ESHRE guideline: number of embryos to transfer during IVF/ICSI†.

STUDY QUESTION: Which clinical and embryological factors should be considered to apply double embryo transfer (DET) instead of elective single embryo transfer (eSET)? SUMMARY ANSWER: No clinical or embryological factor per se justifies a recommendation of DET instead of eSET in IVF/ICSI. WHAT IS KNOWN ALREADY: DET is correlated with a higher rate of multiple pregnancy, leading to a subsequent increase in complications for both mother and babies. These complications include preterm birth, low birthweight, and other perinatal adverse outcomes. To mitigate the risks associated with multiple pregnancy, eSET is recommended by international and national professional organizations as the preferred approach in ART. STUDY DESIGN, SIZE, DURATION: The guideline was developed according to the structured methodology for development and update of ESHRE guidelines. Literature searches were performed in PUBMED/MEDLINE and Cochrane databases, and relevant papers published up to May 2023, written in English, were included. Live birth rate, cumulative live birth rate, and multiple pregnancy rate were considered as critical outcomes. PARTICIPANTS/MATERIALS, SETTING, METHODS: Based on the collected evidence, recommendations were discussed until a consensus was reached within the Guideline Development Group (GDG). A stakeholder review was organized after the guideline draft was finalized. The final version was approved by the GDG and the ESHRE Executive Committee. MAIN RESULTS AND THE ROLE OF CHANCE: The guideline provides 35 recommendations on the medical and non-medical risks associated with multiple pregnancies and on the clinical and embryological factors to be considered when deciding on the number of embryos to transfer. These recommendations include 25 evidence-based recommendations, of which 24 were formulated as strong recommendations and one as conditional, and 10 good practice points. Of the evidence-based recommendations, seven (28%) were supported by moderate-quality evidence. The remaining recommendations were supported by low (three recommendations; 12%), or very low-quality evidence (15 recommendations; 60%). Owing to the lack of evidence-based research, the guideline also clearly mentions recommendations for future studies. LIMITATIONS, REASONS FOR CAUTION: The guideline assessed different factors one by one based on existing evidence. However, in real life, clinicians' decisions are based on several prognostic factors related to each patient's case. Furthermore, the evidence from randomized controlled trials is too scarce to formulate high-quality evidence-based recommendations. WIDER IMPLICATIONS OF THE FINDINGS: The guideline provides health professionals with clear advice on best practice in the decision-making process during IVF/ICSI, based on the best evidence currently available, and recommendations on relevant information that should be communicated to patients. In addition, a list of research recommendations is provided to stimulate further studies in the field. STUDY FUNDING/COMPETING INTEREST(S): The guideline was developed and funded by ESHRE, covering expenses associated with the guideline meetings, the literature searches, and the dissemination of the guideline. The guideline group members did not receive payment. DPB declared receiving honoraria for lectures from Merck, Ferring, and Gedeon Richter. She is a member of ESHRE EXCO, and the Mediterranean Society for reproductive medicine and the president of the Croatian Society for Gynaecological Endocrinology and Reproductive Medicine. CDG is the past Chair of the ESHRE EIM Consortium and a paid deputy member of the Editorial board of Human Reproduction. IR declared receiving reimbursement from ESHRE and EDCD for attending meetings. She holds an unpaid leadership role in OBBCSSR, ECDC Sohonet, and AER. KAR-W declared receiving grants for clinical researchers and funding provision to the institution from the Swedish Cancer Society (200170F), the Senior Clinical Investigator Award, Radiumhemmets Forskningsfonder (Dnr: 201313), Stockholm County Council FoU (FoUI-953912) and Karolinska Institutet (Dnr 2020-01963), NovoNordisk, Merck and Ferring Pharmaceuticals. She received consulting fees from the Swedish Ministry of Health and Welfare. She received honoraria from Roche, Pfizer, and Organon for chairmanship and lectures. She received support from Organon for attending meetings. She participated in advisory boards for Merck, Nordic countries, and Ferring. She declared receiving time-lapse equipment and grants with payment to institution for pre-clinical research from Merck pharmaceuticals and from Ferring. SS-R received research funding from Roche Diagnostics, Organon/MSD, Theramex, and Gedeo-Richter. He received consulting fees from Organon/MSD, Ferring Pharmaceuticals, and Merck Serono. He declared receiving honoraria for lectures from Ferring Pharmaceuticals, Besins, Organon/MSD, Theramex, and Gedeon Richter. He received support for attending Gedeon Richter meetings and participated in the Data Safety Monitoring Board of the T-TRANSPORT trial. He is the Deputy of ESHRE SQART special interest group. He holds stock options in IVI Lisboa and received equipment and other services from Roche Diagnostics and Ferring Pharmaceuticals. KT declared receiving payment for honoraria for giving lectures from Merck Serono and Organon. She is member of the safety advisory board of EDQM. She holds a leadership role in the ICCBBA board of directors. ZV received reimbursement from ESHRE for attending meetings. She also received research grants from ESHRE and Juhani Aaltonen Foundation. She is the coordinator of EHSRE SQART special interest group. The other authors have no conflicts of interest to declare. DISCLAIMER: This guideline represents the views of ESHRE, which were achieved after careful consideration of the scientific evidence available at the time of preparation. In the absence of scientific evidence on certain aspects, a consensus between the relevant ESHRE stakeholders has been obtained. Adherence to these clinical practice guidelines does not guarantee a successful or specific outcome, nor does it establish a standard of care. Clinical practice guidelines do not replace the need for application of clinical judgement to each individual presentation, nor variations based on locality and facility type. ESHRE makes no warranty, express or implied, regarding the clinical practice guidelines and specifically excludes any warranties of merchantability and fitness for a particular use or purpose (full disclaimer available at https://www.eshre.eu/Guidelines-and-Legal).

