Vitrification of cleavage stage day 3 embryos results in higher live birth rates than conventional slow freezing: a RCT

Long-term embryo vitrification is associated with reduced success rates in women undergoing frozen embryo transfer following a failed fresh cycle

OBJECTIVE

To investigate the association of long-term embryo vitrification with the success rates and neonatal outcomes in frozen cycles.

STUDY DESIGN

A single-center, retrospective cohort study was performed in Peking University Third Hospital. We included women who had undergone their first vitrified-warmed cycles following an unsuccessful fresh embryo transfer cycle between January 2013 and December 2019. Restricted cubic splines with 4 knots (at min-3.0 months, 3.1-6.0 months, 6.1-12.0 months, 12.1-max months) were used to map the non-linear relationship between live birth and embryo storage time as a continuous variable after adjustment for covariates. Multiple logistic regression was used to calculate crude odds ratios (OR) and adjusted OR (aOR) with 95 % confidence intervals (CI).

RESULTS

A total of 10,167 women undergoing their first frozen cycle following an unsuccessful fresh embryo transfer cycle were included, among whom 3,708 resulted in a live birth (3,254 singleton live births). Restricted cubic splines, both before and after adjusting for covariates, showed that the predicted live birth rate (LBR) progressively decreased with an increase in the duration of embryo cryopreservation. This trend was also evident when women were categorized into four groups based on the length of cryopreservation. The live birth rate (LBR) was highest in the 0.8-3.0 months group (38 %) compared to the other groups. Multivariable logistic regression with the 0.8-3.0 months group as the reference, demonstrated that the 6.1-12.0 months group and >12.0 months group experienced lower live birth rates (aOR = 0.82 (0.72, 0.94) and aOR = 0.71 (0.57, 0.88), respectively). The LBR for the 3.1-6.0 months group was comparable to that of the 0.8-3.0 months group, with an aOR of 0.98 (0.90, 1.07). Sensitivity analyses in women who underwent single blastocyst transfer, in women with at least one good-quality embryo for transfer, and in women with age less than 36 at embryo transfer demonstrated a similar association between LBR and embryo frozen time. The neonatal outcomes were not significantly different among the four groups.

CONCLUSIONS

Embryo vitrification greater than six months is associated with a reduction in success rate but does not appear to alter neonatal outcome.

Serum uric acid did not affect embryonic and pregnancy outcomes in women without PCOS during IVF procedures

Objectives

Serum uric acid (UA) levels are associated with many systemic diseases. A previous study confirmed the association between high serum uric acid levels and poor prognosis of in vitro fertilization (IVF) treatment in polycystic ovary syndrome (PCOS) patients. This study aimed to explore the correlation between serum uric acid levels and reproductive outcomes in patients without PCOS.

Methods

A retrospective study that included 1057 patients who underwent pre-implantation genetic testing for monogenic disorders (PGT-M) treatment from January 2013 to December 2020 was conducted. The study population was further divided into 3 groups according to serum UA levels: the ≤250 μmol/L group, the 251-360 μmol/L group, and the >360 μmol/L group. The controlled ovarian hyperstimulation (COH) treatment outcomes, embryonic treatment outcomes and pregnancy outcomes of the first frozen embryo transfer (FET) cycle were compared among groups. Multivariable linear regression and binary regression were applied to detect the association between IVF outcomes and serum uric acid levels.

Results

The number of retrieved oocytes, fertilization rate, viable embryo rate, blastocyst formation rate and euploid rate were not associated with serum uric acid levels. The mature oocyte rate was negatively correlated with serum uric acid levels. The pregnancy outcomes of the first FET cycle were also not associated with serum uric acid levels. After adjustment for BMI, the perinatal outcomes were not associated with serum uric acid levels.

Conclusion

IVF treatment outcomes were not associated with serum uric acid levels in patients without PCOS.

Cumulative pregnancy rates of two strategies: Day 3 fresh embryo transfer followed by Day 3 or Day 5/6 vitrification and embryo transfer: a randomized controlled trial

STUDY QUESTION

Are cumulative pregnancy rates better if supernumerary embryos are vitrified on Day 5/6 instead of Day 3?

SUMMARY ANSWER

The results do not show a significant difference in cumulative pregnancy rates between the Day 3 and Day 5/6 vitrification groups.

WHAT IS KNOWN ALREADY

Pregnancy and live birth rates following IVF or ICSI treatment are higher after extended embryo culture and blastocyst transfer (Day 5/6) compared to cleavage-stage (Day 3) transfer. Cumulative pregnancy rates from one oocyte retrieval (OR) cycle show no significant difference after fresh and frozen embryo transfers, but only one study has used vitrification for the cryopreservation of supernumerary embryos while four studies have used a slow freezing protocol.

STUDY DESIGN, SIZE, DURATION

Our prospective randomized controlled trial was performed in an academic centre between January 2018 and August 2020. Patients were randomized into vitrification Day 3 (n = 80) or Day 5/6 (n = 81) groups. The primary outcome was the cumulative ongoing pregnancy rate (cOPR), considering only the first pregnancy for each couple. The power calculation revealed that 75 patients were required in each group, when assuming a 50% cOPR with four embryo transfers in the vitrification Day 3 group vs two transfers in the vitrification Day 5/6 group.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients <38 years undergoing their first or second OR cycles were randomized at the start of the first cycle. Up to two cycles were included in the analysis. A fresh embryo transfer was performed on Day 3. Supernumerary embryos (with ≥6 cells, <25% fragmentation, and equal blastomeres) or blastocysts (with expansion grade ≥2 with inner cell mass and trophectoderm score A/B) were vitrified on Day 3 or Day 5/6, respectively, and then transferred at a later date. A time-to-event analysis was performed with the patient's first ongoing pregnancy as the event of interest and the number of embryo transfers as the time component. The statistical comparison was performed by a Cox proportional hazards model. Cumulative costs of vitrification on Day 3 vs Day 5/6 were explored and compared using Mann-Whitney U tests.

MAIN RESULTS AND THE ROLE OF CHANCE

By December 2021, 233 transfers (96 fresh and 137 frozen) in 77 patients were performed in the vitrification Day 3 group and 201 transfers (88 fresh and 113 frozen) in 77 patients were performed in the vitrification Day 5/6 group. The time-to-event analysis did not show a difference between the two arms with regard to the patient's first ongoing pregnancy as the primary study outcome (hazard ratio [HR] 1.25, 95% CI 0.82; 1.92, P = 0.30). The cumulative ongoing pregnancy rate after eight transfers (from one or two ORs) was 57% in the vitrification Day 3 group vs 58% in the vitrification Day 5/6 group. The median number of embryo transfers until a pregnancy was achieved was five vs four, respectively, in the vitrification Day 3 group vs the Day 5/6 group. Similar results were found for the secondary study outcome, i.e. clinical pregnancy with foetal heart rate (HR 1.19, 95% CI 0.78; 1.80, P = 0.41). The cumulative clinical pregnancy rate (cCPR) after eight embryo transfers was 62% in the vitrification Day 3 group vs 59% in the vitrification Day 5/6 group. The median number of transfers until a pregnancy was achieved was four in both groups. The healthcare consumption pattern differed between the two groups and we observed higher costs for the vitrification Day 3 group compared to the vitrification Day 5/6 group, although these differences were not statistically significant.

LIMITATIONS, REASONS FOR CAUTION

Although our power calculation revealed that only 75 patients were needed in each study group (β = 0.87, α < 0.05), the numbers were low. Also, different numbers of single and double embryo transfers were performed between the two groups, which may have affected the results. The cost analysis was performed on a subset of the patients and is therefore exploratory.

WIDER IMPLICATIONS OF THE FINDINGS

Our study shows no difference in the cumulative pregnancy rate nor costs after fresh and frozen embryo transfers of at most two sequential OR cycles between the Day 3 and Day 5/6 vitrification groups; however, obstetric and perinatal outcomes should be taken into account to determine the best strategy.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded as an investigator-sponsored study of S.D. by Merck nv/sa Belgium, an affiliate of Merck KGaA, Darmstadt, Germany, and by Gedeon Richter Benelux (PA18-0162). The authors declare no conflict of interest related to this study.

TRIAL REGISTRATION NUMBER

NCT04196036.

TRIAL REGISTRATION DATE

15 January 2018.

DATE OF FIRST PATIENT’S ENROLMENT

15 January 2018.

Exploring the effect of cryopreservation in assisted reproductive technology and potential epigenetic risk

Since the birth of the first baby by in vitro fertilization in 1978, more than 9 million children have been born worldwide using medically assisted reproductive treatments. Fertilization naturally takes place in the maternal oviduct where unique physiological conditions enable the early healthy development of the embryo. During this dynamic period of early development major waves of epigenetic reprogramming, crucial for the normal fate of the embryo, take place. Increasingly, over the past 20 years concerns relating to the increased incidence of epigenetic anomalies in general, and genomic-imprinting disorders in particular, have been raised following assisted reproduction technology (ART) treatments. Epigenetic reprogramming is particularly susceptible to environmental conditions during the periconceptional period and non-physiological conditions such as ovarian stimulation, in vitro fertilization and embryo culture, as well as cryopreservation procedure, might have the potential to independently or collectively contribute to epigenetic dysregulation. Therefore, this narrative review offers a critical reappraisal of the evidence relating to the association between embryo cryopreservation and potential epigenetic regulation and the consequences on gene expression together with long-term consequences for offspring health and wellbeing. Current literature suggests that epigenetic and transcriptomic profiles are sensitive to the stress induced by vitrification, in terms of osmotic shock, temperature and pH changes, and toxicity of cryoprotectants, it is therefore, critical to have a more comprehensive understanding and recognition of potential unanticipated iatrogenic-induced perturbations of epigenetic modifications that may or may not be a consequence of vitrification.

Can Cryopreservation in Assisted Reproductive Technology (ART) Induce Epigenetic Changes to Gametes and Embryos?

Since the birth of Louise Brown in 1978, more than nine million children have been conceived using assisted reproductive technologies (ARTs). While the great majority of children are healthy, there are concerns about the potential epigenetic consequences of gametes and embryo manipulation. In fact, during the preimplantation period, major waves of epigenetic reprogramming occur. Epigenetic reprogramming is susceptible to environmental changes induced by ovarian stimulation, in-vitro fertilization, and embryo culture, as well as cryopreservation procedures. This review summarizes the evidence relating to oocytes and embryo cryopreservation and potential epigenetic regulation. Overall, it appears that the stress induced by vitrification, including osmotic shock, temperature and pH changes, and toxicity of cryoprotectants, might induce epigenetic and transcriptomic changes in oocytes and embryos. It is currently unclear if these changes will have potential consequences for the health of future offspring.

Advantages of vitrification preservation in assisted reproduction and potential influences on imprinted genes

Cryopreservation has important application in assisted reproductive technology (ART). The vitrification technique has been widely used in the cryopreservation of oocytes and embryos, as a large number of clinical results and experimental studies have shown that vitrification can achieve a higher cell survival rate and preimplantation development rate and better pregnancy outcomes. Ovarian tissue vitrification is an alternative method to slow freezing that causes comparatively less damage to the original follicular DNA. At present, sperm preservation mainly adopts slow freezing or rapid freezing (LN2 vapor method), although the vitrification method can achieve higher sperm motility after warming. However, due to the use of high-concentration cryoprotectants and ultra-rapid cooling, vitrification may cause strong stress to gametes, embryos and tissue cells, resulting in potentially adverse effects. Imprinted genes are regulated by epigenetic modifications, including DNA methylation, and show single allele expression. Their accurate regulation and correct expression are very important for the placenta, fetal development and offspring health. Considering that genome imprinting is very sensitive to changes in the external environment, we comprehensively summarized the effect of cryopreservation—especially the vitrification method in ART—on imprinted genes. Animal studies have found that the vitrification of oocytes and embryos can have a significant impact on some imprinted genes and DNA methylation, but the few studies in humans have reported almost no influence, which need to be further explored. This review provides useful information for the safety assessment and further optimization of the current cryopreservation techniques in ART.

