The impact of selected embryo culture conditions on ART treatment cycle outcomes: a UK national study

Embryologist staffing in assisted reproductive technology laboratories: An international comparative review

Background

Embryologists are crucial in assisted reproductive technology (ART), yet their duties, education, and licensing requirements vary significantly across countries, complicating the determination of optimal staffing levels in ART laboratories. With anticipated advancements such as automation in ART laboratories, this review comprehensively analyzes factors necessary for appropriate future staffing.

Main Findings

A comprehensive literature search was conducted using PubMed to identify relevant articles up to July 2024, employing keywords such as "embryologist," "staffing," and "certification." Articles were evaluated for content related to laboratory operations, and guidelines from five organizations regarding licensing and education were compared.

Results

The review revealed significant international differences in embryologist certification, duties, and staffing recommendations. These disparities, along with the integration of advanced ART technologies and regulatory requirements, significantly impact future staffing needs in ART laboratories.

Conclusion

The definitions of an ART cycle and required staffing levels vary across organizations, influenced by the certification and duties of embryologists in different countries. Adequate embryologist staffing is essential for ensuring laboratory quality control and impacting patient ART outcomes. As new technologies and automation reshape laboratory workflows, collaborative efforts among organizations, countries, and embryologist associations are essential for developing comprehensive educational curricula and determining appropriate staffing levels.

Neonatal outcomes among twins born through assisted reproduction, compared to those born naturally

The growing prevalence of assisted reproductive technology (ART) is leading to a continuous rise in twin pregnancies. This study assessed the influence of ART on neonatal outcomes of twin pregnancies. Clinical records of twin deliveries at Fujian Maternity and Child Health Hospital between 2019 and 2021 were retrospectively selected and grouped based on the method of conception: ART-conceived and naturally conceived. Neonatal outcomes of interest included low birth weight (LBW), intrauterine growth restriction (IUGR), prematurity, low Appearance, Pulse, Grimace, Activity and Respiration scores, and neonatal intensive care unit admission. Univariate and multivariable logistic regression analyses were conducted to adjust for potential confounders. The results were expressed as odds ratio (OR) with 95% confidence interval (CI). A total of 1270 pairs of twins were included in the analysis. ART-conceived twins had significantly lower odds of being born with LBW (adjusted OR 0.57, 95% CI: 0.43, 0.75), prematurity (adjusted OR 0.71, 95% CI: 0.55, 0.91), and IUGR (adjusted OR 0.21, 95% CI: 0.10, 0.39) compared to naturally conceived twins. Rates of other outcomes were comparable in both groups. Twins born through ART had reduced odds of LBW, prematurity, and IUGR, with no impact on other neonatal outcomes. These findings suggest that ART may have a protective effect on twin fetal growth, although the risks associated with multiple gestations remain. Further studies should explore the mechanisms and long-term effects of these outcomes.

Deep learning pipeline reveals key moments in human embryonic development predictive of live birth after in vitro fertilization

Demand for in vitro fertilization (IVF) treatment is growing; however, success rates remain low partly due to difficulty in selecting the best embryo to be transferred. Current manual assessments are subjective and may not take advantage of the most informative moments in embryo development. Here, we apply convolutional neural networks (CNNs) to identify key windows in pre-implantation human development that can be linked to embryo viability and are therefore suitable for the early grading of IVF embryos. We show how machine learning models trained at these developmental time points can be used to refine overall embryo viability assessment. Exploiting the well-known capabilities of transfer learning, we illustrate the performance of CNN models for very limited datasets, paving the way for the use on a clinic-by-clinic basis, catering for local data heterogeneity.

Do IVF culture conditions have an impact on neonatal outcomes? A systematic review and meta-analysis

PURPOSE

Are embryo culture conditions, including type of incubator, oxygen tension, and culture media, associated with obstetric or neonatal complications following in vitro fertilization (IVF)?

METHODS

A systematic search of MEDLINE, EMBASE, and Cochrane Library was performed from January 01, 2008, until October 31, 2021. The studies reporting quantitative data on at least one of the primary outcomes (birthweight and preterm birth) for the exposure group and the control group were included. For oxygen tension, independent meta-analysis was performed using Review Manager, comparing hypoxia/normoxia. For culture media, a network meta-analysis was carried out using R software, allowing the inclusion of articles comparing two or more culture media.

RESULTS

After reviewing 182 records, 39 full-text articles were assessed for eligibility. A total of 28 studies were kept for review. Meta-analysis about the impact of incubator type on perinatal outcomes could not be carried out because of a limited number of studies. For oxygen tension, three studies were included. The pairwise meta-analysis comparing hypoxia/normoxia did not show any statistical difference for birthweight and gestational age at birth. For culture media, 18 studies were included. The network meta-analysis failed to reveal any significant impact of different culture media on birthweight or preterm birth.

CONCLUSION

No difference was observed for neonatal outcomes according to the embryo culture conditions evaluated in this review. Further research is needed about the safety of IVF culture conditions as far as future children's health is concerned.

