Impact of cell loss after warming of human vitrified day 3 embryos on obstetric outcome in single frozen embryo transfers

PURPOSE

Does cell loss (CL) after vitrification and warming (V/W) of day 3 embryos have an impact on live birth rate (LBR) and neonatal outcomes?

METHOD

This retrospective analysis includes cleavage stage day 3 embryos vitrified/warmed between 2011 and 2018. Only single vitrified/warmed embryo transfers were included. Pre-implantation genetic screening, oocyte donation, and age banking were excluded from the analysis. The sample was divided into two groups: group A (intact embryo after warming) and group B (≤ 50% blastomere loss after warming).

RESULTS

On the total embryos (n = 2327), 1953 were fully intact (83.9%, group A) and 374 presented cell damage (16.1%, group B). In group B, 62% (232/374) of the embryos had lost only one cell. Age at cryopreservation, cause of infertility, insemination procedure, and semen origin were comparable between the two groups. The positive hCG rate (30% and 24.3%, respectively, for intact vs CL group, p = 0.028) and LBR (13.7% and 9.4%, respectively, for intact vs CL group, p = 0.023) per warming cycle were significantly higher for intact embryos. However, LBR per positive hCG was equivalent between intact and damaged embryos (45.6% vs 38.5%, respectively, p = 0.2). Newborn measurements (length, weight, and head circumference at birth) were comparable between the two groups. Multivariate logistic regression showed that the presence of CL is not predictive for LB when adjusting for patients' age.

CONCLUSIONS

LBR is significantly higher after transfer of an intact embryo compared to an embryo with CL after warming; however, neonatal outcomes are comparable between the two groups.

P-253 Shorter duration of compaction during human in-vitro preimplantation embryo development is associated with a higher clinical pregnancy rate

Study question

Is the duration of compaction, KID- (Known Implantation Data) and iDAScore (Intelligent Data Analysis for embryo evaluation) associated to clinical pregnancy rate?

Summary answer

Duration of compaction, KID- or iDAScore can be used to select the best embryo for transfer to increase clinical pregnancy rate.

What is known already

The development of human preimplantation embryos follows a programmed timeline in which a series of critical events occur. Compaction is a typical event at 3 to 4 days post fertilisation that is characterised by flattening of the blastomeres and the formation of tight junctions between the blastomeres. It is considered the first morphological event in the differentiation process of the embryo. Time-lapse technology introduced continuous monitoring of the embryo throughout development in the IVF laboratory. Evaluation of the developmental events combined with calculating KID- and iDAScore can optimise the selection of the most competent embryos for transfer and/or cryopreservation.

Study design, size, duration

This single-centre retrospective observational study included 158 IVF/ICSI cycles with fresh single embryo transfer (SET) was performed between December 2018 and November 2021. Embryos were cultured during 5 days in cleavage/blastocyst medium (Coopersurgical) in the EmbryoScope + (Vitrolife). Transferred embryos were evaluated for start of compaction, time to full compaction and duration of compaction. Embryo quality was calculated using KID- and iDAScore. These parameters were compared between the clinically pregnant and non-pregnant group (primary outcome).

Participants/materials, setting, methods

Only IVF/ICSI cycles with ejaculated sperm and fresh SET on day 5 were included. MNC, IVM and PGT cycles were excluded. Time zero was the start of injection or insemination. Pregnancy was confirmed by hCG and clinical pregnancy was defined by gestational sac visualisation at ultrasound.

GraphPad Prism and R-studio were used for statistical analysis. For prediction of clinical pregnancy, univariate logistic regression was used. Other significant differences were determined using t-test.

Main results and the role of chance

Out of 158 fresh ET, 101 (63.9%) had a positive hCG, of which 88 (55.6%) achieved clinical pregnancy. All 158 transferred blastocysts were annotated to calculate KID- and iDAScore.

There was no statistical difference in age between the two groups (34.7 years vs 35.0 years; p = 0.69).

Start of compaction was heterogeneous (between 50.9 and 98.3 hours post injection/insemination; mean=76.5±7.7), as well as the blastomere number at its initiation (between 4 and 16 blastomeres; mean=11.8±2.1).

Univariate logistic regression showed that each individual parameter, i.e. duration of compaction (p = 0.02), KID-score (p = 0.001) and iDAScore (p = 0.0006) was different between the clinically pregnant and non-pregnant group.

The total duration of compaction was significantly shorter in the clinical pregnant group (mean=8.6±3.4 hours vs 10.2±4.7 hours; p = 0.01; t-test). In the pregnant group the KIDscore (mean=7.7±1.4 vs 6.7±2.3; p = 0.0007) and iDAScore (mean=8.9±0.7 vs 8.3±1.3; p = 0.0002) were significantly higher.

During partial compaction, cells were rather excluded (93%) than extruded from the process; 17 embryos underwent this process, 10 of which resulted in a clinical pregnancy.

Limitations, reasons for caution

As this is a retrospective study, the influence of uncontrolled variables cannot be excluded. In the future, different models will be applied that can combine duration of compaction, KID- and iDAScore in a larger study.

Wider implications of the findings

Our analysis confirms previous findings that KID- and iDAScore are good predictors of clinical pregnancy.

We also show that duration of compaction can be used as a potential predictor for pregnancy, especially in IVF clinics that have no access to KID- or iDAScore.

Trial registration number

not applicable

P-764 Is children’s health up to two years of age affected by embryo vitrification?

Study question

Does embryo vitrification affect children’s health including growth, up to 2 years of age when compared to fresh embryo transfer?

Summary answer

While embryo vitrification had an impact on birth parameters, no differences in growth or health outcomes were found up to 2 years of age.

What is known already

Vitrification has become the preferred cryopreservation method for embryos. Frozen embryo transfer has been repeatedly associated with altered health outcomes when compared with fresh transfer including a decreased risk for small-for gestational age (SGA) and an increased risk for large-for-gestational-age (LGA) and macrosomia. Not only there is uncertainty which factors are responsible for the observed differences, also the heterogeneity among studies limits overall conclusions.

Notwithstanding the observed differences at birth, little is known about growth and health of children born after embryo vitrification beyond birth while aberrant growth trajectories have been linked to cardiometabolic morbidity later in life.

Study design, size, duration

This single-center cohort study compared anthropometry and health outcomes in singletons conceived after cleavage-stage or blastocyst-stage embryo vitrification with results after fresh embryo transfer between 2014 and 2018. Pregnancies after PGT, IVM, oocyte vitrification or oocyte/embryo donation were excluded.

Eligible singletons living in Belgium and randomly selected for continued follow-up were invited for examination in our center at 2 months (infancy) and 2 years of age (early childhood).

Participants/materials, setting, methods

Birth characteristics were available for 1237 and 2063 children born after embryo vitrification and fresh embryo transfer, respectively. Follow-up data were available for 582 and 757 children at 2 months and for 233 and 296 children at 2 years.

Growth parameters were adjusted for neonatal, treatment and maternal characteristics. Subgroup analysis according to cycle regimen (HRT versus NC) and strategy (freeze-all versus previous fresh cycle) was performed. In addition, outcomes restricted to blastocysts are presented.

Main results and the role of chance

Mothers giving birth to a child conceived after embryo vitrification presented more often with pregnancy-induced hypertensive disorders than controls (P < 0.001).

Birthweight, height and head circumference SDS of children born after embryo vitrification were higher than for children born after fresh embryo transfer (all P < 0.001) even after adjustment for neonatal, treatment and maternal characteristics. Embryo vitrification was also associated with a decreased risk of SGA (AOR 0.48; 0.00, 0.44) and an increased risk of macrosomia and LGA (AOR 3.59; 1.12, 11.59)(all P < 0.05).

Restricting the sample to blastocysts (n = 1795), we found a higher birthweight SDS and increased risks of LGA, macrosomia and pregnancy-induced hypertensive disorders after vitrification (all P < 0.05).

At infancy, weight and height SDS were larger for children born after embryo vitrification, but not after adjustment for co-variates. At childhood, no differences in anthropometrics were found between the groups. Weight and height gain from birth to infancy and from infancy to early childhood were comparable between the groups. Until 2 years, comparable rates of severe developmental problems, hospital admissions, surgical interventions and of chronic medication intake were found between the groups.

Subgroup analysis showed that growth parameters at all ages were not affected by cycle regimen or cycle strategy.

Limitations, reasons for caution

Participation rate at 2 years was lower than expected in both groups, probably due to cancellation/postponement of the visit related to the corona pandemic.

Furthermore, although cycle strategy was not found to affect growth parameters, the sample size of the subgroup analysis remains rather small to draw firm conclusions.

Wider implications of the findings

When adjusted for co-variates including birthweight, the observed differences in anthropometrics at birth in children born after embryo vitrification attenuated by 2 years of age. This suggests that outcomes in early childhood are determined by size at birth.

Trial registration number

Not applicable

P-251 Cumulus cell analysis as a non-invasive oocyte selection strategy to reduce the number of oocytes/embryos cultured and increase pregnancy rates

Study question

Can non-invasive gene expression analysis of cumulus cells (CC) improve efficiency in ART by prioritizing oocytes for further culture and fresh single embryo transfer?

Summary answer

CC analysis can be used for the selective processing of oocytes. This may reduce culture work and improve the outcome in ICSI elective SETs (eSET).

What is known already

In an interventional, blinded, prospective cohort study (Van Vaerenbergh et al. 2021), 113 patients underwent a fresh Day3 eSET with embryos ranked and transferred based on morphology and CC gene expression (Aurora Test), while 520 control patients underwent a Day3 eSET without the Aurora Test. This resulted in a significant higher clinical pregnancy of 61% in the patients with eSET based on CC ranking applied on good morphology embryos, compared to 29% in the controls with eSET based on embryo morphology only. Live birth rate was also significantly increased, while time-to-pregnancy was significantly reduced with 3 transfer cycles.

Study design, size, duration

In a retrospective analysis, in a subset of patients with at least 6 growing follicles and at least five 2PN oocytes (n = 80), it was investigated whether the Aurora Test, used to select transferrable Day3-embryos, could also be applied to select oocytes on Day0/1. The effect of processing only the three highest ranked oocytes (based on the Aurora Test) on embryo development and clinical pregnancy was studied compared to processing all oocytes.

Participants/materials, setting, methods

Patients included in this single centre study had their first or second GnRH-antagonist ICSI cycle, were younger than 40y, had normal BMI, were stimulated with HP-hMG and scheduled for Day3 eSET. Two-sided statistical analysis (p < 0,05) was performed between a strategy of processing only the top 3 Aurora ranked oocytes, according to CC gene expression, and a strategy of processing all available oocytes.

Main results and the role of chance

On average, 8 MII oocytes were obtained per patient and the average fertilization rate was 83%. In total, 407 good quality embryos (GQE) on Day3 were generated from these 80 patients when utilising all 639 oocytes. Processing the three top-ranked oocytes only (240/639 oocytes) would have reduced the number of embryos to 169 GQE and would have resulted in 2.1 GQE on average on Day3 per patient; 75/80 (94%) patients would have had a fresh Day3 transfer resulting in a 63% clinical pregnancy rate. Processing all 639 available 2PN oocytes (standard of care) resulted in a fresh Day3 transfer in all 80 patients and a similar 64% clinical pregnancy rate (ns). However, 399 more oocytes would need to be processed. The strategy of restricting the number of oocytes to be processed would not have compromised cumulative cycle outcome. Considering all subsequent freeze/thawing cycles the cumulative clinical pregnancy rate calculated per all 80 patients would increase to 90%.

