysts (27.7%). CONCLUSION: This large study analyses for the first time the independent role of blastocyst morphology in predicting live birth while controlling for female age and PdHCG. Its findings suggest that DevSt and then trophectoderm grade are stronger predictors of live birth over ICM grade when selecting a single blastocyst for transfer.

Embryo morphokinetics is potentially associated with clinical outcomes of single-embryo transfers in preimplantation genetic testing for aneuploidy cycles.

RESEARCH QUESTION: Are the morphokinetics of euploid blastocysts evaluated by a generally applicable algorithm associated with the clinical outcomes of single-embryo transfer (SET)? DESIGN: Time-lapse microscopy was used to compare morphokinetic variables between expanded blastocysts derived from preimplantation genetic testing for aneuploidy cycles using high-resolution next-generation sequencing (hr-NGS). The clinical efficacy of the morphokinetic algorithm KIDScore D5 was evaluated after euploid SET. RESULTS: Compared with euploid blastocysts, low-level mosaic blastocysts presented comparable morphokinetic and morphological features. However, high-level mosaic blastocysts exhibited significant delays in t5 (median 51.9 h post insemination (hpi), P = 0.034) (where t is the time for the embryo to reach the specific stage in hours after ICSI or conventional IVF) and t8 (median 58.6 hpi, P = 0.032) accompanied by a prolonged time period for the third cell cycle (median 14.7 h, P = 0.012). A significantly higher incidence (P = 0.011) of multinucleation indicated a susceptibility of high-level mosaic blastocysts to mitotic errors. Only a delay in the time for the embryo to reach the full blastocyst stage (median 106.0 hpi, P = 0.039) was revealed in aneuploid blastocysts, reflecting the reduced formation of good-quality blastocysts (42.6% versus 65.7%, P < 0.001). Euploid blastocysts with specific morphokinetic characteristics were graded using the KIDScore D5 algorithm. Grade C embryos achieved significantly lower rates of clinical pregnancy, implantation and ongoing pregnancy (25%, 25% and 10%, respectively) compared with the grade A (76.2%, 79.4% and 68.3%, respectively) or grade B (62.5%, 66.7% and 62.5%, respectively) embryos (P = 0.0171 to <0.0001). CONCLUSIONS: Although morphokinetic features appear dissimilar in embryos with different diploid-aneuploid mosaic levels, predicting chromosomal abnormalities using morphokinetics alone is still insufficient. When combined with hr-NGS, use of the generally applicable KIDScore D5 algorithm has the potential to discriminate euploid blastocysts with different developmental competence.

Single embryo transfer: Why and how to identify the embryo with the best developmental potential.

Multiple pregnancies with higher risk of preterm birth and the associated higher morbidity have been a major obstacle from the early days of in vitro fertilization. A good strategy to avoid multiple pregnancies is elective single embryo transfer and cryopreservation of spare embryos. Important factors in adopting this strategy are good counselling of the patients and the selection of embryos with high implantation potential. Technical advances in embryo selection have been described during recent years, time lapse monitoring and genetic assessment of the embryos being the most important achievements. With these studies we have gained new information on early embryos. However, at present, there is insufficient evidence to recommend the routine use of these new techniques. The ultimate goal of infertility treatment is a healthy baby.

Single embryo transfer for all.

There is a global recognition of the need to reduce multiple pregnancies following assisted reproductive technology. Complications of multiple pregnancies can be simply avoided by replacing one embryo at a time. Most policies to reduce the number of double or higher order embryo transfers involve predicting which patients are at most risk by using a multiple birth minimisation strategy. These frequently consider factors such as patient age, previous treatments and embryo quality. However, with improvements in methods of embryo culture, embryo selection and cryopreservation, this chapter will question whether, at present, it is time to move to single embryo transfer (SET) for all.

Guidance on the limits to the number of embryos to transfer: a committee opinion.

Based on American Society for Reproductive Medicine (ASRM) and Society for Assisted Reproductive Technology data available through 2014, ASRM's guidelines for the limits on the number of embryos to be transferred in in vitro fertilization (IVF) cycles have been further refined in continuing efforts to promote singleton gestation and reduce the number of multiple pregnancies. This version replaces the document titled Criteria for number of embryos to transfer: a committee opinion that was published most recently in August of 2013 (Fertil Steril 2013;99:44-6).

How compliant are in vitro fertilization member clinics in following embryo transfer guidelines? An analysis of 59,689 fresh first in vitro fertilization autologous cycles from 2011 to 2012.