Effects of Melatonin, GM-CSF, IGF-1, and LIF in Culture Media on Embryonic Development: Potential Benefits of Individualization

The implantation of good-quality embryos to the receptive endometrium is essential for successful live birth through in vitro fertilization (IVF). The higher the quality of embryos, the higher the live birth rate per cycle, and so efforts have been made to obtain as many high-quality embryos as possible after fertilization. In addition to an effective controlled ovarian stimulation process to obtain high-quality embryos, the composition of the embryo culture medium in direct contact with embryos in vitro is also important. During embryonic development, under the control of female sex hormones, the fallopian tubes and endometrium create a microenvironment that supplies the nutrients and substances necessary for embryos at each stage. During this process, the development of the embryo is finely regulated by signaling molecules, such as growth factors and cytokines secreted from the epithelial cells of the fallopian tube and uterine endometrium. The development of embryo culture media has continued since the first successful human birth through IVF in 1978. However, there are still limitations to mimicking a microenvironment similar to the reproductive organs of women suitable for embryo development in vitro. Efforts have been made to overcome the harsh in vitro culture environment and obtain high-quality embryos by adding various supplements, such as antioxidants and growth factors, to the embryo culture medium. Recently, there has been an increase in the number of studies on the effect of supplementation in different clinical situations such as old age, recurrent implantation failure (RIF), and unexplained infertility; in addition, anticipation of the potential benefits from individuation is rising. This article reviews the effects of representative supplements in culture media on embryo development.

Low E-visibility of embryologists on fertility clinic websites: a web-based cross-sectional study

PURPOSE

This study assessed the visibility of embryologists on fertility clinic websites among Society for Assisted Reproductive Technology (SART) and the Human Fertilisation and Embryology Authority (HFEA) member clinics.

METHODS

During a 1-month interval (March 2022), all Society for Assisted Reproductive Technology (SART) and the Human Fertilisation and Embryology Authority (HFEA) member fertility clinic websites were evaluated. The professional representation of the primary care team was examined including specialties, the presence of headshots, and biographies.

RESULTS

A total of 446 fertility clinic websites were scanned in the search. The embryology team has the least common professional identification by their names (53.58%) compared to gynecology clinicians (96.21%, p < 0.001) and nurses (55.58%, p < 0.001). This trend also applies to other types of professional identifiers, such as headshots and biographies. Professional headshots of embryologists (50.34%) were less prominent than those of gynecology clinicians (93.51%, p < 0.001). A similar trend was observed in the biographies of the embryology team (47.20%) compared to gynecology clinicians (95.08%, p < 0.001).

CONCLUSION

The present study revealed that embryologists have low professional visibility on fertility clinic websites. Fertility clinics may prioritize enhancing the online visibility of their embryology laboratory team. This approach could potentially enhance the recognition of their team, foster transparency, and provide accessible information about the skills and expertise of healthcare professionals involved in the treatment process.

Comparison of the effect of two commercialized vitrification carriers on pregnancy outcomes in freeze-thaw cycles

OBJECTIVE

This study aimed to compare the effects of two brands of commercial vitrification carriers on pregnancy outcomes in freeze-thaw cycles.

METHODS

We included 4871 patients who underwent a "freeze all" strategy using the commercial carriers J.Y. straw and OYASHIPS straw in the Reproductive Center of the First Hospital of Jilin University. The pregnancy outcomes of cleavage-stage embryos and blastocysts were studied separately. Detailed data and the safety of children born from mothers with the two types of carriers were also compared.

RESULTS

Patients who used J.Y. straw had similar clinical pregnancy and live birth rates with one and two cleavage-stage embryo transplantation to those who used OYASHIPS straw. In patients who had blastocyst transplantation, the clinical pregnancy rate of one blastocyst transplanted in those who used OYASHIPS straw was significantly higher than that in those who used J.Y. straw (57.85% vs 47.09%). Among children born from mothers who used J.Y. straw, the congenital disability rate was significantly higher than that in those with OYASHIPS straw.

CONCLUSION

The OYASHIPS straw carrier is cheap and can achieve clinical pregnancy and live birth outcomes comparable to those of J.Y. straw. Therefore, OYASHIPS straw is a good alternative option.

ESHRE Working Group on Embryologist Training Analysis, Scarica C, Woodward BJ, De Santis L, Kovačič B. Training and competency assessment of Clinical Embryologists and licensing of the profession in European countries

STUDY QUESTION

How is the acquisition and testing of theoretical and practical knowledge in Clinical Embryology and the licensing of ART laboratory personnel carried out in European countries?

SUMMARY ANSWER

Twelve out of 31 European countries have established some kind of verification of laboratory competency and skills in ART: in 7 countries, this was related to licensing, but where organized education for Clinical Embryologists existed, there were vast differences in the way these processes were undertaken.

WHAT IS KNOWN ALREADY

In 2015, a report by the ESHRE Embryology Certification Committee concluded that regardless of the large number of people working in IVF laboratories, Clinical Embryology was only recognized as an official profession in 3 out of 27 European national health systems. In most countries, Clinical Embryologists needed to be officially registered under an alternative profession and there were limited opportunities for organized education in this specialist field. Five years after this report, the ESHRE Working Group on Embryologist Training Analysis conducted a survey to collect detailed information about how Clinical Embryologists from different European countries are acquiring their theoretical knowledge and practical skills in ART, and how their level of education and competence in Clinical Embryology is verified.

STUDY DESIGN SIZE DURATION

Two questionnaires about the possibilities for acquiring the education and training needed to work in ART and verification of this knowledge were prepared by the ESHRE Working Group on Embryologist Training Analysis. The first was sent in 2020 to a panel of invited lead European Embryologists who attended an Expert Meeting held in Rome, Italy. In order to have a more comprehensive and updated picture, in 2021 the same survey was also sent to the ESHRE Committee of National Representatives (CNRs). At the end of 2021, the second survey with specific questions, more focused on Clinical Embryologists' training and licencing, was sent to the CNRs who reported on verification of education in Clinical Embryology.

