Vitrified-warmed blastocyst transfer cycles yield higher pregnancy and implantation rates compared with fresh blastocyst transfer cycles—time for a new embryo transfer strategy?

Safety of embryo cryopreservation: insights from mid-term placental transcriptional changes

BACKGROUND

In recent years, with benefits from the continuous improvement of clinical technology and the advantage of fertility preservation, the application of embryo cryopreservation has been growing rapidly worldwide. However, amidst this growth, concerns about its safety persist. Numerous studies have highlighted the elevated risk of perinatal complications linked to frozen embryo transfer (FET), such as large for gestational age (LGA) and hypertensive disorders during pregnancy. Thus, it is imperative to explore the potential risk of embryo cryopreservation and its related mechanisms.

METHODS

Given the strict ethical constraints on clinical samples, we employed mouse models in this study. Three experimental groups were established: the naturally conceived (NC) group, the fresh embryo transfer (Fresh-ET) group, and the FET group. Blastocyst formation rates and implantation rates were calculated post-embryo cryopreservation. The impact of FET on fetal growth was evaluated upon fetal and placental weight. Placental RNA-seq was conducted, encompassing comprehensive analyses of various comparisons (Fresh-ET vs. NC, FET vs. NC, and FET vs. Fresh-ET).

RESULTS

Reduced rates of blastocyst formation and implantation were observed post-embryo cryopreservation. Fresh-ET resulted in a significant decrease in fetal weight compared to NC group, whereas FET reversed this decline. RNA-seq analysis indicated that the majority of the expression changes in FET were inherited from Fresh-ET, and alterations solely attributed to embryo cryopreservation were moderate. Unexpectedly, certain genes that showed alterations in Fresh-ET tended to be restored in FET. Further analysis suggested that this regression may underlie the improvement of fetal growth restriction in FET. The expression of imprinted genes was disrupted in both FET and Fresh-ET groups.

CONCLUSION

Based on our experimental data on mouse models, the impact of embryo cryopreservation is less pronounced than other in vitro manipulations in Fresh-ET. However, the impairment of the embryonic developmental potential and the gene alterations in placenta still suggested it to be a risky operation.

Exopolysaccharide ID1 Improves Post-Warming Outcomes after Vitrification of In Vitro-Produced Bovine Embryos

This study aimed to assess the cryoprotectant role of exopolysaccharide (EPS) ID1, produced by Antarctic Pseudomonas sp., in the vitrification of in vitro-produced (IVP) bovine embryos. IVP day 7 (D7) and day 8 (D8) expanded blastocysts derived from cow or calf oocytes were vitrified without supplementation (EPS0) or supplemented with 10 µg/mL (EPS10) or 100 µg/mL (EPS100) EPS ID1. The effect of EPS ID1 was assessed in post-warming re-expansion and hatching rates, differential cell count, apoptosis rate, and gene expression. EPS100 re-expansion rates were significantly higher than those observed for the EPS0 and EPS10 treatments, regardless of culture length or oocyte source. EPS100 hatching rate was similar to the one of the fresh blastocysts except for those D7 blastocysts derived from calf oocytes. No differences were observed among EPS ID1 treatments when the inner cell mass, trophectoderm, and total cell number were assessed. Although apoptosis rates were higher (p ≤ 0.05) in vitrified groups compared to fresh embryos, EPS100 blastocysts had a lower number (p ≤ 0.05) of apoptotic nuclei than the EPS0 or EPS10 groups. No differences in the expression of BCL2, AQP3, CX43, and SOD1 genes between treatments were observed. Vitrification without EPS ID1 supplementation produced blastocysts with significantly higher BAX gene expression, whereas treatment with 100 µg/mL EPS ID1 returned BAX levels to those observed in non-vitrified blastocysts. Our results suggest that 100 µg/mL EPS ID1 added to the vitrification media is beneficial for embryo cryopreservation because it results in higher re-expansion and hatching ability and it positively modulates apoptosis.

Perinatal outcomes of singletons born after blastocyst or cleavage-stage embryo transfer in FET cycles

PURPOSE

To compare perinatal outcomes of singletons after blastocyst versus cleavage-stage embryo transfer in frozen-thawed embryo transfer (FET) cycles.

METHODS

This was a retrospective cohort study of 4835 women who conceived after frozen-thawed embryo transfer and delivered a singleton baby from January 2015 to March 2020. The perinatal outcomes of the singletons born after blastocyst transfer (N = 3364) were compared to the singletons born after cleavage-stage transfer (N = 1471), including gestational week, birth weight, newborn gender and Apgar score.

RESULTS

Univariate and multivariate analysis found that infants born after blastocyst transfer had a higher risk of preterm birth (PTB) [adjusted odds ratio (aOR) 1.480; 95% confidence interval (CI) 1.213-1.807], large for gestational age (LGA) (aOR 1.329, 95%CI 1.149-1.536) and very large for gestational age (VLGA) (aOR 1.317, 95%CI 1.092-1.590) compared to infants born after cleavage-stage embryo transfer. When categorized by gestational weeks, the proportion of LGA was significantly higher for boys born after BT between GW 37 to 41 (aOR 1.301, 95%CI 1.051-1.609) and for girls born after BT between GW 32 to 41 (aOR 2.690, 95%CI 1.154-6.271, aOR 1.377, 95%CI 1.094-1.733), compared to boys and girls born after CT.

CONCLUSION

Our data suggested that the risk of PTB and LGA increased after blastocyst transfer versus cleavage-stage embryo transfer in FET cycles, and the risk of LGA is more apparent in the last trimester of pregnancy. Further studies are needed to confirm our findings and explored the association between the extended embryo culture and long-term outcomes of offspring.

Retrospective comparison of pregnancy outcomes of fresh and frozen-warmed single blastocyst transfer: a 5-year single-center experience

PURPOSE

To assess whether live birth rates (LBR) and maternal/neonatal complications differed following single fresh and frozen-warmed blastocyst transfer.

METHODS

The present retrospective observational study analyzed 4,613 single embryo transfers (SET) (646 fresh and 3,967 frozen) from January 1, 2014, to December 31, 2018. Fresh embryo transfer at blastocyst stage was considered according to the age of the patient and her prognosis. In case of the risk of ovarian hyperstimulation syndrome, premature progesterone rise, non-optimal endometrial growth, or supernumerary embryos, cryopreservation with subsequent frozen embryo transfer (FET) was indicated.

RESULTS

No differences in LBR were recorded. Fresh embryo transfers yielded an increase both in neonatal complications OR 2.15 (95% CI 1.20-3.86, p 0.010), with a higher prevalence of singletons weighting below the 5th percentile (p 0.013) and of intrauterine growth retardation (p 0.015), as well as maternal complications, with a higher placenta previa occurrence OR 3.58 (95% CI 1.54-8.28, p 0.003), compared to FET.

CONCLUSION

LBR appears not to be affected by the transfer procedure preferred. Fresh embryo transfer is associated with higher risk of neonatal complications (specifically a higher prevalence of singletons weighting below the 5th percentile and of intrauterine growth retardation) and placenta previa. Reflecting on the increased practice of ART procedures, it is imperative to understand whether a transfer procedure yields less complications than the other and if it is time to switch to a "freeze-all" procedure as standard practice.

TRIAL REGISTRATION

Clinical Trial Registration Number: NCT04310761. Date of registration: March 17, 2020, retrospectively registered.

Liquid biopsy: state of reproductive medicine and beyond

Liquid biopsy is the process of sampling and analyzing body fluids, which enables non-invasive monitoring of complex biological systems in vivo. Liquid biopsy has myriad applications in health and disease as a wide variety of components, ranging from circulating cells to cell-free nucleic acid molecules, can be analyzed. Here, we review different components of liquid biopsy, survey state-of-the-art, non-invasive methods for detecting those components, demonstrate their clinical applications and discuss ethical considerations. Furthermore, we emphasize the importance of artificial intelligence in analyzing liquid biopsy data with the aim of developing ethically-responsible non-invasive technologies that can enhance individualized healthcare. While previous reviews have mainly focused on cancer, this review primarily highlights applications of liquid biopsy in reproductive medicine.