OBJECTIVE: To determine whether IVF clinics are compliant with American Society for Reproductive Medicine (ASRM) and Society for Assisted Reproductive Technology (SART) (ASRM/SART) guidelines and assess the multiple pregnancy outcomes according to the number of embryos transferred. DESIGN: Retrospective cohort study. SETTING: Not applicable. PATIENT(S): Data from 59,689 fresh first autologous IVF cycles from the 2011-2012 SART registry. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Percentage of compliant cycles, multiple pregnancy rate (PR). RESULT(S): Between 2011 and 2012, a total of 59,689 fresh first autologous cycles were analyzed. Among cleavage-stage ET cycles, the noncompliance rate ranged from 10%-27.4% depending on the age group. The multiple PR was significantly increased in noncompliant cycles involving patients <35 years (38.1% vs. 28.7%) and 35-37 years (35.4% vs. 24.5%) compared with compliant cycles. Among blastocyst-stage ET cycles, the highest rate of noncompliance was seen in patients <35 years old (71%), which resulted in a statistically higher multiple PR (48.3% vs. 2.8%) compared with compliant cycles. Far fewer cycles were noncompliant in patients 35-40 years of age. In a subanalysis of compliant cycles, transferring two blastocyst embryos in patients 35-37 years and 38-40 years resulted in a higher live birth rate compared with the transfer of one embryo (50.4% vs. 40.9% and 42.1% vs. 30.0%, respectively) but the multiple PR was also significantly higher (40.5% vs. 1.7% and 34.0% vs. 2.0%, respectively). CONCLUSION(S): Most first fresh autologous IVF cycles performed from 2011-2012 were compliant with ASRM/SART guidelines, except those that involved a blastocyst ET in patients <35 years. Despite compliance, cycles that involved the transfer of >1 embryo resulted in a high multiple PR, whereas noncompliant cycles resulted in an even more remarkable multiple PR for both cleavage and blastocyst-stage embryos. Clinics need to be more compliant with ET limits and ASRM/SART need to consider revising their guidelines to limit the number of blastocyst transfer to one in patients ≤40 years of age undergoing their first IVF cycle. Furthermore, decreasing the number of cleavage-stage embryos transferred in patients ≤40 years of age should also be considered.

Do donor oocyte cycles comply with ASRM/SART embryo transfer guidelines? An analysis of 13,393 donor cycles from the SART registry.

OBJECTIVE: To analyze donor oocyte cycles in the Society for Assisted Reproductive Technology (SART) registry to determine: 1) how many cycles complied with the 2009 American Society for Reproductive Medicine/SART embryo transfer guidelines; and 2) cycle outcomes according to the number of embryos transferred. For donor oocyte IVF with donor age <35 years, the consideration of single-embryo transfer was strongly recommended. DESIGN: Retrospective cohort study of United States national registry information. SETTING: Not applicable. PATIENT(S): A total of 13,393 donor-recipient cycles from 2011 to 2012. INTERVENTION(S): Embryos transferred in donor IVF cycles. MAIN OUTCOME MEASURE(S): Percentage of compliant cycles, multiple pregnancy rate. RESULT(S): There were 3,157 donor cleavage-stage transfers and 10,236 donor blastocyst transfers. In the cleavage-stage cycles, 88% met compliance criteria. The multiple pregnancy rate (MPR) was significantly higher in the noncompliant cycles. In a subanalysis of compliant cleavage-stage cycles, 91% transferred two embryos and only 9% single embryos. In those patients transferring two embryos, the MPR was significantly higher (33% vs. 1%). In blastocyst transfers, only 28% of the cycles met compliance criteria. The MPR was significantly higher in the noncompliant blastocyst cohort at 53% (compared with 2% in compliant cycles). CONCLUSION(S): The majority of donor cleavage-stage transfers are compliant with current guidelines, but the transfer of two embryos results in a significantly higher MPR compared with single-embryo transfer. The majority of donor blastocyst cycles are noncompliant, which appears to be driving an unacceptably high MPR in these cycles.

Reduction of multiple pregnancies in the advanced maternal age population after implementation of an elective single embryo transfer policy coupled with enhanced embryo selection: pre- and post-intervention study.