Limitations, reasons for caution

The limitation of this approach is that the Aurora Test requires individual oocyte denudation and individual oocyte vitrification. Secondly, this new strategy should be validated in a prospective study.

Wider implications of the findings

By applying this oocyte selection strategy patients would benefit from a high pregnancy rate in the fresh transfer cycle, while the lab would see reduction in embryo culture work, because freeze/thawing cycles and culture of embryos with lower competence would be prevented.

Trial registration number

NA

O-239 CD147 expression in human embryos and its role during implantation

Study question

Do human pre-implantation embryos express CD147, does it play a role during implantation, and can it be used as non-invasive marker for embryo selection?

Summary answer

CD147 is expressed throughout pre-implantation development. Blocking results in implantation failure in vitro, but CD147 secretion has no immediate link with implantation in vivo.

What is known already

Embryo selection remains a subjective process with room for improvement. Researchers focus on alternative techniques to reduce time to pregnancy. While preimplantation genetic testing and time-lapse studies increased our understanding, they failed to efficiently improve embryo selection. CD147, a cluster domain well studied in cancer, has been proven to positively influence implantation in mice. When the protein is blocked, the embryo develops to blastocyst but fails to implant. This study aims to visualize the expression of CD147 throughout human pre-implantation development and to understand its role during implantation in humans, using both an in vitro and in vivo model.

Study design, size, duration

CD147 expression was studied in oocytes (n = 13) and embryos (n = 30) between 3 and 7 days post-fertilisation (dpf) with immunohistochemistry. To investigate its function, 5dpf blastocysts (n = 45) were co-cultured with Ishikawa cells for two days in an in vitro attachment model with two distinct anti-CD147 antibodies (ab666 and ab119114). Attachment models containing embryos (n = 8) were stained using ActinGreen™ probes. Additionally, spent culture medium was collected in the IVF lab after fresh blastocyst transfer (n = 153, sequential medium).

Participants/materials, setting, methods

Fresh immature oocytes and vitrified/warmed embryos were obtained after patients’ informed consent, fixed in 4% paraformaldehyde and stained using ab666. The counterstained samples were visualized with confocal microscopy. For blocking experiments, embryos were incubated in ab666 or ab119114 (Abcam) and co-cultured in the attachment model. Attachment was measured after 24hrs by gentle pipetting of the medium. Attached embryos were stained for F-actin. CD147 concentrations in spent embryo culture medium were determined by ELISA (EH78RB, Thermo-Fisher-Scientific).

Main results and the role of chance

In immature oocytes, CD147 was present on the oolemma only. After fertilization, CD147 protein was restricted to the membrane of all blastomeres but fluorescence intensity decreased gradually during cleavage stages. After embryonic genome activation the expression increased again mainly on the membranes of the cells. After blastulation (5 dpf), the protein was expressed in all cells but mainly concentrated on the membranes. With the expansion of the blastocysts (6-7 dpf) CD147 became more abundant on the membranes of trophectoderm cells (TE), the signal being the strongest on the apical membranes and TE junctions.

Blocking of CD147 binding in blastocysts was achieved with two anti-CD147 antibodies ab666 and ab119114 with respectively 52% and 70 % reduction of attachment on Ishikawa cells compared to non-treated control groups (n = 45, p < 0.05).

Finally, secreted CD147 was found in culture medium of embryos 5 dpf. Most of the blastocysts (150/153) secreted CD147 with concentrations ranging from 40–229 pg/ml. No correlation with pregnancy outcome or morphology was noted, indicating that CD147 cannot be used as non-invasive marker for embryo selection. Although these results clearly highlight the importance of CD147 in human embryo implantation in vitro, more research is needed to investigate its role.

Limitations, reasons for caution

The experiments have been performed using an in vitro model for attachment, the impact of additional interfering factors in vivo cannot be ruled out.

Wider implications of the findings

Protein expression highlights the importance of CD147 in human blastocysts, especially for the attachment function of the apical TE membrane. Blocking CD147protein reduces implantation dramatically, proving its involvement in establishing a successful pregnancy. In addition, secretion of CD147 demonstrates its potential paracrine role during the interaction with the endometrium.

Trial registration number

not applicable

P-780 Ten years electronic witnessing in the IVF laboratory

Study question

What did we learn after 10 years of electronic witnessing?

Summary answer

Only when applied correctly, electronic witnessing can prevent sample mix-up.

What is known already

In the early days of IVF, manual double witnessing was used to reduce the misidentification of gametes for insemination. However, risk for human errors due to fatigue, automatism, distraction or work load make this a mistake-prone approach. Hence, there is increasing interest in using electronic witnessing systems for patient and sample identification. Although not always mandatory, such systems have been implemented in many fertility laboratories to avoid identification errors. A mismatch is generated when non-matching samples are simultaneously present in a single workstation. Yet, when the system is incorrectly used, corrective intervention by an administrator (administrator assign) may be required.

Study design, size, duration

This evaluation investigates the mismatch (MM) rate and administrator assigns (AA) over a 10-year period (March 2011- December 2021) with the use of RI Witness (RIW) (CooperSurgical). Radio frequency identification tags (RFID) were used for patient and sample identification. Conventional IVF and ICSI cycles, and frozen embryo cycles (FET) were included since 10 years, IUI cycles since 8 years.

Participants/materials, setting, methods

The total number of tags and witness points (WP) were recorded. Witness points represent all the actions in RIW that have been performed during the entire process. MM and AA were collected and stratified by procedure (sperm preparation, oocyte retrieval, IVF/ICSI, (embryo)biopsy, vitrification/warming, embryo transfer, medium changeover and IUI). Critical MM (such as mis-labeling or non-matching samples within one work area) and critical AA (such as non-RIW-identified samples and unconfirmed WP) were selected.

Main results and the role of chance

A total of 109,655 cycles were included: 53,023 IVF/ICSI, 36,347 FET, and 20,285 IUI cycles. The 724,096 used tags, led to a total of 849,650 WP. The overall MM rate per WP was 0.25% (2,132/849,650), 1.9% per cycle, of which 144 critical mismatches occurred in the different procedures: sperm preparation: 66, oocyte retrieval: 5, IVF/ICSI: 33, (embryo)biopsy: 1, vitrification/warming: 26, embryo transfer: 8, medium changeover: 3 and IUI: 2. The mean critical MM rate per WP per year was 0.017% ± 0.007% and 0.13 ± 0.05% per cycle. The overall AA rate per WP was 0.11% (940/849,650), 0.86% per cycle, including 320 critical assigns: sperm preparation: 83, oocyte retrieval: 34, IVF/ICSI: 173, (embryo)biopsy: 3, vitrification/warming: 6, embryo transfer: 0, medium changeover: 21. Critical AA rate per year was on average 0.041%/WP ± 0.01% and 0.30 ± 0.07% per cycle. All MM and AA rates remained stable during this 10-year period, except for sperm preparation, where the removal of a single witness point led to a huge increase in AA. RIW should still be used in combination with the manual labelling of bottom and lid of dishes and tubes to guarantee correct assignment in case of RFID malfunction or AA.

Limitations, reasons for caution

The procedures and method of integration of RIW may vary from one laboratory to another and result in differences in the potential risks. RIW cannot (yet) identify individual embryos, making double manual witnessing indispensable at certain critical steps, where potential errors are not recorded.

Wider implications of the findings

Using an electronic witnessing is considered to be the ultimate tool to safeguard correct identification of gametes and embryos. But this is only possible when used correctly and requires proper training and attention of the staff. It may also induce new risks, i.e. blind witnessing of samples by the operator.

Trial registration number

not applicable

O-046 Reproductive prospects for ICSI children

Intracytoplasmic sperm injection (ICSI), developed 30 years ago in our Center, allowed men with low to extremely low sperm quality to become the genetic father of their child. Overall, ICSI is now applied in up to 70% of all ART cycles and has resulted in the birth of millions of children worldwide.

ICSI circumvents natural sperm selection mechanisms and concerns related to transgenerational inheritance of male infertility following ICSI could not be fully answered till today, given the young age of the offspring born after ICSI. Since genetic abnormalities account for one third of all cases of male factor infertility, it is essential to identify these genetic abnormalities because of the potential risk of their transmission to the offspring through the use of ART. As ICSI is nowadays performed even in couples with normal semen parameters, the disentanglement of procedure-related and parental background-related factors on the health of the offspring is important.

Due to the safety concerns regarding the health of children born after ART, a longitudinal follow-up program was set up in our Center in the 80’s, resulting in data of more than 50 000 pregnancies. To date, more than 25 000 children are conceived after ICSI in our Center. We have not only the worldwide eldest cohort of ICSI offspring but also a uniform cohort of children and young adults conceived by ICSI because of (severe) male factor infertility.

We present the results of these prospective studies with focus on the reproductive health in ICSI children between 8 and 22 years and compare these with available data from others. First of all, we will show data on the gonadal function assessed both clinically and by means of biomarkers at pre-pubertal and pubertal ages in ICSI boys. Secondly, we will present findings on the reproductive status of young adult men and women conceived after ICSI between 1992 and 1996: results of hormonal work-up, physical examination and semen parameters for ICSI men and results of hormone levels and antral follicle counts for ICSI women.

Finally, we will discuss the findings in these cohorts of children and young adults conceived because of male infertility in view of the available literature regarding reproductive function in offspring conceived following ICSI.

P–707 Does the dose or type of gonadotropin affect the reproductive outcomes of poor responders undergoing modified natural cycle IVF (MNC-IVF)?

Study question

Does the dose or type of gonadotropin affect the reproductive outcomes of poor responders undergoing MNC-IVF?

Summary answer

Neither the type nor the dose of gonadotropins affects the reproductive outcomes of poor responders undergoing MNC-IVF.

What is known already

Poor ovarian response (POR) to ovarian stimulation remains a major therapeutic challenge in routine IVF practice, because of the association with low live birth rates and high cancellation rates. Although high doses of gonadotropins are traditionally used to stimulate the ovaries in women with predicted POR, MNC-IVF has been proposed as a mild-approach alternative in this population. Typically, the MNC protocol includes GnRH-antagonists to avoid premature ovulation and gonadotropin add-back stimulation at the late follicular phase. However, evidence is sparse, and there is no consensus regarding a specific dose or type of gonadotropins in this mild stimulation protocol.

Study design, size, duration

This is a retrospective cohort study including patients attending a tertiary referral University Hospital from 1st January 2017 until 1st March 2020.

Participants/materials, setting, methods

All women who underwent MNC-IVF in our center were included. Gonadotropins [recombinant FSH (rFSH), urinary FSH (uFSH) or highly purified human menopausal gonadotrophin (hp-hMG)] were started when a follicle with a mean diameter of 12–14 mm was observed on ultrasound scan, followed by GnRH antagonists (0.25mg/day) from the next day onwards. Mature oocytes were inseminated using ICSI.