Association between sequence variants in the FSHR gene and reproductive outcomes following IVF in predicted normoresponders.

RESEARCH QUESTION: Is there an association between FSHR sequence variants and reproductive outcomes following IVF in predicted normoresponders? DESIGN: Multicentre prospective cohort study conducted from November 2016 to June 2019 in Vietnam, Belgium and Spain including patients aged <38 years, and undergoing IVF with a predicted normal response with fixed-dose 150 IU rFSH in an antagonist protocol. Genotyping was performed for three FSHR (c.919A>G, c.2039A>G, c.-29G>A) and one FSHB sequence variants (c.-211G>T). Clinical pregnancy rate (CPR), live birth rate (LBR) and miscarriage rate in the first embryo transfer and cumulative live birth rate (CLBR) were compared between the different genotypes. RESULTS: A total of 351 patients underwent at least one embryo transfer. Genetic model analysis that adjusted for patient age, body mass index, ethnicity, type of embryo transfer, embryo stage and number of top-quality embryos transferred revealed a higher CPR for homozygous patients for the variant allele G of c.919A>G when compared to patients with genotype AA (60.3% versus 46.3%, adjusted odds ratio [ORadj] 1.96, 95% confidence interval [CI] 1.09-3.53). Also, c.919A>G genotypes AG and GG presented a higher CPR and LBR when compared with genotype AA (59.1% versus 46.3%, ORadj 1.80, 95% CI 1.08-3.00, and 51.3% versus 39.0%, ORadj 1.69, 95% CI 1.01-2.80, respectively). Cox regression models revealed a statistically significantly lower CLBR for c.2039A>G genotype GG in the codominant model (hazard ratio [HR] 0.66, 95% CI 0.43-0.99). CONCLUSION: These results demonstrate a previously unreported association between variant c.919A>G genotype GG and higher CPR and LBR in infertile patients and reinforce a potential role for genetic background in predicting the reproductive prognosis following IVF.

Blastocyst versus cleavage embryo transfer improves cumulative live birth rates, time and cost in oocyte recipients: a randomized controlled trial.

RESEARCH QUESTION: Does embryo transfer day (day 5 versus day 3) affect cumulative live birth rates (CLBR), time to live birth (TLB) and cost per live birth (CPL) in recipients of donated oocytes? STUDY DESIGN: A single-centre RCT conducted between April 2017 and August 2018. Recipients of donated oocytes were randomized to cleavage-stage (day 3) or to blastocyst-stage (day 5) embryo transfer. Eligible recipients were aged 18-50 years and in their first or second synchronous cycle. Primary outcome was CLBR (12 months from first embryo transfer), and fresh and subsequent cryopreserved transfers were considered; TLB and CPL were also analysed. RESULTS: Recipients (n = 134) were randomized to the day-3 group (n = 69) or to the day-5 group (n = 65). Day-5 transfer resulted in a 15.9% relative increase in CLBR and a significant shorter TLB compared with day-3 transfer. To reach a 50% CLBR, the day-3 group required 6 months more than the day-5 group (15.3 versus 8.9 months, respectively). The average CPL in the day-3 strategy cost 24% more than the day-5 strategy (€14817.10 versus €10959.20). Clinical pregnancy rate was 25% less in the day-3 group. The trial was prematurely stopped after poor initial results in the day-3 arm led to unplanned interim analysis. CONCLUSIONS: The transfer of blastocyst-stage embryos in recipients of donated oocytes is preferred as it leads to a higher clinical pregnancy rate, live birth rate, shorter time to pregnancy and lower costs to achieve live birth, compared with cleavage-stage embryo transfer.