STUDY QUESTION: Is an elective single-embryo transfer (eSET) policy an efficient approach for women aged >35 years when embryo selection is enhanced via blastocyst culture and preimplantation genetic screening (PGS)? SUMMARY ANSWER: Elective SET coupled with enhanced embryo selection using PGS in women older than 35 years reduced the multiple pregnancy rates while maintaining the cumulative success rate of the IVF programme. WHAT IS KNOWN ALREADY: Multiple pregnancies mean an increased risk of premature birth and perinatal death and occur mainly in older patients when multiple embryos are transferred to increase the chance of pregnancy. A SET policy is usually recommended in cases of good prognosis patients, but no general consensus has been reached for SET application in the advanced maternal age (AMA) population, defined as women older than 35 years. Our objective was to evaluate the results in terms of efficacy, efficiency and safety of an eSET policy coupled with increased application of blastocyst culture and PGS for this population of patients in our IVF programme. STUDY DESIGN, SIZE, DURATION: In January 2013, a multidisciplinary intervention involving optimization of embryo selection procedure and introduction of an eSET policy in an AMA population of women was implemented. This is a retrospective 4-year (January 2010-December 2013) pre- and post-intervention analysis, including 1161 and 499 patients in the pre- and post-intervention period, respectively. The primary outcome measures were the cumulative delivery rate (DR) per oocyte retrieval cycle and multiple DR. PARTICIPANTS/MATERIALS, SETTING, METHODS: Surplus oocytes and/or embryos were vitrified during the entire study period. In the post-intervention period, all couples with good quality embryos and less than two previous implantation failures were offered eSET. Embryo selection was enhanced by blastocyst culture and PGS (blastocyst stage biopsy and 24-chromosomal screening). Elective SET was also applied in cryopreservation cycles. MAIN RESULTS AND THE ROLE OF CHANCE: Patient and cycle characteristics were similar in the pre- and post-intervention groups [mean (SD) female age: 39.6 ± 2.1 and 39.4 ± 2.2 years; range 36-44] as assessed by logistic regression. A total of 1609 versus 574 oocyte retrievals, 937 versus 350 embryo warming and 138 versus 27 oocyte warming cycles were performed in the pre- and post-intervention periods, respectively, resulting in 1854 and 508 embryo transfers, respectively. In the post-intervention period, 289 cycles were blastocyst stage with (n = 182) or without PGS (n = 107). A mean (SD) number of 2.9 ± 1.1 (range 1-4) and 1.4 ± 0.8 (range 1-3) embryos were transferred pre- and post-intervention, respectively (P < 0.01) and similar cumulative clinical pregnancy rates per transfer and per cycle were obtained: 26.8, 30.9% and 29.7, 26.3%, respectively. The total DR per oocyte retrieval cycle (21.0 and 20.4% pre- and post-intervention, respectively) defined as efficacy was not affected by the intervention [odds ratio (OR) = 0.8, 95% confidence interval (CI) = 0.7-1.1; P = 0.23]. However, a significantly increased live birth rate per transferred embryo (defined as efficiency) was observed in the post-intervention group 17.0 versus 10.6% (P < 0.01). Multiple DRs decreased from 21.0 in the preintervention to 6.8% in the post-intervention group (OR = 0.3. 95% CI = 0.1-0.7; P < 0.01). LIMITATIONS, REASONS FOR CAUTION: In this study, the suitability of SET was assessed in individual women on the basis of both clinical and embryological prognostic factors and was not standardized. For the described eSET strategy coupled with an enhanced embryo selection policy, an optimized culture system, cryopreservation and aneuploidy screening programme is necessary. WIDER IMPLICATIONS OF THE FINDINGS: Owing to the increased maternal morbidity and perinatal complications related to multiple pregnancies, it is recommended to extend the eSET policy to the AMA population. As shown in this study, enhanced embryo selection procedures might allow a reduction in the number of embryos transferred and the number of transfers to be performed without affecting the total efficacy of the treatment but increasing efficiency and safety. STUDY FUNDING/COMPETING INTERESTS: None. TRIAL REGISTRATION NUMBER: None.

Is it time for a paradigm shift in understanding embryo selection?

BACKGROUND: Embryo selection has been an integral feature of in vitro fertilization (IVF) almost since its inception. Since the advent of extended blastocyst stage embryo culture, and especially with increasing popularity of elective single embryo transfer (eSET), the concept of embryo selection has increasingly become a mainstay of routine IVF. DISCUSSION: We here, however, argue that embryo selection via blastocyst stage embryo transfer (BSET), as currently practiced, at best improves IVF outcomes only for a small minority of patients undergoing IVF cycles. For a large majority BSET is either ineffective or, indeed, may actually be harmful by decreasing IVF pregnancy chances. Overall, only a small minority of patients, thus, benefit from prolonged embryo culture, while BSET, as a tool to enhance IVF outcomes, is increasingly utilized as routine care in IVF for all patients. SUMMARY: Since newer methods of embryo selection, like preimplantation genetic screening (PGS) and closed system embryo incubation with time-lapse photography are practically dependent on BSET, these concepts of embryo selection, currently increasingly adopted in mainstream IVF, require reconsideration. They, automatically, transfer the downsides of BSET, including decreases in IVF pregnancy chances in some patients, to these new procedures, and in addition raise serious questions about cost-effectiveness.