PARTICIPANTS/MATERIALS SETTING METHODS

The first survey consisted of 17 questions. It was initially submitted to 14 lead Embryologists and then resubmitted to the 34 ESHRE CNRs. Representatives from 31 countries responded. A second survey with 23 questions was sent to the 12 ESHRE CNRs who reported an established national system of verification of education in Clinical Embryology, with specific questions focused on the training of Clinical Embryologists. All 12 CNRs responded.

MAIN RESULTS AND THE ROLE OF CHANCE

Analysis showed that European national education programmes in Clinical Embryology could be split into 4 categories: non-existent (13 countries), recommended (5 countries), simple compulsory (9 countries), and complex compulsory (4 countries). A national document stating the minimum education requirements for staff to work in an IVF laboratory was reported by 19 respondents. The requirement to follow a prescribed theoretical and laboratory training programme in ART was compulsory in 9 and 10 countries, respectively. Some form of verification of laboratory skills, theoretical knowledge in ART, and continuing professional development was required in 12, 10, and 9 countries, respectively. A national trainee's logbook format was reported by seven respondents and a national tutorial system was available in six countries. Only seven countries had official licensing of ART laboratory staff. The title of Clinical Embryologist was not recognized in 13 countries and in 6 countries, it was used only by professional bodies, while in 12 countries the profession was at least cited in governmental regulations. The ESHRE Clinical Embryologist Certificate was officially recognized in eight countries.

LIMITATIONS REASONS FOR CAUTION

The survey took place in two steps and the results were then combined to provide a representative picture for most of the European countries sampled. The vast majority, but not all, of the CNRs answered the request to participate in the survey.

WIDER IMPLICATIONS OF THE FINDINGS

The professional recognition of Clinical Embryology within Europe is steadily evolving. However, it remains a concern that many countries continue to not recognize Clinical Embryology as a profession, with a vast difference in the reported organization of educational and training programmes and verification of skills. It is recommended that a training programme for Clinical Embryology and ART in Europe should be standardized and relevant issues should be addressed by competent authorities and European Union institutions. ESHRE is best placed to take a leading role in this educational process.

STUDY FUNDING/COMPETING INTERESTS

The Working Group members who are the authors of this article did not receive payments for the completion of this study. The authors have no conflicts of interest to declare.

Leukocyte telomere length in children born following blastocyst-stage embryo transfer

Perinatal and childhood adverse outcomes associated with assisted reproductive technology (ART) has been reported, but it remains unknown whether the initial leukocyte telomere length (LTL), which is an indicator of age-related phenotypes in later life, is affected. Here, we estimated the LTLs of 1,137 individuals from 365 families, including 202 children conceived by ART and 205 children conceived spontaneously from two centers of the China National Birth Cohort, using whole-genome sequencing (WGS) data. One-year-old children conceived by ART had shorter LTLs than those conceived spontaneously (beta, -0.36; P = 1.29 × 10-3) after adjusting for plurality, sex and other potential confounding factors. In particular, blastocyst-stage embryo transfer was associated with shorter LTL (beta, -0.54, P = 2.69 × 10-3) in children conceived by ART. The association was validated in 586 children conceived by ART from five centers using different LTL quantification methods (that is, WGS or qPCR). Blastocyst-stage embryo transfer resulted in shorter telomere lengths in mice at postnatal day 1 (P = 2.10 × 10-4) and mice at 6 months (P = 0.042). In vitro culturing of mice embryos did not result in shorter telomere lengths in the late cleavage stage, but it did suppress telomerase activity in the early blastocyst stage. Our findings demonstrate the need to evaluate the long-term consequences of ART, particularly for aging-related phenotypes, in children conceived by ART.

An examination of mediation by DNA methylation on birthweight differences induced by assisted reproductive technologies

BACKGROUND

Children born after assisted reproductive technologies (ART) differ in birthweight from those naturally conceived. It has been hypothesized that this might be explained by epigenetic mechanisms. We examined whether cord blood DNA methylation mediated the birthweight difference between 890 newborns conceived by ART (764 by fresh embryo transfer and 126 frozen thawed embryo transfer) and 983 naturally conceived newborns from the Norwegian Mother, Father, and Child Cohort Study (MoBa). DNA methylation was measured by the Illumina Infinium MethylationEPIC array. We conducted mediation analyses to assess whether differentially methylated CpGs mediated the differences in birthweight observed between: (1) fresh embryo transfer and natural conception and (2) frozen and fresh embryo transfer.

RESULTS

We observed a difference in birthweight between fresh embryo transfer and naturally conceived offspring of - 120 g. 44% (95% confidence interval [CI] 26% to 81%) of this difference in birthweight between fresh embryo transfer and naturally conceived offspring was explained by differences in methylation levels at four CpGs near LOXL1, CDH20, and DRC1. DNA methylation differences at two CpGs near PTGS1 and RASGRP4 jointly mediated 22% (95% CI 8.1% to 50.3%) of the birthweight differences between fresh and frozen embryo transfer.

CONCLUSION

Our findings suggest that DNA methylation is an important mechanism in explaining birthweight differences according to the mode of conception. Further research should examine how gene regulation at these loci influences fetal growth.

