Research question: Is partial compaction during morula formation associated with an embryo's developmental ability and Design: Retrospective analysis of data from 196 preimplantation genetic testing for aneuploidy (PGT-A) cycles. Embryos starting compaction were grouped according to the inclusion or not of all the blastomeres in the forming morula (full compaction or partial compaction). The possible effect of maternal age and ovarian response on compaction was analysed. Morphokinetic characteristics, blastocyst formation rate, morphology and cytogenetic constitution of the obtained blastocysts were compared. Comparisons of reproductive outcomes after the transfer of euploid blastocysts from both groups were established. Finally, in a subset of embryos, the chromosomal constitution concordance of the abandoned cells and the corresponding blastocyst through trophectoderm biopsies was assessed. Results: A total of 430 embryos failed to include at least one cell during compaction (partial compaction group [49.3%]), whereas the 442 remaining embryos formed a fully compacted morula (full compaction group [50.7%]). Neither female age nor the number of oocytes collected affected the prevalence of partial compaction morulae. Morphokinetic parameters were altered in embryos from partial compaction morulae compared with full compaction. Although an impairment in blastocyst formation rate was observed in partial compaction morulae (57.2% versus 70.8%, P < 0.001), both chromosomal constitution (euploidy rate: partial compaction [38.4%] versus full compaction [34.2%]) and reproductive outcomes (live birth rate: partial compaction [51.9%] versus full compaction [46.2%]) of the obtained blastocysts were equivalent between groups. A high ploidy Conclusions: Partial compaction morulae show a reduced developmental ability compared with full compaction morulae. be a consequence of a compromised embryo development regardless of the chromosomal constitution of the excluded cells.

The Association for the Study of Reproductive Biology (ASEBIR) Interest Group in Embryology (in Spanish 'Grupo de Interés de Embriología') reviewed key morphokinetic parameters to assess the contribution of time-lapse technology (TLT) to the ASEBIR grading system. Embryo grading based on morphological characteristics is the most widely used method in human assisted reproduction laboratories. The introduction and implementation of TLT has provided a large amount of information that can be used as a complementary tool for morphological embryo evaluation and selection. As part of IVF treatments, embryologists grade embryos to decide which embryos to transfer or freeze. At the present, the embryo grading system developed by ASEBIR does not consider dynamic events observed through TLT. Laboratories that are using TLT consider those parameters as complementary data for embryo selection. The aim of this review was to evaluate review time-specific morphological changes during embryo development that are not included in the ASEBIR scoring system, and to consider them as candidates to add to the scoring system.

Research question: Can day-5 blastocysts be ranked according to their likelihood of live birth using an objective and userfriendly grading system?Design: A retrospective multicentre study conducted between 2017 and 2019, including 1044 day-5 blastocysts. Blastocyst expansion degree, trophectoderm and inner cell mass quality were assessed morphologically and morphometrically. Several analyses were conducted: the association between the qualitative and quantitative assessment for the blastocyst expansion degree and the number of trophectoderm cells; the effect of the embryo quality on day 3 and the contribution of the three blastocyst parameters to live birth, with logistic regression; and a decision tree with the most significant variables to create the new scoring system. Results: Cut-off points were found to discriminate between expanding and expanded blastocysts (165 mm for blastocyst diameter) and between trophectoderm grades (A: >14 cells; B: 11-13 cells; C: <10 cells). When the embryos reached the blastocyst stage, their quality on day 3 did not add predictive value for implantation and live birth. In the logistic regression analysis, the only parameter capable of significantly predicting the live birth likelihood was the trophectoderm grade: A versus C (OR 1.95, 95% CI 1.26 to 3.0); B versus C (OR 1.71, 95% CI 1.22 to 2.4). The decision tree supported the finding that the trophectoderm grade had the highest predictive value fora live birth, followed by the blastocyst expansion degree in a second step.Conclusions: This new method makes objective blastocyst assessment feasible, allowing for standardization and exportation to other laboratories worldwide.