[Unselective single embryo transfer: chances of pregnancy related to operator experience]. / Transferencia no selectiva de embrón único: posibilidades de embarazo relacionadas con la experiencia del operador.

BACKGROUND: Selection of best quality embryo aims to achieve higher success rate, the pregnancy is unique and therefore obstetric risks are reduced. OBJECTIVE: To evaluate the pregnancy rate with no transfer of selected single embryo (TSSE) three days versus the experience of the physician performing the embryo transfer. PATIENTS AND METHODS: A retrospective, cross-sectional observational study in 159 patients Mexican Fertility Center in CEPAM protocol in vitro fertilization any indication, other ovulatory disorders and who was only possible obtain an embryo to be transferred in three day. For the analysis were grouped according to age, number of cells of the embryo transfer day and the doctor performed. Continuous variables are reported as means and standard deviations and univariate logistic regression was performed to determine statistical significance. Categorical variables were evaluated in frequencies and percentages. The calculations were performed with the software JMP. RESULTS: Protocol of single-embryo transfer not selected in three day pregnancy rate of 17% was obtained, with lower rates in women over 40 years of age and older embryos of more than 9 cells but also higher rate abortion. More experienced doctors achieved better pregnancy rates. CONCLUSION: This is the first study in Mexican population to assess the possibility of pregnancy with single embryo transfer in selected post-harvest with a three day success rate of 17% and first-order variables: number of cells on the day of transfer and experience of the physician who performed the procedure.

Morphological assessment of embryo viability.

Morphological assessment is discussed in the context of significant literature at all stages of in vitro development, beginning with the oocyte and culminating at the blastocyst stage. Current evidence is used to debate the inclusion of commonly observed morphological features in grading schemes. The biological rationale behind observed phenomena such as multinucleation and fragmentation are also explored. Current limitations as well as technological advancements that increase our ability to assess viability are highlighted. Particular attention is paid to the relationship between developmental timing and assessment schemes. Failure to standardize assessment timing and inclusion criteria is glaring weaknesses of the literature that currently make consensus unattainable. Mounting evidence suggests that the future of static assessment is very likely to be influenced by information gathered from preimplantation genetic screening and other invasive techniques as well as from continuous monitoring tools such as time lapse.

What can we learn from a decade of promoting safe embryo transfer practices? A comparative analysis of policies and outcomes in the UK and Australia, 2001-2010.

STUDY QUESTION: Given similar socio-demographic profiles and costs of healthcare, why has Australia been significantly more successful than the UK in reducing the assisted reproductive technology (ART) multiple birth rate? SUMMARY ANSWER: The Australian model of supportive public ART funding, permissive clinical guidelines and an absence of published clinic league tables has enabled Australian fertility specialists to act collectively to achieve rapid and widespread adoption of single embryo transfer (SET). WHAT IS KNOWN ALREADY: There are striking differences in ART utilization and clinical practice between Australia and the UK. The ART multiple birth rate in Australia is <8% compared with slightly <20% in the UK. The role played by public funding, clinical guidelines, league tables and educational campaigns deserves further evaluation. STUDY DESIGN, SIZE, DURATION: Parallel time-series analysis was performed on ART treatment and outcome data sourced from the Human Fertilisation and Embryology Authority (HFEA) ART Registry and the Australian and New Zealand Assisted Reproduction Database (ANZARD). Funding arrangements, clinical practice guidelines and key professional and public education campaigns were mapped to trends in clinical practice and ART treatment outcomes between 2001 and 2010. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 425 360 and 422 003 autologous treatment cycles undertaken between 2001 and 2010 in the UK and Australia were analysed. MAIN RESULTS AND THE ROLE OF CHANCE: From 2001 to 2010, the most striking difference in clinical practice was the increase in SET cycles in Australia from 21 to 70% of cycles, compared with an increase from 8.4 to 31% in the UK. In 2004-2005, both countries introduced clinical guidelines encouraging safe embryo practices, however, Australia has a history of supportive funding for ART, while the National Health Service has a more restrictive and fragmented approach. While clinical guidelines and education campaigns have an important role to play, funding remains a key element in the promotion of SET. LIMITATIONS, REASONS FOR CAUTION: This is a descriptive population study and therefore quantifying the independent effect of differential levels of public funding was not possible. WIDER IMPLICATIONS OF THE FINDINGS: With demand for ART continuing to increase worldwide, it is imperative that we remove barriers that impede safe embryo transfer practices. This analysis highlights the importance of supportive public funding in achieving this goal.