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.

"Does serum estrogen level have an impact on outcomes in hormonal replacement frozen-warmed embryo transfer cycles?"

AIM

To evaluate the impact of serum estradiol (E2) levels on cycle outcomes in hormone replacement frozen embryo transfer (HR- FET) cycles.

MATERIALS AND METHODS

We retrospectively analyzed 509 HR-FET cycles performed from September 2018 to September 2019. Patients were divided into 6 groups based on their E2 values measured a day before progesterone initiation . Group 1: <100 pg/mL, group 2: 100-200 pg/mL, group 3: 200 - 300 pg/mL, group 4: 300-400 pg/mL, group 5: 400-500 pg/mL, group 6: >500 pg/mL. Implantation rate (IR), clinical pregnancy rate (CPR), miscarriage rate (MR), multiple pregnancy rate (MPR) and ectopic pregnancy rates were compared between all groups.

RESULTS

IR and CPR were similar between a wide range of E2 values, but when E2 values were more than 500 pg/mL there was a non significant fall in the IR (47.3% vs 48.3% vs 48.6% vs 47.8% vs 48.7% vs 39.6% p = .77) and CPR (63.6% vs 65.1% vs 65.6% vs 65.3% vs 65.6% vs 53.1% p = .692). MR was significantly high when E2 was less than 100 pg/mL (28.5%) and when E2 was more than 500 pg/mL (41.1%) (p = .02). MPR and ectopic pregnancy rates were similar between all the groups.

CONCLUSION

Outcomes of FET cycles were similar between a wide range of E2 values (100-500 pg/mL). When E2 levels were less than 100 pg/mL or more than 500 pg/mL there was significant increase in the MR but the numbers in these groups are less and further studies are required to confirm these facts.

Comparison of the Method of Endometrial Preparation Prior to Frozen-Thawed Embryo Transfer: a Retrospective Cohort Study from 9733 Cycles

Our objective was to compare the effectiveness of natural cycles (NC), modified natural cycle (mNC), and artificial cycles (AC) in women undergoing frozen-thawed embryo transfer (FET) after in vitro fertilization (IVF). This is a retrospective cohort study analyzing 9733 women undergoing the first cycle of FET over a 3-year period (June 2014-December 2017) at Northwest Women's and Children's Hospital after IVF-ICSI cycles. The type of endometrial preparation was determined by the treating physician's preference, based on patients' characteristics. Women with regular ovulation were allocated to natural cycles (n = 1480) or modified natural cycles (n = 196) when the leading follicle was triggered with hCG, while patients who were reluctant to frequently monitoring or living far from the hospital were allocated to artificial cycles (n = 8057). A logistic regression model was used to assess the association between endometrial preparation and clinical outcomes while adjusting for potential confounders. Live birth rate was primary outcome while miscarriage rate, clinical pregnancy rate, preterm birth rate, and ectopic pregnancy rate were secondary outcomes. In the adjusted model, type of endometrial preparation did not affect live birth (OR, 0.89; 95% CI, 0.74-0.96), clinical pregnancy (OR, 0.93; 95% CI, 0.81-1.06), preterm birth (OR, 1.03; 95% CI, 0.84-1.26), and ectopic pregnancy (OR, 0.73; 95% CI, 0.33-1.59), while AC significantly increased the miscarriage rate (OR, 1.49; 95% CI, 1.17-1.89, P=0.001). In conclusions, in women undergoing FET, natural cycles and artificial cycles resulted in comparable live birth rate while miscarriage rate was higher in artificial cycles.

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.

Fetal fraction of cell-free DNA in pregnancies after fresh or frozen embryo transfer following assisted reproductive technologies

STUDY QUESTION

Is the fetal fraction (FF) of circulating cell-free DNA (cfDNA) affected in pregnancies following ART treatment with either fresh or frozen embryo transfer (ET) compared with natural conception?

SUMMARY ANSWER

This study shows a significant reduction in the FF in ART patients compared with naturally conceived pregnancies, which seems to be more pronounced after fresh ET compared with frozen ET.

WHAT IS KNOWN ALREADY

Non-invasive prenatal testing (NIPT) is based on cfDNA in maternal blood, of which about 10% is of placental origin and thus represents the fetal karyotype. Validation studies have demonstrated a high sensitivity, specificity and positive predictive value of NIPT for the detection of fetal trisomy 21, 18 and 13. Nevertheless, the FF of cfDNA is an important factor for NIPT test accuracy. Several studies have found a reduction in FF for pregnancies following ART in comparison with natural conception. However, knowledge on how the FF is affected in ART pregnancies after fresh ET compared with frozen ET is very limited.

STUDY DESIGN, SIZE, DURATION

The study was designed as a case-control study. A total of 54 women with an ongoing pregnancy following ART treatment were included. After exclusion for different reasons, statistical analyses were based on 23 NIPT samples from pregnant women treated with fresh ET and 26 NIPT samples from pregnant women treated with frozen-thawed ET in a modified natural cycle. Women were included between February 2018 and November 2018. The results were compared with a control group of 238 naturally conceived pregnancies with a high-risk result from the combined first trimester screening (cFTS).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study included women from the Fertility Clinics at Copenhagen University Hospital Hvidovre and Copenhagen University Hospital Rigshospitalet. Blood samples for NIPT analysis were drawn between 11 + 0 and 14 + 2 weeks of gestation and were all analyzed at the NIPT Center at Copenhagen University Hospital Hvidovre. The NIPT-test was performed by massive-parallel whole-genome sequencing. The FF was determined using the SeqFF algorithm.

MAIN RESULTS AND THE ROLE OF CHANCE

We found a reduction in FF in ART patients compared with naturally conceived pregnancies, and the reduction was more pronounced for ART pregnancies after fresh ET (mean FF = 0.049) compared with frozen ET (mean FF = 0.063) (multivariate analysis adjusted for maternal BMI, P = 0.02). Another multivariate analysis, adjusted for BMI and multiples of median (MoM) values for pregnancy-associated plasma protein-A (PAPP-A), demonstrated a significantly reduced FF for ART pregnancies (mean FF = 0.056) compared with naturally conceived pregnancies (mean FF = 0.072) (P < 0.0001). We found that FF was significantly reduced with increasing maternal BMI (P < 0.0001) and with decreasing MoM values of PAPP-A (P = 0.003).

LIMITATIONS, REASONS FOR CAUTION

A limitation of our study design was the relatively small sample size. Another limitation was that the control group was not matched with the ART-treated women. The majority of the women from the control group had a high risk from cFTS, thereby their biochemical markers were diverging. However, the biochemical markers for the ART-treated women with fresh or frozen ET were not divergent within the subgroups.

WIDER IMPLICATIONS OF THE FINDINGS

Concurrent with other studies demonstrating a reduced FF for singleton pregnancies after ART treatment compared with naturally conceived pregnancies, we found a reduction in FF between the two groups. This is one of the first studies to examine FF in ART pregnancies after fresh ET compared with frozen ET, hence the existing knowledge is limited. We find that FF is even more reduced in pregnancies following fresh ET compared with frozen ET, which might possibly reflect the predisposition of being small for gestational age after fresh ET compared with natural cycle frozen ET.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the A.P. Møller og Hustru Chastine Mc-Kinney Møllers Fond til almene Formaal (the A.P. Møller Foundation for General Purposes). All authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

NA.

Which is better for mothers and babies: fresh or frozen-thawed blastocyst transfer?

BACKGROUND

In recent years, there have been many reports on the pregnancy outcomes of fresh blastocyst transfer (BT) and frozen-thawed BT, but the conclusions are controversial and incomplete. To compare the pregnancy outcomes, maternal complications and neonatal outcomes of fresh and frozen-thawed BT in the context of in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) cycles, we conducted a meta-analysis.

METHODS

A meta-analysis was conducted by searching the PubMed, Embase, and Cochrane Library databases through May 2020. Data were extracted independently by two authors.

