Non-inferiority of cleavage-stage versus blastocyst-stage embryo transfer in poor prognosis IVF patients (PRECiSE trial): study protocol for a randomized controlled trial

Competent blastocyst and receptivity endometrium improved clinical pregnancy in fresh embryo transfer cycles: a retrospective cohort study

BACKGROUND

Embryo quality is usually regarded as a key predictor of successful implantation and clinical pregnancy potential. The identification of embryos that have the capacity to implant and result in a healthy pregnancy is a crucial part of in vitro fertilization (IVF). Usually, morphologically high-quality embryos are chosen for embryo transfer in IVF treatment. The aim of this study was to assess the association between the available blastocyst formation rate and the clinical pregnancy outcome following the first fresh embryo transfer cycle and provide systematic individual treatment to adjust endometrial receptivity for the next transfer cycle.

METHODS

This retrospective, single-center study included 512 fresh embryo transfers conducted between 11/2019 and 08/2021, which consisted of 385 cleavage-stage (Day 3) and 127 blastocyst-stage (Day 5) embryo transfers. The two groups were divided into a clinical pregnancy group and a nonclinical pregnancy group for comparison. The association between the available blastocyst formation rate and the clinical pregnancy rate in the Day 3 and Day 5 transfer groups were considered.

RESULTS

In the Day 3 group, there were 275 clinical pregnancies, and the clinical pregnancy rate was 71.43%. Although the two pronuclei (2PN) oocyte rate and available embryo rate at Day 3 were significantly higher in the clinical pregnancy group than the nonclinical pregnancy group (P < 0.05), the blastocyst formation rate and the available blastocyst formation rate were not significantly different between the clinical pregnancy group and the nonclinical pregnancy group (P > 0.05). In the Day 5 group, there were 81 clinical pregnancies, and the clinical pregnancy rate was 63.78%. No baseline characteristics showed any obvious differences between the clinical pregnancy group and nonclinical pregnancy group (P > 0.05). The blastocyst formation rate in the nonclinical pregnancy group was higher than that in the clinical pregnancy group, but the difference was not statistically significant (81.06% vs. 77.03%, P = 0.083). Interestingly, the available blastocyst formation rate and the Day 5 available blastocyst formation rate were significantly higher in the nonclinical pregnancy group than the clinical pregnancy group (66.19% vs. 60.79%, P = 0.014; 54.58% vs. 46.98%, P = 0.007).

CONCLUSIONS

In fresh cycles, the available blastocyst formation rate was not associated with the clinical pregnancy outcome for Day 3 embryo transfers, and the available blastocyst formation rate was not positively correlated with the clinical pregnancy outcome for Day 5 embryo transfers.

Fresh embryo transfer in the cleavage and blastocyst stages and pregnancy outcomes: A retrospective cross-sectional study

Background

Advances in cell culture media have led to a trend of embryo transfer from the early cleavage stages to blastocyst stage.

Objective

The study aims to compare the effects of fresh embryo transfer in cleavage and blastocyst stage on pregnancy outcomes.

Materials and Methods

This cross-sectional study was conducted on 1422 cases referred to the Umm-al-Banin Infertility Clinic Center, Dezful, Iran, between July 2013 and December 2020 who were candidates for in vitro fertilization/intracytoplasmic sperm injection for fresh embryo transfer. A total of 1246 cases were divided into 4 categories on days 2-5 or 6. Chemical and clinical pregnancy, abortion, multifetal pregnancy, ongoing pregnancy, and live birth rates were analyzed.

Results

Fresh embryo transfer was performed in 28.5% of the cases on the 2nd day, 45.8% on the 3rd, 15.3% on the 4th day, and 10.4% on days 5 or 6. The overall clinical pregnancy and live birth rates were estimated at 20.6% and 17.6% in the cleavage, and 17% and 14% in the blastocyst stages, respectively. However, no significant difference was observed in either group. In addition, there was no significant difference between groups in terms of the abortion, multifetal pregnancy, and ongoing pregnancy rate (p > 0.05).

Conclusion

According to the results, the consequences of pregnancy in fresh embryo transfer at the blastocyst stage were not superior to embryo transfer at different stages of the cleavage process.