Main results and the role of chance

In total, 484 patients undergoing 1398 cycles were included. Mean (SD) age and serum AMH were 38.2 (3.7) years and 0.46 (0.78) ng/ml, respectively. The daily dose of gonadotropins was either <75 IU/d [11/1398 (0.8%)] or 75 to < 100 IU/d [1303/1398 (93.2%)] or ≥ 100 IU/d [84/1398 (6%)]. Patients were stimulated with: rFSH [251/1398 (18%)], uFSH [45/1398 (3.2%)] or hp-hMG [1102/1398 (78.8%)]. Biochemical and clinical pregnancy rates were 142/1398 (10.1%) and 119/1398 (8.5%). Live birth was achieved in 80/1398 (5.7%) of cycles. Live birth rates (LBR) were similar between the different type and doses of gonadotropins (p-value 0.3 and 0.51, respectively). The GEE multivariate regression analysis adjusting for relevant confounders (age, BMI, number of MII oocytes) showed that the type of treatment strategy (rFSH/uFSH/hp-hMG) and the dose of gonadotropins were not significantly associated with LBR (coefficient 0.01 and –0.02, p value 0.09 and 0.3, respectively).

Limitations, reasons for caution

The main limitation is the retrospective design of our study, with an inherent risk of bias.

Wider implications of the findings: This is the first and largest study evaluating MNC-IVF protocol modalities. Our data demonstrate that any type of gonadotropin can be used and there is no benefit from daily doses beyond 75IU.

Trial registration number

N/A

P–165 Using Artificial Intelligence to Classify Embryo Shape: An International Perspective

Study question

Is a pre-trained machine learning algorithm able to accurately detect cellular arrangement in 4-cell embryos from a different continent?

Summary answer

Artificial Intelligence (AI) analysis of 4-cell embryo classification is transferable across clinics globally with 79% accuracy.

What is known already

Previous studies observing four-cell human embryo configurations have demonstrated that non-tetrahedral embryos (embryos in which cells make contact with fewer than 3 other cells) are associated with compromised blastulation and implantation potential. Previous research by this study group has indicated the efficacy of AI models in classification of tetrahedral and non-tetrahedral embryos with 87% accuracy, with a database comprising 2 clinics both from the same country (Brazil). This study aims to evaluate the transferability and robustness of this model on blind test data from a different country (France).

Study design, size, duration

The study was a retrospective cohort analysis in which 909 4-cell embryo images (“tetrahedral”, n = 749; “non-tetrahedral”, n = 160) were collected from 3 clinics (2 Brazilian, 1 French). All embryos were captured at the central focal plane using Embryoscope™ time-lapse incubators. The training data consisted solely of embryo images captured in Brazil (586 tetrahedral; 87 non-tetrahedral) and the test data consisted exclusively of embryo images captured in France (163 tetrahedral; 72 non-tetrahedral).

Participants/materials, setting, methods

The embryo images were labelled as either “tetrahedral” or “non-tetrahedral” at their respective clinics. Annotations were then validated by three operators. A ResNet–50 neural network model pretrained on ImageNet was fine-tuned on the training dataset to predict the correct annotation for each image. We used the cross entropy loss function and the RMSprop optimiser (lr = 1e–5). Simple data augmentations (flips and rotations) were used during the training process to help counteract class imbalances.

Main results and the role of chance

Our model was capable of classifying embryos in the blind French test set with 79% accuracy when trained with the Brazilian data. The model had sensitivity of 91% and 51% for tetrahedral and non-tetrahedral embryos respectively; precision was 81% and 73%; F1 score was 86% and 60%; and AUC was 0.61 and 0.64. This represents a 10% decrease in accuracy compared to when the model both trained and tested on different data from the same clinics.

Limitations, reasons for caution

Although strict inclusion and exclusion criteria were used, inter-operator variability may affect the pre-processing stage of the algorithm. Moreover, as only one focal plane was used, ambiguous cases were interpoloated and further annotated. Analysing embryos at multiple focal planes may prove crucial in improving the accuracy of the model.

Wider implications of the findings: Though the use of machine learning models in the analysis of embryo imagery has grown in recent years, there has been concern over their robustness and transferability. While previous results have demonstrated the utility of locally-trained models, our results highlight the potential for models to be implemented across different clinics.

Trial registration number

Not applicable

P–464 What is the optimal ovarian stimulation (OS) protocol for women who undergo planned oocyte cryopreservation (POC)?

Study question

When repeated cycles of OS for planned oocyte cryopreservation using a standard GnRH antagonist protocol are required, can OS protocol modifications improve oocyte yield?

Summary answer

Compared to repeating a standard GnRH antagonist protocol, switching to a long GnRH agonist protocol for POC results in a higher number of cryopreserved oocytes.

What is known already

The total number of cryopreserved oocytes is a key parameter of POC programs because of its association with livebirth. A substantial proportion of women embarking on POC will undergo repeated cycles of OS to reach their desired target number of vitrified oocytes. According to recent guidelines, the GnRH antagonist protocol with GnRH agonist triggering is considered the first choice protocol for POC, because of its safety profile and convenience. However, in women with normal ovarian reserve, the long GnRH agonist protocol results in a higher number of oocytes retrieved. Evidence regarding the optimal protocol for POC is limited.

Study design, size, duration

This is a single-centre, retrospective cohort study including 283 women who had a first cycle for POC using a standard GnRH antagonist protocol and who requested a second OS cycle to increase their total number of vitrified oocytes for later use. The choice of protocol for the second cycle was left at the discretion of the reproductive medicine specialist. All OS cycles took place between January 2009 and December 2019 in a tertiary referral hospital.

Participants/materials, setting, methods

After ovarian reserve testing, the first cycle OS was performed using rFSH or HPhMG in a GnRH antagonist protocol. For the second cycle, a GnRH antagonist protocol with or without antagonist pretreatment, or a long GnRH agonist protocol was prescribed. The primary outcome was the number of mature oocytes (MII) vitrified per cycle. Cycle characteristics were compared. Data were assessed by generalized estimating equation (GEE) regression analysis adjusting for covariates.

Main results and the role of chance

In total, 226 (79.9%) women had a GnRH antagonist protocol and 57 (20.1%) had a long GnRH agonist protocol in their second OS cycle for POC. Overall, mean age was 36.6±2.4 years. The median (CI) number of mature oocytes vitrified after the second OS cycle was significantly higher than that after the first cycle [8 (5–11) vs. 7 (4–10), p < 0.001]. According to GEE multivariate regression, adjusting for relevant confounders, switching from a GnRH antagonist protocol in the first cycle to a long GnRH agonist protocol in the second cycle was the only significant predictor of the number of vitrified oocytes after the subsequent cycle (coefficient 1.59, CI 0.29–2.89, p-value = 0.017). Age, AFC, initial dose and type of gonadotropins did not predict the number of vitrified oocytes. None of the women developed moderate or severe OHSS.

Similarly, of 174 women who underwent their first OS cycle with a standard GnRH antagonist protocol, 133 women (76.4%) had the same protocol for their second cycle and 41 women (23.6%) an additional three-day course of GnRH antagonist pretreatment. According to GEE multivariate regression, this protocol modification did not result in more mature oocytes available for vitrification (coefficient –0.25, CI –1.86–1.36, p-value = 0.76).

Limitations, reasons for caution

These data should be interpreted with caution because of the retrospective design and limited sample. Although more oocytes were obtained with a long GnRH agonist protocol we have no data on livebirth in women returning to use their oocytes to support the choice for a specific OS protocol for POC.

Wider implications of the findings: Although oocyte yield in the context of POC is an important parameter that may be modulated by the choice of OS protocol, the ultimate outcome measure of a successful POC program is livebirth after oocyte vitrification. Future research of oocyte parameters reflecting oocyte quality is paramount.

Trial registration number

Not applicable

O-161 Cumulative live birth rate after a freeze-all approach in women with polycystic ovaries: does the PCOS phenotype have an impact?

Study question

Do cumulative live birth rates (CLBR) differ between PCOS phenotypes when a freeze-all strategy is used to prevent OHSS after ovarian stimulation (OS)?

Summary answer

When conventional-dose OS resulted in high response, a CLBR of ∼ 70% was observed after “freeze-all” in women with PCOS, irrespective of their phenotype.

What is known already

Previous observational studies have shown that CLBR in women with PCOS who undergo assisted reproductive technologies (ART) may depend on their phenotype. When OS was performed with caution to avoid ovarian hyperresponse, CLBR was lower in women with a hyperandrogenic PCOS phenotype. However, when women with PCOS do exhibit hyperresponse and a freeze-all strategy is used, the impact of the PCOS phenotype on the clinical outcome of the ART cycle is unclear.

Study design, size, duration

This is a single-centre, retrospective cohort study including 422 women with polycystic ovary syndrome (PCOS) as defined by Rotterdam criteria or PCO-like ovarian morphology-only (PCOM) in whom a freeze-all strategy was applied after GnRH agonist triggering in the context of hyperresponse defined as ³19 follicles of ³11mm in their first or second IVF-ICSI cycle between January 2015 and December 2019 in a tertiary referral hospital.

Participants/materials, setting, methods

PCOS phenotype was based on hyperandrogenism (H), ovulatory dysfunction (O) and PCO-like ovarian morphology (P). Ovarian stimulation was performed with rFSH or HPhMG, adjusted to BMI. The primary outcome was cumulative live birth rate (CLBR) resulting from the transfer of all cryopreserved embryos from the same IVF-ICSI cycle. Patient and cycle characteristics and laboratory and clinical data were analysed. Data were analysed by multivariate logistic regression adjusting for covariates.

Main results and the role of chance

In total, 91/422 (21.6%) patients had PCOS phenotype A (HOP); 33 (7.8%) had phenotype C (HP), 161/422 (38.2%) had phenotype D (OP) and 137/422 (32.5%) had PCOM (n = 137). BMI, AMH and AFC were significantly different between phenotype groups (p < 0.001), and highest in PCOS phenotype A. The type of gonadotropin used, as well as the mean daily and total stimulation dose were comparable for all groups. The mean number of retrieved oocytes was comparable among groups (22.4±10.8 for phenotype A, 21.4±7.1 for phenotype C, 20.4±7.8 for phenotype D and 22.2±9.7 for PCOM; p = 0.46). The mean number of embryos available for vitrification differed significantly (4.4±3.7, 5.7±3.4, 5.7±3.4 and 5.2±3.6, respectively; p = 0.005). Following the first frozen embryo transfer, LBR was comparable among groups (41.5%, 43.3%, 49.3% and 38.5%, respectively; p = 0.31). Unadjusted CLBR was also similar (69.2%, 69.7%, 79.5% and 67.9%, respectively; p = 0.11). The multivariate logistic regression model adjusting for age, BMI, number of oocytes and embryo stage (cleavage vs. blastocyst stage) confirmed that the PCOS/PCOM phenotype did not have any impact on CLBR (OR 0.80, CI 0.28-2.29 (phenotype C); OR 1.40, CI 0.67-2.90 (phenotype D); OR 0.65, CI 0.31-1.34 (PCOM); p = 0.1, with phenotype A as reference).

Limitations, reasons for caution

These data should be interpreted with caution as the retrospective nature of the study holds the possibility of unmeasured confounding factors. The results cannot be generalised to all ART cycles in women with polycystic ovaries as they pertain to those cycles where OS leads to hyperresponse.