The impact of embryo vitrification on placental histopathology features and perinatal outcome in singleton live births

STUDY QUESTION

Does embryo vitrification affect placental histopathology pattern and perinatal outcome in singleton live births?

SUMMARY ANSWER

Embryo vitrification has a significant effect on the placental histopathology pattern and is associated with a higher prevalence of dysfunctional labor.

WHAT IS KNOWN ALREADY

Obstetrical and perinatal outcomes differ between live births resulting from fresh and frozen embryo transfers. The effect of embryo vitrification on the placental histopathology features associated with the development of perinatal complications remains unclear.

STUDY DESIGN, SIZE, DURATION

Retrospective cohort study evaluating data of all live births from one academic tertiary hospital resulting from IVF treatment with autologous oocytes during the period from 2009 to 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All patients had placentas sent for pathological evaluation irrelevant of maternal or fetal complications status. Placental, obstetric and perinatal outcomes of pregnancies resulting from hormone replacement vitrified embryo transfers were compared with those after fresh embryo transfers. A multivariate analysis was conducted to adjust the results for determinants potentially associated with the development of placental histopathology abnormalities.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 1014 singleton live births were included in the final analysis and were allocated to the group of pregnancies resulting from fresh (n = 660) and hormone replacement frozen (n = 354) embryo transfers. After the adjustment for confounding factors the frozen embryo transfers were found to be significantly associated with chorioamnionitis with maternal (odds ratio (OR) 2.0; 95% CI 1.2-3.3) and fetal response (OR 2.6; 95% CI 1.2-5.7), fetal vascular malperfusion (OR 3.9; 95% CI 1.4-9.2), furcate cord insertion (OR 2.3 95% CI 1.2-5.3), villitis of unknown etiology (OR 2.1; 95% CI 1.1-4.2), intervillous thrombi (OR 2.1; 95% CI 1.3-3.7), subchorionic thrombi (OR 3.4; 95% CI 1.6-7.0), as well as with failure of labor progress (OR 2.5; 95% CI 1.5-4.2).

LIMITATIONS, REASONS FOR CAUTION

Since the live births resulted from frozen-thawed embryos included treatment cycles with previously failed embryo transfers, the factors over embryo vitrification may affect implantation and placental histopathology.

WIDER IMPLICATIONS OF THE FINDINGS

The study results contribute to the understanding of the perinatal future of fresh and vitrified embryos. Our findings may have an implication for the clinical decision to perform fresh or frozen-thawed embryo transfer.

STUDY FUNDING/COMPETING INTEREST(S)

Authors have not received any funding to support this study. There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

The impact of blastomere loss on pregnancy and neonatal outcomes of vitrified-warmed Day3 embryos in single embryo transfer cycles

BACKGROUND

Blastomere loss is a common phenomenon that occurs following cryopreservation. To date, studies have drawn conflicting conclusions regarding the impact of blastomere loss on pregnancy outcomes. Besides, limited information is available concerning the neonatal safety of embryos with blastomere loss. In the present study, we aimed to investigate the impact of blastomere loss on pregnancy and neonatal outcomes of vitrified/warmed Day3 cleavage-stage embryos in single embryo transfer cycles.

METHODS

This retrospective cohort study included all vitrified/warmed D3 cleavage-stage single frozen-thawed embryo transfer (FET) cycles between April 2015 and February 2021. We compared pregnancy and subsequent neonatal outcomes between the intact embryos group and the blastomere loss group in single FET cycles.

RESULTS

A total of 6287 single FET cycles were included in the study, in which 5873 cycles were classified into the intact embryo group and 414 cycles were classified into the blastomere loss group. The outcomes of the blastomere loss group were significantly inferior to those of the intact embryo group, in terms of implantation/biochemical pregnancy/clinical pregnancy/ongoing pregnancy rate and live birth rate per embryo transfer cycle/per clinical pregnancy. Further binary logistic regression confirmed that blastomere loss was negatively associated with live birth. Moreover, the blastomere loss group presented with an elevated early miscarriage rate. The neonatal conditions were broadly similar between the two groups. Additionally, multiple binary logistic regression analysis demonstrated that primary infertility and intracytoplasmic sperm injection (ICSI) were common influencing factors of blastomere loss (aOR 1.447, 95% CI 1.038-2.019, P = 0.029; aOR: 1.388, 95% CI: 1.044-51.846, P = 0.024).

CONCLUSIONS

The transfer of vitrified/warmed D3 embryos with blastomere loss is related to impaired embryo developmental potentials and reduced probabilities of conception. Moreover, even if the embryos with blastomere loss have implanted and reached clinical pregnancies, they present with a lower possibility of developing to live birth owing to a higher early miscarriage rate. However, once the embryos with blastomere loss result in a live birth, no adverse neonatal outcomes are observed. Primary infertility and ICSI were found to be risk factors for blastomere loss.

A comparative study of post-warming survival rates and clinical outcomes of human blastocysts vitrified/warmed by CryoTouch and Cryotop methods

OBJECTIVE

Advances in embryo culture conditions and the development of vitrification as a revolutionary cryopreservation method have allowed for routine use of blastocyst transfer in assisted reproduction technology (ART) cycles. Several vitrification/warming media and devices have been introduced for commercial use so far. The aim of this retrospective study was to compare post-warming survival rates and clinical outcomes of human blastocysts vitrified/warmed by two different commercial methods (CryoTouch and Cryotop) during ART cycles.

METHODS

This retrospective study assessed a total of 50 frozen embryo transfer (FET) cycles conducted on 56 warmed blastocysts between January 2018 and December 2020. Post-warming blastocyst survival rates and clinical outcomes including clinical pregnancy and live birth rates were calculated after single blastocyst transfer cycles.

RESULTS

The results revealed no significant differences between two groups in post-warming survival rate (p-value=0.8381), clinical pregnancy rate (p-value=0.8157) and live birth rate (p-value=0.7041).

CONCLUSIONS

Post-warming survival rates and clinical outcomes were comparable with no significant difference in blastocysts vitrified/warmed by CryoTouch and Cryotop commercial methods.

Female Oncofertility: Current Understandings, Therapeutic Approaches, Controversies, and Future Perspectives

Recent advances in early detection and oncological therapies have ameliorated the survival rate of young cancer patients. Yet, ovarian impairment induced by chemotherapy and radiotherapy is still a challenging issue. This review, based on clinical and lab-based studies, summarizes the evidence of gonadotoxicity of chemoradiotherapy, the recent approaches, ongoing controversies, and future perspectives of fertility preservation (FP) in female patients who have experienced chemo- or radio-therapy. Existing data indicate that chemotherapeutic agents induce DNA alterations and massive follicle activation via the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. Meanwhile, the radiation causes ionizing damage, leading to germ cell loss. In addition to the well-established methods, numerous therapeutic approaches have been suggested, including minimizing the follicle loss in cryopreserved ovarian grafts after transplantation, in vitro activation or in vitro growing of follicles, artificial ovarian development, or fertoprotective adjuvant to prevent ovarian damage from chemotherapy. Some reports have revealed positive outcomes from these therapies, whereas others have demonstrated conflictions. Future perspectives are improving the live birth rate of FP, especially in patients with adverse ovarian reserve, eliminating the risk of malignancy reintroducing, and increasing society’s awareness of FP importance.

Do vitrified frozen-thawed embryos generated from successful fresh cycles have higher potential for favorable outcome?

BACKGROUND

Many variables, including woman's age, embryo quality and endometrial receptivity, influence the success rate of either fresh embryo transfer (ET) or frozen-thawed ET (FT-ET) cycles. This study aims to examine whether the results of a fresh in-vitro fertilization (IVF) cycle correlate with its frozen-thawed embryos transfer outcomes.

METHODS

A retrospective cohort study conducted in a tertiary medical center single IVF unit between 2014-2017. The study population was comprised of women who underwent fresh ET with the remaining embryos frozen using vitrification and at least one consecutive FT-ET cycle. Comparison of FT-ET cycle's details and outcomes were assessed in relation to the outcome of preceding fresh ET cycle.

RESULTS

A total of 599 women underwent fresh ET and at least one consecutive FT-ET cycle. Significantly higher rates of successful FT-ET cycle outcomes were observed in the group of patients with a successful fresh cycle compared to the group with an unsuccessful fresh cycle (48.9% vs. 20.8%, P<0.001). Logistic regression demonstrated an adjusted OR of 5.02 for successful FT-ET after a successful fresh cycle.

CONCLUSIONS

Frozen-thawed embryos generated from successful fresh IVF cycles have higher potential to implant when compared to frozen-thawed embryos obtained in an unsuccessful fresh cycle.

Semi-automated versus manual embryo vitrification: inter-operator variability, time-saving, and clinical outcomes

PURPOSE

Does semi-automated vitrification have lower inter-operator variability and better clinical outcomes than manual vitrification?

METHODS

Retrospective analyses of 282 patients whose embryos had been cryopreserved, manually with Irvine®-CBS® (MV) or semi-automatically vitrified with the GAVI® method (AV) (from November 2017 to September 2020). Both techniques were performed during the same period by 5 operators. Inter-operator variability was statistically analyzed between operators who performed the vitrification and those who performed the warming process to compare the intact survival rate (% embryos with 100% intact blastomeres) and the positive survival rate (at least 50% intact blastomeres). Additionally, the complete vitrification time was assessed for the 2 techniques according to the number of vitrified embryos.

RESULTS

Manual vitrification involved warming 338 embryos in 266 cycles for 181 couples compared to 212 embryos in 162 AV cycles for 101 patients. The positive survival rate was higher (p < 0.05) after MV (96%; 323/338) than after AV (90%; 191/212). The intact survival rate (86 vs 84%) and the clinical pregnancy rate (27 vs 22%) were not significantly different between MV and AV. Regarding the inter-operator variability, no significant difference in positive and intact survival rate was evident between the 5 technicians, neither by vitrification nor by warming steps with MV and AV. Concerning time-saving, the MV technique proved to be quicker than AV (minus 11 ± 9 min).

CONCLUSIONS

Manual vitrification exhibited favorable total survival rates and was more time efficient, while both MV and AV cooling and warming treatments showed little operator variability.

Embryology outcomes after oocyte vitrification with super-cooled slush nitrogen are similar to outcomes with conventional liquid nitrogen: a randomized controlled trial

OBJECTIVE

To determine whether the use of slush nitrogen (SN), a super-cooled form of nitrogen with a temperature from -207 to -210 °C, can improve oocyte survival after vitrification and warming compared with conventional liquid nitrogen (LN).

DESIGN

Randomized controlled trial.

SETTING

Academic-affiliated private practice.

PATIENT(S)

A total of 556 metaphase II oocytes from 32 oocyte donor cycles were included.

INTERVENTION(S)

Donor oocytes were block randomized to undergo vitrification with either SN or LN. Vitrification was followed by warming, fertilization with donor sperm, embryo culture to the blastocyst stage, and preimplantation genetic testing for aneuploidy via trophectoderm biopsy with targeted next-generation sequencing.

MAIN OUTCOME MEASURE(S)

The primary outcome was oocyte survival after vitrification and warming. Secondary outcomes included rates of fertilization, usable blastocyst formation, and whole chromosome aneuploidy.

RESULT(S)

Half of the metaphase II oocytes (n = 278) were randomized to undergo vitrification with SN, whereas the other half (n = 278) were randomized to undergo vitrification with LN. There were no statistically significant differences noted in oocyte survival rate (85.3% vs. 86.3%), fertilization rate (84.0% vs. 80.0%), rate of usable blastocyst formation (54.3% vs. 55.7%), or rate of whole chromosome aneuploidy (9.4% vs. 11.7%) between the SN and LN arms, respectively.

CONCLUSION(S)

The implementation of an SN oocyte vitrification protocol resulted in similar embryology outcomes compared with LN. The use of SN did not lead to any demonstrable improvement in oocyte survival after vitrification and warming.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04342364.

Viability assessment using fluorescent markers and ultrastructure of human biopsied embryos vitrified in open and closed systems

RESEARCH QUESTION

Are there any differences in viability and ultrastructure amongst embryos biopsied on Day 5 versus Day 3 following vitrification in open and closed systems and compared to fresh embryos?

