Time-lapse systems for embryo incubation and assessment in assisted reproduction

Mature oocyte dysmorphisms may be associated with progesterone levels, mitochondrial DNA content, and vitality in luteal granulosa cells

PURPOSE

To identify whether follicular environment parameters are associated with mature oocyte quality, embryological and clinical outcomes.

METHODS

This retrospective study examined 303 mature oocytes from 51 infertile women undergoing ICSI cycles between May 2018 and June 2021. Exclusion criteria consisted of advanced maternal age (> 36 years old), premature ovarian failure, obesity in women, or use of frozen gametes. Luteal granulosa cells (LGCs) were analyzed for mitochondrial DNA/genomic (g) DNA ratio and vitality. The relationships between hormone levels in the follicular fluid and oocyte features were assessed. Quantitative morphometric measurements of mature oocytes were assessed, and the association of LGC parameters and oocyte features on live birth rate after single embryo transfer was examined.

RESULTS

Results indicated an inverse correlation between the mtDNA/gDNA ratio of LGCs and the size of polar body I (PBI). A 4.0% decrease in PBI size was observed with each one-unit increase in the ratio (p = 0.04). Furthermore, a 1% increase in LGC vitality was linked to a 1.3% decrease in fragmented PBI (p = 0.03), and a 1 ng/mL increase in progesterone levels was associated with a 0.1% rise in oocytes with small inclusions (p = 0.015). Associations were drawn among LGC characteristics, perivitelline space (PVS) debris, cytoplasmic inclusions, PBI integrity, and progesterone levels. Certain dysmorphisms in mature oocytes were associated with embryo morphokinetics; however, live birth rates were not associated with follicular parameters and oocyte quality characteristics.

CONCLUSION

Follicular markers may be associated with mature oocyte quality features.

Embryo classification beyond pregnancy: early prediction of first trimester miscarriage using machine learning

PURPOSE

First trimester miscarriage is a major concern in IVF-ET treatments, accounting for one out of nine clinical pregnancies and for up to one out of three recognized pregnancies. To develop a machine learning classifier for predicting the risk of cleavage-stage embryos to undergo first trimester miscarriage based on time-lapse images of preimplantation development.

METHODS

Retrospective study of a 4-year multi-center cohort of 391 women undergoing intra-cytoplasmatic sperm injection (ICSI) and fresh single or double embryo transfers. The study included embryos with positive indication of clinical implantation based on gestational sac visualization either with first trimester miscarriage or live-birth outcome. Miscarriage was determined based on negative fetal heartbeat indication during the first trimester. Data were recorded and obtained in hospital setting and research was performed in university setting.

RESULTS

A minimal subset of six non-redundant morphodynamic features were screened that maintained high prediction capacity. Features that account for the distribution of the nucleolus precursor bodies within the small pronucleus and pronuclei dynamics were highly predictive of miscarriage outcome as evaluated using the SHapley Additive exPlanations (SHAP) methodology. Using this feature subset, XGBoost and random forest models were trained following a 100-fold Monte-Carlo cross validation scheme. Miscarriage was predicted with AUC 0.68 to 0.69.

CONCLUSION

We report the development of a decision-support tool for identifying the embryos with high risk of miscarriage. Prioritizing embryos for transfer based on their predicted risk of miscarriage in combination with their predicted implantation potential is expected to improve live-birth rates and shorten time-to-pregnancy.

The effects of temperature variation treatments on embryonic development: a mouse study

Since the development of ART, embryos have been cultured at 37 °C in an attempt to mimic the in vivo conditions and the average body temperature of an adult. However, a gradient of temperatures within the reproductive tract has been demonstrated in humans and several other mammalian species. Therefore, the aim of this study was to evaluate the effects of temperature variation treatments on mouse embryo quality through morphokinetic events, blastocyst morphology, the relative gene expression of Igf2, Bax, Bcl2 and Apaf1 and the metabolomics of individual culture media. Study groups consisted of 2 circadian treatments, T1 with embryos being cultured at 37 °C during the day and 35.5 °C during the night, T2 with 38.5 °C during the day and 37 °C during the night and a control group with constant 37 °C. Our main findings are that the lower-temperature group (T1) showed a consistent negative effect on mouse embryo development with “slow” cleaving embryos, poor-quality blastocysts, a higher expression of the apoptotic gene Apaf1, and a significantly different set of amino acids representing a more stressed metabolism. On the other hand, our higher-temperature group (T2) showed similar results to the control group, with no adverse effects on blastocyst viability.

Can Time-Lapse Incubation and Monitoring Be Beneficial to Assisted Reproduction Technology Outcomes? A Randomized Controlled Trial Using Day 3 Double Embryo Transfer

Objective: To determine if the application of time-lapse incubation and monitoring can be beneficial to clinical outcomes in assisted reproductive technology.

Methods: A total of 600 patients were equally randomized to three groups, namely, conventional embryo culture and standard morphological selection (CM group), time-lapse culture and standard morphological selection (TLM group), and time-lapse culture and morphokinetic selection (TLA group). Notably, 424 undergoing fresh autologous in vitro fertilization cycles were analyzed, 132 patients in the CM group, 158 in the TLM group, and 134 in the TLA group. Main outcomes included clinical outcomes, embryo development rates, and perinatal outcomes.