Does PGT-A improve assisted reproduction treatment success rates: what can the UK Register data tell us?

PURPOSE

To show how naïve analyses of aggregated UK ART Register data held by the Human Fertilisation and Embryology Authority to estimate the effects of PGT-A can be severely misleading and to indicate how it may be possible to do a more credible analysis. Given the limitations of the Register, we consider the extent to which such an analysis has the potential to answer questions about the real-world effectiveness of PGT-A.

METHODS

We utilise the publicly available Register datasets and construct logistic regression models for live birth events (LBE) which adjust for confounding. We compare all PGT-A cycles to control groups of cycles that could have had PGT-A, excluding cycles that did not progress to having embryos for biopsy.

RESULTS

The primary model gives an odds ratio for LBE of 0.82 (95% CI 0.68-1.00) suggesting PGT-A may be detrimental rather than beneficial. However, due to limitations in the availability of important variables in the public dataset, this cannot be considered a definitive estimate. We outline the steps required to enable a credible analysis of the Register data.

CONCLUSION

If we compare like with like groups, we obtain estimates of the effect of PGT-A that suggest an overall modest reduction in treatment success rates. These are in direct contrast to an invalid comparison of crude success rates. A detailed analysis of a fuller dataset is warranted, but it remains to be demonstrated whether the UK Register data can provide useful estimates of the impact of PGT-A when used as a treatment add-on.

V, Joseph D, Raval K, Gowda G. A. N, Kalthur G, Adiga SK. Duration of dry and humidified incubation of single-step embryo culture medium and oxygen tension during sham culture do not alter medium composition

Background: The extended embryo culture using single-step medium gained popularity in clinical in vitro fertilisation (IVF). However, there are concerns about the degradation of unstable medium components and their negative effects on the developing embryos. Further, dry-incubation can increase osmolality, which can in-turn enhance the concentration of constituents of the media and their stability. Hence, this study was conducted to understand the immediate changes in the culture media constituents in relation to clinically comparable situations such as single-step extended embryo culture and use of dry and humidified-incubation in two-different gaseous conditions. Methods: Commercially available single-step medium was sham-cultured in droplets under oil in two different conditions viz. dry (37°C; 6%CO 2; 5%O 2) and humidified (37°C; 6% CO 2; atmospheric O 2) for 0h, 72h, and 120h intervals. Droplets were subjected to the sensitivity-enhanced nuclear magnetic resonance (NMR)-based profiling using 800 MHz NMR equipped with a cryogenically cooled micro-coil (1.7mm) probe. NMR profile of the embryo culture medium between the two groups were comprehensively assessed. Results: A total of ten amino acids and four energy substrates were identified from the culture medium. The medium constituents identified showed a non-significant increase in the dry-incubation group at 72h and then declined at 120h. Humidified incubation had no effects on the level of the identified medium constituents until 120h. No significant differences in the levels of medium constituents identified were observed between the dry and humidified-groups at various time-points tested. Conclusions: A non-significant variation in the levels of medium constituents observed in the dry-incubation of single-step medium most unlikely to influence a clinical outcome. However, the impact of these subtle changes on the (epi)genetic integrity of the embryos in a clinical set-up to be addressed.

Does Post-Warming Extended Culture Duration Affect the Clinical and Obstetric Outcomes of Patients of Advanced Maternal Age? A Single-Center Study

BACKGROUND

The single vitrified-warmed blastocyst transfer (SVBT) cycle has been increasingly utilized for assisted reproductive technology. Women of advanced maternal age (AMA) comprise a significant portion of patients who have undergone 'freeze-all' cycles. This study investigated the association between the post-warming extended culture duration and pregnancy outcomes in patients of AMA.

METHODS

This retrospective cohort study analyzed the outcomes of 697 SVBT cycles between January 2016 and December 2017. The cycles were divided into 3 groups based on the age of the female partners: group I: < 35 years (n = 407), group II: 35-37 years (n = 176); and group III, 38-40 years (n = 114). Data are shown as the mean ± standard error of the mean. Data were analyzed using one-way ANOVA followed by Duncan's multiple range test. Statistical significance was set at P < 0.001.

RESULTS

The blastocyst rate, clinical pregnancy rate, and live birth rate (LBR) was significantly lower in the AMA groups. However, there were no significant differences in LBR in the transfer between the AMA and younger groups according to blastocyst morphology and post-warming extended culture duration.

CONCLUSION

Post-warming extended culture of blastocysts is not harmful to patients of AMA. It could be a useful parameter in clinical counseling and decision making for fertility treatments.

Culture medium is associated with the risks of placenta previa and macrosomia in pregnancies after in vitro fertilization

PURPOSE

The culture medium plays an important role in embryonic development and subsequent pregnancy outcomes of in vitro fertilization (IVF) cycles. The sequential culture media of Vitrolife and Cook are the two most commonly used reagents in China. This study aimed to assess their effects on IVF success rates, obstetric outcomes and neonatal outcomes.

METHODS

This was a retrospective cohort study on 6352 patients undergoing first IVF attempts between January 2018 and December 2019, resulting in 3153 clinical pregnancies, 2646 live births, and 2668 babies. Patients were grouped according to the culture media they used. There were 4680 patients in the Vitrolife group and 1672 patients in the Cook group. The primary outcome measures were maternal and neonatal outcomes. ANOVA and Chi-square tests were used for statistical comparison, and multivariate logistic regression and multivariate general linear model were used to adjust for potential confounders.