DESIGN

One hundred human embryos (40 blastocysts biopsied on Day 5 and subsequently vitrified in open or closed systems and 60 Day 3 biopsied embryos that developed to blastocysts but were rejected for transfer following preimplantation genetic testing for monogenic/single gene defects and for aneuploidies were either treated fresh [n = 20] or vitrified [n = 40] in open or closed systems) and following warming and culture for 4 h were subjected to viability staining with carboxyfluorescein-diacetate succinimidylester/propidium iodide or processed for transmission electron microscopy.

RESULTS

No statistically significant differences were observed in the viability of human biopsied embryos following vitrification in open and closed systems. Compared to fresh embryos, vitrified ones had a higher incidence of damage (propidium iodide-stained cells) irrespective of the vitrification method (P = 0.005). These damaged cells were more prominent in Day 5 biopsied blastocysts and mainly located at the position of cutting. Characteristic lipofuscin droplets (representative of apoptosis) and a higher number of vacuoles and distension of mitochondria were also more evident in vitrified embryos, although this was not statistically assessed.

CONCLUSIONS

Vitrification in open and closed systems does not adversely affect the viability and ultrastructure of Day 5 and Day 3 biopsied embryos as revealed by the minimal yet statistically significant cell damage observed. This damage may be compensated by the embryos, which in their attempt to fully recover following vitrification, potentially enable 'rescue' processes to eliminate it.

Genomic Consideration in Chemotherapy-Induced Ovarian Damage and Fertility Preservation

Chemotherapy-induced ovarian damage and fertility preservation in young patients with cancer are emerging disciplines. The mechanism of treatment-related gonadal damage provides important information for targeting prevention methods. The genomic aspects of ovarian damage after chemotherapy are not fully understood. Several studies have demonstrated that gene alterations related to follicular apoptosis or accelerated follicle activation are related to ovarian insufficiency and susceptibility to ovarian damage following chemotherapy. This may accelerate follicular apoptosis and follicle reservoir utilization and damage the ovarian stroma via multiple molecular reactions after chemotherapy. This review highlights the importance of genomic considerations in chemotherapy-induced ovarian damage and multidisciplinary oncofertility strategies for providing high-quality care to young female cancer patients.

Post-warming survival rates and clinical outcomes of human cleavage stage embryos vitrified/warmed using CryoTouch and Cryotop methods

Background

Vitrification has become the method of choice for cryopreservation of human embryos and gametes. There are multiple commercial media, containing different combinations and concentrations of cryoprotectants, available for vitrification and warming procedures. The aim of this retrospective study was to compare post-warming survival rate and clinical outcomes of cleavage stage embryos vitrified/warmed using two different commercial methods (CryoTouch and Cryotop) during intracytoplasmic sperm injection/frozen embryo transfer (ICSI/FET) cycles. This retrospective study evaluated a total of 173 FET cycles performed on 446 warmed cleavage stage embryos between January 2018 and December 2020. Post-warming embryo survival rate and clinical outcomes including clinical pregnancy, implantation, and live birth rates were calculated.

Results

The results showed no significant differences between two groups in terms of post-warming survival rate (p value = 0.5020), clinical pregnancy rate (p value = 0.7411), implantation rate (p value = 0.4694), and live birth rate (p value = 0.5737).

Conclusions

Collectively, high successful rates were observed in outcomes of vitrified/warmed cleavage stage embryos using both CryoTouch and Cryotop commercial methods.

The role of apoptosis in cryopreserved animal oocytes and embryos

Cryopreservation of both gametes and embryos, both for storage and for the preservation of their developmental capacity is a critical aspect of assisted reproductive technology. The survival of reproductive material following cryopreservation protocols is not only vital to clinical applications in the human in vitro fertilisation clinic, but is also important in the in vitro production of livestock embryos. The ability to routinely cryopreserve oocytes and embryos of livestock species has the potential to improve animal welfare, reduce environmental impact, and reduce the associated costs for breeding companies through the reduction of live animal transportation. Unfortunately, frozen oocytes and embryos are regularly documented to contain a higher proportion of apoptotic cells compared to their non-frozen counterparts, with freezing procedures thought to trigger apoptotic pathways of cell death. Comparisons between frozen and non-frozen samples also show changes in the gene expression of apoptotic factors such as Bcl-2 and Bax in response to cryopreservation. Apoptotic inhibition has the potential to improve cryosurvival, and how to achieve this is subject to debate. Here, we review how exposure to low temperatures during cryopreservation may be responsible for the abnormal activation of apoptotic pathways in mammalian oocytes and embryos, and discuss the ways in which they can be influenced to improve cryopreservation protocols, particularly in agriculturally important species.

Molecular Mechanism and Prevention Strategy of Chemotherapy- and Radiotherapy-Induced Ovarian Damage

Fertility preservation is an emerging discipline, which is of substantial clinical value in the care of young patients with cancer. Chemotherapy and radiation may induce ovarian damage in prepubertal girls and young women. Although many studies have explored the mechanisms implicated in ovarian toxicity during cancer treatment, its molecular pathophysiology is not fully understood. Chemotherapy may accelerate follicular apoptosis and follicle reservoir utilization and damage the ovarian stroma via multiple molecular reactions. Oxidative stress and the radiosensitivity of oocytes are the main causes of gonadal damage after radiation treatment. Fertility preservation options can be differentiated by patient age, desire for conception, treatment regimen, socioeconomic status, and treatment duration. This review will help highlight the importance of multidisciplinary oncofertility strategies for providing high-quality care to young female cancer patients.

Vitrification yields higher cryo-survival rate than slow freezing in biopsied bovine in vitro produced blastocysts

Vitrification and slow freezing are the two commonly used embryo cryopreservation methods. In most studies, vitrification of intact embryos has proven superior in several respects, including cell and embryo survival and pregnancy rate. However, there is a lack of data for comparing these two methods in in vitro produced (IVP) bovine blastocysts, which have been subjected to the retrieval of trophectoderm (TE) biopsy. Day 7 IVP blastocysts were pooled and randomized into four groups: 1) non-biopsy (NB), 2) biopsy (B), 3) biopsy-vitrification (BV), 4) biopsy-slow freeze (BSF). The blastocysts in the B, BV, and BSF groups were subjected to TE biopsy. For the B group, this was followed by 5 hours (h) incubation and subsequent scoring of the biopsy-survival (re-expansion) rate before processing for further analyses. For the BV and BSF groups, the biopsy procedure was followed by 2 h incubation, allowing for a quick re-expansion, after which the blastocysts were subjected to vitrification and slow freezing, respectively. After warming and thawing, respectively, they were then incubated for 5 h followed by scoring the cryo-survival (re-expansion) rates before processing for further analyses. These included quantification of ICM and TE cells, cleaved caspase-3- and TUNEL-positive cells, quantitative PCR on cellular stress markers (SOD1 and PRDX1), and ultrastructural analysis. The biopsy-survival rate in the B group was 94% (307/326). The cryo-survival rate in BV (86%, 138/161) was higher than that in BSF (57%, 81/142; P < 0.001). No differences were noted between the average ICM, TE, and total cell numbers of the groups. The percentages of cleaved caspase-3-positive cells were higher in BV vs. NB (P < 0.05), in BSF vs. NB (P < 0.001), and in BSF vs. B (P < 0.001). The percentages of TUNEL-positive cells were higher in BV vs. NB (P < 0.05) and in BSF vs. NB (P < 0.001). The levels of mRNA abundance for SOD1 and PRDX1 in B, BV, and BSF were not different from that in NB. The ultrastructural analysis of blastocysts in the BV and BSF groups showed distension of extracellular spaces and appearance of intracellular vacuoles in the ICM, distension of mitochondria, and disorganization of mitochondrial cristae in both ICM and TE, and weakened tight junctions between adjacent TE cells. In summary, our findings demonstrate that vitrification yields a higher cryo-survival rate than slow freezing in biopsied bovine IVP blastocysts. However, biopsy-vitrification and biopsy-slow-freeze values are comparable in terms of ICM, TE, and total blastocyst cell numbers, as well as cleaved caspase-3- and TUNEL-positive cell rates. Moreover, biopsy and cryopreservation performed alone had no effect on ICM, TE, total blastocyst cell numbers, or TUNEL-positive cell rates. Biopsy and vitrification performed alone had no effect on the cleaved caspase-3 positive cell rates, whereas slow freezing resulted in an increased rate. Furthermore, double traumatization with a combination of biopsy and cryopreservation, either vitrification or slow freezing, resulted in increased rates of cleaved caspase-3- and TUNEL-positive cells.

Effect of embryo cryopreservation duration on pregnancy-related complications and birthweight after frozen-thawed embryo transfer: a retrospective cohort study

Frozen embryo transfer (FET) has been adopted by growing number of reproductive medicine centers due to the improved outcome compared with fresh embryo transfer. However, few studies have focused on the impact of embryo cryopreservation duration on pregnancy-related complications and neonatal birthweight. Thus, a retrospective cohort study including all FET cycles with livebirth deliveries in a university affiliated hospital from May 2010 to September 2017 was conducted. These deliveries were grouped by the cryopreservation duration of the transferred embryo (≤3 months, 4-6 months, 7-12 months, and >12 months). The associations between embryo cryopreservation duration and pregnancy-related complications were evaluated among the groups using multinomial logistic regression. Neonatal birthweight was compared according to the stratification of singletons and multiples using multinomial and multilevel logistic regression, respectively. Among all 12,158 FET cycles, a total of 3864 livebirth deliveries comprising 2995 singletons and 1739 multiples were included. Compared with those within 3 months, women undergoing FET after a cryopreservation time longer than 3 months did not show any increased risk of gestational diabetes mellitus, gestational hypertension, preeclampsia, meconium staining of the amniotic fluid, or preterm birth. Furthermore, the risk of lower birthweight, macrosomia, small-for-gestational-age, or large-for-gestational-age for either singletons or multiples was not affected by long-term cryopreservation. In summary, embryo cryopreservation duration does not have negative effects on pregnancy-related complications or birthweight after FET.

The exact synchronization timing between the cleavage embryo stage and duration of progesterone therapy-improved pregnancy rates in frozen embryo transfer cycles: A cross-sectional study

Background

Synchronization between the embryonic stage and the uterine endometrial lining is important in the outcomes of the vitrified-warmed embryo transfer (ET) cycles.

Objective

The aim was to investigate the effect of the exact synchronization between the cleavage stage of embryos and the duration of progesterone administration on the improvement of clinical outcomes in frozen embryo transfer (FET) cycles.

Materials and Methods

312 FET cycles were categorized into two groups: (A) day-3 ET after three days of progesterone administration (n = 177) and (B) day-2 or -4 ET after three days of progesterone administration (n = 135). Group B was further divided into two subgroups: B1: day-2 ET cycles, that the stage of embryos were less than the administrated progesterone and B2: day-4 ET cycles, that the stage of embryos were more than the administrated progesterone. The clinical outcome measures were compared between the groups.

Results

The pregnancy outcomes between groups A and B showed a significant differences in the chemical (40.1% vs 27.4%; p = 0.010) and clinical pregnancies (32.8% vs 22.2%; p = 0.040), respectively. The rate of miscarriage tended to be higher and live birth rate tended to be lower in group B than in group A. Also, significantly higher rates were noted in chemical pregnancy, clinical pregnancy, and live birth in group A when compared with subgroup B2.

Conclusion

Higher rates of pregnancy and live birth were achieved in day-3 ET after three days of progesterone administration in FET cycles.

Fertility technologies and how to optimize laboratory performance to support the shortening of time to birth of a healthy singleton: a Delphi consensus

PURPOSE

To explore how the assisted reproductive technology (ART) laboratories can be optimized and standardized to enhance embryo culture and selection, to bridge the gap between standard practice and the new concept of shortening time to healthy singleton birth.

METHODS

A Delphi consensus was conducted (January to July 2018) to assess how the ART laboratory could be optimized, in conjunction with existing guidelines, to reduce the time to a healthy singleton birth. Eight experts plus the coordinator discussed and refined statements proposed by the coordinator. The statements were distributed via an online survey to 29 participants (including the eight experts from step 1), who voted on their agreement/disagreement with each statement. Consensus was reached if ≥ 66% of participants agreed/disagreed with a statement. If consensus was not achieved for any statement, that statement was revised and the process repeated until consensus was achieved. Details of statements achieving consensus were communicated to the participants.