Results: Clinical pregnancy rates in the time-lapse groups were significantly higher than in the CM group (CM 65.2% vs. TLM 77.2% vs. TLA 81.3%). Implantation rates and live birth rates were significantly higher for the TLA group (59.7 and 70.9%) compared with the CM group (47.7 and 56.1%) but not compared with the TLM group (55.4 and 67.1%). There was no statistical difference in miscarriage and ectopic pregnancy rates among the three groups. Overall, birth weight was significantly higher in the time-lapse groups (CM 2,731.7 ± 644.8 g vs. TLM 3,066.5 ± 595.4 g vs. TLA 2,967.4 ± 590.0 g). The birth height of newborns in the TLM group was significantly longer than that of the CM group and TLA group (CM 48.3± 4.4 cm vs. TLM 49.8± 2.3 cm vs. TLA 48.5± 2.7 cm).

Conclusion: Time-lapse incubation and monitoring have a significant benefit on clinical pregnancy rates and on overall birth weights while morphokinetic analysis is not necessary.

Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [NCT02974517].

Neonatal Outcomes of Embryos Cultured in a Time-Lapse Incubation System: an Analysis of More Than 15,000 Fresh Transfer Cycles

In the past 5 years, the time-lapse culture system (TLS) has gradually been applied to the field of assisted reproduction. However, there are few reports on the comparison between this system and the conventional culture system (CS) on the outcome of newborns. As a new model in embryo culture, we should pay attention to its neonatal outcomes. We examined 15,252 fresh transfer cycles processed between January 2016 and December 2019. After propensity score matching, embryos in two groups, TLS and CS, had similar rates of miscarriages, ectopic pregnancy, and live delivery (P > 0.05). Embryos in the TLS group achieved higher clinical pregnancy and implantation rates (P < 0.05). Of the perinatal and neonatal outcomes, singletons and twins were analyzed separately. No significant differences were observed in gestational age, preterm deliveries, birth weight, and sex ratio (P > 0.05). Incidences of malformations of babies delivered from CS and TLS groups were also similar between the two groups. Embryos cultured in a TLS are as safe as CS with regard to neonatal outcomes, including congenital malformations.

Pronuclear score improves prediction of embryo implantation success in ICSI cycles

BACKGROUND

In assisted reproduction technology embryo competence is routinely evaluated on morphological criteria but efficacy remains relatively low. Additional information could be obtained by evaluating pronuclear (PN) morphology. Up to now controversial results have been reported about the prognostic value of PN score. One of the main limitations of literature data is the use of different PN classification methods. In this regard, in 2011 the ESHRE and Alpha Scientists in Reproductive Medicine defined three PN categories to standardize zygote assessment. In this study we evaluated whether the consensus ESHRE-Alpha system for the pronuclear scoring could be an useful additional criterion to improve prediction of embryo implantation potential.

METHODS

This is a retrospective, longitudinal, observational, cohort study. We included 3004 zygotes from 555 women who underwent ICSI treatment at our Center between January 2014 and June 2019. The PN were categorized as score 1: symmetrical, 2: non-symmetrical, 3: abnormal. A subset of 110 zygotes did not cleaved. On day 2-3 1163 embryos were transferred, 232 arrested, and 9 were cryopreserved. Among the 1490 embryos cultured up to day 5-7, 516 became blastocysts: 123 were transferred on day 5 and 393 were cryopreserved. Comparisons of age, cleavage and blastocyst rate, quality of embryos, implantation success among PN score groups were evaluated by chi-square test or Kruskal-Wallis test as appropriate. Potential predictors of embryo implantation were first tested in univariable analysis using generalized estimating equations taking into account correlation between embryos originated from the same patient. Then, variables potentially associated with implantation success (P<0.05) were included in a multivariable analysis for calculating the adjusted odds ratio (OR) and 95% confidence interval (CI).

RESULTS

There was no significant difference in patients'age, cleavage and blastulation rates, and embryo morphology among the three PNscore groups. The PN score 1-embryos had a greater implantation success respect to score 2-3-ones (OR 1.83; 95% CI 1.34-2.50, P=0.0001). Consistently, the pronuclear score remained predictive of implantation in top quality embryos (OR 1.68; 95%CI 1.17-2.42, P= 0.005).

CONCLUSIONS

The consensus pronuclear score may be routinely included among criteria for embryo evaluation to increase patients' chance of becoming pregnant.

Single-embryo transfer: a key strategy to reduce the risk for multiple pregnancy in assisted human reproduction

In the early days of assisted reproductive technology (ART), the main target was achieving gestation. Success rates were low, and multiple embryo transfers became common practice, with multiple pregnancies being 20 times higher than in natural conception. Multiple pregnancy is associated with a higher risk of complications for the mother and the baby than a singleton pregnancy. Added to healthcare costs, multiple pregnancy also involves other costs and psychosocial risks, with a high social and health costs. At present, success rates of assisted human reproduction (AHR) have improved dramatically, partially due to advances in laboratory techniques such as culture of blastocyst-stage embryos and vitrification. Additionally, there is a wide range of counseling, health and economic policies that have demonstrated being effective in increasing single-embryo transfer (SET) practices and reducing multiple pregnancies, which ensures satisfactory success rates. Therefore, single-embryo transfer emerges as the approach of choice for AHR to result in a full-term healthy newborn.