Wider implications of the findings

In subfertile women with PCOS eligible for ART, hyperresponse after OS confers excellent cumulative live birth rates when a freeze-all strategy is used, eliminating unfavourable clinical outcomes that had previously been observed in hyperandrogenic PCOS women after mild OS targeting normal ovarian response and fresh embryo transfer.

Trial registration number

not applicable

O-205 Aneuploidy induces proteotoxic stress and autophagy-mediated apoptosis in human preimplantation embryos

Study question

Are aneuploid cells in human preimplantation embryos eliminated by apoptosis due to proteotoxic stress and autophagy-mediated apoptosis?

Summary answer

Proteotoxic stress, autophagy and apoptosis are differentially activated in aneuploid embryos, showing that aneuploid cells are eliminated by these mechanisms during early human embryogenesis.

What is known already

Aneuploidies are a common feature of human preimplantation embryos which could explain low success rates after in vitro fertilization (IVF). While most aneuploidies of meiotic origin are detrimental, transfer of euploid-aneuploid mosaic embryos can lead to healthy live-births. Moreover, the proportion of aneuploid cells are lower in blastocysts when compared to cleavage stage embryos. In the mouse, aneuploid cells are eliminated from the epiblast by autophagy-mediated apoptosis in a p53-dependent manner. We propose that in human embryos, aneuploidy causes chronic protein misfolding which leads to autophagy-induced apoptosis.

Study design, size, duration

Eighty-one blastocysts that were diagnosed by PGT as euploid (n = 49) or uniformly combined abnormal (CA, n = 32), i.e. 2 or more chromosomes were abnormal in every cell, were warmed. Sixty-seven were suitable for trophectoderm (TE) biopsy, 54 biopsies were successfully tubed and sent for RNA-sequencing while the remainder of the embryos was fixed for immunostaining. Thirty-three day-3 embryos were overnight incubated in 0.5µM reversine allowed to develop into blastocysts and treated as the PGT embryos.

Participants/materials, setting, methods

After TE biopsy, we live-stained the embryos with either Caspase-3/7 or 8 and subsequently fixed them. The biopsies underwent RNA-sequencing using the SMART-seqv4 and the fixed embryos were immunostained for LC3B, p62 (autophagy) and HSP70 (proteotoxic stress). Confocal imaging was performed using a Zeiss LSM800 confocal microscope and the presence of signal was quantified using the Zen Blue 2.0 and Arivis software.

Main results and the role of chance

Forty-two percent of the embryos in which we induced aneuploidies using reversine developed into blastocysts, which is comparable to untreated embryos. After immunostaining, we observed that CA and reversine-treated (RT) embryos contained less cells than euploid embryos (median number of nuclei: 43.5, 47, 90, respectively). This correlates with a higher expression of apoptotic markers Caspase-3/7 in CA embryos (p = 0.0199) and Caspase-8 in both aneuploid groups (CA: p = 0.0085 and RT: p = 0.0394). Aneuploid embryos showed significantly increased HSP70 levels (median intensity per cell: euploid=165, CA = 313, RT = 400), LC3B (median puncta per cell: euploid=3.07, CA = 10.10, RT = 19.62) and p62 (median puncta per cell: euploid=17.60, CA = 30.53), suggesting increased proteotoxic stress and autophagy. Preliminary analysis of the RNA-sequencing data reveals enrichment for pathways such as the p53-pathway, protein secretion, TNFA signaling via NFkB and apoptosis, supporting the hypothesis of a link between aneuploidy and apoptosis.

Limitations, reasons for caution

No functional tests e.g. with inhibitors of autophagy were carried out. RNA-sequencing was carried out on a small sample; we will expand this sample in the near future.

Wider implications of the findings

This study shows for the first time the mechanism by which aneuploid cells are eliminated from the human preimplantation embryo, explaining how mosaic embryos can still lead to a healthy and genetically normal live birth.

Trial registration number

not applicable

P–259 Blastocyst quality is associated with both the start and the duration of compaction after ICSI

Study question

Is the start and the total duration of compaction related to embryo quality?

Summary answer

The timing of the start, the end and the total duration of compaction are associated with blastocyst quality grade in the IVF laboratory.

What is known already

Preimplantation embryo development follows a programmed timeline during which a series of critical events take place. One event typically occurring on day 3/4 post fertilisation is the formation of adherence junctions between blastomeres in a process called compaction. It is considered the first morphological event in the differentiation process of the mammalian embryo. Evaluation of developmental events are used to optimize the selection of the most competent embryos for transfer and/or cryopreservation in the IVF laboratory. It has already been shown that the time of full compaction is indicative for high-quality blastocysts with a higher implantation rate.

Study design, size, duration

A single-centre retrospective observational study including 74 ICSI cycles performed in 2020. Injected oocytes were cultured in blastocyst medium (Origio) in the EmbryoScope + (Vitrolife) for 5/6 days. Embryos that reached the blastocyst stage were evaluated for the start of compaction, the time to reach full compaction and the total duration of compaction. These parameters were compared between good- and poor-quality blastocysts; the primary outcome parameter of the study was embryo quality.

Participants/materials, setting, methods

Only ICSI cycles with ejaculated fresh/frozen-thawed sperm and monitored in time-lapse incubator were included. All MNC, IVM and PGT cycles were excluded. Time zero was the start of ICSI. Good-quality embryos were full and expanded blastocysts with good-quality inner cell mass and trophectoderm (AA, AB, BA and BB according to Gardner and Schoolcraft (1999)). GraphPad Prism was used for statistical analysis. After testing for normality and homogeneity, unpaired t-test or Mann-Whitney test determined significant differences.

Main results and the role of chance

In this study, of the 528 included 2PN oocytes, 229 (43.4%) reached the blastocyst stage and 299 (56.6%) were arrested. Among the former, 131 (57.2%) blastocysts were classified in the good-quality group and 98 (42.8%) blastocysts in the poor-quality group. In general, human embryos compacted slowly while dividing further and the blastomeres moved during the compaction process. The start of compaction was heterogeneous (between 50.9 and 102.7 hours post ICSI; mean=80.0 hours), as well as the cell number at the initiation (between 4 and 18 blastomeres; mean=12 blastomeres). The time analysis showed that the embryos in the good-quality group started to compact significantly earlier than those in the poor-quality group (mean=78.6 vs 82.2 hours; R²=0.06; p < 0.01). We confirmed that blastocysts in the good-quality group reached full compaction earlier than those in the poor-quality group (mean=86.8 vs 93.8 hours; R²=0.17; p < 0.01). Furthermore, the total duration of compaction was significantly lower in the good-quality than in the poor-quality group (median=7.4 vs 10.7 hours; p < 0.01).

Limitations, reasons for caution

As this is a retrospective study, the influence of uncontrolled variables cannot be excluded. The absence of the pregnancy outcome and live birth rate is a shortcoming and will be subject of a larger patient-to-patient study.

Wider implications of the findings: These results indicate that an earlier start and a shorter duration of compaction are associated with better blastocyst quality. These morphological events can be valuable additional parameters in selecting the embryo of better quality when using a time-lapse incubator.

Trial registration number

Not applicable

Is a freeze-all policy the optimal solution to circumvent the effect of late follicular elevated progesterone? A multicentric matched-control retrospective study analysing cumulative live birth rate in 942 non-elective freeze-all cycles

STUDY QUESTION

Is late follicular elevated progesterone (LFEP) in the fresh cycle hindering cumulative live birth rates (CLBRs) when a freeze only strategy is applied?

SUMMARY ANSWER

LFEP in the fresh cycle does not affect the CLBR of the frozen transfers in a freeze only approach, nor the embryo freezing rate.

WHAT IS KNOWN ALREADY

Ovarian stimulation promotes the production of progesterone (P) which has been demonstrated to have a deleterious effect on IVF outcomes. While there is robust evidence that this elevation produces impaired endometrial receptivity, the impact on embryo quality remains a matter of debate. In particular, previous studies have shown that LFEP is associated with a hindered CLBR. However, most clinical insight on the effect of progesterone on embryo quality in terms of CLBRs have focused on embryo transfers performed after the fresh transfer, thus excluding the first embryo of the cohort. To be really informative on the possible detrimental effects of LFEP, evidence should be derived from freeze-all cycles where no fresh embryo transfer is performed in the presence of progesterone elevation, and the entire cohort of embryos is cryopreserved.

STUDY DESIGN, SIZE, DURATION

This was a matched case-control, multicentre (three centres), retrospective analysis including all GnRH antagonist ICSI cycles in which a freeze all (FA) policy of embryos on day 3/5/6 of embryonic development was applied between 2012 and 2018. A total of 942 patients (471 cases with elevated P and 471 matched controls with normal P values) were included in the analysis. Each patient was included only once.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The sample was divided according to the following P levels on the day of ovulation triggering: <1.50 ng/ml and ≥1.50 ng/ml. The matching of the controls was performed according to age (±1 year) and number of oocytes retrieved (±10%). The main outcome was CLBR defined as a live-born delivery after 24 weeks of gestation.

MAIN RESULTS AND THE ROLE OF CHANCE

The baseline characteristics of the two groups were similar. Estradiol levels on the day of trigger were significantly higher in the elevated P group. There was no significant difference in terms of fertilisation rate between the two groups. The elevated P group had significantly more cleavage stage frozen embryos compared to the normal P group while the total number of cryopreserved blastocyst stage embryos was the same. The CLBR did not differ between the two study groups (29.3% and 28.2% in the normal versus LFEP respectively, P = 0.773), also following confounder adjustment using multivariable GEE regression analysis (accounting for age at oocyte retrieval, total dose of FSH, progesterone levels on the day of ovulation trigger, day of freezing, at least one top-quality embryo transferred and number of previous IVF cycles, as the independent variables).

LIMITATIONS, REASONS FOR CAUTION

This is a multicentre observational study based on a retrospective data analysis. Better extrapolation of the results could be validated by performing a prospective analysis.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study demonstrating that LFEP in the fresh cycle does not hinder CLBR of the subsequent frozen cycles in a FA approach. Thus, a FA strategy circumvents the issue of elevated P in the late follicular phase.

STUDY FUNDING/COMPETING INTEREST(S)

No funding was received for this study. Throughout the study period and manuscript preparation, authors were supported by departmental funds from: Centre for Reproductive Medicine, Brussels, Belgium; Infertility Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy; Centro Scienze Natalità, San Raffaele Scientific Institute, Milan, Italy; and IVI-RMA, Lisbon, Portugal. E.S. has competing interests with Ferring, Merck-Serono, Theramex and Gedeon-Richter outside the submitted work. E.P. reports grants from Ferring, grants and personal fees from Merck-Serono, grants and personal fees from MSD and grants from IBSA outside the submitted work. All the other authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Expanding the time interval between ovulation triggering and oocyte injection: does it affect the embryological and clinical outcome?

STUDY QUESTION

Is the time interval between ovulation triggering and oocyte denudation/injection associated with embryological and clinical outcome after ICSI?

SUMMARY ANSWER

Expanding the time interval between ovulation triggering and oocyte denudation/injection is not associated with any clinically relevant impact on embryological or clinical outcome.

WHAT IS KNOWN ALREADY

The optimal time interval between ovulation triggering and insemination/injection appears to be 38-39 h and most authors agree that an interval of >41 h has a negative influence on embryological and clinical pregnancy outcomes. However, in ART centres with a heavy workload, respecting these exact time intervals is frequently challenging. Therefore, we questioned to what extent a wider time interval between ovulation triggering and oocyte injection would affect embryological and clinical outcome in ICSI cycles.