Biomarkers identified with time-lapse imaging: discovery, validation, and practical application.

"Time-lapse markers," which are defined by time-lapse imaging and correlated with clinical outcomes, may provide embryologists with new opportunities for improving embryo selection. This article provides an overview of noninvasive biomarkers defined by time-lapse imaging studies. In addition to comprehensively reviewing the discovery of each time-lapse marker, it focuses on the criteria necessary for their successful integration into clinical practice, including [1] statistical and biological significance, [2] validation through prospective clinical studies, and [3] development of reliable technology to measure and quantify the time-lapse marker. Because manual analysis of time-lapse images is labor intensive and limits the practical use of the image data in the clinic, automated image analysis software platforms may contribute substantially to improvements in embryo selection accuracy. Ultimately, time-lapse markers that are based on a foundation of basic research, validated through prospective clinical studies, and enabled by a reliable quantification technology may improve IVF success rates, encourage broader adoption of single-embryo transfer, and reduce the risks associated with multiple gestation pregnancies.

Elective single embryo transfer trends and predictors of a good perinatal outcome--United States, 1999 to 2010.

OBJECTIVE: To assess trends in elective single ET and identify factors associated with a good perinatal outcome. DESIGN: Retrospective cohort study. SETTING: Clinic-based data. PATIENT(S): A total of 886,686 fresh, nondonor cycles reported to the National Assisted Reproductive Technology Surveillance System during 1999-2010, of which 17,166 met criteria for elective single ET. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Rates of elective single ET and good perinatal outcome (term, singleton infant with normal birth weight). RESULT(S): In 2010, elective single ET comprised 5.6% of all fresh transfers, representing an eightfold increase since publication of first guidelines in 2004 recommending elective single ET. Compared with other ETs, elective single ETs were nearly twice as likely to result in a good perinatal outcome (37.1% vs. 18.9%, respectively). Among women using elective single ET, those aged <35 and 35-37 years had a good perinatal outcome (40.2% and 32.5%, respectively). In multivariable, log-binomial analyses, factors positively associated with a good perinatal outcome included male factor infertility, day 5 ET, and having ≥3 supernumerary embryos for cryopreservation. CONCLUSION(S): Between 1999 and 2010, national rates of elective single ET increased. Given the frequency of good perinatal outcomes among women aged 35-37 years, guidelines for elective single ET could be expanded to include patients in this age group with favorable prognoses.

[Impact of elective single embryo transfer criteria on the twin pregnancy rate in a French population]. / L'impact des critères du élective single embryo transfer sur le taux de grossesses gémellaires dans la population française.

To reduce the twin pregnancy rate and their morbidity, several recommendations have been proposed to practice the "elective single embryo transfer" in a selected population. We decided to apply the criteria that were proposed in five articles from the literature to our population to evaluate the percentage of our population concerned and the impact on our twin pregnancy rate. The result is that these criteria only concern 2,4 to 10,8% of our population with a minor reduction of our twin pregnancy rate with a potential lake of chance concerning the pregnancy rate. We should study others possibilities than the population's criteria to reduce the number of embryo transferred.

Biological predictive criteria for clinical pregnancy after elective single embryo transfer.

In this prospective observational study, the onset of a clinical pregnancy after elective single embryo transfer (eSET) was significantly associated with: 1) the woman's age as well as the number of good- and top-quality embryos; and 2) the day of the embryo transfer (day 3>day 2). Good-quality embryos had the same ability to implant, regardless of the zygotic score, the day 1 early cleavage rate, the fragmentation degree, and the top-quality assessment, specifying the eligibility criteria for eSET.

Embryo quality and impact of specific embryo characteristics on ongoing implantation in unselected embryos derived from modified natural cycle in vitro fertilization.

OBJECTIVE: To study the implantation potential of unselected embryos derived from modified natural cycle IVF according to their morphological characteristics. DESIGN: Cohort study. SETTING: Academic department of reproductive medicine. PATIENT(S): A series of 449 single embryo transfers derived from modified natural cycle IVF. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Ongoing implantation rate according to embryo characteristics. RESULT(S): The best implantation was found in embryos with 4 and 8 cells on day 2 and 3 respectively,