RESULTS

Fifty-four studies, including 12 randomized controlled trials (RCTs), met the inclusion criteria. Fresh BT was associated with a lower implantation rate, pregnancy rate, ongoing pregnancy rate, and clinical pregnancy rate and higher ectopic pregnancy rate than frozen-thawed BT according to the results of the RCTs. The risks of moderate or severe ovarian hyperstimulation syndrome, placental abruption, placenta previa and preterm delivery were higher for fresh BT than for frozen-thawed BT. The risk of pregnancy-induced hypertension and pre-eclampsia was lower for fresh BT; however, no significant differences in risks for gestational diabetes mellitus and preterm rupture of membrane were found between the two groups. Compared with frozen-thawed BT, fresh BT appears to be associated with small for gestational age and low birth weight. No differences in the incidences of neonatal mortality or neonatal malformation were observed between fresh and frozen-thawed BT.

CONCLUSIONS

At present there is an overall slight preponderance of risks in fresh cycles against frozen, however individualization is required and current knowledge does not permit to address a defintive response.

THE EFFECTIVENESS OF PROGRAMS AND THE COURSE OF PREGNANCY DURING THE TRANSFER OF THAWED AND FRESH EMBRYOS

In recent years, IVF programs have been increasingly carried out in which cryopreserved embryos are used. Along with these programs, IVF procedures are carried out, in which "fresh" embryos are transferred. The problem of choice naturally arises before reproductive specialists: which program to give preference to - FRESH and FET? Specialists of the Institute of Reproductive Medicine (Almaty, RK) conducted a number of observations. After careful sampling of these data, no differences in CNB% were found in Fresh and FET (Frozen Embryo Transfer) programs. The incidence of complications during pregnancy and childbirth with FET protocols was significantly higher in comparison with Fresh, which requires further study. When analyzing the "Take home baby" indicator, there were no statistically significant differences between the FET and Fresh protocols.

Patients' attitudes and preferences towards a freeze-all strategy in ART treatment

STUDY QUESTION

What are the attitudes towards different aspects of a freeze-all strategy and elective frozen embryo transfer (eFET) in comparison with fresh embryo transfer in assisted reproductive technology treatment among female and male patients before and after their first ART treatment cycle in a public health care setting?

SUMMARY ANSWER

Despite concerns about the delay in embryo transfer associated with eFET, nearly 60% of the participants were in favor of eFET compared with fresh embryo transfer assuming that the clinical pregnancy rate was equivalent.

WHAT IS KNOWN ALREADY

Vitrification and blastocyst transfer have considerably improved success rates after FET with ongoing pregnancy rates in frozen cycles approaching those seen in fresh treatment cycles. Furthermore, the risk of ovarian hyperstimulation syndrome (OHSS) is essentially eliminated in FET cycles, and FET may be beneficial to the endometrial and fetal development because a hormonal environment mirroring the natural cycle is enabled. However, the freeze-all strategy is not yet implemented as standard care. One reason is the presumption of negative patient attitudes towards a freeze-all embryo strategy. So far, no data regarding patients' attitudes on a freeze-all strategy have been published.

STUDY DESIGN, SIZE, DURATION

This study was designed as a descriptive cross-sectional study including 165 fertility patients referred for their first ART treatment from December 2014 to June 2016.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All newly referred patients participating in a mandatory meeting before initiating ART treatment at the Fertility Clinic, Hvidovre Hospital, Copenhagen, Denmark were requested to fill in an online web-based questionnaire separately for men and women covering attitudes towards a freeze-all strategy, socio-demographic data and reproductive history. The patients were informed about both conventional fresh embryo transfer strategy and the freeze-all strategy prior to answering the questionnaire.

MAIN RESULTS AND THE ROLE OF CHANCE

The total response rate was 77.1% (n = 165), and for women and men respectively 85.8 versus 66.0%. The female respondents were significantly more likely to consider the postponement of embryo transfer difficult compared to the male population (78.6 versus 35.5%; P < 0.001) and they were significantly more willing to accept a risk in treatment on own health to achieve a pregnancy than were the male respondents on their partners health (82.5 versus 96.8%; P = 0.025). However, 59.2% of the women and 59.7% of the men agreed that they would choose eFET over fresh embryo transfer if the chance of pregnancy were the same. Most of the patients furthermore agreed that the health of the mother and their baby was of highest importance. In the adjusted analyses we found no significant predictive factors for preferences towards a freeze-all strategy apart from a negative attitude towards delay of transfer in case of previous unsuccessful ART attempts.

LIMITATIONS, REASONS FOR CAUTION

Selection bias cannot be excluded, as the total response rate was 77.1%. The hypothetical nature of the items may furthermore limit the validity of the results. In addition, the participants were from a single Fertility Clinic in the Capital Region of Denmark and may therefore not be representative for all fertility patients.

WIDER IMPLICATIONS OF THE FINDINGS

In a clinical setting with similar pregnancy rates for eFET and fresh embryo transfer, these results indicate that patients, when given access to information on advantages and disadvantages of both fresh embryo transfer and eFET, are less prone to opt for fresh embryo transfer. This may be ground breaking for a patient-centered paradigm shift in routine ART treatment with a wider implementation of a freeze-all and eFET-strategy eliminating the risk of OHSS.

STUDY FUNDING/COMPETING INTEREST(S)

The Danish Council for Independent Research and Merck Serono supported the study. The study is part of the Reprounion Collaborative study, co-financed by the European Union, Interreg V ÖKS. No competing interests exist.

Does fresh single embryo transfer outcome predict the result of a subsequent vitrified-warmed blastocyst of the same cohort?

Reflecting the current trends, the utilization of frozen-thawed transfer cycles has been steadily increasing worldwide; outcome predictors of these cycles are therefore a major research goal. Our aim was to investigate whether the outcome of a fresh single blastocyst transfer (SBT) can serve as a prognostic factor for the subsequent vitrified-warmed SBT originating from the same cohort. A retrospective cohort study was performed at a single unit. Non-donor fresh cycles were analyzed as predictors of the following vitrified-warmed cycle. Only SBTs were included. Cycles designated to a freeze-all policy and cycles involving pre-implantation genetic analysis were excluded. A total of 1127 vitrified-warmed single blastocyst cycles were included. The indications for artificial reproductive technologies were comparable across the study groups. Vitrified-warmed cycles following a live birth outcome in the fresh cycle were more likely to result in a clinical pregnancy than those following a fresh cycle, which failed to reach a live birth. The same trend was observed for live birth rate following vitrified-warmed transfer in the fresh cycle. After correcting for possible confounders, age and embryo quality were significantly correlated with the chance for a live birth, but the previous fresh cycle did not affect the results. We therefore conclude that after adjustment for age, embryo quality and number of previous oocyte retrieval cycles, the fresh cycle outcome was not a significant influential factor for the following vitrified-warmed cycle.

Does the sex ratio of singleton births after frozen single blastocyst transfer differ in relation to blastocyst development?

PURPOSE

To investigate the associations between blastocyst development and the sex ratio (male:female) among singleton live births resulting from single-blastocyst frozen embryo transfer (FET) cycles.

METHODS

Patients with singleton live births following the first autologous single FET of non- preimplantation genetic testing (PGT) blastocysts in a single reproductive medicine department between January 2015 and February 2019 were included in this retrospective study. The primary outcome measure was the singleton sex ratio. Multivariable logistic regression models were used to estimate the associations between blastocyst quality and singleton sex ratio after adjustment for some potential confounders.

RESULTS

There were 638 high-quality and 572 poor-quality single blastocyst FETs, and the blastocysts were conceived via 855 IVF and 355 ICSI treatments. A total of 1210 singleton live births were assessed. High-quality single blastocyst FET resulted in a significantly higher sex ratio than did poor-quality single blastocyst FET (60% vs. 49.7%, P < 0.001). The infertility cause was not associated with sex ratio among singleton live births (P = 0.537). The results of a multivariate analysis revealed that a high-quality blastocyst has a 150% higher probability of being male than a poor-quality blastocyst (adjusted odds ratio (aOR) 1.57; 95% CI 1.24-2, P < 0.001). Among the three blastocyst morphological parameters, Grade B trophectoderm was significantly associated with a higher sex ratio than Grade C (aOR 1.71; 95% CI 1.33-2.21. P < 0.001). Neither expansion degree nor inner cell mass degree were significantly associated with the singleton sex ratio.