STUDY DESIGN, SIZE, DURATION

A single-centre retrospective cohort analysis was performed including 8811 ICSI cycles from 2010 until 2015. Regarding the time interval between ovulation triggering and oocyte injection, seven categories were considered: <36 h, 36 h, 37 h, 38 h, 39 h, 40 h and ≥41 h. In all cases, denudation was performed immediately prior to injection. The main outcome measures were oocyte maturation, fertilization and embryo utilization rate (embryos adequate for transfer or cryopreservation) per fertilized oocyte. Clinical pregnancy rate (CPR) and live birth rate (LBR) were considered as secondary outcomes. Utilization rate, CPR and LBR were subdivided into two groups according to the day of embryo transfer: Day 3 or Day 5.

PARTICIPANTS/MATERIALS, SETTING, METHODS

During the study period, oocyte retrieval was routinely performed 36 h post-triggering except in the <36 h group. The interval of <36 h occurred only if OR was carried out before the planned 36 h trigger interval and was followed by immediate injection. Only cycles with fresh autologous gametes were included. The exclusion criteria were: injection with testicular/epididymal sperm, managed natural cycles, conventional IVF, combined conventional IVF/ICSI, preimplantation genetic testing and IVM cycles. Female age, number of oocytes, pre-preparation sperm concentration, post-preparation sperm concentration and motility, day of transfer, number of embryos transferred and quality of the best embryo transferred were identified as potential confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

Among the seven interval groups, adjusted mean maturation rates ranged from 76.4% to 83.2% and differed significantly (P < 0.001). Similarly, there was a significant difference in adjusted mean fertilization rates (range 69.2-79.3%; P < 0.001). The adjusted maturation and fertilization rates were significantly higher when denudation/injection was performed >41 h post-triggering compared to 38 h post-triggering (reference group). Oocyte denudation/injection at <36 h post-triggering had no significant effect on maturation, fertilization or embryo utilization rates compared to injection at 38 h. No effect of the time interval was observed on CPRs and LBRs, after adjusting for potential confounders. When oocyte injection was performed before 36 h the adjusted analysis showed that compared to 38 h after ovulation triggering the chance of having a live birth tends to be lower although the difference was not statistically significant (odds ratio 0.533, 95% CI: 0.252-1.126; P = 0.099). Injection ≥41 h post-triggering did not affect LBR compared to injection at 38 h post-ovulation.

LIMITATIONS, REASONS FOR CAUTION

As this is a large retrospective study, the influence of uncontrolled variables cannot be excluded. These results should not be extrapolated to other ART procedures such as IVM, conventional IVF or injection with testicular/epididymal sperm.

WIDER IMPLICATIONS OF THE FINDINGS

Our results indicate that the optimal injection time window may be less stringent than previously thought as both embryological and clinical outcome parameters were not significantly affected in our analysis. This is reassuring for busy ART centres that might not always be able to follow strict time intervals.

STUDY FUNDING/COMPETING INTEREST(S)

No funding. The authors declare no conflict of interest related to the present study.

TRIAL REGISTRATION NUMBER

N/A.

Chromosomal abnormalities after ICSI in relation to semen parameters: results in 1114 fetuses and 1391 neonates from a single center

STUDY QUESTION

Is there a relationship between karyotype abnormalities in fetuses and children conceived by ICSI and their father's semen parameters?

SUMMARY ANSWER

The de novo chromosomal abnormality rate in pre- and postnatal karyotypes of ICSI offspring was higher than in the general population and related to fathers' sperm parameters.

WHAT IS KNOWN ALREADY

Several studies have reported a higher rate of de novo chromosomal anomalies in ICSI fetuses but recent data from large cohorts are limited. Overall, reported prevalences of non-inherited karyotype aberrations are increased in fetuses conceived after ICSI and vary between 1.6% and 4.2%. Only a few studies focus on the relation between karyotype anomalies in ICSI offspring and semen parameters of their fathers. Furthermore, an increased incidence of abnormal karyotypes in ICSI neonates has been described, but the rates vary widely across studies.

STUDY DESIGN, SIZE, DURATION

We report on karyotype results from prenatal testing by means of chorionic villus sampling and amniocentesis and results from postnatal blood sampling in offspring conceived by ICSI in a single center. Ongoing pregnancies resulting from an oocyte retrieval between January 2004 and December 2012 and after transfer of fresh ICSI embryos obtained using ejaculated or non-ejaculated sperm (fresh or frozen-thawed) were considered. Pregnancies following frozen embryo transfer, oocyte or sperm donation, IVF, preimplantation genetic testing and IVM were excluded. All abnormal prenatal results after sampling are reported irrespective of the outcome of the pregnancy.

PARTICIPANTS/MATERIALS, SETTING, METHODS

From the 4816 ongoing ICSI pregnancies, information on pregnancy outcome was available for 4267 pregnancies. Prenatal testing was performed in 22.3% of the pregnancies, resulting in a diagnosis in 1114 fetuses. A postnatal karyotype was obtained in 29.4% of the pregnancies in which no invasive prenatal diagnosis was performed, resulting in a total of 1391 neonates sampled. The prevalence of chromosomal anomalies according to maternal age and semen quality was analyzed with logistic regression. For definitions of normal semen quality, the World Health Organization reference values for human semen characteristics were adopted.

MAIN RESULTS AND THE ROLE OF CHANCE

An abnormal fetal karyotype was found in 29 singletons and 12 multiples (41/1114; 3.7%; 95% CI 2.7-4.9%): 36 anomalies were de novo (3.2%; 95% CI 2.3-4.4), either numerical (n = 25), sex (n = 6) or structural (n = 5), and five were inherited. Logistic regression analysis did not show a significant association between maternal age and a de novo chromosomal fetal abnormality (odds ratio (OR) 1.05; 95% CI 0.96-1.15; P = 0.24). In all but one case, fetuses with an abnormal karyotype were conceived by ICSI using ejaculated sperm.Abnormal karyotypes were found in 14 (1.0%; 95% CI 0.6-1.7) out of 1391 postnatal samples of children born after ICSI who were not tested prenatally: 12 were de novo anomalies and two were inherited balanced karyotypes. The 14 abnormal karyotypes were all found in children born after ICSI using ejaculated sperm.The odds of a de novo karyotype aberration increased with maternal age when combining pre- and postnatal data (OR 1.11; 95% CI 1.04-1.19). A higher rate of de novo chromosomal abnormalities was found in fetuses and children of couples with men having a sperm concentration <15 million/ml (adjusted OR (AOR) 2.10; 95% CI 1.14-3.78), sperm concentration <5 million/ml (AOR 1.9; 95% CI 1.05-3.45) and total sperm count <10 million (AOR 1.97; 95% CI 1.04-3.74).

LIMITATIONS, REASONS FOR CAUTION

We cannot exclude that the observation of a higher prevalence of karyotype anomalies in ICSI offspring compared to literature data in the general population is due to enhanced surveillance after ART given the lack of a control group. Although we did not find more chromosomal anomalies after ICSI with non-ejaculated sperm, the small numbers do not allow firm conclusions.

WIDER IMPLICATIONS OF THE FINDINGS

The observed increased risk of a de novo karyotype anomaly after ICSI conception in couples with poor sperm warrants continued counseling toward prenatal testing.The current and widespread use of innovative non-invasive prenatal testing will result in larger datasets, adding to a balanced estimation of the prevalence of karyotype anomalies in ICSI offspring.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the Methusalem grants issued by the Vrije Universiteit Brussel. All authors declared no conflict of interest related to this study.

TRIAL REGISTRATION NUMBER

N/A.

Predicting suboptimal oocyte yield following GnRH agonist trigger by measuring serum LH at the start of ovarian stimulation

STUDY QUESTION

Are the LH levels at the start of ovarian stimulation predictive of suboptimal oocyte yield from GnRH agonist triggering in GnRH antagonist down-regulated cycles?

SUMMARY ANSWER

LH levels at the start of ovarian stimulation are an independent predictor of suboptimal oocyte yield following a GnRH agonist trigger.

WHAT IS KNOWN ALREADY

A GnRH agonist ovulation trigger may result in an inadequate oocyte yield in a small subset of patients. This failure can range from empty follicle syndrome to the retrieval of much fewer oocytes than expected. Suboptimal response to a GnRH agonist trigger has been defined as the presence of circulating LH levels <15 IU/l 12 h after triggering. It has been shown that patients with immeasurable LH levels on trigger day have an up to 25% risk of suboptimal response.

STUDY DESIGN, SIZE, DURATION

In this retrospective cohort study, all patients (n = 3334) who received GnRH agonist triggering (using Triptoreline 0.2 mg) for final oocyte maturation undergoing a GnRH antagonist cycle in our centre from 2011 to 2017 were included. The primary outcome of the study was oocyte yield, defined as the ratio between the total number of collected oocytes and the number of follicles with a mean diameter >10 mm prior to GnRH agonist trigger.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The endocrine profile of all patients was studied at initiation as well as at the end of ovarian stimulation. In order to evaluate whether LH levels, not only at the end but also at the start, of ovarian stimulation predicted oocyte yield, we performed multivariable regression analysis adjusting for the following confounding factors: female age, body mass index, oral contraceptives before treatment, basal and trigger day estradiol levels, starting FSH levels, use of highly purified human menopausal gonadotrophin and total gonadotropin dose. Suboptimal response to GnRH agonist trigger was defined as <10th percentile of oocyte yield.

MAIN RESULTS AND THE ROLE OF CHANCE

The average age was 31.9 years, and the mean oocyte yield was 89%. The suboptimal response to GnRH agonist trigger cut-off (<10th percentile) was 45%, which was exhibited by 340 patients. Following confounder adjustment, multivariable regression analysis showed that LH levels at the initiation of ovarian stimulation remained an independent predictor of suboptimal response even in the multivariable model (adjusted OR 0.920, 95% CI 0.871-0.971). Patients with immeasurable LH levels at the start of stimulation (<0.1 IU/l) had a 45.2% risk of suboptimal response, while the risk decreased with increasing basal LH levels; baseline circulating LH <0.5 IU/L, <2 IU/L and <5 IU/L were associated with a 39.1%, 25.2% and 13.6% risk, respectively.

LIMITATIONS, REASONS FOR CAUTION

The main limitation of the study is its retrospective design.

WIDER IMPLICATIONS OF THE FINDINGS

This is the largest study of GnRH agonist trigger cycles only, since most of the previous research on the predictive value of basal LH levels was performed in dual trigger cycles. LH values should be measured prior to start of ovarian stimulation. In cases where they are immeasurable, suboptimal response to GnRH agonist trigger can be anticipated, and an individualized approach is warranted.

STUDY FUNDING/COMPETING INTEREST(S)

There was no funding and no competing interests.

TRIAL REGISTRATION NUMBER

Not applicable.

Factors influencing the clinical outcome of preimplantation genetic testing for polycystic kidney disease

STUDY QUESTION

What are the factors influencing the success rate for couples undergoing preimplantation genetic testing (PGT) for polycystic kidney disease (PKD)?

SUMMARY ANSWER

In our study cohort, the live birth delivery rate is significantly associated with female age while the male infertility accompanying autosomal dominant PKD (ADPKD) does not substantially affect the clinical outcome.