Transition from blastomere to trophectoderm biopsy: comparing two preimplantation genetic testing for aneuploidies strategies.

SummaryShortly after the implementation of comprehensive chromosome screening (CCS) techniques for preimplantation genetic testing for aneuploidies (PGT-A), the discussion about the transition from day 3 to blastocyst stage biopsy was initiated. Trophectoderm biopsy with CCS is meant to overcome the limitations of cleavage-stage biopsy and single-cell analysis. The aim of this study was to assess the results obtained in our PGT-A programme after the implementation of this new strategy. Comparisons between the results obtained in 179 PGT-A cycles with day 3 biopsy (D+3) and fresh embryo transfer, and 204 cycles with trophectoderm biopsy and deferred (frozen-thawed) embryo transfer were established. Fewer embryos were biopsied and a higher euploidy rate was observed in the trophectoderm biopsy group. No differences in implantation (50.3% vs. 61.4%) and clinical pregnancy rate per transfer (56.1% vs. 65.3%) were found. Although the mean number of euploid embryos per cycle did not differ between groups (1.5 ± 1.7 vs. 1.7 ± 1.8), the final number of euploid blastocysts available for transfer per cycle was significantly higher in the trophectoderm biopsy group (1.1 ± 1.3 vs. 1.7 ± 1.8). This factor led to an increased cumulative live birth rate in this last group (34.1% vs. 44.6%). Although both strategies can offer good results, trophectoderm biopsy offers a more robust diagnosis and the intervention is less harmful for the embryos so more euploid blastocysts are finally available for transfer and/or vitrification.

Characterization of a suboptimal IVF population and clinical outcome after two IVF cycles.

The number of oocytes retrieved in in vitro fertilization (IVF) cycles is an independent factor influencing pregnancy rate (PR), and optimal number of oocytes would be between 10 and 15. This has led to the hypothesis that the identification of a suboptimal group of responders beforehand (4-9 oocytes retrieved) would allow physicians to optimize their PR. A retrospective observational study counting on 735 women doing an IVF treatment in our center was performed. Multivariable logistic regression was used to analyze the relationship between anti-Mullerian hormone (AMH) and antral follicle count (AFC), within suboptimal and optimal responders. We also analyzed the outcome of those patients with an estimated high probability of having an optimal response and the second cycles of those who did not get pregnant in the first cycle to observe the main significant traits that made them change from one group of responders to the other. Main results are that suboptimal responders account for almost half of our patients. Ovarian reserve markers (AMH and AFC) are significantly different in optimal and suboptimal responders, even when adjusted by age. There is a significant difference in the cumulative PR between both groups. Interestingly, 18.9% shifted from suboptimal to optimal response, and 36.9% from optimal to suboptimal.

Selecting embryos with the highest implantation potential using data mining and decision tree based on classical embryo morphology and morphokinetics.

PURPOSE: The objective of this work was to determine which embryonic morphokinetic parameters up to D3 of in vitro development have predictive value for implantation for the selection of embryos for transfer in clinical practice based upon information generated from embryo transfers with known implantation data (KID). METHODS: A total of 800 KID embryos (100% implantation rate (IR) per transfer and 0% IR per transfer) cultured in an incubator with Time-Lapse system were retrospectively analysed. Of them, 140 embryos implanted, whereas 660 did not. RESULTS: The analysis of morphokinetic parameters, together with the embryo morphology assessment on D3, enabled us to develop a hierarchical model that places the classical morphological score, the t4 and t8 morphokinetic values, as the variables with the best prognosis of implantation. CONCLUSION: In our decision tree, the classical morphological score is the most predictive parameter. Among embryos with better morphological scores, morphokinetics permits deselection of embryos with the lowest implantation potential.

Comparison of starting ovarian stimulation on day 2 versus day 15 of the menstrual cycle in the same oocyte donor and pregnancy rates among the corresponding recipients of vitrified oocytes.