RESULTS

Consensus was achieved for all 13 statements, which underlined the need for professional guidelines and standardization of lab processes to increase laboratory competency and quality. The most important points identified were the improvement of embryo culture and embryo assessment to shorten time to live birth through the availability of more high-quality embryos, priority selection of the most viable embryos and improved cryosurvival.

CONCLUSION

The efficiency of the ART laboratory can be improved through professional guidelines on standardized practices and optimized embryo culture environment, assessment, selection and cryopreservation methodologies, thereby reducing the time to a healthy singleton delivery.

Frozen Embryo Transfer in Mildly Stimulated Cycle With Letrozole Compared to Natural Cycle in Ovulatory Women: A Large Retrospective Study

OBJECTIVE

To evaluate the clinical effect of mild stimulation with letrozole on pregnancy outcomes in ovulatory women undergoing frozen embryo transfer (FET) compared to natural cycle.

DESIGN

Retrospective observational study.

SETTING

Tertiary care academic medical center.

POPULATION

A total of 6,874 infertile women with regular menstrual cycles (21-35 days) met the criteria for this study in the period from 2013 to 2020.

METHODS

All patients who were prepared for and underwent FET were divided into two groups: a modified natural cycle (NC) group (n=3,958) and a letrozole cycle group (n=2,916).

MAIN OUTCOME MEASURES

The primary outcome of the study was clinical pregnancy rate. Secondary outcome measures were endometrial thickness, rates of implantation, positive HCG test, live birth, early miscarriage and ectopic pregnancy.

RESULTS

The clinical pregnancy rate was not statistically different between the modified NC-FET group and the letrozole-FFT group before (crude OR 0.99, 95% CI 0.90-1.09, P=0.902>0.05) and after propensity score matching (PSM) (crude OR 1.01, 95% CI 0.91-1.12, P=0.870>0.05). After multivariable logistic regression analysis, the clinical pregnancy rate remained insignificant before (adjusted OR 1.00, 95% CI 0.91-1.10, P=0.979>0.05) and after matching (adjusted OR 1.00, 95% CI 0.89-1.11, P=0.936>0.05), respectively. Similarly, in the crude and adjusted analysis, the positive HCG test, implantation, live birth and early miscarriage rates were also comparable in the letrozole-FFT group and modified NC-FET group before and after matching. Furthermore, the endometrial thickness of letrozole-FFT group was similar to that of modified NC-FET group with adjusted analysis.

CONCLUSION

Our observation suggests that mild stimulation with letrozole could produce similar pregnancy outcomes in ovulatory patients who undergo FET when compared with a natural cycle.

Ovarian tissue cryopreservation and novel bioengineering approaches for fertility preservation

PURPOSE OF REVIEW

Breast cancer patients who cannot delay treatment or for whom hormone stimulation and egg retrieval are contraindicated require alternative methods of fertility preservation prior to gonadotoxic treatment. Ovarian tissue cryopreservation is an alternative approach that may offer patients the opportunity to preserve fertility and carry biologically-related children later in life. Various experimental approaches are being explored to obtain mature gametes from cryopreserved and thawed ovarian tissue for fertilization and implantation using biomimetic tissue culture in vitro. Here we review the most recent developments in ovarian tissue cryopreservation and exciting advances in bioengineering approaches to in vitro tissue and ovarian follicle culture.

RECENT FINDINGS

Slow freezing is the most widely accepted method for ovarian tissue cryopreservation, but efforts have been made to modify vitrification for this application as well. Numerous approaches to in vitro tissue and follicle culture are in development, most prominently two-step culture systems for ovarian cortical tissue and encapsulation of ovarian follicles in biomimetic matrices for in vitro culture.

SUMMARY

Refinements to slow freeze and vitrification protocols continue to address challenges associated with cryopreservation, such as ice crystal formation and damage to the stroma. Similarly, improvements to in vitro tissue and follicle culture show promise for utilizing patients' cryopreserved tissues to obtain mature gametes after disease treatment and remission. Development of an effective and reproducible culture system for human ovarian follicles will serve as a broad assisted reproductive technology for cancer survivors who cryopreserved tissue prior to treatment.

ESHRE guideline: female fertility preservation

STUDY QUESTION

What is the recommended management for women and transgender men with regards to fertility preservation (FP), based on the best available evidence in the literature?

SUMMARY ANSWER

The ESHRE Guideline on Female Fertility Preservation makes 78 recommendations on organization of care, information provision and support, pre-FP assessment, FP interventions and after treatment care. Ongoing developments in FP are also discussed.

WHAT IS KNOWN ALREADY

The field of FP has grown hugely in the last two decades, driven by the increasing recognition of the importance of potential loss of fertility as a significant effect of the treatment of cancer and other serious diseases, and the development of the enabling technologies of oocyte vitrification and ovarian tissue cryopreservation (OTC) for subsequent autografting. This has led to the widespread, though uneven, provision of FP for young women.

STUDY DESIGN SIZE DURATION

The guideline was developed according to the structured methodology for development of ESHRE guidelines. After formulation of key questions by a group of experts, literature searches and assessments were performed. Papers published up to 1 November 2019 and written in English were included in the review.

PARTICIPANTS/MATERIALS SETTING METHODS

Based on the collected evidence, recommendations were formulated and discussed until consensus was reached within the guideline group. A stakeholder review was organized after finalization of the draft. The final version was approved by the guideline group and the ESHRE Executive Committee.

MAIN RESULTS AND THE ROLE OF CHANCE

This guideline aims to help providers meet a growing demand for FP options by diverse groups of patients, including those diagnosed with cancer undergoing gonadotoxic treatments, with benign diseases undergoing gonadotoxic treatments or those with a genetic condition predisposing to premature ovarian insufficiency, transgender men (assigned female at birth), and women requesting oocyte cryopreservation for age-related fertility loss.The guideline makes 78 recommendations on information provision and support, pre-FP assessment, FP interventions and after treatment care, including 50 evidence-based recommendations-of which 31 were formulated as strong recommendations and 19 as weak-25 good practice points and 3 research only recommendations. Of the evidence-based recommendations, 1 was supported by high-quality evidence, 3 by moderate-quality evidence, 17 by low-quality evidence and 29 by very low-quality evidence. To support future research in the field of female FP, a list of research recommendations is provided.

LIMITATIONS REASONS FOR CAUTION

Most interventions included are not well studied in FP patients. As some interventions, e.g. oocyte and embryo cryopreservation, are well established for treatment of infertility, technical aspects, feasibility and outcomes can be extrapolated. For other interventions, such as OTC and IVM, more evidence is required, specifically pregnancy outcomes after applying these techniques for FP patients. Such future studies may require the current recommendations to be revised.

WIDER IMPLICATIONS OF THE FINDINGS

The guideline provides clinicians with clear advice on best practice in female FP, based on the best evidence currently available. In addition, a list of research recommendations is provided to stimulate further studies in FP.

STUDY FUNDING/COMPETING INTERESTS

The guideline was developed and funded by ESHRE, covering expenses associated with the guideline meetings, with the literature searches and with the dissemination of the guideline. The guideline group members did not receive payment. R.A.A. reports personal fees and non-financial support from Roche Diagnostics, personal fees from Ferring Pharmaceuticals, IBSA and Merck Serono, outside the submitted work; D.B. reports grants from Merck Serono and Goodlife, outside the submitted work; I.D. reports consulting fees from Roche and speaker's fees from Novartis; M.L. reports personal fees from Roche, Novartis, Pfizer, Lilly, Takeda, and Theramex, outside the submitted work. The other authors have no conflicts of interest to declare.

DISCLAIMER

This guideline represents the views of ESHRE, which were achieved after careful consideration of the scientific evidence available at the time of preparation. In the absence of scientific evidence on certain aspects, a consensus between the relevant ESHRE stakeholders has been obtained. Adherence to these clinical practice guidelines does not guarantee a successful or specific outcome, nor does it establish a standard of care. Clinical practice guidelines do not replace the need for application of clinical judgment to each individual presentation, nor variations based on locality and facility type. ESHRE makes no warranty, express or implied, regarding the clinical practice guidelines and specifically excludes any warranties of merchantability and fitness for a particular use or purpose. (Full disclaimer available at  www.eshre.eu/guidelines.) ^†ESHRE Pages content is not externally peer reviewed. The manuscript has been approved by the Executive Committee of ESHRE.

Advances in the Treatment and Prevention of Chemotherapy-Induced Ovarian Toxicity

Due to improvements in chemotherapeutic agents, cancer treatment efficacy and cancer patient survival rates have greatly improved, but unfortunately gonadal damage remains a major complication. Gonadotoxic chemotherapy, including alkylating agents during reproductive age, can lead to iatrogenic premature ovarian insufficiency (POI), and loss of fertility. In recent years, the demand for fertility preservation has increased dramatically among female cancer patients. Currently, embryo and oocyte cryopreservation are the only established options for fertility preservation in women. However, there is growing evidence for other experimental techniques including ovarian tissue cryopreservation, oocyte in vitro maturation, artificial ovaries, stem cell technologies, and ovarian suppression. To prevent fertility loss in women with cancer, individualized fertility preservation options including established and experimental techniques that take into consideration the patient’s age, marital status, chemotherapy regimen, and the possibility of treatment delay should be provided. In addition, effective multidisciplinary oncofertility strategies that involve a highly skilled and experienced oncofertility team consisting of medical oncologists, gynecologists, reproductive biologists, surgical oncologists, patient care coordinators, and research scientists are necessary to provide cancer patients with high-quality care.

Predicting the chance on live birth per cycle at each step of the IVF journey: external validation and update of the van Loendersloot multivariable prognostic model

OBJECTIVE

To study the performance of the 'van Loendersloot' prognostic model for our clinic's in vitro fertilisation (IVF) in its original version, the refitted version and in an adapted version replacing previous by current cycle IVF laboratory variables.

METHODS

This retrospective cohort study in our academic tertiary fertility clinic analysed 1281 IVF cycles of 591 couples, who completed at least one 2nd-6th IVF cycle with own fresh gametes after a previous IVF cycle with the same partner in our clinic between 2010 and 2018. The outcome of interest was the chance on a live birth after one complete IVF cycle (including all fresh and frozen embryo transfers from the same episode of ovarian stimulation). Model performance was expressed in terms of discrimination (c-statistics) and calibration (calibration model, comparison of prognosis to observed ratios of five disjoint groups formed by the quintiles of the IVF prognoses and a calibration plot).

RESULTS

A total of 344 live births were obtained (26.9%). External validation of the original van Loendersloot model showed a poor c-statistic of 0.64 (95% CI: 0.61 to 0.68) and an underestimation of IVF success. The refitted and the adapted models showed c-statistics of respectively 0.68 (95% CI: 0.65 to 0.71) and 0.74 (95% CI: 0.70 to 0.77). Similar c-statistics were found with cross-validation. Both models showed a good calibration model; refitted model: intercept=0.00 (95% CI: -0.23 to 0.23) and slope=1.00 (95% CI: 0.79 to 1.21); adapted model: intercept=0.00 (95% CI: -0.18 to 0.18) and slope=1.00 (95% CI: 0.83 to 1.17). Prognoses and observed success rates of the disjoint groups matched well for the refitted model and even better for the adapted model.

CONCLUSION

External validation of the original van Loendersloot model indicated that model updating was recommended. The good performance of the refitted and adapted models allows informing couples about their IVF prognosis prior to an IVF cycle and at the time of embryo transfer. Whether this has an impact on couple's expected success rates, distress and IVF discontinuation can now be studied.

Perinatal and maternal outcome after vitrification of blastocysts: a Nordic study in singletons from the CoNARTaS group

STUDY QUESTION

Is transfer of vitrified blastocysts associated with higher perinatal and maternal risks compared with slow-frozen cleavage stage embryos and fresh blastocysts?