WHAT IS KNOWN ALREADY

While women with ADPKD have no specific fertility problems, male ADPKD patients may present with reproductive system abnormalities and infertility.

STUDY DESIGN, SIZE, DURATION

This retrospective cohort study involves 91 PGT cycles for PKD for 43 couples (33 couples for PKD1, 2 couples for PKD2 and 8 couples for autosomal recessive PKD (ARPKD)) from January 2005 until December 2016 with follow-up of transfers until end of 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Sixteen single-cell clinical tests for PKD based on multiplex PCR of short tandem repeat markers, with or without a specific mutation were developed and applied for diagnosis of 584 Day 3 cleavage stage embryos. In 18 couples, the male partner was affected with ADPKD (=Group A) and 12 of them had a documented infertility status. Group A underwent 52 cycles to oocyte retrieval. For 18 other couples, the female partner was affected with ADPKD (=Group B) and four male partners from this group had a documented history of infertility. This group underwent 31 cycles to OR.

MAIN RESULTS AND THE ROLE OF CHANCE

Genetic analysis resulted in 545 embryos (93.3%) with a diagnosis, of which 215 (36.8%) were genetically transferable. Transfer of 74 embryos in 53 fresh cycles and of 34 cryopreserved embryos in 33 frozen-warmed embryo transfer cycles resulted in a live birth delivery rate of 38.4% per transfer with 31 singleton live births, two twin live births and one ongoing pregnancy. The observed cumulative delivery rate was 57.8% per couple after five treatment cycles. Thirty cryopreserved embryos still remain available for transfer. The clinical pregnancy rate per transfer (fresh + frozen; 45.9% in group A versus 60.0% in group B, P < 0.05) and the live birth delivery rate per transfer (fresh + frozen; 27.0% in group A versus 42.9% in group B, P < 0.05) was significantly lower for couples with the male partner affected with ADPKD compared with couples with the female partner affected with ADPKD. However, a multivariate logistic regression analysis showed that only female age was associated with live birth delivery rate (odds ratio = 0.87; 95% CI: 0.77-0.99; P = 0.032).

LIMITATIONS, REASONS FOR CAUTION

This study is based on retrospective data from a single centre with Day 3 one-cell and two-cell biopsy. Further analysis of a larger cohort of PKD patients undergoing PGT is required to determine the impact of male infertility associated with ADPKD on the cumulative results.

WIDER IMPLICATIONS OF THE FINDINGS

Knowledge about factors affecting the clinical outcome after PGT can be a valuable tool for physicians to counsel PKD patients about their reproductive options. Males affected with ADPKD who suffer from infertility should be advised to seek treatment in time to improve their chances of conceiving a child.

STUDY FUNDING/COMPETING INTEREST(S)

No funding was obtained. There are no competing interests to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

Influence of ultra-low oxygen (2%) tension on in-vitro human embryo development

STUDY QUESTION

Is a reduction in the oxygen tension from 5 to 2% during extended culture from Day 3 onwards beneficial for human blastocyst development in vitro?

SUMMARY ANSWER

A reduction in oxygen concentration from 5 to 2% O2 after Day 3 did not improve embryo development, quality and utilization rate.

WHAT IS KNOWN ALREADY

The human embryo leaves the fallopian tube to reach the uterine cavity around Day 3-4 post-ovulation. As the oxygen concentration ranges from 5 to 7% in the fallopian tube and decreases to 2% in the uterus, reducing the oxygen tension during extended culture from Day 3 onwards seems more physiological. We aim to mimic the in-vivo environment during in-vitro embryo culture. Therefore, we compared the effect of extended culture performed at 5% (control arm) or 2% oxygen (O2; study arm) tension on blastocyst formation and quality.

STUDY DESIGN, SIZE, DURATION

Between December 2016 and September 2017, in two prospective studies, sibling embryos were randomized on Day 3 to either 5% O2 (control) or 2% O2 (study) for extended culture. In the control arms of both studies 1 and 2, the dishes with blastocyst medium were pre-equilibrated overnight in 5% O2, 6% CO2 and 89% N2 at 37°C. In the 2% study groups, the overnight pre-equilibration of blastocyst media was performed in either 2% O2 (study 1, 99 cycles) or 5% O2 (study 2, 126 cycles). The latter provides a gradual transition from 5 to 2% O2 environment for the study arm.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

Embryo culture until Day 3 was always performed in 5% O2; if at least four embryos of moderate to excellent quality were obtained on Day 3, the sibling embryos were randomized to either 5% O2 or 2% O2 for extended culture. The endpoints were embryo development and quality on Day 5/6 and the utilization rate (embryos transferred and cryopreserved). Statistical analysis was performed using the chi-square test, a P-value of <0.05 was considered significantly different.

MAIN RESULTS AND THE ROLE OF CHANCE

In study 1, 811 embryos were randomized on Day 3: 405 to the 2% O2 and 406 to the 5% O2 condition. No differences were observed in the blastulation rate (68.6 versus 71.9%; P = 0.319) and the proportion of good quality blastocysts on Day 5 (55.8 versus 55.2%; P = 0.888), nor in the utilization rate (53.1 versus 53.2%; P = 1.000). In study 2, 1144 embryos were randomized: 572 in each arm. Similarly, no significant difference was demonstrated in terms of the blastulation rate (63.6 versus 64.7%; P = 0.758), the proportion of good quality blastocysts (46.9 versus 48.8%; P = 0.554) or the utilization rate (49.8 versus 48.1%; P = 0.953).

LIMITATIONS, REASON FOR CAUTION

This study evaluated embryo development only until Day 5/6. The effect of oxidative stress on the developing embryo may only become evident at later stages (i.e. during implantation) and should therefore be studied in an RCT. The question also remains as to whether the switch to ultra-low oxygen tension from Day 4 onwards, when the embryo arrives in the uterus in vivo, would be preferential.

WIDER IMPLICATIONS OF THE FINDINGS

Based on the present study results, there is no benefit in lowering the oxygen tension from 5 to 2% from Day 3 onwards during extended human embryo culture.

STUDY FUNDING/COMPETING INTEREST(s)

No funding was received for this study and the authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Do we need to measure progesterone in oocyte donation cycles? A retrospective analysis evaluating cumulative live birth rates and embryo quality

STUDY QUESTION

Does late follicular-phase elevated serum progesterone (LFEP) during ovarian stimulation for oocyte donation have an impact on embryo quality (EQ) and cumulative live birth rate (CLBR)?

SUMMARY ANSWER

LFEP does not have an influence on EQ nor CLBR in oocyte donation cycles.

WHAT IS KNOWN ALREADY

Ovarian stimulation promotes the production of progesterone (P) which, when elevated during the follicular phase, has been demonstrated to have a deleterious effect in autologous fresh IVF outcomes. While there is robust evidence that this elevation results in impaired endometrial receptivity, the impact on EQ remains a matter of debate. The oocyte donation model is an excellent tool to assess the effects of LFEP on EQ from those on endometrium receptivity separately. Previous studies in oocyte donation cycles investigating the influence of elevated P on pregnancy outcomes in oocyte recipients showed conflicting results.

STUDY DESIGN, SIZE, DURATION

This is a retrospective analysis including all GnRH antagonist down-regulated cycles for fresh oocyte donation taking place in a tertiary referral university hospital between 2010 and 2017. A total of 397 fresh donor-recipient cycles were included. Each donor was included only once in the analysis and could be associated to a single recipient.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The sample was stratified according to serum P levels of ≤1.5 and &gt;1.5 ng/mL on the day of ovulation triggering. The primary endpoint of the study was the top-quality embryo rate on Day 3, and the secondary outcome measure was CLBR defined as a live-born delivery beyond 24 weeks.

MAIN RESULTS AND THE ROLE OF CHANCE

Three hundred ninety-seven fresh oocyte donation cycles were included in the analysis, of which 314 (79%) had a serum P ≤ 1.5 ng/mL and 83 (20.9%) had a serum P &gt; 1.5 ng/mL. The average age of the oocyte donors was 31.4 ± 4.7 and 29.9 ± 4.5 years, respectively, for normal and elevated P (P = 0.017). The mean number of oocytes retrieved was significantly higher in the elevated P group with 16.6 ± 10.6 vs 11.5 ± 6.9 in the P ≤ 1.5 group (P &lt; 0.001).

In parallel, the total number of embryos on Day 3, as well as the number of good-quality embryos at this stage, was significantly higher in the elevated P group (6.6 ± 5.6 vs 4.15 ± 3.5 and 8.7 ± 6.3 vs 6.1 ± 4.4; respectively, P &lt; 0.001). However, maturation and fertilization rates did not vary significantly between the two study groups and neither did the top- and good-quality embryo rate and the embryo utilization rate, all evaluated on Day 3 (P = 0.384, P = 0.405 and P = 0.645, respectively). A multivariable regression analysis accounting for P groups, age of the donor, number of retrieved oocytes and top-quality embryo rate as potential confounders showed that LFEP negatively influenced neither the top-quality embryo rate nor the CLBR.

LIMITATIONS, REASONS FOR CAUTION

This is an observational study based on a retrospective data analysis. Better extrapolation of the results could be validated by performing a prospective trial. Furthermore, this study was focused on oocyte donation cycles and hence the results cannot be generalized to the entire infertile population.

WIDER IMPLICATIONS OF THE FINDINGS

This is the first study providing evidence that LFEP does not influence CLBR and is adding strong evidence to the existing literature that LFEP does not harm EQ in oocyte donation programs.

STUDY FUNDING/COMPETING INTERESTS

Not applicable.

Clinical performance of a specific granulocyte colony stimulating factor ELISA to determine its concentration in follicular fluid as a predictor of implantation success during in vitro fertilization

This study aimed to demonstrate the clinical performance of an ultra-sensitive follicular fluid (FF) granulocyte colony stimulating factor (G-CSF) immunoassay to confirm previous work, indicating a correlation between FF G-CSF concentration and live birth potential of the corresponding embryo after in vitro fertilization. This study was a noninterventional, prospective, diagnostic clinical multicentric study conducted between August 2012 and January 2014 with 396 single embryo transfers (SETs) from 278 subjects. During oocyte retrieval, FF was individually collected. Embryo morphology and implantation success were evaluated. The implantation success rate in the high G-CSF group (32.3%) was higher than the overall rate (27.5%). Similarly, for embryos with optimal morphology, implantation success rates were highest among those in the high G-CSF concentration category (34.5%) compared with low (19.6%) and intermediate (29.8%) G-CSF concentration categories. Significant differences in mean G-CSF concentrations were observed between the study sites. To minimize bias, analyses were repeated using data from the center with the largest number of SETs. In alignment with the overall analysis, this center demonstrated a 43% greater probability of implantation for optimal embryos with high G-CSF compared to the general implantation rate among optimal embryos and a 327% increase compared with the implantation rate of optimal embryos with low G-CSF.

Cumulus-corona gene expression analysis combined with morphological embryo scoring in single embryo transfer cycles increases live birth after fresh transfer and decreases time to pregnancy

PURPOSE

Clinical pregnancy rate after IVF with eSET stagnates between 30 and 40%. In order to increase pregnancy and live birth rates, multiple embryo transfer is still common practice. Providing additional non-invasive tools to choose the competent embryo for transfer could avoid multiple pregnancy and improve time to pregnancy. Cumulus mRNA analysis with quantitative PCR (QPCR) is a non-invasive approach. However, so far, no gene sets have been validated in prospective interventional studies.