CONCLUSIONS

A single high-quality blastocyst FET has a higher chance of resulting in a male infant than a female infant. The results demonstrate that grade B trophectoderm confers benefits in improving the implantation potential of male blastocysts.

Freeze-all, for whom, when, and how

Background: The 'freeze-all' practice refers to the cryopreservation of all mature oocytes or viable embryos after ovarian stimulation. The development of the vitrification technique has been crucial to make this approach a reality, since it increases the post-thaw survival rates and permits comparable implantation rates with fresh embryos. Nonetheless, as implantation probabilities are comparable to fresh embryo transfer in normo-responder patients, the freeze- all strategy has demonstrated no benefits overall.Method: Narrative review in which we give an overview of this approach, discuss recent advances in the field, as well as for whom, when and how it is recommended to emply the freeze-all technique.Results: However, there is some clinical evidence that shows its feasibility. Thus, it has been demonstrated that elevation of progesterone at the end of ovarian stimulation decreases the implantation rates after the transfer of day 6 blastocysts in fresh and some uterine pathologies; freeze-all is also the preferred option for patients undergoing pre-implantation genetic testing, since there is an improvement of the results and it allows for inclusion of all blastocysts of the cohort. In high responders, the freeze-all strategy optimizes the response whilst also minimizing the risk of ovarian hyperstimulation syndrome.Conclusion: Due to the different cases that a reproductive expert might encounter, it is essential to highlight benefits and drawbacks of this practice.

Preparation of the endometrium and timing of blastocyst transfer in modified natural cycle frozen-thawed embryo transfers (mNC-FET): a study protocol for a randomised controlled multicentre trial

INTRODUCTION

Despite the high number of frozen embryo transfer (FET) cycles being conducted (190 000 cycles/year) in Europe, the timing of blastocyst transfer and the use of luteal phase progesterone support in modified natural cycle FET (mNC-FET) in assisted reproductive technologies are controversial. In mNC-FET, the timing of blastocyst warming and transfer is determined according to the time of implantation in a natural cycle, aiming to reach blastocyst endometrial synchronicity. However, the optimal day of blastocyst transfer following ovulation trigger is not determined. In addition, the value of luteal phase support to maintain the endometrium remains uncertain. Thus, there is a need to identify the optimal timing of blastocyst warming and transfer and the effect of luteal phase support in a randomised controlled trial design. The aim of this randomised controlled trial is to investigate if progesterone supplementation from the early luteal phase until gestational age 8 weeks is superior to no progesterone supplementation and to assess if blastocyst warming and transfer 6 days after ovulation trigger is superior to 7 days after ovulation trigger in mNC-FET with live birth rates as the primary outcome.

METHODS AND ANALYSIS

Multicentre, randomised, controlled, single-blinded trial including 604 normo-ovulatory women aged 18-41 years undergoing mNC-FET with a high-quality blastocyst originating from their first to third in vitro fertilisation/intracytoplasmic sperm injection cycle. Participants are randomised (1:1:1:1) to either luteal phase progesterone or no luteal phase progesterone and to blastocyst warming and transfer on day 6 or 7 after human chorionic gonadotropin trigger. Only single blastocyst transfers will be performed.

ETHICS AND DISSEMINATION

The study is approved by the Danish Committee on Health Research Ethics (H-18025839), the Danish Medicines Agency (2018061319) and the Danish Data Protection Agency (VD-2018-381). The results of the study will be publicly disseminated.

TRIAL REGISTRATION NUMBER

The study is registered in EudraCT (2018-002207-34) and on ClinicalTrials.gov (NCT03795220); Pre-results.

Survival, re-expansion, and pregnancy outcome following vitrification of dromedary camel cloned blastocysts: A possible role of vitrification in improving clone pregnancy rate by weeding out poor competent embryos

There is a clinical demand for efficient cryopreservation of cloned camel embryos with considerable logistic and economic advantage. Vitrification of in vivo derived embryos has been reported in camels, but there is no study on vitrification of cloned embryos. Moreover, whether characteristic differences between cloned and in vivo derived embryos imply different vitrification requirement is unresolved. Here, we compared survival, re-expansion and pregnancy rates of cloned embryos vitrified using two commercial vitrification kits (Cryotec and Kitazato), developed basically for human embryos, and a vitrification protocol developed for in vivo camel embryos (CVP). Cloned embryos responded dynamically to vitrification-warming steps in commercial kits, with a flat shrinkage in the final vitrification solution and a quick re-expansion to the original volume immediately after transferring to the isotonic warming solution. Contrarily, full shrinkage was not observed in CVP method, and majority of embryos were still collapsed post-warming. The immediate re-expansion was highly associated and predictive of higher survival and total cell number, and also better redox state of embryos vitrified by Cryotec and Kitazato kits compared to CVP method. Importantly, while 30% blastomere loss, verified by differential dye exclusion test, was tolerated in vitrified embryos, >50% blastomeres loss in non-expanded blastocysts implied the minimal essential cell survival rate for blastocoelic cavity re-expansion in vitrified cloned camel blastocysts, irrespective of vitrification method. A protocol-based exposure of embryos to cryoprotectants indicated that cryoprotectant toxicity, per se, may not be involved in lower cryosurvival of embryos in CVP vs. Cryotec and Kitazato. The initial pregnancy rates were numerically higher in Cryotec and Kitazato frozen transfers compared to fresh transfer (56.3, 60 and 33.3%, respectively), and importantly, a higher percentage of established pregnancies in vitrified groups passed the critical 3 months period of early embryonic loss compared to sibling fresh clone pregnancies (50, 40, and 10%, respectively). Results confirmed the suitability of Cryotec and Kitazato kits for vitrification of cloned camel embryos and that vitrification may improve pregnancy outcome by weeding out poor competent embryos.

Increased pregnancy complications following frozen-thawed embryo transfer during an artificial cycle

PURPOSE

This study aimed to clarify the risks of adverse pregnancy outcomes in patients and their offspring after frozen embryo transfer (FET) during an artificial cycle (AC).

METHODS

We conducted a retrospective cohort study that included all FET cycles and subsequent deliveries in a single centre between August 2013 and March 2016. Pregnancy, obstetric and neonatal outcomes were compared among patients treated during an AC or a natural cycle with luteal phase support (NC-LPS). Multivariate logistic regression was performed to evaluate the relationship between endometrial preparation schemes and pregnancy, obstetric and neonatal outcomes.

RESULTS

AC-FET was not a significant risk factor for clinical pregnancy rate, multiple birth rate or miscarriage rate after adjusting for potential confounders. However, AC-FET was a significant risk factor for ectopic pregnancy rate (adjusted odds ratio (AOR), 1.738; 95% confidence interval (CI), 1.086-2.781) and live birth rate (AOR, 0.709; 95% CI, 0.626-0.802). Regarding obstetric outcomes, AC-FET was found to be associated with an increased risk for hypertension disorder (AOR, 1.780; 95% CI, 1.262-2.510) and caesarean section (AOR, 1.507; 95% CI, 1.195-1.900). In multiples, birth weight (2550 g (2150-2900 g) in AC-FET vs. 2600 g (2350-2900 g) in NC-LPS; P = 0.023), gestational age (36.6 weeks (35.3-37.6 weeks) vs. 37.1 weeks (36.1-37.9 weeks); P < 0.001), and z-score (- 0.5 (- 1.1, - 0.0) vs. - 0.4 (- 1.0, 0.2); P = 0.009) were higher in the NC-LPS group than in the AC-FET group, although there were no differences in these variables among singletons.

CONCLUSION

Compared with NC-LPS, AC-FET seemed to have a negative effect on obstetric outcomes.

Cumulative live birth rate in freeze-all cycles is comparable to that of a conventional embryo transfer policy at the cleavage stage but superior at the blastocyst stage

OBJECTIVE

To determine whether the freeze-all policy ensures a higher efficacy in terms of cumulative live birth rate (CLBR) in comparison with a conventional fresh/frozen embryo transfer (ET) approach in patients with normal ovarian response.

DESIGN

Retrospective, matched, multicenter cohort study.