The Inclusion Principles of Human Embryos in the WOW-Based Time-Lapse System: A Retrospective Cohort Study

A time-lapse system (TLS) with a well-of-the-well (WOW) dish, which allows individual identification and the possibility of autocrine and paracrine signaling between group-cultured embryos, has been widely used in clinic. However, there is a need to re-think the inclusion principles of human embryos in WOW-based TLS, especially for grade IV (G4) embryos, which are considered to potentially have detrimental effects on surrounding embryos. Here, we carried out a single-center, large-cohort, retrospective study, comprising 303 patients undergoing IVF (148 cases) and ICSI (155 cases), with a total of 3282 embryos, to compare embryonic development until the blastocyst stage in the group culture system with or without G4 embryos. Further, LC-MS/MS was used to analyze the G1-G4 embryo secretome to understand the influence of G4 embryos on the group culture microenvironment. We proved that polypronuclear (PPN) embryos positively contribute to the development of the neighboring embryos through secretion of ILIAP, ITI-H4, and keratin. Existence of more than one G4 embryo had a negative effect on the other embryos (p < 0.05). Moreover, G4 embryos were found to secrete KLKB1 and VTDB, which might harm the neighboring embryos. Thus, our study clarified that when embryos are subjected to group culture in WOW-based TLS, the PPN-derived embryos need not be removed, and it is important to ensure that no more than one G4 embryo is present to avoid negative effects on the neighboring embryos.

Can novel early non-invasive biomarkers of embryo quality be identified with time-lapse imaging to predict live birth?

STUDY QUESTION

Can time-lapse imaging systems make it possible to identify novel early non-invasive biomarkers to predict live birth?

SUMMARY ANSWER

From mostly high-grade embryos, out of 35 morphometric, morphologic and morphokinetic variables, only pronuclei (PN) position at time of PN juxtaposition and the absence of multinucleated blastomeres at the 2-cell stage (MNB2cell), were potentially associated with live birth.

WHAT IS KNOWN ALREADY

Previous studies indicate that some kinetic markers may be predictive of blastocyst development and embryonic implantation. Certain teams have suggested including some of them in decisional algorithms for embryo transfers.

STUDY DESIGN, SIZE, DURATION

Using a time-lapse incubator (EmbryoScope, Unisense FertiliTech), we retrospectively explored the associations between the morphometric, morphologic and morphokinetic parameters of oocytes, zygotes and embryos, and their associations with live birth. This study assessed 232 embryos from single embryo transfers after ICSI cycles performed between January 2014 and December 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The morphometric, morphologic and morphokinetic parameters (18, 4 and 13, respectively) of oocytes, zygotes and early embryos were studied retrospectively. The associations between these parameters were examined using a Spearman's correlation, Mann-Whitney or chi-squared test as appropriate. We examined whether these parameters were associated with outcomes in univariate and multivariate logistic regression analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

Central PN juxtaposition was associated with a 2-fold increase in the odds of live birth (OR = 2.20; 95% CI, [1.26-3.89]; P = 0.006), while the presence of MNB2cell was associated with half the odds of live birth (OR = 0.51; 95% CI, [0.27-0.95]; P = 0.035). These two parameters were independent of embryo kinetics. The 33 remaining parameters had no significant association with the capacity of transferred embryos to develop to term.

LIMITATIONS, REASONS FOR CAUTION

Even though the population size was relatively small, our analyses were based on homogeneous cycles, i.e. young women whose transferred embryos were found to be high-grade according to conventional morphology evaluation. In addition, our conclusions were established from a specific, highly selected population, so other study populations, such as women in an older age bracket, may yield different results. Finally, because we assessed day 2/3 transfers, our findings cannot be generalized to embryos cultured up to the blastocyst stage.

WIDER IMPLICATIONS OF THE FINDINGS

It would be interesting to explore, prospectively, whether PN localisation is a relevant measure to predict embryo development when added into further algorithms and whether this parameter could be suitable for use in other IVF clinics. Further studies are needed, notably to explore the added value of timing evaluation in cohorts of embryos with low or intermediate morphology grade, as well as in other maternal populations (i.e. older women).

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used for this study. P. Sagot received funding from the following commercial companies: Merck Serono, Finox Biotech, Ferring, MSD France SAS, Teva Sante ́ SAS, Allergan France, Gedeon Richter France, Effik S.A., Karl Storz Endoscopie France, GE Medical Systems SCS, Laboratoires Genevrier, H.A.C. Pharma and Ipsen.All the authors confirm that none of this funding was used to support the research in this study. There are no patents, products in development or marketed products to declare. This does not alter the authors' adherence to all the journal policies on sharing data and materials.

Non-invasive Amino Acid Profiling of Embryo Culture Medium Using HPLC Correlates With Embryo Implantation Potential in Women Undergoing in vitro Fertilization

This study aimed to determine the correlation between amino acid profiling of a 3-day-old embryo culture medium and embryo implantation potential in women undergoing in vitro fertilization (IVF). The data of 98 patients who received IVF treatment in our hospital from December 2015 to February 2017 were retrospectively analyzed. The 98 patients were grouped into a pregnant group (gemellary pregnancy), a non-pregnant group (non-pregnancy), and a blank control group. The amino acids from a 3-day-old embryo culture medium and blank control medium were collected and were analyzed using high performance liquid chromatography (HPLC). The HPLC results showed that amino acids including aspartate (ASP), serine (SER), glycine (GLY), histidine (HIS), taurine (TAU), arginine (ARG), threonine (THR), alanine (ALA), and proline (PRO) were detected in the 3-day-old embryo culture medium and blank control medium. There are significant differences between the pregnant group and non-pregnant group in peak height (H)-SER, surface area (S)-ASP, S-SER, S-HIS, and S-ALA. The discrimination analysis according to the peak height and peak area of amino acids revealed that the prediction rate of the pregnant group, non-pregnant group, and blank control group were 82.7, 95.7, and 100%. Further, by using the principal component analysis, we found that the prediction rate in these three groups were 90.4, 91.3, and 100%. Our data may suggest that using amino acid concentrations for principal component analysis and discriminant analysis has high accuracy in predicting the relationship between amino acid fingerprint and embryo implantation potential.