SUMMARY ANSWER

Transfer of vitrified blastocysts is associated with a higher risk of preterm birth (PTB) when compared with slow-frozen cleavage stage embryos and with a higher risk of a large baby, hypertensive disorders in pregnancy (HDPs) and postpartum hemorrhage (PPH) but a lower risk of placenta previa when compared with fresh blastocysts.

WHAT IS KNOWN ALREADY

Transfer of frozen-thawed embryos (FETs) plays a central role in modern fertility treatment, limiting the risk of ovarian hyperstimulation syndrome and multiple pregnancies. Following FET, several studies report a lower risk of PTB, low birth weight (LBW) and small for gestational age (SGA) yet a higher risk of fetal macrosomia and large for gestational age (LGA) compared with fresh embryos. In recent years, the introduction of new freezing techniques has increased treatment success. The slow-freeze technique combined with cleavage stage transfer has been replaced by vitrification and blastocyst transfer. Only few studies have compared perinatal and maternal outcomes after vitrification and slow-freeze and mainly in cleavage stage embryos, with most studies indicating similar outcomes in the two groups. Studies on perinatal and maternal outcomes following vitrified blastocysts are limited.

STUDY DESIGN, SIZE, DURATION

This registry-based cohort study includes singletons born after frozen-thawed and fresh transfers following the introduction of vitrification in Sweden and Denmark, in 2002 and 2009, respectively. The study includes 3650 children born after transfer of vitrified blastocysts, 8123 children born after transfer of slow-frozen cleavage stage embryos and 4469 children born after transfer of fresh blastocysts during 2002-2015. Perinatal and maternal outcomes in singletons born after vitrified blastocyst transfer were compared with singletons born after slow-frozen cleavage stage transfer and singletons born after fresh blastocyst transfer. Main outcomes included PTB, LBW, macrosomia, HDP and placenta previa.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Data were obtained from the CoNARTaS (Committee of Nordic ART and Safety) group. Based on national registries in Sweden, Finland, Denmark and Norway, the CoNARTaS cohort includes all children born after ART treatment in public and private clinics 1984-2015. Outcomes were assessed with logistic multivariable regression analysis, adjusting for the country and year of birth, maternal age, body mass index, parity, smoking, parental educational level, fertilisation method (IVF/ICSI), single embryo transfer, number of gestational sacs and the child's sex.

MAIN RESULTS AND THE ROLE OF CHANCE

A higher risk of PTB (<37 weeks) was noted in the vitrified blastocyst group compared with the slow-frozen cleavage stage group (adjusted odds ratio, aOR [95% CI], 1.33 [1.09-1.62]). No significant differences were observed for LBW (<2500 g), SGA, macrosomia (≥4500 g) and LGA when comparing the vitrified blastocyst with the slow-frozen cleavage stage group. For maternal outcomes, no significant difference was seen in the risk of HDP, placenta previa, placental abruption and PPH in the vitrified blastocyst versus the slow frozen cleavage stage group, although the precision was limited.When comparing vitrified and fresh blastocysts, we found higher risks of macrosomia (≥4500 g) aOR 1.77 [1.35-2.31] and LGA aOR 1.48 [1.18-1.84]. Further, the risks of HDP aOR 1.47 [1.19-1.81] and PPH aOR 1.68 [1.39-2.03] were higher in singletons born after vitrified compared with fresh blastocyst transfer while the risks of SGA aOR 0.58 [0.44-0.78] and placenta previa aOR 0.35 [0.25-0.48] were lower.

LIMITATIONS, REASONS FOR CAUTION

Since vitrification was introduced simultaneously with blastocyst transfer in Sweden and Denmark, it was not possible to explore the effect of vitrification per se in this study.

WIDER IMPLICATIONS OF THE FINDINGS

The results from the change of strategy to vitrification of blastocysts are reassuring, indicating that the freezing technique per se has no major influence on the perinatal and maternal outcomes. The higher risk of PTB may be related to the extended embryo culture rather than vitrification.

STUDY FUNDING/COMPETING INTEREST(S)

The study is part of the ReproUnion Collaborative study, co-financed by the European Union, Interreg V ÖKS. The study was also financed by grants from the Swedish state under the agreement between the Swedish government and the county councils, the ALF agreement (LUA/ALF 70940), Hjalmar Svensson Research Foundation and NordForsk (project 71 450). There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

ISRCTN11780826.

Perinatal outcomes of singletons following vitrification versus slow-freezing of embryos: a multicenter cohort study using propensity score analysis

STUDY QUESTION

Is embryo vitrification associated with a higher risk of adverse perinatal outcomes than slow-freezing?

SUMMARY ANSWER

Embryo vitrification was not associated with increased risks of adverse perinatal outcomes of pre-term birth (PTB), low birthweight (LBW), small for gestational age (SGA), large for gestational age (LGA) and macrosomia, as compared to slow-freezing.

WHAT IS KNOWN ALREADY

Vitrification is becoming a widely adopted technology for embryo cryopreservation with higher embryo survival rate and live birth rate than the slow-freezing technique. However, limited data are currently available on risks of adverse perinatal outcomes following vitrification as compared to that of slow-freezing. The impact of vitrification on perinatal outcomes remains further to be elucidated.

STUDY DESIGN, SIZE, DURATION

Six large reproductive medical centers in Guangdong province, Southeast of China, took part in this multicenter retrospective cohort study. Cohorts of 3199 live born singletons after Day 3 frozen-thawed embryo transfer (FET) cycles with either vitrification or slow-freezing between January 2011 and December 2015 were included in the study. Each patient only contributed one cycle per cohort and vanishing twins were excluded. Propensity score (PS) matching was used to control for potential confounding factors.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All live-born singletons following either a vitrified or a slow-frozen cleavage FET cycle during the period from 2011 to 2015 were analyzed. Perinatal outcomes of PTB, LBW, macrosomia, SGA and LGA were compared. The vitrified and slow-frozen cohorts were matched by propensity scores with a 1:1 ratio accounting for potential confounding factors associated with perinatal outcomes. These variables included baseline demographics (maternal age, BMI, education level, parity, type of infertility and cause of infertility), as well as IVF characteristics (insemination method, endometrial preparation protocol and embryo cryopreservation duration).

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 2858 cases from vitrified embryo transfer (ET) and 341 babies from the slow-freezing group were included. After PS matching, 297 pairs of newborns were generated for comparison. The median gestational age was 39 weeks for both cohorts and the birthweights were comparable (3187.7 ± 502.1 g in the vitrified group vs. 3224.6 ± 483.6 in the slow-freezing group, P>0.05). There were no significant differences between the two groups on the incidence of PTB (5.4% vs. 7.7%), LBW (6.7% vs. 5.7%), macrosomia (5.7% vs. 6.1%), SGA (12.5% vs. 8.4%) and LGA (6.4% vs. 8.1%). Parallel logistic regression analysis indicated that vitrification was non-inferior to slow-freezing method in terms of the occurrence of PTB (OR, 0.68 [95% CI, 0.35, 1.31]), LBW (OR, 1.19[0.61-2.32]), macrosomia (OR, 0.94 [0.48-1.86]), SGA (1.55[0.91-2.64]) and LGA (0.78[0.42-1.45]), P>0.05. Sex-stratified PS matching models with multivariable regression analysis further confirmed that vitrification did not increase the risks of above-mentioned adverse perinatal outcomes in either the male or female infant cohort.

LIMITATIONS, REASONS FOR CAUTION

Although the analysis was adjusted for a number of important confounders, the hospital dataset did not contain other potential confounders such as the medical history and obstetrics outcomes of women during pregnancy to allow adjustment. In addition, the current findings are only applicable to cleavage stage FET, but not pronuclei stage or blastocyst stage ET.

WIDER IMPLICATIONS OF THE FINDINGS

Vitrified ET, in comparison with slow-frozen ET, was not associated with increased risks of adverse neonatal outcomes. With its superiority on live birth rates and non-inferiority on safety perinatal outcomes, transition from slow-freezing to the use of vitrification for embryo cryopreservation is reassuring. Nonetheless, future research is needed for the long-term effects of vitrification method on offspring's health outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by the National Key Research and Development Program (2016YFC100205), Guangzhou Science and Technology Project (201804020087), Guangdong Province Science and Technology Project (2016A020218008) and Guangdong Provincial Key Laboratory of Reproductive Medicine (2012A061400003). The authors have no conflicts of interest to declare.

Effect of newborn gender on placental histopathology and perinatal outcome in singleton live births following IVF

RESEARCH QUESTION

Does newborn gender affect placental histopathology pattern and perinatal outcome in singleton live births following IVF treatment?

DESIGN

Retrospective cohort study evaluating data of all live births from one academic tertiary hospital following IVF treatment during 2009-2017. All patients had placentas sent for pathological evaluation irrelevant of maternal and fetal complications status. Exclusion criteria were abnormal uterine cavity findings, previous uterine surgery, in-vitro maturation cycles, gestational carrier cycles, oocyte recipient cycles, preimplantation genetic diagnosis cycles and multiple pregnancies. The primary outcomes included anatomical, inflammation, vascular malperfusion and villous maturation placental features. The secondary outcomes included fetal, maternal, perinatal and delivery complications. A multivariate analysis was conducted to adjust the results for factors potentially associated with placental pathology features.

RESULTS

A total of 1057 live births were included in the final analysis and were allocated to the study groups according to fetal gender: males (n = 527) and females (n = 530). After adjustment for potential confounding factors, male gender was significantly associated with villous agglutination (odds ratio [OR] 9.8; 95% confidence interval [CI] 1.4-78.2), avascular villi (OR 4.1; 95% CI 1.3-12.6) and maternal vascular malperfusion (OR 1.8; 95% CI 1.2-2.7). Female gender was significantly associated with bilobed placenta (OR 0.2; 95% CI 0.06-0.8) and subchorionic thrombi (OR 0.5; 95% CI 0.3-0.9). The prevalence of adverse fetal, maternal and delivery outcomes was similar between the groups.

CONCLUSIONS

Newborn gender has a significant impact on the placental histopathology pattern, which can contribute to the development of adverse perinatal outcomes.

Fertility Preservation in Women: Indications and Options for Therapy

Fertility preservation (FP) is a vital issue for individuals in either reproductive or prepubescent stage of life when future fertility may be compromised. The objective of any FP intervention is to minimize or eliminate primary disease burden and to ensure maintaining or preserving reproductive health. Fertility potential can be affected by cancer therapy and numerous other factors, including advancing age, metabolic conditions, autoimmune diseases, specific surgical interventions, and sex affirmation procedures. A paradigm shift focusing on quality-of-life issues and long-term survivorship has emerged, especially because of advances in cancer diagnostics and treatment. Several FP techniques have been widely distributed, while others are still in the research stage. In addition, specific procedures and some potentially fertoprotective agents are being developed, aiming to minimize the hazards of gonadal damage caused by cancer therapy and decrease the need for more costly, invasive, and time-consuming FP methods. This review highlights the advances, indications, and options for FP, both experimental and well-established, in females of various age groups. An electronic search in PubMed, Embase, and Google Scholar databases was conducted, including retrospective studies, prospective clinical trials, meta-analyses, original reviews, and online abstracts published up to June 30, 2019. The search terms used included fertility preservation, oncofertility, embryo cryopreservation, oocyte cryopreservation, and ovarian tissue cryopreservation. The meeting proceedings of the American Society for Reproductive Medicine and the European Society of Human Reproduction and Embryology were also hand searched.