METHODS

A prospective interventional single-center pilot study with two matched controls (day-3 and day-5 eSET) was performed in 96 patients consenting to the analysis of the cumulus-corona of their oocytes. All patients were super-ovulated for ICSI and eSET at day 3. All oocytes were denuded individually and cumulus was analyzed by quantitative PCR using three predictive genes (EFNB2, SASH1, CAMK1D) and two housekeeping genes (UBC and β2M). Patients (n = 62) with 2 or more day-3 embryos (good or excellent morphology) had their embryo chosen following the normalized expression of the genes.

RESULTS

Corona testing significantly increased the clinical pregnancy and live births rates (63% and 55%) compared to single embryo transfer (eSET) on day 3 (27% and 23%: p < 0.001) and day 5 (43% and 39%: p = 0.022 and p = 0.050) fresh transfer cycle controls with morphology-only selection. Time-to-pregnancy was significantly reduced, regardless of the number of good-quality embryos available on day 3.

CONCLUSION

Combining standard morphology scoring and cumulus/corona gene expression analysis increases day-3 eSET results and significantly reduces the time to pregnancy.

TRIAL REGISTRATION NUMBER

This is not an RCT study and was only registered by the ethical committee of the University Hospital UZBRUSSEL of the Vrije Universiteit Brussel VUB (BUN: 143201318000).

An improved IVM method for cumulus-oocyte complexes from small follicles in polycystic ovary syndrome patients enhances oocyte competence and embryo yield

STUDY QUESTION

Are meiotic and developmental competence of human oocytes from small (2-8 mm) antral follicles improved by applying an optimized IVM method involving a prematuration step in presence of C-Type Natriuretic Peptide (CNP) followed by a maturation step in presence of FSH and Amphiregulin (AREG)?

SUMMARY ANSWER

A strategy involving prematuration culture (PMC) in the presence of CNP followed by IVM using FSH + AREG increases oocyte maturation potential leading to a higher availability of Day 3 embryos and good-quality blastocysts for single embryo transfer.

WHAT IS KNOWN ALREADY

IVM is a minimal-stimulation ART with reduced hormone-related side effects and risks for the patients, but the approach is not widely used because of an efficiency gap compared to conventional ART. In vitro systems that enhance synchronization of nuclear and cytoplasmic maturation before the meiotic trigger are crucial to optimize human IVM systems. However, previous PMC attempts have failed in sustaining cumulus-oocyte connections throughout the culture period, which prohibited a normal cumulus-oocyte communication and precluded an adequate response by the cumulus-oocyte complex (COC) to the meiotic trigger.

STUDY DESIGN, SIZE, DURATION

A first prospective study involved sibling oocytes from a group of 15 patients with polycystic ovary syndrome (PCOS) to evaluate effects of a new IVM culture method on oocyte nuclear maturation and their downstream developmental competence. A second prospective study in an additional series of 15 women with polycystic ovaries characterized and fine-tuned the culture conditions.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Fifteen women with PCOS (according to Rotterdam criteria) underwent IVM treatment after 3-5 days of highly purified human menopausal gonadotropin (HP-hMG) stimulation and no human chorionic gonadotropin (hCG) trigger before oocyte retrieval. A first study was designed with sibling oocytes to prospectively evaluate the impact of an IVM culture method: 24 h PMC with CNP + 30 h IVM with FSH and AREG, on embryo yield, in comparison to the standard (30 h) IVM clinical protocol (Group I, n = 15). A second prospective study was performed in 15 women with polycystic ovaries, to characterize and optimize the PMC conditions (Group II, n = 15). The latter study involved the evaluation of oocyte meiotic arrest, the preservation of cumulus-oocyte transzonal projections (TZPs), the patterns of oocyte chromatin configuration and cumulus cells apoptosis following the 24 and 46 h PMC. Furthermore, oocyte developmental potential following PMC (24 and 46 h) + IVM was also evaluated. The first 20 good-quality blastocysts from PMC followed by IVM were analysed by next generation sequencing to evaluate their aneuploidy rate.

MAIN RESULTS AND THE ROLE OF CHANCE

PMC in presence of CNP followed by IVM using FSH and AREG increased the meiotic maturation rate per COC to 70%, which is significantly higher than routine standard IVM (49%; P ≤ 0.001). Hence, with the new system the proportion of COCs yielding transferable Day 3 embryos and good-quality blastocysts increased compared to routine standard IVM (from 23 to 43%; P ≤ 0.001 and from 8 to 18%; P ≤ 0.01, respectively). CNP was able to prevent meiosis resumption for up to 46 h. After PMC, COCs had preserved cumulus-oocyte TZPs. The blastocysts obtained after PMC + IVM did not show increased aneuploidy rates as compared to blastocysts from conventional ART.

LIMITATIONS REASONS FOR CAUTION

The novel IVM approach in PCOS patients was tested in oocytes derived from small antral follicles which have an intrinsically low developmental potential. Validation of the system would be required for COCs from different (larger) follicular sizes, which may involve further adjustment of PMC conditions. Furthermore, considering that this is a novel strategy in human IVM treatment, its global efficiency needs to be confirmed in large prospective randomized controlled trials. The further application in infertile patients without PCOS, e.g. cancer patients, remains to be evaluated.

WIDER IMPLICATIONS OF THE FINDINGS

The findings of this pilot study suggest that the efficiency gap between IVM and conventional IVF can be reduced by fine-tuning of the culture methods. This novel strategy opens new perspectives for safe and patient-friendly ART in patients with PCOS.

STUDY FUNDING/COMPETING INTEREST(S)

IVM research at the Vrije Universiteit Brussel has been supported by grants from: the Institute for the Promotion of Innovation by Science and Technology in Flanders (Agentschap voor Innovatie door Wetenschap en Technologie-IWT, project 110680); the Fund for Research Flanders (Fonds Wetenschappelijk Onderzoek-Vlaanderen-FWO, project G.0343.13), the Belgian Foundation Against Cancer (HOPE project, Dossier C69). The authors have no conflicts of interest.

Semen quality of young adult ICSI offspring: the first results

STUDY QUESTION

What is the semen quality of young adult men who were conceived 18-22 years ago by ICSI for male infertility?

SUMMARY ANSWER

In this cohort of 54 young adult ICSI men, median sperm concentration, total sperm count and total motile sperm count were significantly lower than in spontaneously conceived peers.

WHAT IS KNOWN ALREADY

The oldest ICSI offspring cohort worldwide has recently reached adulthood. Hence, their reproductive health can now be investigated. Since these children were conceived by ICSI because of severe male-factor infertility, there is reasonable concern that male offspring have inherited the deficient spermatogenesis from their fathers. Previously normal pubertal development and adequate Sertoli and Leydig cell function have been described in pubertal ICSI boys; however, no information on their sperm quality is currently available.

STUDY DESIGN, SIZE, DURATION

This study was conducted at UZ Brussel between March 2013 and April 2016 and is part of a large follow-up project focussing on reproductive and metabolic health of young adults, between 18 and 22 years and conceived after ICSI with ejaculated sperm. Results of both a physical examination and semen analysis were compared between young ICSI men being part of a longitudinally followed cohort and spontaneously conceived controls who were recruited cross-sectionally.

PARTICIPANTS/MATERIALS, SETTING, METHOD

Results of a single semen sample in 54 young adult ICSI men and 57 spontaneously conceived men are reported. All young adults were individually assessed, and the results of their physical examination were completed by questionnaires. Data were analysed by multiple linear and logistic regression, adjusted for covariates. In addition, semen parameters of the ICSI fathers dating back from their ICSI treatment application were analysed for correlations.

MAIN RESULTS AND THE ROLE OF CHANCE

Young ICSI adults had a lower median sperm concentration (17.7 million/ml), lower median total sperm count (31.9 million) and lower median total motile sperm count (12.7 million) in comparison to spontaneously conceived peers (37.0 million/ml; 86.8 million; 38.6 million, respectively). The median percentage progressive and total motility, median percentage normal morphology and median semen volume were not significantly different between these groups. After adjustment for confounders (age, BMI, genital malformations, time from ejaculation to analysis, abstinence period), the statistically significant differences between ICSI men and spontaneously conceived peers remained: an almost doubled sperm concentration in spontaneously conceived peers in comparison to ICSI men (ratio 1.9, 95% CI 1.1-3.2) and a two-fold lower total sperm count (ratio 2.3, 95% CI 1.3-4.1) and total motile count (ratio 2.1, 95% CI 1.2-3.6) in ICSI men compared to controls were found. Furthermore, compared to men born after spontaneous conception, ICSI men were nearly three times more likely to have sperm concentrations below the WHO reference value of 15 million/ml (adjusted odds ratio (AOR) 2.7; 95% CI 1.1-6.7) and four times more likely to have total sperm counts below 39 million (AOR 4.3; 95% CI 1.7-11.3). In this small group of 54 father-son pairs, a weak negative correlation between total sperm count in fathers and their sons was found.

LIMITATIONS, REASONS FOR CAUTION

The main limitation is the small study population. Also, the results of this study where ICSI was performed with ejaculated sperm and for male-factor infertility cannot be generalized to all ICSI offspring because the indications for ICSI have nowadays been extended and ICSI is also being performed with non-ejaculated sperm and reported differences may thus either decrease or increase.

WIDER IMPLICATIONS OF THE FINDINGS

These first results in a small group of ICSI men indicate a lower semen quantity and quality in young adults born after ICSI for male infertility in their fathers.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by Methusalem grants and by grants from Wetenschappelijk Fonds Willy Gepts, all issued by the Vrije Universiteit Brussel (VUB). All co-authors except M.B. and H.T. declared no conflict of interest. M.B. has received consultancy fees from MSD, Serono Symposia and Merck. The Universitair Ziekenhuis Brussel (UZ Brussel) and the Centre for Medical Genetics have received several educational grants from IBSA, Ferring, Organon, Shering-Plough and Merck for establishing the database for follow-up research and organizing the data collection. The institution of H.T. has received research grants from the Research Fund of Flanders (FWO), an unconditional grant from Ferring for research on testicular stem cells and research grants from Ferring, Merck, MSD, Roche, Besins, Goodlife and Cook for several research projects in female infertility. H.T. has received consultancy fees from Finox, Abbott and ObsEva for research projects in female infertility.

Do ARTs affect the incidence of monozygotic twinning?

STUDY QUESTION

Does the manipulation of gametes or embryos during ARTs increase the risk for monozygotic twinning (MZT)?

SUMMARY ANSWER

Frozen embryo transfer (ET) is associated with a lower MZT rate, while blastocyst culture is associated with an increased risk of monozygotic pregnancy.

WHAT IS KNOWN ALREADY

Monozygotic twins have a higher risk for perinatal complications. Although an increased incidence of monozygotic pregnancies after ART has been previously reported, data regarding the possible impact of different laboratory procedures are conflicting.