Between-laboratory reproducibility of time-lapse embryo selection using qualitative and quantitative parameters: a systematic review and meta-analysis

PURPOSE

To investigate the between-laboratory reproducibility of embryo selection/deselection effectiveness using qualitative and quantitative time-lapse parameters.

METHODS

A systematic search was performed on MEDLINE, EMBASE, and the Cochrane Library (up to February 2020) without restriction on date, language, document type, and publication status. Measuring outcomes included implantation, blastulation, good-quality blastocyst formation, and euploid blastocyst.

RESULTS

We detected 6 retrospective cohort studies externally validating the first clinical time-lapse model (Meseguer) emphasizing quantitative parameters, of which 3 (including one involving 2 independent centers) were included for the pooled analysis. Receiver operating characteristics analysis showed reduced predictive power of the model when either including or not including sister clinic validation. Fifteen cohort studies evaluating qualitative parameters were included for meta-analysis, and the mean Newcastle-Ottawa Scale was 5.3. Overall, meta-analysis showed significantly adverse association between the presence of ≥ 1 cleavage abnormalities and embryo implantation rates (11 studies, n = 7266; RR = 0.39[0.28, 0.55]_{95% CI}; I² = 57%). Further analysis showed adverse impacts of direct cleavage (7 studies, n = 7065; RR = 0.28 [0.15, 0.54] _{95% CI}; I² = 46%), reverse cleavage (2 studies, n = 3622; RR = 0.16 [0.03, 0.75] _{95% CI}; I² = 0%), chaotic cleavage (2 studies, n = 3643; RR = 0.11 [0.02, 0.69] _{95% CI}; I² = 24%), and multinucleation (5 studies, n = 2576; RR = 0.59 [0.50, 0.69] _{95% CI}; I² = 0%), but not the < 6 intercellular contact points at the 4-cell stage (1 study, n = 185; RR = 0.17 [0.02, 1.15] _{95% CI}).

CONCLUSIONS

Qualitative time-lapse parameters are reliably associated with embryo developmental potential among laboratories, whereas the reproducibility of time-lapse embryo selection model that emphasizes quantitative parameters may be compromised when externally applied.

Levels of caspase-3 and histidine-rich glycoprotein in the embryo secretome as biomarkers of good-quality day-2 embryos and high-quality blastocysts

Morphological assessment at defined developmental stages is the most important method to select viable embryos for transfer and cryopreservation. Timing of different developmental stages in embryo development has been shown to correlate with its potential to develop into a blastocyst. However, improvements in pregnancy rates by using time-lapse techniques have been difficult to validate scientifically. Therefore, there is a need for new methods, preferably non-invasive methods based on metabolomics, genomics and proteomics, to improve the evaluation of embryo quality even further. The aim of this study was to investigate if different levels of caspase-3 and histidine-rich glycoprotein (HRG), secreted by the embryo into the culture media, can be used as biomarkers of embryo quality. In this study, a total of 334 samples of culture media were collected from in vitro fertilization (IVF) treatments at three different clinics. Protein analysis of the culture media was performed using multiplex proximity extension protein analysis to detect levels of caspase-3 and HRG in the embryo secretome. Protein levels were compared in secretome samples from high- and low-quality blastocysts and embryos that became arrested during development. Correlation between protein levels and time to morula formation was also analyzed. Furthermore, protein levels in secretomes from day-2 cultured embryos were compared on the basis of whether or not pregnancy was achieved. The results showed that caspase-3 levels were lower in secretomes from high-quality vs. low-quality blastocysts and those that became arrested (p ≤ 0.05 for both). In addition, higher HRG levels correlated with a shorter time to morula formation (p ≤ 0.001). Caspase-3 levels were also lower in secretomes from day-2 cultured embryos resulting in a pregnancy vs. those that did not (p ≤ 0.05). Furthermore, it was shown that caspase-3 might be used as a marker for predicting potential success rate after transfer of day-2 cultured embryos, where a caspase-3 cutoff level of 0.02 gave a prediction probability of 68% (p = 0.038). In conclusion, in future prediction models, levels of caspase-3 and HRG might be used as potential markers of embryo quality, and secreted caspase-3 levels could to some extent predict the outcome after transfer of day-2 cultured embryos.

Effect of embryo selection based morphokinetics on IVF/ICSI outcomes: evidence from a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Debate exists for the optimal tool to select embryos for transfer in assisted reproductive technology (ART). Time-lapse monitoring (TLM) is a noninvasive tool suggested where each embryo can be captured every 5-20 min. Given the inconsistency in the existing studies, we conducted this meta-analysis of RCTs to summarize the evidence available concerning the predictive ability of morphokinetics compared with the routine assessment of embryo development in ART.