SETTING

Private IVF centers.

PATIENT(S)

This study analyzed 564 completed IVF cycles in which an average of 12-18 oocytes were retrieved. In 435 cycles the conventional strategy was applied, with initial ET followed by frozen embryo replacements, whereas in 129 cycles the freeze-all policy was performed, with elective cryopreservation and deferred use of all viable embryos.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The primary endpoint was CLBR. The secondary endpoint was cumulative clinical pregnancy rate.

RESULT(S)

Overall, statistically comparable CLBRs were achieved in the fresh/frozen and freeze-all groups (45.5% vs. 53.5%). Stratification of data for age and number of retrieved oocytes confirmed the absence of differences between the two groups. In a subanalysis in which the day of ET and cryopreservation were taken into account, a similar outcome was achieved in cleavage-stage groups (45.6% vs. 46.4%), whereas when ET was performed at the blastocyst stage the CLBR was significantly higher in the freeze-all group (45.3% vs. 66.7%).

CONCLUSION(S)

Our CLBR analysis indicates that clinical performance of the freeze-all policy is equivalent to that of the conventional strategy when ET is carried out at the cleavage stage. However, it seems to be superior if associated with cryopreservation and transfer at the blastocyst stage.

Blastocoele expansion: an important parameter for predicting clinical success pregnancy after frozen-warmed blastocysts transfer

OBJECTIVE

To assess the predictive value of each individual morphological parameter: blastocoele expansion degree, inner cell mass (ICM), and trophectoderm (TE) grades on the clinical pregnancy outcome in frozen-warmed embryo transfer (FET) cycles.

METHODS

This is a retrospective cohort study, including 1154 FET cycles receiving vitrified-warmed one or two blastocysts transfer from August 2011 through to May 2018. The correlation between blastocyst morphology parameters and clinical outcome after FET was assessed.

RESULTS

In the subgroup analysis based on clinical pregnancy, the patients who achieved clinical pregnancy had a significantly higher degree of blastocyst expansion (3.69 ± 0.68 vs. 3.53 ± 0.78, P = 0.000) and had a thicker endometrium (9.65 ± 1.63 vs. 9.28 ± 1.64) compared with those with non-clinical pregnancy. The logistic regression analysis showed that among the three blastocyst morphology parameters, only the blastocoele expansion degree was significantly correlated with the clinical pregnancy outcome and had ability to predict the outcome after FET cycles with one or two vitrified-warmed blastocysts transferred. Both ICM and TE stages were not associated with pregnancy outcomes.

CONCLUSIONS

The blastocoele expansion degree may be essential for successful pregnancy and should be given priority when selecting frozen blastocyst for transfer.

High implantation and clinical pregnancy rates with single vitrified-warmed blastocyst transfer and optional aneuploidy testing for all patients

This study reports the results of a 2-year long IVF programme ('One by One') in which all patients (median age 40 years; range 27-45 years) were offered preimplantation genetic testing for aneuploidy (PGT-A) and had all blastocysts vitrified (freeze-only), followed later by single vitrified-warmed blastocyst transfer (vSET) in managed cycles. Between January 2016 and December 2017, a total of 155 patients started 222 treatment cycles and 99 (45%) cycles resulted in one or more vitrified blastocysts (untested or with normal copy number for all chromosomes) available for transfer. Seventeen patients (11%) aged ≤35 years opted out of PGT-A. Over this period, 85 vSETs in 74 patients resulted in an implantation rate of 80% (68/85) and a singleton clinical pregnancy rate of 66% (56/85). Cumulative live birth rates will not be known for 1-2 years. Nevertheless, these high success rates with vSET confirm larger studies using selected patients and are likely to deliver similar, if not higher, live birth rates per cycle started than rates typically reported in national registries with conventional IVF and transfer of one or more fresh and/or frozen embryos.

Single fresh blastocyst transfer or single cryopreserved-thawed blastocyst transfer: which is preferable for infertile patients in IVF/ICSI cycles? A meta-analysis

PURPOSES

Nowadays, an increasing number of studies have proposed single embryo transfer (SET), especially single blastocyst transfer (SBT). To compare the clinical outcomes of single fresh blastocyst transfer (BT) and single cryopreserved-thawed BT in patients undergoing in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) cycles.

METHODS

The PubMed, Embase, and Cochrane Library databases were searched from the start dates until February 2018. The primary outcomes were clinical pregnancy rate (CPR) and embryo implantation rate (IR). The secondary outcomes were multiple pregnancy rate (MPR), live birth rate (LBR), and miscarriage rate (MR). Using the Mantel-Haenszel random effects model to analyze summary risk ratio (RR) with 95% confidence intervals (CIs). Statistical heterogeneity scores were assessed with the standard Cochrane's Q test and I² statistic.

RESULTS

In total, eight studies (two prospective studies, six retrospective studies) were included in our analysis. There was no statistically significant difference regarding clinical pregnancy (RR = 1.18, 95% CI = 0.91-1.55) and embryo implantation (RR = 1.04, 95% CI = 0.77-1.41). Regarding secondary outcomes, there was no significant difference regarding miscarriage (RR = 0.79, 95% CI = 0.60-1.03) and multiple pregnancy (RR = 1.23, 95% CI = 0.75-2.04). However, single fresh BT is associated with an increased live birth (RR = 1.28, 95% CI = 1.05-1.57) compared with single cryopreserved-thawed BT.

CONCLUSIONS

In summary, this meta-analysis supports the hypothesis that single cryopreserved BT might not be the best choice compared with single fresh BT in patients undergoing IVF/ICSI cycles.

A comparison of the survival and implantation rates of blastocysts that were vitrified on post-fertilization day five, six and seven

The goal of this retrospective cohort study was to compare survival, implantation, clinical and ongoing pregnancy rates between blastocysts that were vitrified on post-fertilization days 5, 6 and 7. Before vitrification, blastocysts were evaluated in terms of morphology and blastocyst expansion, inner cell mass and trophectoderm quality. They were thawed and transfered in a subsequent artificial cycle. Embryo implantation rates were 39%, 25% and 25% for blastocysts that were vitrified on days 5, 6, and 7, respectively (p = 0.006). Clinical and ongoing pregnancy rates were 19%, 12%, 13% (p = 0.100) and 9%, 7%, 12% (p = 0.99) for days 5, 6 and 7 blastocysts, respectively. Day 5 blastocysts had significantly higher full-collapsing score after assisted-hatching compared to days 6 and 7 blastocysts (p = 0.014). As blastocyst quality increased, implantation and clinical pregnancy rates increased in all groups and both parameters were statistically significantly higher on day 5 blastocysts than on days 6 or 7 (p = 0.001). It was clearly found that good quality blastocysts obtained on day 5 have higher implantation and clinical pregnancy rates than 6th and 7th day cryopreserved embryos. There were no statistically significant differences between the cryopreserved embryos on days 6 and 7 regarding the implantation, clinic and ongoing pregnancy rates.

Synchrony of the first division as an index of the blastocyst formation rate during embryonic development

Purpose

To devise an uninvasive selection system for human embryos with high developmental potential after a single oocyte retrieval cycle by comparing the in vitro and in vivo effectiveness of first division synchrony against subsequent embryonic developmental stages.

Methods

The effects of using assisted reproductive technology on 948 embryos that were produced in 137 cycles were examined by dividing the embryos into “early cleavage” (first division within 25.90 hours) and “late cleavage” (first division at or after 25.90 hours) groups and comparing the blastocysts and good‐quality blastocyst formation rates between the two groups. These two groups were each divided further into “high synchrony” (first division synchrony within 3.96 hours) and “low synchrony” (first division synchrony at or after 3.96 hours) groups. The blastocysts, good‐quality blastocyst formation rates, and pregnancy rates were compared among these four groups.

Results

Both the blastocysts and good‐quality blastocyst formation rates were significantly higher in the early‐cleavage groups than in the late‐cleavage groups. The blastocyst formation rate of the latter was also significantly increased in the high‐synchrony, compared with the low‐synchrony, group.

Conclusion

First division synchrony in a single oocyte retrieval cycle could be a useful assessment of the blastocyst formation rate that enables the selection of viable embryos at an early stage of culture.