RESULTS

The rates of live birth, clinical pregnancy, monozygotic twins, miscarriage, and ectopic pregnancy were all comparable between the groups of Vitrolife and Cook. The incidence of placenta previa was higher in the Vitrolife group [4.86 vs. 3.09%, adjusted odds ratio = 2.048 (1.146-3.657)]. The incidence of macrosomia was higher in the Cook group [7.51 vs. 5.39%, adjusted odds ratio = 1.445 (1.010-2.069)].

CONCLUSION

The culture media of Vitrolife and Cook are comparably effective in IVF success. Vitrolife is associated with a higher risk of placenta previa, while Cook is associated with a higher risk of macrosomia.

An expert commentary on essential equipment, supplies and culture media in the ART laboratory

The ART laboratory is a complex system designed to sustain the fertilization, survival, and culture of the preimplantation embryo to the blastocyst stage. ART outcomes depend on numerous factors, among which are the equipment, supplies and culture media used. The number and type of incubators also may affect ART results. While large incubators may be more suitable for media equilibration, bench-top incubators may provide better embryo culture conditions in separate or smaller chambers and may be coupled with time-lapse systems that allow continuous embryo monitoring. Microscopes are essential for observation, assessment, and micromanipulation. Workstations provide a controlled environment for gamete and embryo handling and their quantity should be adjusted according to the number of ART cycles treated in order to provide a steady and efficient workflow. Continuous maintenance, quality control and monitoring of equipment is essential and quality control devices such as the thermometer, and pH-meter are necessary to maintain optimal culture conditions. Tracking, appropriate delivery and storage conditions, and quality control of all consumables is recommended so that the adequate quantity and quality is available for use. Embryo culture media have evolved: preimplantation embryos are cultured either by sequential media or single-step media that can be used for interrupted or uninterrupted culture. There is currently no sufficient evidence that any individual commercially-available culture system is better than others in terms of embryo viability. In this review, we aim to analyse the various parameters that should be taken into account when choosing the essential equipment, consumables and culture media systems that will create optimal culture conditions and provide the most effective patient treatment.

Morphometric and morphokinetic differences in the sperm- and oocyte-originated pronuclei of male and female human zygotes: a time-lapse study

PURPOSE

To study the morphometric and morphokinetic profiles of pronuclei (PN) between male and female human zygotes.

METHOD(S)

This retrospective cohort study included 94 consecutive autologous single day 5 transfer cycles leading to a singleton live birth. All oocytes were placed in the EmbryoScope + incubator post-sperm injection with all annotations performed retrospectively by one embryologist (L-SO). Timing parameters included 2nd polar body extrusion (tPB2), sperm-originated PN (tSPNa) or oocyte-originated PN (tOPNa) appearance, and PN fading (tPNF). Morphometrics were evaluated at 8 (stage 1), 4 (stage 2), and 0 h before PNF (stage 3), measuring PN area (um²), PN juxtaposition, and nucleolar precursor bodies (NPB) arrangement.

RESULTS

Male zygotes had longer time intervals of tPB2_tSPNa than female zygotes (4.8 ± 0.2 vs 4.2 ± 0.1 h, OR = 1.442, 95% CI 1.009-2.061, p = 0.044). SPN increased in size from stage 1 through 2 to 3 (435.3 ± 7.2, 506.7 ± 8.0, and 556.3 ± 8.9 um², p = 0.000) and OPN did similarly (399.0 ± 6.1, 464.3 ± 6.7, and 513.8 ± 6.5 um², p = 0.000), with SPN being significantly larger than OPN at each stage (p < 0.05 respectively). More male than female zygotes reached central PN juxtaposition at stage 1 (76.7% vs 51.0%, p = 0.010), stage 2 (97.7% vs 86.3%, p = 0.048), and stage 3 (97.7% vs 86.3%, p = 0.048). More OPN showed aligned NPBs than in SPN at stage 1 only (44.7% vs 28.7%, p = 0.023).

CONCLUSION(S)

Embryos with different sexes display different morphokinetic and morphometric features at the zygotic stage. Embryo selection using such parameters may lead to unbalanced sex ratio in resulting offspring.

Back to the future: optimised microwell culture of individual human preimplantation stage embryos

Although in vitro culture of human embryos is a crucial step in assisted reproduction, the lack of focused research hampers worldwide standardisation and consistent outcomes. Only 1.2% of research papers published in five leading journals in human reproduction in 2019 focused on in vitro culture conditions, creating the impression that the optimisation process has approached its limits. On the other hand, in vitro culture of mammalian embryos is based on old principles, while there is no consensus on basic issues as density, time, medium change, gas atmosphere and small technical details including the way of drop preparation. This opinion paper aims to highlight and analyse the slow advancement in this field and stimulate research for simple and affordable solutions to meet the current requirements. A possible way for advancement is discussed in detail. Selection of embryos with the highest developmental competence requires individual culture and modification of the widely used "drop under oil" approach. Current use of three-dimensional surfaces instead of large flat bottoms is restricted to time-lapse systems, but these wells are designed for optical clarity, not for the needs of embryos. The size and shape of the original microwells (Well of the Well; WOW) offer a practical and straightforward solution to combine the benefits of communal and individual incubation and improve the overall quality of cultured embryos.