No difference in cumulative live birth rates between cleavage versus blastocyst transfer in patients with four or fewer zygotes: results from a retrospective study

STUDY QUESTION

Is the cumulative live birth rate (CLBR) per oocyte collection cycle (OCC) comparable after cleavage-stage or blastocyst-stage transfer in combination with supernumerary blastocyst vitrification on Day 5 (D5) in patients with four or fewer zygotes on Day 1?

SUMMARY ANSWER

The CLBR in a fresh blastocyst-transfer or cleavage-stage transfer policy followed by vitrification on D5 is comparable in patients with four or fewer zygotes.

WHAT IS KNOWN ALREADY

Blastocyst transfer enhances the self-selection of the embryo and shortens the time to pregnancy in patients with normal or high ovarian response. Whether these advantages are also present in patients with a low ovarian response and/or a limited number of available zygotes is a continuous debate.

STUDY DESIGN, SIZE, DURATION

This was a retrospective, observational cohort study of 2359 consecutive OCCs between January 2014 and December 2018. According to a shift in transfer policy in our center, 571 OCCs had been scheduled for a fresh transfer on Day 3 (D3) and 1788 on D5. The D5 group was matched to the D3 group by propensity score (PS) matching according to multiple maternal baseline covariates. After PS matching, there were 571 OCCs in each group.

PARTICIPANTS/MATERIALS, SETTING, METHODS

OCCs scheduled for a D3 transfer (n = 571) or for a D5 transfer (n = 1788) were matched by PS matching in a 1:1 ratio accounting for potential confounding factors associated with CLBR. The model included patient characteristics, such as maternal age and cycle rank, as well as treatment characteristics such as GnRH analog regimen and ovarian response. Embryological variables included the number of zygotes and the number of 6- to 7- and 8-cell embryos on D3. The delivery outcomes of the fresh treatment cycle and the consecutive vitrified-warmed embryo transfers were analyzed up to the first live birth. The primary endpoint of this study was CLBR per OCC. Secondary outcomes were live birth rate per fresh transfer and embryo implantation rate per transferred embryo.

MAIN RESULTS AND THE ROLE OF CHANCE

The CLBR per OCC was comparable between the D5 and D3 groups (16.8% versus 17.7%, respectively, P = 0.600). Live birth rates per OCC did not differ between a cleavage-stage transfer and blastocyst-stage transfer policy (15.2% versus 12.4%, respectively, P = 0.160). In the D5 group, 201 cycles did not result in a blastocyst to perform an embryo transfer or cryopreservation; in the D3 group, only 59 cycles did not have an embryo transfer because of poor embryo quality (35.2% versus 10.3%, respectively; P < 0.001). A significantly higher number of fresh double embryo transfers were performed in the D3 group compared to D5 (23.8% versus 7.0%, respectively, P < 0.001).

LIMITATIONS, REASONS FOR CAUTION

Although adjusted for important confounders in the PS matching, BMI and embryo quality of the transferred embryo(s) were not taken into account. This study is limited by its retrospective design and is a single-center study, which may limit the generalizability of our findings.

WIDER IMPLICATIONS OF THE FINDINGS

The CLBR in a fresh blastocyst-transfer or cleavage-stage transfer policy followed by vitrification on D5 is comparable. A fresh embryo transfer on D3 can still be considered in patients with a poor ovarian response and/or limited number of zygotes when combined with blastocyst vitrification without impacting the overall CLBR of the cycle.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was obtained for this study. There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

This retrospective study was approved by the local ethical committee at Ghent University Hospital (B 670201731234).

Cleavage-stage versus blastocyst-stage embryo transfer in assisted reproductive technology

BACKGROUND

Advances in embryo culture media have led to a shift in in vitro fertilisation (IVF) practice from cleavage-stage embryo transfer to blastocyst-stage embryo transfer. The rationale for blastocyst-stage transfer is to improve both uterine and embryonic synchronicity and enable self selection of viable embryos, thus resulting in better live birth rates.

