Benefits of Blastocyst Transfer With at Least Three Good-Quality Cleavage-stage Embryos in Women of Advanced Maternal Age: A Retrospective Analysis

OBJECTIVES

Limited studies on the benefits of blastocyst transfer in advanced maternal age (AMA) (≥40 years) have been reported. Our objective was to find whether blastocyst-stage embryo transfer improves pregnancy and live birth rates in women ≥40 years who have 3 or more good-quality cleavage-stage embryos.

METHODS

All fresh in vitro fertilization-intracytoplasmic sperm injection cycles performed from January 2020 to December 2021 in AMA women that progressed to transfer were considered for analysis. We compared fresh and cumulative ongoing pregnancy rates in AMA women of those who had a cleavage-stage transfer, while meeting the criteria for extended culture (≥3 high-quality embryos, group 1), and those who underwent blastocyst transfer (group 2). Demographic parameters, stimulation, embryology, fresh and cumulative ongoing pregnancy rates, and clinical miscarriage rates were compared.

RESULTS

During the study period, 255 cycles were analyzed including group 1 (n = 99) and group 2 (n = 156). Group 1 participants were older and had a greater number of embryos for transfer. Fresh and cumulative ongoing pregnancy rates per transfer were higher in group 2 compared to group 1 (23.4% vs. 13.1%, P = 0.04; 25.5% vs. 14.1%, P = 0.03), while overall miscarriage rates were higher in group 1 than group 2 (51.7% vs. 25%, P = 0.01).

CONCLUSIONS

Blastocyst culture provides a benefit to AMA women who have at least 3 good-quality embryos on day 3 resulting in significantly higher fresh and cumulative ongoing pregnancy rates and lower miscarriage compared to cleavage-stage transfers.

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

STUDY QUESTION

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

SUMMARY ANSWER

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

WHAT IS KNOWN ALREADY

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

STUDY DESIGN, SIZE, DURATION

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

PARTICIPANTS/MATERIALS, SETTING, METHODS

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

MAIN RESULTS AND THE ROLE OF CHANCE

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

LIMITATIONS, REASONS FOR CAUTION

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

WIDER IMPLICATIONS OF THE FINDINGS

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

STUDY FUNDING/COMPETING INTEREST(S)

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

TRIAL REGISTRATION NUMBER

NCT04196036.

TRIAL REGISTRATION DATE

15 January 2018.

DATE OF FIRST PATIENT’S ENROLMENT

15 January 2018.

No major differences in perinatal and maternal outcomes between uninterrupted embryo culture in time-lapse system and conventional embryo culture

STUDY QUESTION

Is embryo culture in a closed time-lapse system associated with any differences in perinatal and maternal outcomes in comparison to conventional culture and spontaneous conception?

SUMMARY ANSWER

There were no significant differences between time-lapse and conventional embryo culture in preterm birth (PTB, <37 weeks), low birth weight (LBW, >2500 g) and hypertensive disorders of pregnancy for singleton deliveries, the primary outcomes of this study.

WHAT IS KNOWN ALREADY

Evidence from prospective trials evaluating the safety of time-lapse incubation for clinical use show similar embryo development rates, implantation rates, and ongoing pregnancy and live birth rates when compared to conventional incubation. Few studies have investigated if uninterrupted culture can alter risks of adverse perinatal outcomes presently associated with IVF when compared to conventional culture and spontaneous conceptions.

STUDY DESIGN, SIZE, DURATION

This study is a Swedish population-based retrospective registry study, including 7379 singleton deliveries after fresh embryo transfer between 2013 and 2018 from selected IVF clinics. Perinatal outcomes of singletons born from time-lapse-cultured embryos were compared to singletons from embryos cultured in conventional incubators and 71 300 singletons from spontaneous conceptions. Main perinatal outcomes included PTB and LBW. Main maternal outcomes included hypertensive disorders of pregnancy (pregnancy hypertension and preeclampsia).