Cohort profile: a national, population-based cohort of children born after assisted conception in the UK (1992-2009): methodology and birthweight analysis

PURPOSE

To generate a large cohort of children born after assisted reproductive technology (ART) in the UK between 1992 and 2009, their naturally conceived siblings (NCS) and matched naturally conceived population (NCP) controls and linking this with health outcome data to allow exploration of the effects of ART. The effects of fresh and frozen embryo transfer on birth weight (BW) were analysed to test the validity of the cohort.

PARTICIPANTS

Children recorded on the Human Fertilisation and Embryology Authority (HFEA) register as being born after ART between 1992 and 2009, their NCS and matched NCP controls linked to Office for National Statistics birth registration dataset (HFEA-ONS cohort). This cohort was further linked to the UK Hospital Episode Statistics database to allow monitoring of the child's post-natal health outcomes up to 2015 (HFEA-ONS-HES subcohort).

FINDINGS TO DATE

The HFEA-ONS cohort consisted of 75 348 children born after non-donor ART carried out in the UK between 1 April 1992 and 31 July 2009 and successfully linked to birth registration records, 14 763 NCS and 164 823 matched NCP controls. The HFEA-ONS-HES subcohort included 63 877 ART, 11 343 NCS and 127 544 matched NCP controls further linked to health outcome data. The exemplar analysis showed that children born after fresh embryo transfers were lighter (BW difference: -131 g, 95% CI: -140 to -123) and those born after frozen embryo transfers were heavier (BW difference: 35 g, 95% CI: 19 to 52) than the NCP controls. The within-sibling analyses were directionally consistent with the population control analyses, but attenuated markedly for the fresh versus natural conception (BW difference: -54 g; 95% CI: -72 to -36) and increased markedly for the frozen versus natural conception (BW difference: 152 g; 95% CI: 113 to 190) analyses.

FUTURE PLANS

To use this cohort to explore the relationship between ART conception and short-term and long-term health outcomes in offspring.

Associations of IVF singleton birthweight and gestation with clinical treatment and laboratory factors: a multicentre cohort study

STUDY QUESTION

Do IVF treatment and laboratory factors affect singleton birthweight (BW)?

SUMMARY ANSWER

BWs of IVF-conceived singleton babies are increasing with time, but we cannot identify the specific treatment factors responsible.

WHAT IS KNOWN ALREADY

IVF-conceived singleton babies from fresh transfers have slightly lower BW than those conceived naturally, whilst those from frozen embryo transfer (FET) cycles are heavier and comparable to naturally conceived offspring. Our recent studies have shown that BW varies significantly between different IVF centres, and in a single centre, is also increasing with time, without a corresponding change in BWs of naturally conceived infants. Although it is likely that factors in the IVF treatment cycle, such as hormonal stimulation or embryo laboratory culture conditions, are associated with BW differences, our previous study designs were not able to confirm this.

STUDY DESIGN, SIZE, DURATION

Data relating to BW outcomes, IVF treatment and laboratory parameters were collated from pre-existing electronic records in five participating centres for all singleton babies conceived between August 2007 and December 2014.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Seven thousand, five hundred and eighty-eight births, 6207 from fresh and 1381 from FET. Infants with severe congenital abnormalities were excluded. The primary outcome of gestation-adjusted BW and secondary outcomes of unadjusted BW and gestation were analysed using multivariable regression models with robust standard errors to allow for the correlation between infants with the same mother. The models tested treatment factors allowing for confounding by centre, time and patient characteristics. A similar matched analysis of a subgroup of 379 sibling pairs was also performed.

MAIN RESULTS AND THE ROLE OF CHANCE

No significant associations of birth outcomes with IVF embryo culture parameters were seen independent of clinic or time, including embryo culture medium, incubator type or oxygen level, although small differences cannot be ruled out. We did not detect any significant differences associated with hormonal stimulation in fresh cycles or hormonal synchronization in FET cycles. Gestation-adjusted BW increased by 13.4 (95% CI 0.6-26.1) g per year over the period of the study, and babies born following FET were 92 (95% CI 57-128) g heavier on average than those from the fresh transfer.

LIMITATIONS, REASONS FOR CAUTION

Although no specific relationships have been identified independent of clinic and time, the confidence intervals remain large and do not exclude clinically relevant effect sizes. As this is an observational study, residual confounding may still be present.

WIDER IMPLICATIONS OF THE FINDINGS

This study demonstrates the potential for large scale analysis of routine data to address critical questions concerning the long-term implications of IVF treatment, in accordance with the Developmental Origins of Health and Disease hypothesis. However, much larger studies, at a national scale with sufficiently detailed data, are required to identify the treatment parameters associated with differences in BW or other relevant outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the EU FP7 project grant, EpiHealthNet (FP7-PEOPLE-2012-ITN-317146). No competing interests were identified.

TRIAL REGISTRATION NUMBER

N/A.

Deep learning early warning system for embryo culture conditions and embryologist performance in the ART laboratory

Staff competency is a crucial component of the in vitro fertilization (IVF) laboratory quality management system because it impacts clinical outcomes and informs the key performance indicators (KPIs) used to continuously monitor and assess culture conditions. Contemporary quality control and assurance in the IVF lab can be automated (collect, store, retrieve, and analyze), to elevate quality control and assurance beyond the cursory monthly review. Here we demonstrate that statistical KPI monitoring systems for individual embryologist performance and culture conditions can be detected by artificial intelligence systems to provide systemic, early detection of adverse outcomes, and identify clinically relevant shifts in pregnancy rates, providing critical validation for two statistical process controls proposed in the Vienna Consensus Document; intracytoplasmic sperm injection (ICSI) fertilization rate and day 3 embryo quality.