The effect on twinning rate of transferring double vitrified-warmed embryos in women of advanced reproductive age: a retrospective study

Twin pregnancies are associated with greater risk of neonatal morbidity and mortality than a singleton. This study was performed to investigate the twin pregnancy rate when two vitrified-warmed embryos are transferred in women of advanced reproductive age (≥35 years at the time of oocyte retrieval) and to evaluate the implications of findings in selecting candidates for elective single embryo transfer (eSET). A retrospective analysis of data which included 2,038 women aged 35–45 years, who underwent vitrified-warmed double embryo transfer (DET), from January 2013 to December 2016 was undertaken. Pregnancy and twin rates were estimated after stratifying by prognostic profile. The twin pregnancy rate was lower in women with poor prognosis (12/96, 12.5%) as compared with that in women with favorable prognosis (102/374, 27.3%) and average prognosis (78/346, 22.5%) with significant differences (P < 0.05). The twin rate for women with favorable prognosis was 29.2% (70/240) in the cycles of women aged 35–37 years, 26.8% (26/97) in the cycles of women aged 38–40 years and 16.2% (6/37) in the cycles of women >40 years. The twin rate for women with average prognosis was 25.8% (51/198) in the cycles of women aged 35–37 years, 22.0% (22/100) in the cycles of women aged 38–40 years and 10.4% (5/48) in the cycles of women >40 years. The twin rate for women with poor prognosis was 15.3% (9/59) in the cycles of women aged 35–37 years, 10.3% (3/29) in the cycles of women aged 38–40 years and 0% (0/8) in the cycles of women >40 years. From these results, it was concluded that women with a favorable or average prognosis have a high risk of twin pregnancies. The finding can be used to guide future practice: that is, performing eSET in women with favorable or average prognosis and DET in women with poor prognosis.

Preclinical validation of the new vitrification device possessing a feature of absorbing excess vitrification solution for the cryopreservation of human embryos

AIM

The cryopreservation of embryos is essential for assisted reproductive technology field. The aim of the present study is to examine the efficacy and ease of use of a new vitrification device, Kitasato Vitrification System (KVS), in cryopreservation of human embryos.

METHODS

Human embryos at the cleavage or blastocyst stage were vitrified and warmed by KVS or Cryotop (control device). The survival of cleavage- and blastocyst-stage embryos and the developmental competence of cleavage-stage embryos were evaluated. Four individuals inexperienced in vitrification and warming embryos tested both KVS and Cryotop. The vitrification time and the detachment time of the embryos were evaluated.

RESULTS

At the cleavage stage, there were no significant differences in the survival rate and the development rate to the blastocyst stage between KVS and Cryotop (100 vs 96.8% and 63.3 vs 61.3%, respectively). At the blastocyst stage, there was no significant difference in the re-expansion rate between KVS and Cryotop (100 vs 88.9%). The vitrification time was shorter for KVS than Cryotop. There was no significant difference in the detachment time between KVS and Cryotop.

CONCLUSION

Kitasato Vitrification System is easy to operate, even for inexperienced users, and the viability of human embryos vitrified by KVS is comparable to that of Cryotop, a widely used vitrification device.

A monocentric analysis of the efficacy of extracellular cryoprotectants in unfrozen solutions for cleavage stage embryos

BACKGROUND

In the absence of international guidelines indicating the usage of vitrification rather than slow-freezing, the study aim was to analyze a large cohort of slow-frozen/thawed embryos to produce a rationale supporting the standardization of IVF cryopreservation policy.

METHODS

This retrospective analysis included 4779 cleavage stage embryos cryopreserved by slow-freezing/thawing from September 2009 to April 2017 at a single Center. Biological and clinical outcomes of three different commercial kits adopted sequentially, i.e. Vitrolife Cleave Kit® from Vitrolife (kit 1) vs. K-SICS-5000 Kit® and K-SITS-5000 Kit® from Cook Medical (kit 2) and Freeze/Thaw 1™ Kit® from Vitrolife (kit 3) were collected and compared in the light of cryoprotectants composition.

RESULTS

Kit 3 compared to kit 1 and kit 2 showed significantly (P < 0.001) higher embryo survival (79.9% vs. 75.6 and 68.1%, respectively) and frozen embryo replacement (91.5% vs. 86.5 and 83.3%, respectively) rates, and significantly (P < 0.001) lower blastomere degeneration rate (41.5% vs. 43.6 and 52.4%, respectively). No significant difference for clinical outcomes was observed among kits. Only a slight positive trend was observed for kit 3 vs. kit 1 and kit 2 on delivery rate per thawing cycle (7.12% vs. 4.19 and 4.51%, respectively; P < 0.058) and live birth rate (3.07% vs. 2.59 and 1.93%, respectively, P < 0.069). Thawing solutions of kit 3 were similar to those of any warming protocol.

CONCLUSIONS

A defined concentration of extracellular cryoprotectants in thawing/warming solutions had a beneficial effect on the embryo cryosurvival rate. Results could provide the rationale for the adoption of a single standardized warming protocol.

Cleavage Stage versus Blastocyst Stage Embryo Transfer in Oocyte Donation Cycles

Background and Objective: During the last few years, a trend has been noted towards embryos being transferred at the blastocyst stage, which has been associated with improved rates regarding implantation and clinical pregnancy in comparison to cleavage stage embryo transfers. There is a limited number of studies investigating this notion in oocyte donation cycles employing cryopreserved embryos. The aim of this study is to evaluate the implantation potential and clinical pregnancy rates between the day 3 cleavage stage and blastocyst stage embryo transfers in oocyte donation cycles employing vitrified embryos. Methods: This is a retrospective evaluation of oocyte donation frozen–thawed transfers completed in our clinic from January 2017 to December 2017. Intracytoplasmic sperm injection was conducted for all oocytes. Following fertilization, all embryos were cryopreserved either at the cleavage or blastocyst stage. Embryo transfer of two embryos was performed under direct sonographic guidance in all cases. Results: Our results confirmed a 55.6% clinical pregnancy (CP) resulting from day 3 embryo transfers, a 68.8% CP from day 5, and 71.4% CP from day 6. Significantly improved pregnancy rates were related to embryo transfers at the blastocyst stage when compared to cleavage stage transfers (68.9% and 55.6% respectively, p = 0.016). The risk with regards to multiple pregnancies was similar. Conclusion: Our findings indicate that in oocyte donation cycles employing vitrified embryos, embryo transfer at the blastocyst stage is accompanied with a significant improvement in pregnancy rates and merits further investigation.

The endometrium during and after ovarian hyperstimulation and the role of segmentation of infertility treatment

Controlled ovarian hyperstimulation (COH) is a crucial part of assisted reproductive technologies (ART) that resulted in a substantial increase in pregnancy rates from in vitro fertilization (IVF). However, in spite of the apparent benefit of COH on an increase in the number of follicles and the number of oocytes retrieved, allowing for extended embryo culture and enabling the selection of the best quality embryo for transfer, several reports has shown that the supraphysiologic hormonal levels may indeed have a detrimental effect at the endometrial level. The current article revises the pathophysiological mechanisms through which ovarian stimulation may negatively affect endometrial receptivity. Also, the evidence is analyzed explaining how segmentation of IVF treatment may allow us to overcome the deleterious effects of hyperstimulation on endometrial receptivity. Deferred embryo transfer may be performed in a more physiologic uterine environment in a subsequent cycle, improve endometrial receptivity, decrease uterine contractility, diminishes the impact of premature luteinization and allow individualized stimulation according to the level of response.

Luteal phase stimulation, the future of fertility preservation? Retrospective cohort study of luteal phase versus follicular phase stimulation

RESEARCH QUESTION

Is luteal phase stimulation capable of improving fertility preservation?

MATERIALS AND METHODS

We performed a retrospective cohort study of consecutive ovarian stimulations, during July 2012 and September 2018 at Strasbourg University Teaching Hospital in France. Enrollment criteria were patients aged below 40 who had been referred to our center following a diagnosis of cancer or requiring gonadotoxic treatment. All patients enrolled had regular menstrual cycles and normal ovulation. Non-enrollment criteria were an expected low ovarian response (defined by an anti-Müllerian hormone (AMH) level <0.75μg/L and/or an antral follicle count inferior (AFC) inferior than 5), polycystic ovarian syndrome, amenorrhea, prior history of infertility or gonadotoxic treatment. The primary endpoint is the number of mature oocytes (metaphase II) obtained. Secondary outcomes were oocyte yields obtained, stimulation duration, initial gonadotropin dose and total gonadotropin dose.

RESULTS

A total of 100 patients were included: 20 in luteal phase and 80 in follicular phase. A larger number of mature oocytes was obtained in luteal phase versus follicular phase (13.1+/8.0 versus 9.2+/-5.8 with p=0.01). A greater amount of total (mature and immature) oocytes was obtained in luteal phase versus follicular phase with a significant difference (16.8+/-9.3 versus 11.8+/-7.3 with p=0.01). No difference was found for the initial and total doses of gonadotropin.

CONCLUSIONS

Luteal phase stimulation has the advantage of a better flexibility with positives results as to the number of oocytes obtained in fertility preservation.

Outcomes of neonates born following transfers of frozen-thawed cleavage-stage embryos with blastomere loss: a prospective, multicenter, cohort study

BACKGROUND

Despite limited information on neonatal safety, the transfer of frozen-thawed cleavage-stage embryos with blastomere loss is common in women undergoing in vitro fertilization. We aimed to evaluate the pregnancy outcomes and safety of frozen-thawed cleavage-stage embryos with blastomere loss.

METHODS

This prospective, multicenter, cohort study included all frozen-thawed cleavage-stage embryo transfer (FET) cycles between 2002 and 2012. Pregnancy outcomes and subsequent neonatal outcomes were compared between FET cycles with intact embryos and those with blastomere loss.

RESULTS

A total of 12,105 FET cycles were included in the analysis (2259 cycles in the blastomere loss group and 9846 cycles in the intact embryo group). The blastomere loss group showed significantly poorer outcomes with respect to implantation, pregnancy, and live birth rates than the intact embryo group. However, following embryo implantation, the two groups were similar with respect to live birth rates per clinical pregnancy. Among multiple pregnancies (4229 neonates), neonates from the blastomere loss group were at an increased risk of being small for gestational age (aOR = 1.50, 95% CI 1.00-2.25) compared to those from the intact group. A similar trend was observed among singletons (aOR = 1.84, 95% CI 0.99-3.37). No associations were found between blastomere loss and the subsequent occurrence of congenital anomalies or neonatal mortality. However, neonates from the blastomere loss group were at an increased risk of transient tachypnea of the newborn (aOR = 5.21, 95% CI 2.42-11.22).

CONCLUSIONS

The transfer of embryos with blastomere loss is associated with reduced conception rates. Once the damaged embryos have implanted, pregnancies appear to have the same probability of progressing to live birth but with an increased risk of small for gestational age neonates and transient tachypnea of the newborn.

STUDY REGISTRATION

This study was retrospectively registered at Chinese Clinical Trial Registry. Registration number: ChiCTR-OOC-16007753 . Registration date: 13 January 2016.

Transparent collaboration between industry and academia can serve unmet patient need and contribute to reproductive public health

The pharmaceutical and device industry has greatly contributed to diagnostic and therapeutic approaches in reproductive medicine in a very highly regulated environment, ensuring that development and manufacturing follow the highest standards. In spite of these achievements, collaboration between industry and physicians/academia is often presented in a negative context. However, today more than ever, partnership between industry and academia is needed to shorten the timeline between innovation and application, and to achieve faster access to better diagnostics, drugs and devices for the benefit of patients and society, based on complementary knowledge, skills and expertise. Such partnerships can include joined preclinical/clinical and post-marketing research and development, joint intellectual property, and joint revenue. In Europe, the transparency of this collaboration between pharmaceutical industry and medical doctors has been made possible by the Compliance and Disclosure Policy published by the European Federation of Pharmaceutical Industries and Associations (EFPIA), which represents the major pharmaceutical companies operating in Europe, and includes as members some but not all companies active in infertility and women's health. Under the EFPIA Disclosure Code of conduct, companies need to disclose transfers of value including amounts, activity type and the names of the recipient Health Care Professionals and Organizations. EFPIA member companies have also implemented very strict internal quality control processes and procedures in the design, statistical analysis, reporting, publication and communication of clinical research, according to Good Clinical Practice and other regulations, and are regularly inspected by competent authorities such as the US Food and Drug Administration (FDA) or European Medicines Agency (EMA) for all trials used in marketing authorization applications. The risk of scientific bias exists not only in the pharmaceutical industry but also in the academic world. When academics believe in a hypothesis, they may build their case by emphasizing the arguments supporting their case, and either refute, refuse, oppose or ignore arguments that challenge their assumptions. A possible solution to reduce this bias is international consensus on study design, data collection, statistical analysis and reporting of outcomes, especially in the area of personalized reproductive medicine, e.g. to demonstrate superiority or non-inferiority of personalized ovarian stimulation using biomarkers. Equally important is that declarations of interest are reported transparently and completely in scientific abstracts and publications, and that ghost authorship is replaced by proactive and clear co-authorship for experts from industry where such co-authorship is required based on the prevailing ICMJE criteria. In that context, however, reviewers should stop believing that publications by industry authors only, or by mixed groups of co-authors from industry and academia, are more prone to bias than papers from academic groups only. Instead, the scientific quality of the work should be the only relevant criterion for acceptance of papers or abstracts, regardless of the environment where the work was done. In the end, neutrality does not exist and different beliefs and biases exist within and between healthcare professionals and organizations and pharmaceutical industries. The challenge is to be transparent about this reality at all times, and to behave in an informed, balanced and ethical way as medical and scientific experts, taking into account compliance and legal regulations of both industry and academic employers, in the best interest of patients and society.