Comparison of pregnancy outcomes after vitrification at the cleavage and blastocyst stage: a meta-analysis

OBJECTIVE

This systematic review sought to evaluate the clinical outcomes of vitrification at the cleavage stage and blastocyst stage for embryo transfer in patients undergoing assisted reproductive technology (ART) treatment.

METHODS

We searched for related comparative studies published in the PubMed, EMBASE, and Cochrane Library databases up to July 2017. The primary outcomes were clinical pregnancy rate (CPR) and embryo implantation rate (IR). Secondary outcomes were multiple pregnancy rate (MPR), miscarriage rate (MR), live birth rate (LBR), and ongoing pregnancy rate (OPR). The Mantel-Haenszel fixed effects model and random effects model were used to analyze the summary risks ratios (RRs) with 95% confidence intervals (CIs).

RESULTS

Eight studies with more than 6590 cycles were included in our meta-analysis. Seven studies were observational retrospective comparative studies. One was a prospective study. Overall, the current study summarizes information from 6590 vitrification warming cycles (cleavage stage n = 4594; blastocysts n = 1996). There was no difference in the primary outcome clinical pregnancy rate (RR = 0.97, 95% CI = 0.90-1.04; fixed effects model; I ²  = 21%), whereas vitrified blastocyst transfer was significantly superior to vitrified cleavage-stage embryo transfer regarding the implantation rate (RR = 0.85, 95% CI = 0.74-0.97; random effects model; I ²  = 43). Regarding the secondary outcomes, no differences were found in the multiple pregnancy rate (RR = 1.20, 95% CI = 0.79-1.82; fixed effects model; I ²  = 22), live birth rate (RR = 1.07, 95% CI = 0.98-1.16; fixed effects model; I ²  = 0), and ongoing pregnancy rate (RR = 1.01, 95% CI = 0.92-1.120; fixed effects model; I ²  = 0), whereas a higher miscarriage rate was observed with vitrified blastocyst transfer (RR = 0.65, 95% CI = 0.45-0.93; random effects model; I ²  = 23).

CONCLUSION

In summary, this meta-analysis shows that vitrification at any stage has no detrimental effect on clinical outcome. Blastocyst transfer will still remain a favorable and promising option in ART. Due to the small sample evaluated in the pool of included studies, large-scale, prospective, and randomized controlled trials are required to determine if these small effects are clinically relevant.

Elevated serum estradiol levels in artificial autologous frozen embryo transfer cycles negatively impact ongoing pregnancy and live birth rates

PURPOSE

The aim of this study is to evaluate the correlation between serum estradiol (E₂) levels during artificial autologous frozen embryo transfer (FET) cycles and ongoing pregnancy/live birth rates (OP/LB).

METHODS

A historical cohort study was conducted in an academic setting in order to correlate peak and average estradiol levels with ongoing pregnancy/live birth rates for all autologous artificial frozen embryo transfer cycles performed from 1/2011 to 12/2014.

RESULTS

Average and peak E₂ levels from 110 autologous artificial FET cycles from 95 patients were analyzed. Average E₂ levels were significantly lower in cycles resulting in OP/LB compared to those that did not (234.1 ± 16.6 pg/ml vs. 315 ± 24.8 pg/ml, respectively, p = 0.04). Although peak E₂ levels were not significantly different between cycles resulting in OP/LB compared with those that did not (366.9 ± 27.7 pg/ml vs. 459.1 ± 32.3 pg/ml, respectively, p = 0.19), correlation analysis revealed a statistically significant (p = 0.02) downward trend in OP/LB rates with increasing peak E₂ levels.

CONCLUSIONS

This study suggests that elevated E₂ levels in artificial autologous FET cycles are associated with lower OP/LB rates. Estradiol levels should be monitored during artificial FET cycles.

Comparison of a 'freeze-all' strategy including GnRH agonist trigger versus a 'fresh transfer' strategy including hCG trigger in assisted reproductive technology (ART): a study protocol for a randomised controlled trial

INTRODUCTION

Pregnancy rates after frozen embryo transfer (FET) have improved in recent years and are now approaching or even exceeding those obtained after fresh embryo transfer. This is partly due to improved laboratory techniques, but may also be caused by a more physiological hormonal and endometrial environment in FET cycles. Furthermore, the risk of ovarian hyperstimulation syndrome is practically eliminated in segmentation cycles followed by FET and the use of natural cycles in FETs may be beneficial for the postimplantational conditions of fetal development. However, a freeze-all strategy is not yet implemented as standard care due to limitations of large randomised trials showing a benefit of such a strategy. Thus, there is a need to test the concept against standard care in a randomised controlled design. This study aims to compare ongoing pregnancy and live birth rates between a freeze-all strategy with gonadotropin-releasing hormone (GnRH) agonist triggering versus human chorionic gonadotropin (hCG) trigger and fresh embryo transfer in a multicentre randomised controlled trial.

METHODS AND ANALYSIS

Multicentre randomised, controlled, double-blinded trial of women undergoing assisted reproductive technology treatment including 424 normo-ovulatory women aged 18-39 years from Denmark and Sweden. Participants will be randomised (1:1) to either (1) GnRH agonist trigger and single vitrified-warmed blastocyst transfer in a subsequent hCG triggered natural menstrual cycle or (2) hCG trigger and single blastocyst transfer in the fresh (stimulated) cycle. The primary endpoint is to compare ongoing pregnancy rates per randomised patient in the two treatment groups after the first single blastocyst transfer.

ETHICS AND DISSEMINATION

The study will be performed in accordance with the ethical principles in the Helsinki Declaration. The study is approved by the Scientific Ethical Committees in Denmark and Sweden. The results of the study will be publically disseminated.

TRIAL REGISTRATION NUMBER

NCT02746562; Pre-results.

Deferred Frozen Embryo Transfer: What Benefits can be Expected from this Strategy in Patients with and without Endometriosis?

Progress with cryopreservation techniques have enabled development of the deferred frozen-thawed embryo transfer (DET) strategy as an alternative to relying on fresh embryo transfers.

With DET, the entire embryo cohort is cryopreserved, and embryo transfer is then performed in a subsequent cycle that takes place separately from the controlled ovarian stimulation (COS).

Initially developed to limit the risk of ovarian hyperstimulation syndrome that occurs with high responders, this strategy has been applied extensively with other populations in an effort to improve implantation rates. The assumption is that COS, which is essential for in vitro fertilization/intra cytoplasmic sperm injection (IVF/ICSI) procedures to obtain a multi-follicular development, could have a detrimental impact on the endometrium as a result of greatly elevated levels of steroids. It is currently not clear whether the DET strategy can be generally applied to all women requiring an IVF/ICSI procedure.

The objectives of this literature review regarding DET, were hence: (i) to present the scientific background that contributed to extensive adoption of this technique, (ii) to detail the pregnancy outcomes and potential obstetric and neonatal consequences, (iii) to report on its ability to prevent risks induced by COS, and (iv) to propose indications for the DET strategy in clinical practice.

GnRH agonist administration prior to embryo transfer in freeze-all cycles of patients with endometriosis or aberrant endometrial integrin expression

Prolonged gonadotrophin-releasing hormone agonist (GnRHa) administration before IVF with fresh embryo transfer to patients with endometriosis or aberrant endometrial integrin expression (-integrin) improves outcomes but may suppress ovarian response and prevents elective cryopreservation of all embryos. This retrospective cohort pilot study evaluates freeze-all cycles with subsequent prolonged GnRHa before embryo transfer in these populations. Patients from 2010 to 2015 who met inclusion criteria and received a long-acting GnRHa every 28 days twice before FET were evaluated. A subset underwent comprehensive chromosomal screening (CCS) after trophectoderm biopsy. Three groups were identified: Group 1: + CCS, +endometriosis (20 patients, 20 transfers); Group 2: +CCS, -integrin (12 patients, 13 transfers); Group 3: no CCS, +endometriosis or -integrin (10 patients, 12 transfers); Group 4: all transfers after CCS for descriptive comparison only (n = 2809). Baseline characteristics were similar among Groups 1-3 except that the mean surgery to oocyte aspiration interval was longer for Group 1 than Group 3. Implantation and ongoing pregnancy rates were statistically similar among the three groups and compared favourably to Group 4. A non-significant trend towards improved outcomes was noted in Group 1. Prolonged GnRHa after freeze-all in these patients avoids excessive ovarian suppression and results in excellent outcomes.