Back to the future: optimised microwell culture of individual human preimplantation stage embryos

Although in vitro culture of human embryos is a crucial step in assisted reproduction, the lack of focused research hampers worldwide standardisation and consistent outcomes. Only 1.2% of research papers published in five leading journals in human reproduction in 2019 focused on in vitro culture conditions, creating the impression that the optimisation process has approached its limits. On the other hand, in vitro culture of mammalian embryos is based on old principles, while there is no consensus on basic issues as density, time, medium change, gas atmosphere and small technical details including the way of drop preparation. This opinion paper aims to highlight and analyse the slow advancement in this field and stimulate research for simple and affordable solutions to meet the current requirements. A possible way for advancement is discussed in detail. Selection of embryos with the highest developmental competence requires individual culture and modification of the widely used "drop under oil" approach. Current use of three-dimensional surfaces instead of large flat bottoms is restricted to time-lapse systems, but these wells are designed for optical clarity, not for the needs of embryos. The size and shape of the original microwells (Well of the Well; WOW) offer a practical and straightforward solution to combine the benefits of communal and individual incubation and improve the overall quality of cultured embryos.

Euploidy rates are not affected when embryos are cultured in a continuous (CCM) or sequential culture medium (SCM): a sibling oocyte study

PURPOSE

To determine if euploidy rates and embryo development differ when blastocysts are cultured in CCM or SCM.

METHOD

A single-center retrospective observational study was performed from September 2018 to March 2019. Patients [23-46 years] with at least four fresh mature oocytes (MII) without severe male factor infertility were included. Sibling MII were injected and cultured in Global®Total®LP (CCM) or Sage Quinn's Advantage® Cleavage and Blastocyst media (SCM) under 6% CO₂, 5% O₂, and 89% N₂. Fertilization, cleavage, day (D) 5 blastulation, usable blastocyst (blastocysts biopsied/normally fertilized oocytes), and euploidy rates were recorded. Blastocysts were graded prior to trophectoderm (TE) biopsy on D5, 6, or 7 for genetic testing and mitochondrial DNA (mtDNA) quantification.

RESULTS

According to clinical practice, 1452 MII were randomly distributed: 751 in CCM and 701 in SCM. No differences were observed in fertilization and cleavages rates for CCM and SCM (77.4% vs 75.5%, p = 0.429 and 97.6% vs 99.1%, p = 0.094, respectively). Blastulation rate on D5 was higher in CCM (70.6% vs 62.2, p = 0.009); however, usable blastocyst rates were comparable (CCM: 58.3% vs SCM: 56.7%, p = 0.625). From a Poisson regression model adjusted for confounding factors, euploidy rates were not different between media (aOR = 1.18, [0.94-1.48], p = 0.157). Euploid blastocyst's mtDNA values were similar (CCM: 32.2, [30.5, 34.1] and SCM: 33.5, [31.8, 35.2], p = 0.345) and top-quality blastocysts (AA/BA) were increased in SCM (OR=1.04, [1.00-1.09], p = 0.037).

CONCLUSION

Under controlled in vitro conditions, euploidy rates and embryo development are comparable when embryos are cultured in CCM or SCM.

Clinical efficacy of hyaluronate-containing embryo transfer medium in IVF/ICSI treatment cycles: a cohort study

STUDY QUESTION

Does the duration of embryo exposure to hyaluronic acid (HA) enriched medium improve the rate of live birth events (LBEs)?

SUMMARY ANSWER

The use of embryo transfer (ET) medium rich in HA improves LBE (a singleton or twin live birth) regardless of the duration of exposure evaluated in this study, but does not alter gestation or birthweight (BW).

WHAT IS KNOWN ALREADY

HA-enriched medium is routinely used for ET in ART to facilitate implantation, despite inconclusive evidence on safety and efficacy.

STUDY DESIGN SIZE DURATION

A cohort study was performed evaluating clinical treatment outcomes before and after HA-enriched ET medium was introduced into routine clinical practice. In total, 3391 fresh ET procedures were performed using low HA and HA-rich medium in women undergoing publicly funded IVF/ICSI treatment cycles between May 2011 and April 2015 were included in this cohort study.

PARTICIPANTS/MATERIALS SETTING METHODS

A total of 1018 ET performed using low HA medium were compared with 1198, and 1175 ET following exposure to HA-rich medium for 2-4 h (long HA exposure) or for 10-30 min (short HA exposure), respectively. A multiple logistic regression analysis was used to compare clinical outcomes including BW, gestational age and sex ratios between groups, whilst adjusting for patient age, previous attempt, incubator type and the number of embryos transferred.

MAIN RESULTS AND THE ROLE OF CHANCE

The use of HA-rich medium for ET was positively and significantly associated with improved clinical pregnancy rate and LBE, for both exposure durations: long HA (odds ratio (OR) = 1.21, 95% CI: 0.99-1.48), short HA (OR = 1.32, 95% CI: 1.02-1.72) and pooled OR = 1.26, 95% CI: 1.03-1.54, relative to the use of low HA medium. A comparative analysis of the risks of early pregnancy loss following long HA exposure (OR = 0.76, 95% CI: 0.54-1.06), short HA exposure (OR = 0.84, 95% CI: 0.54-1.30) and late miscarriage (OR = 0.88, 95% CI: 0.51-1.53) (OR = 1.41, 95% CI 0.72-2.77), were lower and not statistically significant. Similarly, ordinary regression analysis of the differences in BW at both HA exposures; pooled OR = -0.9 (-117.1 to 115.3), and adjusted BW between both HA cohorts; pooled OR = -13.8 (-106.1 to 78.6) did not show any differences. However, a difference in gestational age (pooled OR -0.3 (-3.4 to 2.9)) and sex ratio (pooled OR 1.43 (0.95-2.15)) were observed but these were not statistically significant relative to low HA medium.