To determine whether embryo mosaicism prevalence in preimplantation genetic testing for aneuploidy (PGT-A) cycles is associated with the trophectoderm biopsy technique used (a. number of laser pulses or b. the use of flicking or pulling) or the time to tubing. Prospective observational study performed in a single IVF-PGT-A setting from May 2019 to May 2021. Trophectoderm biopsies were analysed by next-generation sequencing. Mosaicism was analysed in relation to the biopsy methodology (number of laser pulses and pulling vs flicking), time elapsed from biopsy to tubing (min), and time of sample cryostorage from tubing to amplification (days). As a secondary objective, the number of laser pulses and biopsy methodology were studied in relation to clinical outcomes of transferred euploid blastocysts. None of the analysed variables were associated to mosaicism prevalence. Multivariable regression analysis demonstrated that mosaicism prevalence was comparable either when  > 3 laser pulses were used as compared to ≤ 3 (13.9% vs 13.8%, aOR = 0.8726 [0.60–1.28]) and pulling compared to flicking (13.1% vs 14.0%, aOR = 0.86 [0.60–1.23]). Moreover, neither the number of laser pulses during biopsy (> 3 vs ≤ 3) nor the technique used (pulling vs flicking) were associated with clinical pregnancy after the transfer of frozen-thawed euploid blastocysts (54.9% vs 55.2%, aOR = 1.05 [0.53–2.09]; 61.1% vs 52.9%, aOR = 1.11 [0.55–2.25], respectively). Our results suggest that, as long as the biopsy and tubing procedures are performed following standardized high quality procedures, no specific approach would increase the generation of artefactual mosaicism as a result of trophectoderm biopsy. Trophectoderm biopsies should be performed regardless of the methodology but always aiming on minimising blastocyst manipulation.

Summary The aim of this study was to provide a more comprehensive understanding of 1PN intracytoplasmic sperm injection (ICSI) zygotes. To achieve this objective, we assessed whether all 1PN-derived embryos showed a similar morphokinetic pattern, and if the morphokinetic behaviour of 1PN-derived embryos was comparable with that of 2PN-derived embryos. In total, 149 1PN ICSI zygotes (study group) and 195 2PN ICSI zygotes (control group) were included in the study. Embryo development potential was evaluated in terms of blastocyst rate. Morphokinetic parameters, including the pronucleus diameter and kinetics of in vitro development, were also analyzed. Embryos derived from 1PN ICSI zygotes showed impaired development compared with 2PN-derived embryos, with blastocyst rates of 28.9% and 67.2%, respectively. The diameter of the pronucleus of 1PN zygotes was larger than that of 2PN zygotes. When compared with 2PN-derived embryos, those derived from 1PN zygotes had a visible pronucleus for a shorter time, in addition to a longer syngamy time and slower kinetic behaviour from two to nine cells. When 1PN-derived blastocysts and 2PN-derived blastocysts were compared, the developmental kinetics were similar in both groups, except for a delayed and longer duration of the compaction phase in 1PN-derived embryos. In conclusion, monopronucleated ICSI zygotes present differences in developmental capacity and morphokinetic behaviour compared with 2PN ICSI zygotes, showing particular morphokinetic parameters related to pronucleus formation. Only the 1PN ICSI-derived embryos that reached the blastocyst stage have similar morphokinetic development to blastocysts from 2PN zygotes.