STUDY DESIGN, SIZE, DURATION

All clinical pregnancies after single ET carried out in our centre between 2004 and 2013 (n = 6096) were retrospectively analysed for the incidence of MZT. The effect of different laboratory procedures on the incidence of MZT was evaluated.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The following ART risk factors were assessed: maternal age, type of ET (fresh versus frozen), zona pellucida (ZP) manipulation (specifically, ICSI, embryo biopsy and assisted hatching), use of donor oocytes, embryo stage at time of ET (cleavage, compaction, early or advanced blastocyst) and culture media.

MAIN RESULTS AND THE ROLE OF CHANCE

The overall MZT rate was 2.2% (136/6096). Frozen ET was associated with a significant reduction in MZT incidence (adjusted odds ratio (aOR) 0.48, 95% CI 0.29-0.80), while blastocyst transfer (early or advanced blastocyst) was associated with a significant increase in MZT risk (aOR 2.70, 95% CI 1.36-5.34; aOR 2.05, 95% CI 1.29-3.26, respectively). No significant differences were found between the MZT and singleton (non-MZT) groups regarding maternal age, the use of different ZP manipulation techniques, not type of culture media used.

LIMITATION, REASONS FOR CAUTION

This study is limited by its retrospective nature and the fact that monozygosity was not confirmed by genetic testing. Furthermore, since monozygotic pregnancy is a rare event, other ART parameters that may influence its incidence could not be assessed during our analysis.

WIDER IMPLICATION OF THE FINDINGS

Our findings warrant future studies designed to investigate the association between specific ART procedures and MZT, namely the potential risk of blastocyst transfer to increase MZT.

STUDY FUNDING/COMPETING INTERESTS

No external funding was used for this study. There are no conflicts of interest.

Open versus closed oocyte vitrification in an oocyte donation programme: a prospective randomized sibling oocyte study

STUDY QUESTION

Is the survival of donor oocytes with the CryotopSC device superior to the survival with the closed CBSvit device?

SUMMARY ANSWER

The CryotopSC device and the CBSvit device showed similar survival rates.

WHAT IS KNOWN ALREADY

Health authorities are cautious about possible cross contamination during liquid nitrogen storage or handling when working with open vitrification devices. At present, the use of open devices is still allowed since little information is available on the efficiency of closed devices.

STUDY DESIGN, SIZE, DURATION

A prospective randomized sibling oocyte study was performed in the Centre for Reproductive Medicine (UZBrussel) between January 2014 and July 2015. The survival after warming and the embryological outcome of donor oocytes vitrified using two devices was compared: the CBSvit device (closed vitrification and closed storage) and the CryotopSC device (open vitrification and closed storage). A difference of 10% was defined to prove the superiority of the CryotopSC device. In total, 250 warmed oocytes were needed in each arm.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Oocytes from 48 donors were included in the study: 253 vitrified with the CBSvit device and 257 with the CryotopSC device. Equal numbers of oocytes from both devices and originated from the same donor cycle were allocated to each of 78 recipients, in order to exclude donor and recipient (male factor) effects.

MAIN RESULTS AND THE ROLE OF CHANCE

There were no differences found between the CBSvit and the CryotopSC in terms of survival after warming (93.7 versus 89.9%) or fertilization per injected oocyte (74.3 versus 81.4%). The degeneration rate after ICSI was significantly higher for the CBSvit device: 11.4 versus 6.1% (P = 0.041). A significantly higher number of zygotes in the CryotopSC group finished their first mitosis 25-27 h post-injection (34.1 versus 52.1%, P = 0.001). On Day 3, the overall embryo quality distribution did not vary between groups, but a significantly higher cell number was obtained in the CryotopSC device: 6.8 ± 2.8 versus 7.6 ± 2.8 (P = 0.01). The utilization rate per mature oocyte, per surviving oocyte or per fertilized oocyte did not differ. The embryos with the highest quality were selected for transfer on Day 3. The clinical pregnancy rate per transfer cycle was 36.5%.

LIMITATIONS, REASONS FOR CAUTION

The results of this study should not be extrapolated to other female groups, since oocytes from young fertile donors were used in this study.

WIDER IMPLICATIONS OF THE FINDINGS

In many countries, the use of open devices is still allowed due to the limited reports on the efficiency of closed devices. Knowing the caution of health authorities about the use of open devices, there is an urgent need for efficiency studies with closed devices. The results obtained in the current study shows the efficiency of a safe closed vitrification device, leaving behind any concern about possible cross contamination during handling or storage.

STUDY FUNDING/COMPETING INTERESTS

No funding was obtained. The authors have no conflict of interest to declare.

TRIAL REGISTRATION NUMBER

NCT01952184.

TRIAL REGISTRATION DATE

24 September 2013.

DATE OF FIRST PATIENT'S ENROLMENT

23 January 2014.

How successful is TESE-ICSI in couples with non-obstructive azoospermia?

STUDY QUESTION

What are the chances of a couple with infertility due to non-obstructive azoospermia (NOA) having their genetically own child by testicular sperm extraction combined with ICSI (TESE-ICSI)?

SUMMARY ANSWER

Candidate TESE-ICSI patients with NOA should be counselled that, when followed-up longitudinally, only a minority (13.4%) of men embarking for TESE eventually become a biological father.

WHAT IS KNOWN ALREADY

Data available in the literature are only fragmentary because they report either on sperm retrieval rates after TESE or on the outcome of ICSI once testicular spermatozoa has been obtained, mostly in a selected subpopulation. Unfortunately, reliable data to counsel men with NOA on their chance to become a biological father are still lacking.

STUDY DESIGN, SIZE, DURATION

This is a retrospective cohort study performed in the Centre for Reproductive Medicine, University Hospital of Brussel, approved by the institutional review board of the hospital.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

We identified all patients with NOA, based on histology, who had their first testicular biopsy between 1994 and 2009. Patients were followed longitudinally during consecutive ICSI cycles with testicular sperm. The primary outcome measure was live birth delivery. The cumulative live birth delivery rate was calculated, based only on ICSI cycles with testicular sperm (fresh and/or frozen) available for injection. When patients delivered after transfer of supernumerary frozen embryos, this delivery was tallied up to the (unsuccessful) original fresh ICSI cycle. The sperm retrieval rate and pregnancy rate were secondary outcome measures.

MAIN RESULTS AND THE ROLE OF CHANCE

Among the 714 men with NOA, 40.5% had successful sperm retrieval at their first TESE. In total, 261 couples had 444 ICSI cycles and 48 frozen embryo transfer cycles, leading to 129 pregnancies and 96 live birth deliveries. Crude and expected cumulative delivery rates after six ICSI cycles were 37 and 78%.

LIMITATIONS AND REASON FOR CAUTION

A retrospective cohort study design was the only way to study the cumulative delivery rate after TESE-ICSI in couples with NOA. Intrinsic limitations are related to the observational study design.

WIDER IMPLICATION OF THE FINDING

TESE-ICSI is a breakthrough in the treatment of infertility due to NOA, with almost 4 out of 10 (37%) couples having ICSI obtaining a delivery. However, unselected candidate NOA patients should be counselled, before undergoing TESE, that only one out of seven men (13.4%) eventually father their genetically own child.

STUDY FUNDING AND COMPETING INTERESTS

None declared.

Deposition of the spermatozoon in the human oocyte at ICSI: impact on oocyte survival, fertilization and blastocyst formation

PURPOSE

To evaluate whether the deposition of the spermatozoon in the human oocyte at ICSI has any effect on oocyte survival, fertilization, blastocyst development and quality.

METHODS

In a prospective study, including 78 ICSI cycles, sibling oocytes were injected with "no intention" (group A, standard ICSI, n = 393) or "intention" to deposit the spermatozoon under the cortex (group B, n = 354). Outcome parameters were oocyte survival and fertilization, as well as blastocyst formation and quality.

RESULTS

Depositing the sperm under the cortex of the oocyte was not always successful for its final position, therefore, group B was divided into three subgroups: B1 successful deposition (119 oocytes, 33.6 % of oocytes in group B); B2 initially successful but spermatozoon spontaneously relocated after 2 min (136 oocytes, 38.4 %); and B3 unsuccessful deposition (99 oocytes, 28.0 %). Group A and B were compared on an intention-to-treat basis. Additionally, A, B1, B2 and B3 were also compared. The oocyte survival and fertilization, blastocyst and top-quality blastocyst developmental rates were not significantly different.

CONCLUSIONS

The procedure of depositing the spermatozoon intentionally under the oocyte cortex demanded high technical skills. Successful positioning was only obtained in 34 % of the attempts. We obtained no evidence of improved oocyte survival and fertilization, blastocyst formation and quality when the spermatozoon was permanently positioned under the oocyte cortex. Taken together, depositing the spermatozoon under the oocyte cortex is not recommended for routine ICSI application.

The type of culture medium and the duration of in vitro culture do not influence birthweight of ART singletons

STUDY QUESTION

Does the type of in vitro culture medium or the duration of in vitro culture influence singleton birthweight after IVF/ICSI treatment?

SUMMARY ANSWER

In a comparison of two culture media, neither the medium nor the duration of culture (Day 3 versus Day 5 blastocyst transfer) had any effect on mean singleton birthweight.

WHAT IS KNOWN ALREADY

Previous studies indicated that in vitro culture of human embryos may affect birthweight of live born singletons. Both the type of culture medium and the duration of culture may be implicated. However, these studies are small and report conflicting results.

STUDY DESIGN, SIZE, DURATION

A large retrospective analysis was performed including all singleton live births after transferring fresh Day 3 or Day 5 embryos. IVF and ICSI cycles performed between April 2004 and December 2009 at a tertiary care centre were included for analysis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 2098 singleton live births resulting from singleton pregnancies were included for analysis. Two different sequential embryo culture media were concurrently used in an alternating way: Medicult (n = 1388) and Vitrolife (n = 710). Maternal age, maternal and paternal BMI, maternal parity, maternal smoking, main cause of infertility, cycle rank, stimulation protocol, method of fertilization (IVF or ICSI), time in culture and number of embryos transferred were taken into account. Embryo transfers were performed either on Day 3 (n = 1234) or on Day 5 (n = 864). Singleton birthweight was the primary outcome parameter. Gestational age and gender of the newborn were accounted for in the multiple regression analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

No significant differences in mean singleton birthweight were observed between the two culture media: Medicult 3222 g (±15 SE) and Vitrolife 3251 g (±21 SE) (P = 0.264). The mean singleton birthweight was not different between Day 3 embryo transfers (3219 ± 16 g) and Day 5 blastocyst transfers (3250 ± 19 g; P = 0.209). Multiple regression analysis controlling for potential maternal, paternal, treatment and newborn confounders confirmed the non-significant differences in mean singleton birthweight between the two culture media. Likewise, the adjusted mean singleton birthweight was not different according to the duration of in vitro culture (P = 0.521).

LIMITATIONS, REASONS FOR CAUTION

The conclusions are limited by its retrospective design; however, the two different sequential culture systems were used in an alternating way during the same time period. Pregnancy-associated factors possibly influencing birthweight (such as diabetes, hypertension, pre-eclampsia) were not included in the analysis.

WIDER IMPLICATIONS OF THE FINDINGS

This large retrospective study does not support earlier concerns that both the type of culture medium and the duration of embryo culture influence singleton birthweight. However, a continuous surveillance of human embryo culture procedures (medium type, culture duration and other culture conditions) should remain a priority within assisted reproduction technology.

STUDY FUNDING/COMPETING INTERESTS

None.