IVF Transfer of Fresh or Frozen Embryos in Women without Polycystic Ovaries

BACKGROUND

Among women who are undergoing in vitro fertilization (IVF), the transfer of frozen embryos has been shown to result in a higher rate of live birth than the transfer of fresh embryos in those with infertility associated with the polycystic ovary syndrome. It is not known whether frozen-embryo transfer results in similar benefit in women with infertility that is not associated with the polycystic ovary syndrome.

METHODS

We randomly assigned 782 infertile women without the polycystic ovary syndrome who were undergoing a first or second IVF cycle to receive either a frozen embryo or a fresh embryo on day 3. In the frozen-embryo group, all grade 1 and 2 embryos had been cryopreserved, and a maximum of two embryos were thawed on the day of transfer in the following cycle. In the fresh-embryo group, a maximum of two fresh embryos were transferred in the stimulated cycle. The primary outcome was ongoing pregnancy after the first embryo transfer.

RESULTS

After the first completed cycle, ongoing pregnancy occurred in 142 of 391 women (36.3%) in the frozen-embryo group and in 135 of 391 (34.5%) in the fresh-embryo group (risk ratio in the frozen-embryo group, 1.05; 95% confidence interval [CI], 0.87 to 1.27; P=0.65). Rates of live birth after the first transfer were 33.8% and 31.5%, respectively (risk ratio, 1.07; 95% CI, 0.88 to 1.31).

CONCLUSIONS

Among infertile women without the polycystic ovary syndrome who were undergoing IVF, the transfer of frozen embryos did not result in significantly higher rates of ongoing pregnancy or live birth than the transfer of fresh embryos. (Funded by My Duc Hospital; ClinicalTrials.gov number, NCT02471573 .).

Effect of day 3 embryo morphometrics and morphokinetics on survival and implantation after slow freezing-thawing and after vitrification-warming: a retrospective cohort study

BACKGROUND

Morphometric and morphokinetic evaluation of in vitro cultured human embryos allows evaluation without time restriction and reduces intra- and inter-observer variability. Even though these technologies have been reported to improve the quality of cleavage stage embryo evaluation during fresh culture, possible advantages in the evaluation of cryopreserved embryos have been scarcely explored. This study aims to compare morphometric and morphokinetic parameters between slow frozen and vitrified embryos and to determine their relationship to embryo survival and implantation rate (IR) after thawing/warming.

METHODS

During fresh culture, morphometric characteristics (Total Cell Volume (TCV), symmetry, fragmentation and number of blastomeres) were measured in 286 thawed/warmed embryos. Likewise, after thawing/warming, similar morphometric characteristics were measured in 135 survived embryos. Moreover, morphokinetic parameters (time to mitosis resumption and time to compaction) were measured in 90 embryos after thawing/warming. Then, using linear regression, we investigated the differences between vitrified and slow frozen embryos and the relation of the measured characteristics to embryo survival and IR. Statistical corrections were applied to account for data clustering and for multiple testing.

RESULTS

Vitrified embryos resume mitosis and start compaction significantly earlier than slow frozen embryos. Mitosis resumption rate was 82% for vitrified and 63% for slow frozen embryos and median time to mitosis resumption was 7.6 h and 13.1 h (p = 0.02), respectively. Compaction rate was 62% in vitrified and only 23% in slow frozen embryos. Median time to compaction was 18.1 h for vitrified embryos but, for slow frozen could not be computed since less than half of the slow frozen embryos reached compaction (p = 0.0001). Moreover, intact embryos resume mitosis significantly earlier than not intact ones regardless of the freezing method (rate: 79% vs. 66%, median time: 7.6 h vs 14.6 h, respectively, p = 0.03). Regarding morphometrics, slow frozen embryos showed lower TCV and higher blastomere symmetry after thawing than vitrified embryos despite having similar blastomere number. IR was related to blastomere number at cryopreservation in slow frozen embryos, but not in vitrified ones.

CONCLUSIONS

Interestingly, vitrified/warmed embryos undergo mitosis resumption and compaction significantly earlier than slow frozen/thawed embryos. However, the clinical use of this morphokinetic parameters still remains to be investigated in larger studies.

TRIAL REGISTRATION

Retrospectively registered on December 15, 2015 NCT02639715 .

New stimulation regimens: endogenous and exogenous progesterone use to block the LH surge during ovarian stimulation for IVF

BACKGROUND

The advent of embryo and oocyte vitrification today gives reproductive specialists an opportunity to consider new strategies for improving the practice and results of IVF attempts. As the freezing of entire cohorts does not compromise, and may even improve, the results of IVF attempts, it is possible to break away from the standard sequence of stimulation-retrieval-transfer. The constraints associated with ovarian stimulation in relation to the potential harmful effects of the hormonal environment on endometrial receptivity can be avoided.

OBJECTIVE AND RATIONALE

This review will look at the new stimulation protocols where progesterone is used to block the LH surge. Thanks to 'freeze all' strategies, the increase in progesterone could actually be no longer a cause for concern. There are two ways of using progesterone, whether it be endogenous, as in luteal phase stimulation, or exogenous, as in the use of progesterone in the follicular phase i.e. progestin primed ovarian stimulation.

SEARCH METHODS

A literature search was carried out (until September 2016) on MEDLINE. The following text words were utilized to generate the list of citations: progestin primed ovarian stimulation, luteal phase stimulation, luteal stimulation, duostim, double stimulation, random start. Articles and their references were then examined in order to identify other potential studies. All of the articles are reported in this review.

OUTCOMES

The use of progesterone during ovarian stimulation is effective in blocking the LH surge, whether endogenous or exogenous, and it does not affect the number of oocytes collected or the quality of the embryos obtained. Its main constraint is that it requires total freezing and delayed transfer. A variety of stimulation protocols can be derived from these two methods, and their implications are discussed, from fertility preservation to ovarian response profiles to organization for the patients and clincs. These new regimens enable more flexibility and are of emerging interest in daily practice. However, their medical and economic significance remains to be demonstrated.

WIDER IMPLICATIONS

The use of luteal phase or follicular phase protocols with progestins could rapidly develop in the context of oocyte donation and fertility preservation not related to oncology. Their place could develop even more in the general population of patients in IVF programs. The strategy of total freezing continues to develop, thanks to technical improvements, in particular vitrification and PGS on blastocysts, and thanks to studies showing improvements in embryo implantation when the transfer take place far removed from the hormonal changes caused by ovarian stimulation.

A comparison of live birth rates and perinatal outcomes between cryopreserved oocytes and cryopreserved embryos

PURPOSE

Prior studies suggest that pregnancy outcomes after autologous oocyte cryopreservation are similar to fresh in vitro fertilization (IVF) cycles. It is unknown whether there are differences in pregnancy and perinatal outcomes between cryopreserved oocytes and cryopreserved embryos.

METHODS

This is a retrospective cohort study comparing pregnancy and perinatal outcomes between oocyte and embryo cryopreservation at a university-based fertility center. We included 42 patients and 68 embryo transfers in patients who underwent embryo transfer after elective oocyte preservation (frozen oocyte-derived embryo transfer (FOET)) from 2005 to 2015. We compared this group to 286 patients and 446 cycles in women undergoing cryopreserved embryo transfer (frozen embryo transfer (FET)) from 2012 to 2015.

RESULTS

Five hundred fourteen transfer cycles were included in our analysis. The mean age was lower in the FOET vs FET group (34.3 vs 36.0 years), but there were no differences in ovarian reserve markers. Thawed oocytes had lower survival than embryos (79.1 vs 90.1%); however, fertilization rates were similar (76.2 vs 72.8%). In the FOET vs FET groups, clinical pregnancies were 26.5 and 30%, and live birth rates were 25 and 25.1%. Miscarriages were higher in the FET group, 8.1 vs 1.5%. There were no differences in perinatal outcomes between the two groups. The mean gestational age at delivery was 39.1 vs 38.6 weeks, mean birth weight 3284.2 vs 3161.1 gms, preterm gestation rate 5.9 vs 13.4%, and multiple gestation rate 5.9 vs 11.6%.

CONCLUSIONS

In our study, live birth rates and perinatal outcomes were not significantly different in patients after oocyte and embryo cryopreservation.

Oocyte, embryo and blastocyst cryopreservation in ART: systematic review and meta-analysis comparing slow-freezing versus vitrification to produce evidence for the development of global guidance

BACKGROUND

Successful cryopreservation of oocytes and embryos is essential not only to maximize the safety and efficacy of ovarian stimulation cycles in an IVF treatment, but also to enable fertility preservation. Two cryopreservation methods are routinely used: slow-freezing or vitrification. Slow-freezing allows for freezing to occur at a sufficiently slow rate to permit adequate cellular dehydration while minimizing intracellular ice formation. Vitrification allows the solidification of the cell(s) and of the extracellular milieu into a glass-like state without the formation of ice.

OBJECTIVE AND RATIONALE

The objective of our study was to provide a systematic review and meta-analysis of clinical outcomes following slow-freezing/thawing versus vitrification/warming of oocytes and embryos and to inform the development of World Health Organization guidance on the most effective cryopreservation method.

SEARCH METHODS

A Medline search was performed from 1966 to 1 August 2016 using the following search terms: (Oocyte(s) [tiab] OR (Pronuclear[tiab] OR Embryo[tiab] OR Blastocyst[tiab]) AND (vitrification[tiab] OR freezing[tiab] OR freeze[tiab]) AND (pregnancy[tiab] OR birth[tiab] OR clinical[tiab]). Queries were limited to those involving humans. RCTs and cohort studies that were published in full-length were considered eligible. Each reference was reviewed for relevance and only primary evidence and relevant articles from the bibliographies of included articles were considered. References were included if they reported cryosurvival rate, clinical pregnancy rate (CPR), live-birth rate (LBR) or delivery rate for slow-frozen or vitrified human oocytes or embryos. A meta-analysis was performed using a random effects model to calculate relative risk ratios (RR) and 95% CI.

OUTCOMES

One RCT study comparing slow-freezing versus vitrification of oocytes was included. Vitrification was associated with increased ongoing CPR per cycle (RR = 2.81, 95% CI: 1.05-7.51; P = 0.039; 48 and 30 cycles, respectively, per transfer (RR = 1.81, 95% CI 0.71-4.67; P = 0.214; 47 and 19 transfers) and per warmed/thawed oocyte (RR = 1.14, 95% CI: 1.02-1.28; P = 0.018; 260 and 238 oocytes). One RCT comparing vitrification versus fresh oocytes was analysed. In vitrification and fresh cycles, respectively, no evidence for a difference in ongoing CPR per randomized woman (RR = 1.03, 95% CI: 0.87-1.21; P = 0.744, 300 women in each group), per cycle (RR = 1.01, 95% CI: 0.86-1.18; P = 0.934; 267 versus 259 cycles) and per oocyte utilized (RR = 1.02, 95% CI: 0.82-1.26; P = 0.873; 3286 versus 3185 oocytes) was reported. Findings were consistent with relevant cohort studies. Of the seven RCTs on embryo cryopreservation identified, three met the inclusion criteria (638 warming/thawing cycles at cleavage and blastocyst stage), none of which involved pronuclear-stage embryos. A higher CPR per cycle was noted with embryo vitrification compared with slow-freezing, though this was of borderline statistical significance (RR = 1.89, 95% CI: 1.00-3.59; P = 0.051; three RCTs; I2 = 71.9%). LBR per cycle was reported by one RCT performed with cleavage-stage embryos and was higher for vitrification (RR = 2.28; 95% CI: 1.17-4.44; P =  0.016; 216 cycles; one RCT). A secondary analysis was performed focusing on embryo cryosurvival rate. Pooled data from seven RCTs (3615 embryos) revealed a significant improvement in embryo cryosurvival following vitrification as compared with slow-freezing (RR = 1.59, 95% CI: 1.30-1.93; P < 0.001; I2 = 93%).