METHODS

The primary databases MEDLINE, EMBASE, Cochrane, NHS, WHO, and Other Non-Indexed Citations were consulted for RCTs that have been published until November 2018, with no language restriction.

RESULTS AND CONCLUSION

Our review includes 6 RCTs (n = 2057 patients). The data showed an improvement (~ 9%) in live birth TLM (OR 1.43; 95% CI 1.10-1.85; P = 0.007), with low-quality evidence. There was no evidence of a significant difference between both groups concerning ongoing pregnancy, clinical pregnancy and implantation rates. The data further showed that morphokinetics is associated with decreased early pregnancy loss rate. These estimates must be interpreted with caution owing to the statistical and clinical heterogeneities and the consequent difficulty in drawing any meaningful conclusion.

Should We Offer In Vitro Fertilization to Couples with Unexplained Recurrent Pregnancy Loss?

In clinical practice, empirical treatments are often offered to couples with recurrent pregnancy loss, including in vitro fertilization. Given that most patients with recurrent pregnancy loss are fertile, the scientific rationale of in vitro fertilization for these couple is debatable. This review will discuss the potential benefits of using in vitro fertilization in couples with recurrent pregnancy loss, such as shortening the time to conceive, optimizing the timing of conception, improving gamete and embryo quality, endometrial receptivity and the use of "adds-on". At present, there is not enough evidence to justify IVF as a treatment option in couples with unexplained recurrent pregnancy loss.

Artificial intelligence in reproductive medicine

Artificial intelligence (AI) has experienced rapid growth over the past few years, moving from the experimental to the implementation phase in various fields, including medicine. Advances in learning algorithms and theories, the availability of large datasets and improvements in computing power have contributed to breakthroughs in current AI applications. Machine learning (ML), a subset of AI, allows computers to detect patterns from large complex datasets automatically and uses these patterns to make predictions. AI is proving to be increasingly applicable to healthcare, and multiple machine learning techniques have been used to improve the performance of assisted reproductive technology (ART). Despite various challenges, the integration of AI and reproductive medicine is bound to give an essential direction to medical development in the future. In this review, we discuss the basic aspects of AI and machine learning, and we address the applications, potential limitations and challenges of AI. We also highlight the prospects and future directions in the context of reproductive medicine.

Temperature of embryo culture for assisted reproduction

BACKGROUND

'Infertility' is defined as the failure to achieve pregnancy after 12 months or more of regular unprotected sexual intercourse. One in six couples experience a delay in becoming pregnant. In vitro fertilisation (IVF) is one of the assisted reproductive techniques used to enable couples to achieve a live birth. One of the processes involved in IVF is embryo culture in an incubator, where a stable environment is created and maintained. The incubators are set at approximately 37°C, which is based on the human core body temperature, although several studies have shown that this temperature may in fact be lower in the female reproductive tract and that this could be beneficial. In this review we have included randomised controlled trials which compared different temperatures of embryo culture.

OBJECTIVES

To assess different temperatures of embryo culture for human assisted reproduction, which may lead to higher live birth rates.

SEARCH METHODS

We searched the following databases and trial registers: the Cochrane Gynaecology and Fertility (CGF) Group Specialised Register of Controlled Trials, the Cochrane Central Register of Studies Online, MEDLINE, Embase, PsycINFO, CINAHL, clinicaltrials.gov, The World Health Organization International Trials Registry Platform search portal, DARE, Web of Knowledge, OpenGrey, LILACS database, PubMed and Google Scholar. Furthermore, we manually searched the references of relevant articles and contacted experts in the field to obtain additional data. We did not restrict the search by language or publication status. We performed the last search on 6 March 2019.

SELECTION CRITERIA

Two review authors independently screened the titles and abstracts of articles retrieved by the search. Full texts of potentially eligible randomised controlled trials (RCTs) were obtained and screened. We included all RCTs which compared different temperatures of embryo culture in IVF or intracytoplasmic sperm injection (ICSI), with a minimum difference in temperature between the two incubators of ≥ 0.5°C. The search process is shown in the PRISMA flow chart.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial eligibility and risk of bias and extracted data from the included studies; the third review author resolved any disagreements. We contacted trial authors to provide additional data. The primary review outcomes were live birth and miscarriage. Clinical pregnancy, ongoing pregnancy, multiple pregnancy and adverse events were secondary outcomes. All extracted data were dichotomous outcomes, and odds ratios (OR) were calculated with 95% confidence intervals (CIs) on an intention-to-treat basis. We assessed the overall quality of the evidence for the main comparisons using GRADE methods.