OBJECTIVES

To determine whether blastocyst-stage (day 5 to 6) embryo transfer improves the live birth rate (LBR) per fresh transfer, and other associated outcomes, compared with cleavage-stage (day 2 to 3) embryo transfer.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Specialised Register of controlled trials, CENTRAL, MEDLINE, Embase, PsycINFO, and CINAHL, from inception to October 2021. We also searched registers of ongoing trials and the reference lists of studies retrieved.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) which compared the effectiveness of IVF with blastocyst-stage embryo transfer versus IVF with cleavage-stage embryo transfer.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. Our primary outcomes were LBR per fresh transfer and cumulative clinical pregnancy rates (cCPR). Secondary outcomes were clinical pregnancy rate (CPR), multiple pregnancy, high-order multiple pregnancy, miscarriage (all following first embryo transfer), failure to transfer embryos, and whether supernumerary embryos were frozen for transfer at a later date (frozen-thawed embryo transfer). We assessed the overall quality of the evidence for the main comparisons using GRADE methods.

MAIN RESULTS

We included 32 RCTs (5821 couples or women). The live birth rate following fresh transfer was higher in the blastocyst-stage transfer group (odds ratio (OR) 1.27, 95% confidence interval (CI) 1.06 to 1.51; I² = 53%; 15 studies, 2219 women; low-quality evidence). This suggests that if 31% of women achieve live birth after fresh cleavage-stage transfer, between 32% and 41% would do so after fresh blastocyst-stage transfer. We are uncertain whether blastocyst-stage transfer improves the cCPR. A post hoc analysis showed that vitrification could increase the cCPR. This is an interesting finding that warrants further investigation when more studies using vitrification are published. The CPR was also higher in the blastocyst-stage transfer group, following fresh transfer (OR 1.25, 95% CI 1.12 to 1.39; I² = 51%; 32 studies, 5821 women; moderate-quality evidence). This suggests that if 39% of women achieve a clinical pregnancy after fresh cleavage-stage transfer, between 42% and 47% will probably do so after fresh blastocyst-stage transfer. We are uncertain whether blastocyst-stage transfer increases multiple pregnancy (OR 1.05, 95% CI 0.83 to 1.33; I² = 30%; 19 studies, 3019 women; low-quality evidence) or miscarriage rates (OR 1.12, 95% CI 0.90 to 1.38; I² = 24%; 22 studies, 4208 women; low-quality evidence). This suggests that if 9% of women have a multiple pregnancy after fresh cleavage-stage transfer, between 8% and 12% would do so after fresh blastocyst-stage transfer. However, a sensitivity analysis restricted only to studies with low or 'some concerns' for risk of bias, in the subgroup of equal number of embryos transferred, showed that blastocyst transfer probably increases the multiple pregnancy rate. Embryo freezing rates (when there are frozen supernumerary embryos for transfer at a later date) were lower in the blastocyst-stage transfer group (OR 0.48, 95% CI 0.40 to 0.57; I² = 84%; 14 studies, 2292 women; low-quality evidence). This suggests that if 60% of women have embryos frozen after cleavage-stage transfer, between 37% and 46% would do so after blastocyst-stage transfer. Failure to transfer any embryos was higher in the blastocyst transfer group (OR 2.50, 95% CI 1.76 to 3.55; I² = 36%; 17 studies, 2577 women; moderate-quality evidence). This suggests that if 1% of women have no embryos transferred in planned fresh cleavage-stage transfer, between 2% and 4% probably have no embryos transferred in planned fresh blastocyst-stage transfer. The evidence was of low quality for most outcomes. The main limitations were serious imprecision and serious risk of bias, associated with failure to describe acceptable methods of randomisation.

AUTHORS' CONCLUSIONS

There is low-quality evidence for live birth and moderate-quality evidence for clinical pregnancy that fresh blastocyst-stage transfer is associated with higher rates of both than fresh cleavage-stage transfer. We are uncertain whether blastocyst-stage transfer improves the cCPR derived from fresh and frozen-thawed cycles following a single oocyte retrieval. Although there is a benefit favouring blastocyst-stage transfer in fresh cycles, more evidence is needed to know whether the stage of transfer impacts on cumulative live birth and pregnancy rates. Future RCTs should report rates of live birth, cumulative live birth, and miscarriage. They should also evaluate women with a poor prognosis to enable those undergoing assisted reproductive technology (ART) and service providers to make well-informed decisions on the best treatment option available.