OBJECTIVE: To assess the clinical pregnancy rate per transfer in recipients of embryos from donor oocytes obtained after ovarian stimulation initiated on day 2 (D2) or day 15 (D15) of the menstrual cycle with a secondary end point of comparing the response to stimulation. DESIGN: Prospective observational comparative study. SETTING: Private in vitro fertilization (IVF) program. PATIENT(S): Oocyte donors (OD) and recipients. INTERVENTION(S): Donors stimulated within 3 months, starting on day 2 or day 15 after bleeding, with recombinant follicle-stimulating hormone (FSH), gonadotropin-releasing hormone (GnRH) antagonist, and GnRH agonist trigger, and oocytes vitrified and later assigned to recipients, followed by routine IVF procedures one to two embryos transferred. MAIN OUTCOME MEASURE(S): Primary outcome pregnancy rate, and secondary outcome number of mature oocytes retrieved. RESULT(S): Nine D2 and nine D15 cycles were performed in nine donors. There were no differences between D2 and D15 in the number of mature oocytes obtained (14.0±6.96 vs. 16.89±7.52). To date, 20 recipients have received vitrified oocytes (8 recipients received D2 oocytes and 12 recipients received D15 oocytes). There were no differences between the groups of recipients in fertilization rate (77.3% vs. 76.5%) or number of embryos transferred (1.50±0.53 vs. 1.67±0.65). Twelve clinical pregnancies were obtained. No differences were noted in pregnancy rates (62.5% vs. 58.3%) or implantation rates (41.67% vs. 45%) between recipients of D2 oocytes and recipients of D15 oocytes. CONCLUSION(S): Donor oocytes obtained after ovarian stimulation initiated on day 15 of the cycle achieve good pregnancy rates. This information is useful for patients with cancer undergoing fertility preservation. CLINICAL TRIAL REGISTRATION NUMBER: NCT 01645241.

A multicenter prospective study to assess the effect of early cleavage on embryo quality, implantation, and live-birth rate.

OBJECTIVE: To investigate the impact of early cleavage (EC) on embryo quality, implantation, and live-birth rates. DESIGN: Prospective cross-sectional study. SETTING: Multicenter study. PATIENT(S): Seven hundred embryo transfers and 1,028 early-stage human embryos. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Implantation according to the presence of EC and embryo quality. RESULT(S): The presence of EC is associated with embryo quality, especially in cycles with autologous oocytes. However, the use of EC as an additional criterion for selecting an embryo for transfer does not appear to significantly improve likelihood of implantation. Furthermore, embryos that presented EC had live-birth rates per implanted embryo similar to those that did not show any sign of cleavage. CONCLUSION(S): At least for conventional embryo culture and morphologic evaluations, the additional evaluation of EC in embryos may not be valuable to improve embryo implantation.

Pronuclear morphology, embryo development and chromosome constitution.

The aim of the present study was to evaluate the usefulness of pronuclear patterns, according to the classifications of Tesarik and Scott, as predictors of embryo chromosome constitution. Up to 73 preimplantation genetic diagnosis/preimplantation genetic screening (PGD/PGS) cycles were analysed in this retrospective study including 17 cycles of translocation carriers and 56 PGS cycles. A total of 331 biopsied embryos were studied assessing pronuclear (PN) pattern, embryo quality and chromosome constitution. As regards to the relationship between PN pattern and embryo quality, the data obtained in this study show no correlation between both parameters. Although there were no significant differences when comparing the distribution of chromosomally normal and abnormal embryos with respect to embryo quality, such differences were observed when distinguishing between normal, aneuploid and polyploid embryos. The results show that the PN pattern using Tesarik's and Scott's classification systems is not related to the embryo developmental potential or its chromosome constitution. Therefore, in the context of a PGD/PGS programme, the PN pattern cannot be used as a tool to predict embryo quality or chromosome status.

Developmental prognosis for zygotes based on pronuclear pattern: usefulness of pronuclear scoring.

PURPOSE: To relate pronuclear patterns (PN) and zygote cytoplasmic appearance and embryo morphology. METHODS: The usefulness of PN classification described by Tesarik et al. 1999 (patterns p0-5) and Scott et al. 2000 (Z1-4), for embryo selection is assessed. RESULTS: Sinchrony on polarization and number of nucleolar precursor bodies (NPB) were associated with good quality embryos (p0 60.9% and p3 67.3%, and Z1 62.5% and Z2 64.7%; p<0.01). Pattern 4 zygotes were associated with small number of NPB developed into multinucleated embryos (14.3%) and poor quality embryos (61.9%). No significant differences were found in the pregnancy rate between transfer of at least one good prognosis PN pattern and transfer of poor prognosis PN patterns, although 75% of the transfers included at least one embryo derived from a pattern 0 zygote, and 55% included embryos from categories Z1 or Z2. CONCLUSIONS: Sequential assessment involving the evaluation of oocyte quality, the classification of PN patterns and embryo morphology allows a more accurate evaluation of embryos to be selected for transfer.