WIDER IMPLICATIONS

Data from available RCTs suggest that vitrification/warming is superior to slow-freezing/thawing with regard to clinical outcomes (low quality of the evidence) and cryosurvival rates (moderate quality of the evidence) for oocytes, cleavage-stage embryos and blastocysts. The results were confirmed by cohort studies. The improvements obtained with the introduction of vitrification have several important clinical implications in ART. Based on this evidence, in particular regarding cryosurvival rates, laboratories that continue to use slow-freezing should consider transitioning to the use of vitrification for cryopreservation.

The Human Oocyte Preservation Experience (HOPE) Registry: evaluation of cryopreservation techniques and oocyte source on outcomes

BACKGROUND

This prospective, Phase IV, multicenter, observational registry of assisted reproductive technology clinics in the USA studied outcomes of first cycles using thawed/warmed cryopreserved (by slow-freezing/vitrification) oocytes (autologous or donor).

METHODS

Patients were followed up through implantation, clinical pregnancy, and birth outcomes. The main outcome measure was live birth rate (LBR), defined as the ratio of live births to oocytes thawed/warmed minus the number of embryos cryopreserved for each cycle, averaged over all thawing cycles. Clinical pregnancy rate (CPR) was also evaluated, and was defined as the presence of a fetal sac with heart activity, as detected by ultrasound scan performed on Day 35-42 after embryo transfer.

RESULTS

A total of 16 centers enrolled 204 patients; data from 193 patients were available for analyses. For donor oocytes, in the slow-freezing (n = 40) versus vitrification (n = 94) groups, respectively, CPR and LBR were significantly different: 32.4% versus 62.6%, and 25.0% versus 52.1%; outcomes from Day 3 transfers did not differ significantly. For vitrified oocytes, in the autologous (n = 46) versus donor (n = 94) group, respectively, CPR and LBR were significantly different: 30.0% versus 62.6% and 17.4% versus 52.1%. This was largely due to a significant difference in CPR with Day 5/6 transfers.

CONCLUSIONS

In two subgroup data analyses, in women who received cryopreserved oocytes from donors, CPR and LBR were significantly higher in cycles using oocytes cryopreserved via vitrification versus slow-freezing, reflecting differences in methodologies and more Day 5/6 transfers; in women who received vitrified oocytes, CPR and LBR were significantly higher in cycles using donor versus autologous oocytes with Day 5/6 transfers.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00699400 . Registered June 13, 2008.

Effects of vitrification on blastomere viability and cytoskeletal integrity in mouse embryos

Vitrification is widely used to cryopreserve supernumerary embryos following in vitro fertilization (IVF). The mouse model was used to investigate the effects of vitrification on blastomere viability, using viability markers, and on the cytoskeleton, by analysing spindle/chromosome configurations, using confocal scanning microscopy. Ninety cleavage and morula stage dimethyl sulphoxide (DMSO)/EG vitrified mouse embryos were either processed immediately following warming for viability assessment by labelling with the fluorescent markers carboxyfluorescein-diacetate succinimidylester (CFSE) and propidium iodide (PI) or were cultured to the blastocyst stage and immunostained with α-tubulin antibody to visualize microtubules and DAPI or PI to visualize DNA. Sixty-five fresh embryos were also used as the control. Vitrified embryos showed high survival rates following warming, but they had a higher incidence of damaged blastomeres compared with fresh embryos. Most mitotic spindles examined in all groups were normal, but multivariable analysis revealed that the proportion of abnormal spindles was significantly higher in vitrified/warmed embryos (P < 0.05). This study is the first to examine the immediate effects of vitrification on blastomere viability, using fluorescent markers and shows that although vitrification results in a higher incidence of damaged blastomeres, vitrified embryos may compensate for this limited number of damaged/abnormal cells, as development to the blastocyst stage was not compromised.

Population trends and live birth rates associated with common ART treatment strategies

STUDY QUESTION

Have ART live birth rates improved in Australia over the last 12 years?

SUMMARY ANSWER

There were striking improvements in per-cycle live birth rates observed for frozen/thaw embryo transfers, blastocyst transfer and single embryo transfer (SET), while live birth rates following ICSI were lower than IVF for non-male factor infertility in most years.

WHAT IS ALREADY KNOWN

ART and associated techniques have become the predominant treatment of infertility over the past 30 years in most developed countries. However, there are differences in ART laboratory and clinical practices, and success rates worldwide. Australia has one of the highest ART utilization rates and lowest multiple birth rates in the world, thus providing a unique setting to investigate the contribution of common ART strategies in an unrestricted population of patients to ART success rates.

STUDY DESIGN, SIZE, DURATION

A retrospective cohort study of 585 065 ART treatment cycles performed in Australia between 2002 and 2013 using the Australian and New Zealand Assisted Reproduction Database (ANZARD).

PARTICIPANTS MATERIALS, SETTING, METHOD

An unrestricted population of all women who underwent autologous ART treatment between 2002 and 2013. Visual descriptive analysis was used to assess the trends in ART procedures by the calendar years. Adjusted odds ratios (aORs) of a live birth for four common ART techniques were calculated after controlling for important confounders including female age, infertility diagnosis, stage of the embryo (blastocyst versus cleavage stage), type of embryo (fresh versus thawed), fertilization method (IVF versus ICSI) and number of embryos transferred (SET versus multiple embryos).

MAIN RESULTS AND THE ROLE OF CHANCE

The overall live birth rate per embryo transfer increased from 19.2% in 2002 to 23.3% in 2013 (21.9-24.3% for fresh embryo transfers and 14.6-23.3% for frozen/thaw embryo transfers). This occurred concurrently with an increase in SET from 29.7% to 78.9%, and an increase in the average age of women undergoing treatment from 35.0 to 35.9 years. Individuals who had a frozen/thaw embryo transfer cycle in 2002 had 43% (aOR: 0.57, 95% CI: 0.53-0.61) reduced odds of a live birth compared with a fresh embryo transfer cycle. This contrasted with 16% (aOR: 0.84, 95% CI: 0.80-0.98) reduced odds of a live birth from frozen/thaw embryo transfer cycles in 2013. In 2013, the odds of blastocyst transfer resulting in a live birth were more than twice as great as for cleavage stage transfer (aOR 2.01, 95% CI: 1.92-2.11). The adjusted odds of live birth per SET compared with multiple embryo transfer increased significantly over the last 12 years, from a 38% reduced odds of a live birth follow SET in 2002 (aOR: 062, 95% CI: 0.57-0.67) compared to an 8% reduced odds in 2013 (aOR: 0.92, 95% CI: 0.87-0.98). The aOR of a live birth using ICSI compared to IVF in non-male factor patients was lower in most years bringing into question its widespread use.

LIMITATION, REASONS FOR CAUTION

This is a retrospective cohort analysis and cannot confirm causality. High-level evidence on the effectiveness of particular ART techniques, particularly ICSI and blastocyst culture, requires prospective randomized controlled trials or detailed statistical analysis using large-scale data that counts for fertilization failure, embryo loss, prognostic factors and cycle characteristics.

WIDER IMPLICATION OF THE FINDINGS

The most striking improvements in ART success rates in Australia have been observed for frozen/thaw embryo transfers, blastocyst transfer and SET. Further studies of the role of ICSI in non-male factor infertility and blastocyst transfer success rates that take into account embryo loss are needed.

STUDY FUNDING/COMPETING INTERESTS

No funding was received to undertake this study. The authors declare that they do not have competing interests with this study.

TRIAL REGISTRATION NUMBER

NA.

Effect of embryo morphology and morphometrics on implantation of vitrified day 3 embryos after warming: a retrospective cohort study

BACKGROUND

Characteristics routinely used to evaluate embryo quality after thawing include number of blastomeres survived and presence of mitosis resumption after overnight culture. It is unknown to which extent symmetry and fragmentation affect implantation after warming and whether application of stricter criteria either before vitrification or after warming would improve implantation rate (IR) of vitrified/warmed embryos. This study aimed to find new parameters to improve selection criteria for vitrification and for transfer after warming.

METHODS

Firstly, we evaluated standard morphological characteristics (intact survival, mitosis resumption, number of blastomeres, symmetry and fragmentation) of 986 warmed day 3 embryos and, from a subset of 654, we evaluated morphometric characteristics (fragmentation, symmetry and volume change). Secondly, we tested the hypothesis that IR of day 3 vitrified/warmed embryos is influenced by morphometric characteristics. IR per embryo transferred was calculated using embryos that were transferred in a single embryo transfer (SET) or a double embryo transfer (DET) with either 0 or 100 % implantation (830/986). We investigated the significant differences in IR between the different categories of a specific characteristic. These categories were based on our standard embryo evaluation system. The statistical tests Chi-square, Fisher's exact or Cochrane-Armitage were used according to the type and/or categories of the variable.

RESULTS

The 986 embryos were transferred in 671 FET cycles with 16.9 % (167/986) IR. After exclusion of DET with 1 embryo implanted, IR per embryo transferred was 12.4 % (103/830). Embryo symmetry, fragmentation and volume change in vitrified/warmed day 3 embryos were not associated with IR. However, when mitosis resumption was present after overnight culture, intact embryos reached significantly higher IR than non-intact embryos and only when the embryo compacted after overnight culture the number of cells damaged after warming had no effect on IR. Concretely, embryos with 8 cells after warming or >9 cells after overnight culture-including compacted embryos-reached the highest IR (>15 %) while embryos with <6 cells after warming or with ≤6 cells after overnight culture had extremely low IR (<1 %).

CONCLUSIONS

IR of vitrified embryos is determined by the number of cells lost, by the occurrence of mitosis resumption, and by the specific number of blastomeres present but not by fragmentation, blastomere symmetry or volume change. Unselecting embryos for cryopreservation because of fragmentation >10 % and/or symmetry < 75 % only leads to unwanted loss of embryos with acceptable implantation potential.

TRIAL REGISTRATION

Retrospectively registered NCT02639715 .

Clinical evaluation of two formulations of slow-freezing solutions for cleavage stage embryos

PURPOSE

The aim was to investigate if improved survival rates could be achieved using a new formulation of solutions for slow freezing of human cleavage stage embryos.

METHODS

The evaluation was divided into two parts. The first part was a retrospective analysis of results obtained after freezing and thawing of day 3 embryos from 400 women using an old formulation of cryopreservation solutions compared to results from 108 women for which cryopreservation had been performed using new compositions of solutions. The second part was prospective, adding cycles until similar numbers of patients had been included in both groups. In total, 2274 embryos from 897 patients were thawed using the old formulation of solutions while 1273 embryos from 542 patients were frozen and thawed using the new solutions. The primary endpoint was survival rate.

RESULTS

With the new solutions, the survival rate increased from 82.1 to 94.4 % and the complete embryo survival rate increased from 54.9 to 81.3 %. The implantation rate, clinical pregnancy rate per embryo transfer, and per cycle were 28.2, 45.2, and 43.7 %, respectively, using the old formulations of cryosolutions. With the new solutions, the results reached 33.7, 54.1, and 54.1 %, respectively. All differences in results were statistically significant. The number of cancelled embryo transfers due to no survived embryos was 18 with the old solutions and 0 using the new solutions.

CONCLUSION

With the new composition of solutions for slow freezing and thawing of embryos, significantly improved results were obtained. Additionally, the number of cancelled embryo transfers was reduced.