MAIN RESULTS

We included three RCTs, with a total of 563 women, that compared incubation of embryos at 37.0°C or 37.1°C with a lower incubator temperature (37.0°C versus 36.6°C, 37.1°C versus 36.0°C, 37.0° versus 36.5°C). Live birth, miscarriage, clinical pregnancy, ongoing pregnancy and multiple pregnancy were reported. After additional information from the authors, we confirmed one study as having no adverse events; the other two studies did not report adverse events. We did not perform a meta-analysis as there were not enough studies included per outcome. Live birth was not graded since there were no data of interest available. The evidence for the primary outcome, miscarriage, was of very low quality. The evidence for the secondary outcomes, clinical pregnancy, ongoing pregnancy and multiple pregnancy was also of very low quality. We downgraded the evidence because of high risk of bias (for performance bias) and imprecision due to limited included studies and wide CIs.Only one study reported the primary outcome, live birth (n = 52). They performed randomisation at the level of oocytes and not per woman, and used a paired design whereby two embryos, one from 36.0°C and one from 37.0°C, were transferred. The data from this study were not interpretable in a meaningful way and therefore not presented. Only one study reported miscarriage. We are uncertain whether incubation at a lower temperature decreases the miscarriage (odds ratio (OR) 0.90, 95% CI 0.52 to 1.55; 1 study, N = 412; very low-quality evidence).Of the two studies that reported clinical pregnancy, only one of them performed randomisation per woman. We are uncertain whether a lower temperature improves clinical pregnancy compared to 37°C for embryo incubation (OR 1.08, 95% CI 0.73 to 1.60; 1 study, N = 412; very low-quality evidence). For the outcome, ongoing pregnancy, we are uncertain if a lower temperature is better than 37°C (OR 1.10, 95% CI 0.75 to 1.62; 1 study, N = 412; very low quality-evidence). Multiple pregnancy was reported by two studies, one of which used a paired design, which made it impossible to report the data per temperature. We are uncertain if a temperature lower than 37°C reduces multiple pregnancy (OR 0.80, 95% CI 0.31 to 2.07; 1 study, N = 412; very low-quality evidence). There was insufficient evidence to make a conclusion regarding adverse events, as no studies reported data suitable for analysis.

AUTHORS' CONCLUSIONS

This review evaluated different temperatures for embryo culture during IVF. There is a lack of evidence for the majority of outcomes in this review. Based on very low-quality evidence, we are uncertain if incubating at a lower temperature than 37°C improves pregnancy outcomes. More RCTs are needed for comparing different temperatures of embryo culture which require reporting of clinical outcomes as live birth, miscarriage, clinical pregnancy and adverse events.

Performance of Day 5 KIDScore™ morphokinetic prediction models of implantation and live birth after single blastocyst transfer

PURPOSE

While several studies reported the association between morphokinetic parameters and implantation, few predictive models were developed to predict implantation after day 5 embryo transfer, generally without external validation. The objective of this study was to evaluate the respective performance of 2 commercially available morphokinetic-based models (KIDScore™ Day 5 versions 1 and 2) for the prediction of implantation and live birth after day 5 single blastocyst transfer.

METHODS

This monocentric retrospective study was conducted on 210 ICSI cycles with single day 5 embryo transfer performed with a time-lapse imaging (TLI) system between 2013 and 2016. The association between both KIDScore™ and the observed implantation and live birth rates was calculated, as well as the agreement between embryologist's choice for transfer and embryo ranking by the models.

RESULTS

Implantation and live birth rate were both 35.7%. A significant positive correlation was found between both models and implantation rate (r = 0.96 and r = 0.90, p = 0.01) respectively. Both models had statistically significant but limited predictive power for implantation (AUC 0.60). There was a fair agreement between the embryologists' choice and both models (78% and 61% respectively), with minor differences in case of discrepancies.

CONCLUSIONS

KIDScore™ Day 5 predictive models are significantly associated with implantation rates after day 5 single blastocyst transfer. However, their predictive performance remains perfectible. The use of these predictive models holds promises as decision-making tools to help the embryologist select the best embryo, ultimately facilitating the implementation of SET policy. However, embryologists' expertise remains absolutely necessary to make the final decision.

Endometriosis accelerates synchronization of early embryo cell divisions but does not change morphokinetic dynamics in endometriosis patients

OBJECTIVE

The pathology of endometriosis and its impact on embryo development is still a black box in reproductive medicine. In this time-lapse study we investigated the influence of endometriosis on morphokinetic parameters of embryo development, taking variables of dynamic monitoring into account. Furthermore we evaluated reproductive medicine treatment outcome such as fetal heartbeat and live birth rate.

METHODS

1148 embryos (control: n = 596, endometriosis: n = 552) were retrospectively analyzed. Patients were stimulated with GnRH antagonist protocol. After fertilization, embryos were incubated in a time-lapse system (EmbryoScope).

RESULTS

The mixed-model analysis revealed a significant main effect of time (p<0.001), with post-hoc tests showing that any time needed to reach a specific developmental stage was significantly different from all the others (all p<0.001). Embryos of endometriosis patients showed the same absolute morphokinetic time parameters as the control group, however, synchronization of early embryo cell divisions (s2) was faster in endometriosis patients compared to the control group.

CONCLUSION

In general, endometriosis does not induce changes in early embryo morphokinetics. However, observed acceleration in cell cycle synchronization of embryo cleavage patterns might be a missing explanation for contradicting results in literature regarding the impairments in reproductive medicine treatment outcome of endometriosis patients.

Time-lapse systems for embryo incubation and assessment in assisted reproduction

BACKGROUND

Embryo incubation and assessment is a vital step in assisted reproductive technology (ART). Traditionally, embryo assessment has been achieved by removing embryos from a conventional incubator daily for quality assessment by an embryologist, under a microscope. In recent years time-lapse systems (TLS) have been developed which can take digital images of embryos at frequent time intervals. This allows embryologists, with or without the assistance of embryo selection software, to assess the quality of the embryos without physically removing them from the incubator.The potential advantages of a TLS include the ability to maintain a stable culture environment, therefore limiting the exposure of embryos to changes in gas composition, temperature, and movement. A TLS has the potential advantage of improving embryo selection for ART treatment by utilising additional information gained through continuously monitoring embryo development. Use of a TLS often adds significant extra cost to ART treatment.