Placental Abnormalities are Associated With Specific Windows of Embryo Culture in a Mouse Model

Assisted Reproductive Technologies (ART) employ gamete/embryo handling and culture in vitro to produce offspring. ART pregnancies have an increased risk of low birth weight, abnormal placentation, pregnancy complications, and imprinting disorders. Embryo culture induces low birth weight, abnormal placental morphology, and lower levels of DNA methylation in placentas in a mouse model of ART. Whether preimplantation embryos at specific stages of development are more susceptible to these perturbations remains unresolved. Accordingly, we performed embryo culture for several discrete periods of preimplantation development and following embryo transfer, assessed fetal and placental outcomes at term. We observed a reduction in fetal:placental ratio associated with two distinct windows of preimplantation embryo development, one prior to the morula stage and the other from the morula to blastocyst stage, whereas placental morphological abnormalities and reduced imprinting control region methylation were only associated with culture prior to the morula stage. Extended culture to the blastocyst stage also induces additional placental DNA methylation changes compared to embryos transferred at the morula stage, and female concepti exhibited a higher loss of DNA methylation than males. By identifying specific developmental windows of susceptibility, this study provides a framework to optimize further culture conditions to minimize risks associated with ART pregnancies.

Embryo attrition in planned PGT-A: predicting the number of available blastocysts for transfer

PURPOSE

During a typical IVF cycle, there is unavoidable attrition from oocytes retrieved to blastocysts formed. Some patients will not have blastocysts available to biopsy or embryos for transfer. The purpose of this study was to predict the number of transferable blastocysts available for patients based on their age and number of 2pn zygotes.

METHODS

This was a retrospective cohort study of all fresh autologous IVF and ICSI cycles in which PGT-A was planned from 1/2012 to 3/2020. In total, 746 cycles from 571 patients were analyzed. Patient cycles were stratified into two groups: less than four 2pn zygotes (n = 85) and at least four 2pn zygotes (n = 661). Cycles were then stratified by patient age. Cycle outcomes, including number of cleavage-stage embryos, blastocysts, euploid blastocysts, and low level mosaic blastocysts, were determined.

RESULTS

Cleavage-rate was independent of age and number of 2pn zygotes and ranged between 96 and 100%. Blastocyst conversion and euploid blastocyst conversion rates were directly correlated to age, ranging from 52 to 83% for blastocyst conversion and 0-28% for euploid blastocyst conversion. For patients above the age of 40 years with less than four 2pn zygotes, the risk of having no transferable embryos was 99.7%.

CONCLUSION

While the literature demonstrates higher live birth rates with the use of PGT-A in women of advancing age, this is inconsequential if there is no embryo available to transfer. Women over 40 years with less than four 2pn zygotes should consider transfer of one or more untested embryos either on day 3 or on day 5.

Impact of endometriosis on oocyte morphology in IVF-ICSI: retrospective study of a cohort of more than 6000 mature oocytes

BACKGROUND

Infertility associated with endometriosis can be explained by several non-exclusive mechanisms. The oocyte plays a crucial role in determining embryonic competence and this is particularly relevant for in vitro fertilization (IVF) outcomes. According to some authors, the morphology of oocytes could also be a non-invasive marker of oocyte quality. The aim of this study was to evaluate the relationship between endometriosis and oocyte morphology after controlled ovarian stimulation for intracytoplasmic sperm injection (ICSI) on a large oocyte cohort.

METHODS

Single-center comparative retrospective study in the academic In Vitro Fertilization (IVF) unit of the Lille University Hospital. A total of 596 women treated for IVF-ICSI with ejaculated spermatozoa for sperm alterations were included. They were classified as endometriosis (n = 175) or control groups (n = 401). The morphological evaluation of 2,016 mature oocytes from 348 cycles of patients with endometriosis was compared with that of 4,073 mature oocytes from 576 control cycles. The main outcome measures were Average Oocyte Quality Index (AOQI) and metaphase II oocyte morphological scoring system (MOMS). Comparison of groups was carried out by a mixed linear model and by a generalized estimation equation model with a "patient" random effect to consider that a patient might have several attempts.

RESULTS

No difference in AOQI and MOMS scores was found between endometriosis and control women (adjusted p = 0.084 and 0.053, respectively). In case of endometriosis, there were significantly fewer metaphase II oocytes retrieved, embryos obtained, grade 1 embryos and number of cumulative clinical pregnancies compared to controls. In the endometriosis group, endometriosis surgery was associated with a reduced number of mature oocytes retrieved, and the presence of endometrioma(s) was associated with some abnormal oocyte shapes. Nevertheless, no difference concerning the AOQI and MOMS scores was found in these subgroups.