Vitrified-warmed single-embryo transfers may be associated with increased maternal complications compared with fresh single-embryo transfers

Cryopreservation of embryos allows single-embryo transfer and storage of supernumerary embryos, maximizing cumulative pregnancy rates. The purpose of this retrospective cohort study was to compare pregnancy outcome in singletons born after fresh or vitrified-warmed single blastocyst transfer (SBT). Singleton live births resulting from SBT of fresh or vitrified-warmed embryos were compared. Primary outcomes were perinatal outcomes including small for gestational age (SGA), low birthweight, preterm deliveries (PTD), large for gestational age (LGA) and congenital malformations. Maternal complications included pre-eclampsia, placenta previa, placental abruption, gestational diabetes mellitus (GDM) and chorioamnionitis. Adjustment for confounding factors was performed. Of 1886 fresh SBTs and 1200 vitrified-warmed SBTs during the study period, vitrified-warmed SBTs compared with fresh SBTs resulted in significantly lower clinical pregnancy rate (P < 0.0001). Live birth and miscarriage rates calculated only for pregnancy with known outcome revealed lower live birth rates and higher miscarriage rates for the vitrified-warmed group. Perinatal complications were calculated for clinical pregnancies with known outcomes (12.9% catchment failure was excluded from analysis). The vitrified-warmed group showed a trend toward higher rates of pre-eclampsia, GDM, Caesarean delivery and LGA neonates. Rates of PTD and SGA were comparable. In conclusion, vitrified-warmed SBT might be associated with increased feto-maternal complications.

Assisted reproduction technique outcomes for fresh versus deferred cryopreserved day-2 embryo transfer: a retrospective matched cohort study

Ovarian stimulation could adversely affect endometrial receptivity and consequently embryo implantation. One emerging strategy is the 'freeze-all' approach. Most studies have focused on blastocyst transfers, with limited research on day-2 deferred cryopreserved embryo transfers. In this large retrospective cohort study, outcomes were compared between day-2 fresh versus deferred cryopreserved embryo transfers. After matching by age and number of previous cycles, 325 cycles were included in the fresh group and 325 in the deferred cryopreserved embryo transfers group: no significant differences were found between groups in implantation (0.20 ± 0.33 versus 0.17 ± 0.31, respectively) and ongoing pregnancy rates (21.85% versus 18.46%). Independent predictors for ongoing pregnancy after a multiple logistic regression analysis were the women's age (OR = 0.92; 95% CI 0.88 to 0.97), body mass index (OR = 0.94; 95% CI 0.89 to 0.99), the number of two pronuclei embryos (OR = 1.19; 95% CI 1.04 to 1.40) and at least one grade 1 embryo transferred (OR = 1.97; 95% CI 1.26 to 3.05). In the case of a day-2 embryo transfer, outcomes after treatment with assisted reproduction techniques are similar for fresh versus deferred cryopreserved embryo transfers when pre-transfer progesterone exposures are similar in the two groups.

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.

A direct healthcare cost analysis of the cryopreserved versus fresh transfer policy at the blastocyst stage

A cost analysis covering direct healthcare costs relating to IVF freeze-all policy was conducted. Normal- and high- responder patients treated with a freeze-all policy (n = 63) compared with fresh transfer IVF (n = 189) matched by age, body mass index, duration and cause of infertility, predictive factors for IVF (number of oocytes used for fertilization) and study period, according to a 1:3 ratio were included. Total costs per patient (€6952 versus €6863) and mean costs per live birth were similar between the freeze-all strategy (€13,101, 95% CI 10,686 to 17,041) and fresh transfer IVF (€15,279, 95% CI 13,212 to 18,030). A mean per live birth cost-saving of €2178 (95% CI -1810 to 6165) resulted in a freeze-all strategy owing to fewer embryo transfer procedures (1.29 ± 0.5 versus 1.41 ± 0.7); differences were not significant. Sensitivity analysis revealed that the freeze-all strategy remained cost-effective until the live birth rate is either higher or only slightly lower (≥-0.59%) in the freeze-all group compared with fresh cycles. A freeze-all policy does not increase costs compared with fresh transfer, owing to negligible additional expenses, i.e. vitrification, endometrial priming and monitoring, against fewer embryo transfer procedures required to achieve pregnancy.

Getting Older Women Pregnant: Contemporary Thoughts

For women of advanced age with abnormally increased FSH levels, standardized hormonal stimulation often represents a cost-intensive procedure with a low success rate. It is well established now that with mild ovarian stimulation, there is a greater percentage of good-quality eggs (although a smaller number) than with higher-dose conventional stimulation. Mild stimulation protocols reduce the mean number of days of stimulation, the total amount of gonadotropins used and the mean number of oocytes retrieved. The proportion of high-quality and euploid embryos seems to be higher compared with conventional stimulation protocols, and the pregnancy rate per embryo transfer is comparable. Moreover, the reduced costs, the better tolerability for patients and the less time needed to complete an IVF cycle make mild approaches clinically and cost-effective over a given period of time. The low number of embryos available for transfer poses a great challenge in the management of older women going in for IVF. A potential management of these older women is to create a sufficient pool of embryos by accumulating vitrified good-grade embryos over several minimal stimulation and natural cycles. At the end of the accumulation process, these embryos can be subjected to a preimplantation genetic screening using next-generation sequencing and then the pool would have only chromosomal normal embryos with maximal chances of implantation. This would potentially make the chances of success for older women similar to normal responders. This management, however, is unthinkable without an outstanding vitrification program. The option of accumulating embryos has become a promising reality with the advent of vitrification technologies.

Developmental ability of embryos produced from oocytes with fragile oolemma by intracytoplasmic sperm injection

PURPOSE

In intracytoplasmic sperm injection (ICSI) of oocytes with a fragile oolemma (fragile oocytes), breakage can occur at injection. In this study, we produced embryos from oocytes with a fragile and normal oolemma (normal oocytes) by ICSI and compared their ability to be fertilized and develop in vitro. We also investigated whether fragile oocyte-derived embryos could implant after blastocyst transfer to determine whether fragile oocytes should be used for assisted reproductive technology treatment.

METHODS

Oocytes were divided into three groups-normal oocytes from cycles containing no fragile oocytes (group A), normal oocytes from cycles containing at least one fragile oocyte (group B), and fragile oocytes (group C), and their fertilization abilities after ICSI and the developmental abilities of resultant embryos were compared.

RESULTS

The fertilization rate in group C (65.3 %) was significantly (P < 0.01) lower than those in groups A (84.6 %) and B (86.9 %), and the degeneration rate in group C (24.2 %) was significantly (P < 0.01) higher than those in groups A (0.71 %) and B (0.28 %). However, there were no significant differences in the blastocyst formation rates (59.7-67.5 %) of embryos among the different groups. In addition, the pregnancy rate after transfer of blastocysts in group C (50.0 %) was not significantly different from those in groups A (35.6 %) and B (45.8 %).

CONCLUSIONS

The fertilization ability after ICSI of fragile oocytes is lower than that of normal oocytes but the resultant embryos have the same developmental ability as those of normal oocyte-derived embryos.

Single center validation of routine blastocyst biopsy implementation

Purpose

The study aims to contrast the efficacy of trophectoderm biopsy preimplantation genetic screening (PGS)/vitrification (VTF)-all cycles to past treatment protocols. Specifically, do these applied technologies increase live birth rates on a per cycle/first transfer basis?

Materials and methods

An observational, retrospective cohort study of first transfer outcomes was performed in two groups. Group 1 (PGS) included PGS/VTF-all cycles, and group 2 (no PGS) included the first transfer from non-PGS fresh cycles or VTF-ALL cycles. In group 1, all blastocysts were biopsied on days 5/6, vitrified and array CGH performed. Group 2 patients had embryo transfers on day 3 or day 5. All blastocysts were vitrified and warmed according to μS-VTF protocols. Clinical pregnancies and implantation were confirmed by ultrasound and live birth information attained. Results were stratified by age with donor cycles excluded, and to eliminate bias, the same groups were then validated on a per cycle basis. Chi-squared used to determine significance.