OBJECTIVES

To determine the effect of a TLS compared to conventional embryo incubation and assessment on clinical outcomes in couples undergoing ART.

SEARCH METHODS

We used standard methodology recommended by Cochrane. We searched the Cochrane Gynaecology and Fertility (CGF) Group Trials Register, CENTRAL, MEDLINE, Embase, CINAHL, and two trials registers on 7 January 2019 and checked references of appropriate papers.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing TLS, with or without embryo selection software, versus conventional incubation with morphological assessment; and TLS with embryo selection software versus TLS without embryo selection software among couples undergoing ART.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. The primary review outcomes were live birth or ongoing pregnancy, miscarriage and stillbirth, and cumulative live birth or ongoing pregnancy rate. The secondary outcomes were clinical pregnancy and cumulative clinical pregnancy. We assessed the quality of the evidence using GRADE methodology. We made the following comparisons.TLS with conventional morphological assessment of still TLS images versus conventional incubation and assessmentTLS utilising embryo selection software versus TLS with conventional morphological assessment of still TLS images TLS utilising embryo selection software versus conventional incubation and assessment MAIN RESULTS: We included nine RCTs (N = 2955 infertile couples). The quality of the evidence ranged from very low to low. The main limitations were high risk of bias in the included studies, imprecision, indirectness, and inconsistency. There were no data on cumulative live birth or ongoing pregnancy rate or cumulative clinical pregnancy rate.TLS with conventional morphological assessment of still TLS images versus conventional incubation and assessmentIt is unclear whether there is any difference between interventions in rates of live birth or ongoing pregnancy (odds ratio (OR) 0.91, 95% confidence interval (CI) 0.67 to 1.23, 3 RCTs, N = 826, I² = 33%, low-quality evidence) or in miscarriage rates (OR 1.90, 95% CI 0.99 to 3.61, 3 RCTs, N = 826, I² = 0%, low-quality evidence). The evidence suggests that if the rate of live birth or ongoing pregnancy associated with conventional incubation and assessment is 35%, the rate with the use of TLS with conventional morphological assessment of still TLS images would be between 27% and 40%, and if the miscarriage rate with conventional incubation is 4%, the rate associated with conventional morphological assessment of still TLS images would be between 4% and 14%. It is unclear whether there is a difference between the interventions in rates of stillbirth (OR 1.00, 95% CI 0.13 to 7.49, 1 RCT, N = 76, low-quality evidence) or clinical pregnancy (OR 1.06, 95% CI 0.79 to 1.41, 4 RCTs, N = 875, I² = 0%, low-quality evidence).TLS utilising embryo selection software versus TLS with conventional morphological assessment of still TLS imagesAll findings for this comparison were very uncertain due to the very low-quality of the evidence. No data were available on live birth, but one RCT reported ongoing pregnancy. It is unclear whether there is any difference between the interventions in rates of ongoing pregnancy (OR 0.61, 95% CI 0.32 to 1.20, 1 RCT, N = 163); miscarriage (OR 1.39, 95% CI 0.64 to 3.01, 2 RCTs, N = 463, I² = 0%); or clinical pregnancy (OR 0.97, 95% CI 0.67 to 1.42, 2 RCTs, N = 463, I² = 0%). The evidence suggests that if the rate of ongoing pregnancy associated with TLS with conventional morphological assessment of still TLS images is 47%, the rate associated with TLS utilising embryo selection software would be between 22% and 52%, and if the miscarriage rate associated with conventional morphological assessment of still TLS images is 5%, the rate associated with TLS utilising embryo selection software would be between 4% and 15%. No studies reported stillbirth.TLS utilising embryo selection software versus conventional incubation and assessmentThe findings for this comparison were also very uncertain due to the very low quality of the evidence. It is unclear whether there is any difference between the interventions in rates of live birth (OR 1.12, 95% CI 0.92 to 1.36, 3 RCTs, N = 1617, I² = 84%). There was very low-quality evidence that TLS might reduce miscarriage rates (OR 0.63, 95% CI 0.45 to 0.89, 3 RCTs, N = 1617, I² = 0%). It is unclear whether there is any difference between the interventions in rates of clinical pregnancy (OR 0.95, 95% CI 0.78 to 1.16, 3 RCTs, N = 1617, I² = 89%). The evidence suggests that if the rate of live birth associated with conventional incubation and assessment is 48%, the rate with TLS utilising embryo selection software would be between 46% and 55%, and if the miscarriage rate with conventional incubation and assessment is 11%, the rate associated with TLS would be between 5% and 10%. No stillbirths occurred in the only study reporting this outcome.

AUTHORS' CONCLUSIONS

There is insufficient good-quality evidence of differences in live birth or ongoing pregnancy, miscarriage and stillbirth, or clinical pregnancy to choose between TLS, with or without embryo selection software, and conventional incubation. As the evidence is of low or very low-quality, our findings should be interpreted with caution.

Time-lapse videography for embryo selection/de-selection: a bright future or fading star?