CONCLUSION

Endometriosis does not have a negative impact on oocytes' morphology in IVF-ICSI.

TRIAL REGISTRATION

On December 16, 2019, the Institutional Review Board of the Lille University Hospital gave unrestricted approval for the anonymous use of all patients' clinical, hormonal and ultrasound records (reference DEC20150715-0002).

Comparison of day 2 and overnight day 3 frozen embryo transfers: A prospective randomized controlled trial

In certain patients cleavage stage embryos may be preferred. The relationship between an additional day in culture and pregnancy outcomes is not well established. We aimed to compare outcomes of day 2 versus overnight day 3 frozen embryo transfer (FET). In this randomized controlled trial, patients with day 2 cryopreserved embryos were allocated to two groups. In group A embryos were transferred on day 2, the same day of thawing. In group B embryos were transferred one day after thawing, on day 3 after overnight incubation. Out of 410 patients eligible, 92 were recruited. Finally, 72 patients participated, 39 in group A and 33 in group B. No significant difference in implantation (11 % in group A and 14 % in group B, p = 0.81), clinical pregnancy (18 % in group A and 21 % in group B, p = 0.73) or live birth rates (13 % in group A and 18 % in group B, p = 0.53) was found. To conclude, no significant difference in reproductive outcomes was found when comparing patients with day 2 or overnight day 3 FET. Considering published data on blastocyst transfer, cleavage stage ET may still be a relevant option and the decision between day 2 or overnight day 3 ET depends on patients' and physicians' preference and recommendation.

Progesterone and estrogen levels are associated with live birth rates following artificial cycle frozen embryo transfers

PURPOSE

Does an association exist between serum progesterone and estradiol levels and live birth rates in artificial cycle frozen embryo transfer (AC-FET)?

METHODS

Retrospective cohort study was based on prospectively collected data at a university-affiliated fertility center. Included were all cycles using an artificial endometrial preparation with estradiol hemihydrate (Estrofem, 2 mg/8 h) and vaginal progesterone (Endometrin 100 mg/8 h), autologous oocytes, and cleavage stage embryo transfers. Serum progesterone and estradiol levels were measured 14 days after FET. A total of 921 cycles in 568 patients from to December 2010 to June 2019 were investigated. Live birth was the primary outcome measure.

RESULTS

Significant association was found between live birth and progesterone as well as estradiol levels (progesterone 14.65 vs 11.62 ng/ml, p = 0.001; estradiol 355.12 vs 287.67 pg/ml, p = 0.001). A significant difference in live birth rate was found below and above the median progesterone level (10.9 ng/ml, p = 0.007). Lower estradiol level was significantly associated with lower live birth rate (< 188.2 pg/ml 8.3%, > 263.1 pg/ml 16%, p = 0.02).

CONCLUSIONS

Serum progesterone and estradiol levels impact live birth rate in AC-FET.

The Mare: A Pertinent Model for Human Assisted Reproductive Technologies?

Although there are large differences between horses and humans for reproductive anatomy, follicular dynamics, mono-ovulation, and embryo development kinetics until the blastocyst stage are similar. In contrast to humans, however, horses are seasonal animals and do not have a menstrual cycle. Moreover, horse implantation takes place 30 days later than in humans. In terms of artificial reproduction techniques (ART), oocytes are generally matured in vitro in horses because ovarian stimulation remains inefficient. This allows the collection of oocytes without hormonal treatments. In humans, in vivo matured oocytes are collected after ovarian stimulation. Subsequently, only intra-cytoplasmic sperm injection (ICSI) is performed in horses to produce embryos, whereas both in vitro fertilization and ICSI are applied in humans. Embryos are transferred only as blastocysts in horses. In contrast, four cells to blastocyst stage embryos are transferred in humans. Embryo and oocyte cryopreservation has been mastered in humans, but not completely in horses. Finally, both species share infertility concerns due to ageing and obesity. Thus, reciprocal knowledge could be gained through the comparative study of ART and infertility treatments both in woman and mare, even though the horse could not be used as a single model for human ART.