Results

Analyzing 287 embryo transfers and 1,000+ PGS-tested blastocysts, an overall 97 % increase in live births favored group 1 (PGS). When utilizing PGS/VTF-ALL cycles, patients under 43 years old exhibited higher implantation, clinical pregnancy, and ongoing/live birth rates. Re-analyzing the data to include all cycles initiated revealed higher live birth rates in group 1 age groups ≤34 and 38–40 years old.

Conclusion

Validating PGS on a per cycle basis eliminated data bias by including patients without blastocysts to biopsy or euploid embryos. Clearly, PGS uses blastocysts more efficiently to achieve success, while many women over 40 may benefit most by understanding why some failures occur.

Support

None

Electronic supplementary material

The online version of this article (doi:10.1007/s10815-016-0792-3) contains supplementary material, which is available to authorized users.

Concurrent oocyte retrieval and hysteroscopy: a novel approach in assisted reproduction freeze-all cycles

In this matched-controlled study (n = 300), the effect of hysteroscopic surgery performed concurrently with oocyte retrieval on the reproductive outcomes of intracytoplasmic sperm injection (ICSI) freeze-all cycles was investigated in patients screened for intrauterine anomalies. Conventionally, hysterscopic surgery is performed in a different cycle from IVF, delaying treatment completion and increasing patient anxiety. One hundred and fifty patients who had hysteroscopic surgery concurrently with oocyte retrieval (hysteroscopy group) in ICSI freeze-all cycles were matched according to age and oocyte number with 150 ICSI freeze-all cycles, in which the patients required no hysteroscopy (control group). In the hysteroscopy group, hysteroscopy was performed for diagnostic (n = 5) and therapeutic (n = 145) purposes. Blastocyst culture and Cryotop vitrification was performed in both groups. Frozen embryo transfer (FET) was successfully performed in the hysteroscopy group from 35 days after oocyte retrieval. No significant differences were observed for implantation, pregnancy, clinical pregnancy and early pregnancy loss rates in the hysteroscopy and control groups (48.9%, 72.0%, 61.3% and 14.8% versus 48.3%, 75.3%, 64.7% and 14.3%, respectively). Performing hysteroscopic surgery concurrently with oocyte retrieval in a segmented-IVF programme has no negative impact on reproductive outcomes, increases efficiency, and provides patients with low-risk treatment.

Segmented ART - The new era in ART?

Currently up to 4% of infants born in developing countries are conceived through assisted reproductive technology (ART). Even though most of these conceptions occur and progress without complications, ART procedures and processes may increase iatrogenesis through complications in - and after conception. We herein review and discuss the clinically and scientific implications and evidence of iatrogenesis, and show how the evolution in ART technologies and procedures has led to the current presumption that frozen embryo transfer might be a more optimal strategy than fresh embryo transfer, in terms of not only reproduction, but also of maternal and fetal outcomes. There is increasing scientific evidence to support the notion that controlled ovarian stimulation could induce significant changes to the endocrine profile of a reproductive cycle, especially to the reproductively important early luteal phase. These changes may not only have a negative effect on implantation and early placentation, but also on the mother, the fetus, and the infant. The overt consequences of controlled ovarian stimulation include ovarian hyperstimulation syndrome, reduced embryo implantation, increased ectopic pregnancy, and altered placentation and fetal growth. The cumulative scientific evidence from this review suggests that GnRHa trigger in segmented ART might constitute the future routine treatment regimen for IVF patients, providing a safe, effective, and patient friendly treatment.

Supplementation With Cell-Penetrating Peptide-Conjugated Estrogen-Related Receptor β Improves the Formation of the Inner Cell Mass and the Development of Vitrified/Warmed Mouse Embryos

Estrogen-related receptor β (ESRRB), which is a member of the nuclear orphan receptor family, regulates the messenger RNA (mRNA) expression levels of the transcription factors, Oct4 and Nanog, in early embryos and germ cells, thereby maintaining the undifferentiated state and pluripotency of the relevant cells. The present study was designed to determine whether the upregulation of pluripotency-related genes by direct delivery of ESRRB protein may affect on the commitment into inner cell mass (ICM) or the development of vitrified/warmed mouse embryos. Recombinant cell-penetrating peptide (CPP) ESRRB protein was synthesized and then added into a culture medium for cryopreserved mouse embryos. Vitrified/warmed 8-cell embryos were cultured in KSOM with/without 2 μg/mL CPP-ESRRB for 48 hours and then analyzed or transferred to the uteri of foster mothers. The mRNA expression of Oct4 and Nanog was higher in CPP-ESRRB-treated blastocysts compared to the untreated controls. No difference was observed in embryonic development, but ICM:trophectoderm ratio was increased in the CPP-ESRRB-treated group compared to the untreated group, and after embryo transfer, a higher implantation rate was obtained in the CPP-ESRRB-treated group compared to the untreated group. This study shows for the first time that recombinant CPP-ESRRB can be easily integrated into vitrified/warmed mouse embryos and that it increases Oct4 expression (via a pluripotency-related gene pathway), ICM formation, and the further embryonic and full-term development of vitrified/warmed mouse embryos. This CPP-conjugated protein delivery system could therefore be a useful tool for improving assisted reproductive technology.

Use of the CryoPredict algorithm to predict live birth from cryopreserved embryos

BACKGROUND

Currently, the viability of cryostored blastocysts that are subsequently re-warmed is determined via the percentage of cell survival. However, the large number of cells that forms the blastocyst can make this estimate difficult and unreliable. Studies have shown that fast re-expanding blastocysts have superior pregnancy rates.

AIM

To determine whether the degree and speed of blastocoele re-expansion following cryopreservation and warming correlate with rates of live birth.

MATERIALS AND METHODS

A retrospective cohort study of 757 frozen embryo transfer cycles over a 4-year period at Royal Prince Alfred Hospital, Sydney. Clinical and embryology notes were retrieved. Details regarding patient demographics, stimulation cycle from which embryos were derived, frozen embryo transfer cycles, embryology and pregnancy outcomes were recorded.

RESULTS

Female (P = 0.01) and male age (P = 0.02) at the time of embryo creation were inversely associated with live birth. Fertilisation method (P = 0.03), embryo type at cryopreservation (P = 0.009), embryo grade at cryopreservation (P < 0.0001), percentage of cell survival post-thaw (P < 0.0001) and the degree of re-expansion (P = 0.003) were the IVF and embryology factors significantly associated with live birth. A predictive model (CryoPredict) was created in order to individualise the probability that the transfer of a given embryo would result in live birth.

CONCLUSIONS

The degree and speed of blastocoele re-expansion postcryopreservation and subsequent warming can be used in conjunction with other parameters to predict live birth.

Determining the need for rescue intracytoplasmic sperm injection in partial fertilisation failure during a conventional IVF cycle

To explore the need for rescue intracytoplasmic sperm injection (ICSI) in cases of partial fertilisation failure during a conventional in vitro fertilisation cycle, rescue ICSI was performed for cycles with a fertilisation rate of <50%. The data were divided into three groups based on the fertilisation rate: group 1 (0%), group 2 (<25%) and group 3 (>25%). The impact of rescue ICSI on each group was then analysed in terms of ovum fertilisation, embryo development, embryo utilisation and selection of embryos for transfer. Rescue ICSI was performed on 1831 unfertilised oocytes from 313 cycles. The fertilisation rates for group 1, group 2 and group 3 were 74.66, 68.35 and 65.46%, and the rate of polyploidy in the three groups was 8.55, 11.33, and 14.47%. The percentage of embryos that can be transferred from rescue ICSI for group 2 was 38.33%, and this value was higher than those of the other two groups. It is concluded that rescue ICSI is not recommended for patients with an IVF rate of >25% as the procedure is associated with a greater risk and low returns. However, it is feasible to perform rescue ICSI for patients with IVF rates of <25%.