To determine the developmental competence of fast-cleaving D3 embryos. Retrospective study including 4028 embryos from 513 PGT-A cycles performed between July 2014 and June 2017. Embryos were cultured in time-lapse incubators and biopsied at blastocyst stage. Embryos were classified in groups according to the number of cells on D3 (from 2-cell to ≥13 -cell and compacted). A generalized linear mixed model adjusted for confounding factors was performed to assess the chance to give rise to an euploid blastocyst in each group compared with the chance of 8-cell embryos. Implantation and live birth rates were also analyzed. The statistical analysis showed that embryos with 9 to 11 cells had a slightly lower euploid blastocyst rate than 8-cell embryos (OR (95% CI) 0.77 (0.61–0.96)) while embryos with more than 11 cells were found to be just as likely to give rise to an euploid blastocyst as the 8-cell embryos (OR (95% CI) 1.20 (0.92–1.56)). Conversely, slow-cleaving embryos had a significantly lower euploid blastocyst rate than 8-cell embryos (OR (95% CI) 0.31 (0.24–0.39)). Moreover, euploid blastocysts derived from fast-cleaving embryos and from 8-cell embryos exhibit similar live birth rates. No significant differences were found in the chance to give rise a live birth between 8-cell and 9- to 11-cell embryos (OR (95% CI) 1.23 (0.70–2.15)) and > 11-cell embryos (OR (95% CI) 1.09 (0.57–2.09)). Embryos with more than 11 cells exhibit similar developmental competence to 8-cell embryos. Their poor prognosis should be reconsidered.

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.

OBJECTIVE:To compare the outcomes of patients with confirmed endometriosis undergoing in vitro fertilization (IVF)-embryo transfer (ET) treated with either gonadotropin-releasing hormone agonist (GnRHa) or gonadotropin-releasing hormone antagonist (GnRHant) using the propensity score (PS) matching.DESIGN:Observational, retrospective analysis from January 2000 to December 2010.SETTING:Private tertiary fertility clinic.PATIENT(S):Patients with endometriosis confirmed by ultrasound or surgery (American Fertility Society; AFS grades I-IV) that underwent an IVF-ET, stimulated with standard controlled ovarian hyperstimulation (COH) and GnRHa or GnRHant.INTERVENTION(S):A PS was assigned to all patients, which calculates the conditional probability of receiving a certain treatment; a higher PS (1) meant a higher probability of receiving treatment with GnRHa, and a lower PS (0) meant a higher probability of receiving GnRHant. The PS was calculated with a logistic regression model adjusted specifically for age, follicle stimulating hormone, antral follicle count and previous IVF cycles. All patients were divided into three groups according to their PS.MAIN OUTCOME MEASURE(S):pregnancy rate (PR) per cycle.RESULTS:1180 patients were analyzed. Raw PR per cycle was 41.8% and 23.4%, and PR per ET was 44.3 and 27%, respectively. PR per cycle: 41.9 versus 30% in group A; in group B, 39.7% versus 36.4% and in group C, 15.4% versus 18.9%. The overall odds ratio for PR adjusted by PS was 1.10 [0.58-2.19].CONCLUSIONS:After matching patients by PS, PR after COH with either GnRHa or GnRHant may be equally effective.

Objective: To determine whether the type of medium used to culture human embryos in vitro influences neonatal birth weight after IVF/intracytoplasmic sperm injection (ICSI).Design: A prospective study and a retrospective study.Setting: Private assisted reproduction center.Patient(s): The prospective study included 449 IVF/ICSI cycles from August to December 2008. The retrospective analysis was performed for 2,518 IVF/ICSI cycles from October 2006 to December 2010.Intervention(s): In the prospective study, patients were randomized for embryo culture in Cook or Vitrolife medium. The retrospective study was performed with three different culture media (MediCult, Cook, and Vitrolife).Main Outcome Measure(s): Mean birth weight, adjusted for gestational age and gender (z score) of newborns.Result(s): In the prospective study, the average z score was -0.19 +/- 0.85 in Cook and 0.08 +/- 1.40 in Vitrolife. In the retrospective study, the z scores obtained in each group were as follows: Cook, -0.14 +/- 0.96; MediCult, 0.06 +/- 1.13; and Vitrolife, 0.03 +/- 1.05. No significant differences were observed regarding the birth weight of children born in the different groups in both studies.Conclusion(s): The results do not show any relationship between the medium used for in vitro culture and mean birth weight adjusted for gestational age and gender of singletons born after IVF/ICSI. (C)2013 by American Society for Reproductive Medicine.