LIMITATIONS REASONS FOR CAUTION

The strength of a randomized treatment allocation was not available in this evaluation study, therefore effects of unmeasured or unknown confounding variables cannot be ruled out.

WIDER IMPLICATIONS OF THE FINDINGS

The result of this large cohort study strengthens the case for using HA-rich medium routinely at transfer, while adding the important clinical information that duration of exposure may not be critical. The composition and effects of commercial IVF culture media on success rate and safety remains a major controversy despite increasing calls for transparency and evidence-based practice in ART. Nonetheless, the lack of differences in BW and gestational age observed in this study were reassuring. However, an appraisal of clinical outcomes and appropriate research investigations are required for the continuous evaluation of efficacy and safety of HA.

STUDY FUNDING/COMPETING INTERESTS

T.A. is funded by a Clinical Doctoral Research Fellowship (CDRF) grant (reference: ICA-CDRF-2015-01-068) from the National Institute for Health Research (NIHR). The views expressed in this publication are those of the authors and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health. The authors declare no conflict of interest.

The Morphology of Inner Cell Mass Is the Strongest Predictor of Live Birth After a Frozen-Thawed Single Embryo Transfer

Background

The scoring system for human blastocysts is traditionally based on morphology; however, there are controversies on the effect of morphology parameters on pregnancy outcomes. The aim of this study is to evaluate the predicting value of each morphology parameter on pregnancy outcomes in a setting of single embryo transfer.

Methods

This is a retrospective cohort study on patients undergoing frozen-thawed single blastocyst transfer at our center, between Jan. 2009 and Dec. 2018. A total of 10,482 cycles were analyzed. The blastocysts were scored according to the expansion and hatching status, morphology of inner cell mass (ICM), and cells of trophectoderm (TE). The primary outcome measure was live birth rate. One-way analysis of variance, chi-square test, and multiple logistic regression were used for statistical analysis.

Results

The clinical pregnancy rate was lower in the blastocysts of stage 3 (48.15%), compared with those of stage 4 (56.15%), stage 5 (54.91%), and stage 6 (53.37%). The live birth rate was lower in the blastocysts of stage 3 (37.07%), compared with those of stage 4 (44.21%) and stage 5 (41.67%). The rates of clinical pregnancy (A: 66.60%, B: 53.25%, C: 39.33%) and live birth (A: 54.62%, B: 41.29%, C: 28.45%) were both decreased with decreasing grade of ICM morphology, and these differences were pairwise significant. The miscarriage rate of blastocysts with ICM grade A was lower, compared with ICM grade C (17.53 vs. 27.66%). Blastocysts with TE morphology of C had lower rates of clinical pregnancy (43.53%) and live birth (32.57%), compared with those with TE morphology of A and B (clinical pregnancy rate: 64.26% for A, 58.11% for B; live birth rate: 52.74% for A, 45.64% for B). There were no significant differences in rates of clinical pregnancy, live birth, and miscarriage between the blastocysts with TE grade A and B.

Conclusions

The blastocyst expansion stage, ICM grade, and TE grade are all associated with pregnancy outcomes. ICM grade is the strongest predictor of live birth. A blastocyst with stage 4-5, ICM grade A, and TE grade A/B should be given priority for single embryo transfer.

Protein O-GlcNAcylation Promotes Trophoblast Differentiation at Implantation

Embryo implantation begins with blastocyst trophectoderm (TE) attachment to the endometrial epithelium, followed by the breaching of this barrier by TE-derived trophoblast. Dynamic protein modification with O-linked β-N-acetylglucosamine (O-GlcNAcylation) is mediated by O-GlcNAc transferase and O-GlcNAcase (OGA), and couples cellular metabolism to stress adaptation. O-GlcNAcylation is essential for blastocyst formation, but whether there is a role for this system at implantation remains unexplored. Here, we used OGA inhibitor thiamet g (TMG) to induce raised levels of O-GlcNAcylation in mouse blastocysts and human trophoblast cells. In an in vitro embryo implantation model, TMG promoted mouse blastocyst breaching of the endometrial epithelium. TMG reduced expression of TE transcription factors Cdx2, Gata2 and Gata3, suggesting that O-GlcNAcylation stimulated TE differentiation to invasive trophoblast. TMG upregulated transcription factors OVOL1 and GCM1, and cell fusion gene ERVFRD1, in a cell line model of syncytiotrophoblast differentiation from human TE at implantation. Therefore O-GlcNAcylation is a conserved pathway capable of driving trophoblast differentiation. TE and trophoblast are sensitive to physical, chemical and nutritive stress, which can occur as a consequence of maternal pathophysiology or during assisted reproduction, and may lead to adverse neonatal outcomes and associated adult health risks. Further investigation of how O-GlcNAcylation regulates trophoblast populations arising at implantation is required to understand how peri-implantation stress affects reproductive outcomes.