The recent clinical introduction of time-lapse videography into in vitro fertilization laboratories has offered a novel opportunity for embryologists to explore improved methods for embryo selection. While the concept of uninterrupted culture of embryos provided by such systems is welcomed, the current evidence does not support its full application in routine clinical practice. The issue of whether or not algorithms for embryo selection can be extrapolated between laboratories, which may represent a major hurdle to its wide application, is currently gaining increasing attention amongst embryologists worldwide. In this commentary issues identified in time-lapse embryo selection/de-selection algorithms, such as quantitative versus qualitative parameters, are discussed alongside the reference start point for the timing system, and types of datasets used for developing and validating time-lapse algorithms. Considering these factors, alternative future research directions which could potentially solve current issues are proposed.

Artificial intelligence and machine learning for human reproduction and embryology presented at ASRM and ESHRE 2018

Sixteen artificial intelligence (AI) and machine learning (ML) approaches were reported at the 2018 annual congresses of the American Society for Reproductive Biology (9) and European Society for Human Reproduction and Embryology (7). Nearly every aspect of patient care was investigated, including sperm morphology, sperm identification, identification of empty or oocyte containing follicles, predicting embryo cell stages, predicting blastocyst formation from oocytes, assessing human blastocyst quality, predicting live birth from blastocysts, improving embryo selection, and for developing optimal IVF stimulation protocols. This represents a substantial increase in reports over 2017, where just one abstract each was reported at ASRM (AI) and ESHRE (ML). Our analysis reveals wide variability in how AI and ML methods are described (from not at all or very generic to fully describing the architectural framework) and large variability on accepted dataset sizes (from just 3 patients with 16 follicles in the smallest dataset to 661,060 images of 11,898 human embryos in one of the largest). AI and ML are clearly burgeoning methodologies in human reproduction and embryology and would benefit from early application of reporting standards.

An integrated investigation of oocyte developmental competence: expression of key genes in human cumulus cells, morphokinetics of early divisions, blastulation, and euploidy

PURPOSE

To investigate the association of cumulus cell (CC)-related expression of a selected cluster of key genes (PTGS2, CAMK1D, HAS2, STC1, and EFNB2) with embryo development to blastocyst.

METHODS

Exploratory study at a private clinic. Eighteen advanced maternal age patients were enrolled (37.3 ± 4.0 years). Seventy-five cumuli were collected, whose oocytes resulted in either developmental arrest (N = 33) or blastocyst formation (N = 42). The noninvasive CC gene expression was combined with time-lapse morphokinetic parameters and, for blastocysts, with qPCR-based aneuploidy testing on trophectoderm biopsies.

RESULTS

The detection rate was 100% for all transcripts, but STC1 (96%) and CAMK1D (89%). Among amplified assays, CC mean expression levels of CAMK1D, PTGS2, and HAS2 were higher from oocytes that developed to blastocyst. No difference in CC key gene expression was reported between euploid (N = 21) and aneuploid (N = 21) blastocysts. Some timings of early embryo development were faster in embryos developing to blastocyst (time of pronuclei appearance and fading, division to two- and four-cells, first and second cell cycles). However, the generalized linear models outlined increasing CAMK1D expression levels as the strongest parameter associated with oocytes' developmental potential from both a general (AUC = 0.78 among amplified samples) and an intrapatient perspectives (AUC = 0.9 among patients obtaining ≥ 2 zygotes from the cohort with different developmental outcomes).

CONCLUSIONS

CAMK1D level of expression in CCs associated with blastocyst development. If confirmed from larger studies in wider populations of patients, the investigation of CC key gene expression might suit IVF clinics not adopting blastocyst culture. Future investigations should clarify the role of CAMK1D in ovarian physiology and could provide novel insights on how oocytes gain competence during folliculogenesis.

Human frozen-thawed blastocyst morphokinetics observed using time-lapse cinematography reflects the number of trophectoderm cells

Recent studies reported morphokinetic indices for optimal selection of embryos in assisted reproductive technology (ART). The morphokinetics in blastocyst stage include the collapse and re-expansion rates after thawing. However, evaluation methods using these morphokinetics have not been established, mainly because the underlying molecular mechanisms remain unclarified. In this study, we focused on the relationship between these morphokinetic observation of the blastocyst behaviour and the number of cells constituting the blastocyst. We evaluated 38 surplus human frozen-thawed blastocysts using time-lapse cinematography and recorded their expansion, contraction, and hatching. A total of 28 blastocysts expanded in culture (cross-sectional area ≥ 5,000 π μm²). In comparison to the ones that did not, the expanded group presented significantly more number of inner cell mass (ICM) and trophectoderm (TE) cells, which eventually develop into the fetus and placenta, respectively (ICM: Expanded 10.2 ± 6.3 vs. Non-Expanded 6.0 ± 12.3, p < 0.05; TE: Expanded 165.7 ± 74.8 vs. Non-Expanded 57.0 ± 29.4, p < 0.05). Moreover, a positive correlation was found between the expansion rate (up to 4 h) and the number of TE cells (r = 0.558, p = 0.0021). Additionally, blastocysts that hatched had a significantly higher number of TE cells than those that did not (hatching 225.2 ± 61.2 vs. no hatching 121.1 ± 48.6, p < 0.0001). The number of TE cells per unit of cross-sectional area correlated negatively with the contraction time (r = –0.601, p = 0.0007). No correlation between the number of ICM cells and these morphokinetics was detected. In conclusion, our study demonstrates that different morphokinetics of frozen-thawed blastocysts reflect the number of TE cells. The differentiation of blastocysts containing sufficient TE cells would be beneficial for implantation and prognosis of a subsequent pregnancy. Thus, evaluation of these morphokinetics can be an effective method to screen good embryos for ART.