PARTICIPANTS/MATERIALS, SETTING, METHODS

From nine IVF clinics, 2683 singletons born after fresh embryo transfer in a time-lapse system were compared to 4696 singletons born after culture in a conventional incubator and 71 300 singletons born after spontaneous conception matched for year of birth, parity, and maternal age. Patient and treatment characteristics from IVF deliveries were cross-linked with the Swedish Medical Birth Register, Register of Birth Defects, National Patient Register and Statistics Sweden. Children born after sperm and oocyte donation cycles and after Preimplantation Genetic testing cycles were excluded. Odds ratio (OR) and adjusted OR were calculated, adjusting for relevant confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

In the adjusted analyses, no significant differences were found for risk of PTB (adjusted OR 1.11, 95% CI 0.87-1.41) and LBW (adjusted OR 0.86, 95% CI 0.66-1.14) or hypertensive disorders of pregnancy; preeclampsia and hypertension (adjusted OR 0.99, 95% CI 0.67-1.45 and adjusted OR 0.98, 95% CI 0.62-1.53, respectively) between time-lapse and conventional incubation systems. A significantly increased risk of PTB (adjusted OR 1.31, 95% CI 1.08-1.60) and LBW (adjusted OR 1.36, 95% CI 1.08-1.72) was found for singletons born after time-lapse incubation compared to singletons born after spontaneous conceptions. In addition, a lower risk for pregnancy hypertension (adjusted OR 0.72 95% CI 0.53-0.99) but no significant difference for preeclampsia (adjusted OR 0.87, 95% CI 0.68-1.12) was found compared to spontaneous conceptions. Subgroup analyses showed that some risks were related to the day of embryo transfer, with more adverse outcomes after blastocyst transfer in comparison to cleavage stage transfer.

LIMITATIONS, REASONS FOR CAUTION

This study is retrospective in design and different clinical strategies may have been used to select specific patient groups for time-lapse versus conventional incubation. The number of patients is limited and larger datasets are required to obtain more precise estimates and adjust for possible effect of additional embryo culture variables.

WIDER IMPLICATIONS OF THE FINDINGS

Embryo culture in time-lapse systems is not associated with major differences in perinatal and maternal outcomes, compared to conventional embryo culture, suggesting that this technology is an acceptable alternative for embryo incubation.

STUDY FUNDING/COMPETING INTEREST(S)

The study was financed by a research grant from Gedeon Richter. There are no conflicts of interest for all authors to declare.

TRIAL REGISTRATION NUMBER

N/A.

Simultaneous transfer of one good-quality and one poor-quality cleavage stage embryo does not improve pregnancy outcomes

Embryo quality and quantity are key factors that determine the success of IVF-ET. Yet it is still unclear if, for those patients with only one good-quality embryo in an IVF cycle, the inclusion of a poor-quality embryo increases the procedure's success rate. This is a common question for both clinicians and patients in determining their course of treatment. The purpose of this work was to answer this intriguing question in the context of prognosis of patients undergoing fresh cycles with only one good-quality and more than one poor-quality cleavage-stage embryos. To control for confounding effects, we only included patients at similar age, body mass index (BMI), level of basal follicle stimulating hormone (FSH) and endometrial thickness from January 2015 to June 2021. A propensity score-matched analysis was performed to extract the matched pairs. Then we evaluated pregnancy outcome, including the rate of clinical pregnancy, live birth, embryo implantation, early miscarriage, and ectopic pregnancy. We found that the clinical pregnancy rate (34.8 vs. 38.0%, p = 0.553), live birth rate (27.1 vs. 29.9%, p = 0.598), early miscarriage rate (18.1 vs. 9.5%, p = 0.171) and ectopic pregnancy rate (1.3 vs. 1.2%, p = 1.000) did not significantly differ between those two groups, notwithstanding significant difference of the implantation rate (34.8 vs. 21.3%, p <0.001). Our work indicates that, for prognosis patients at approximately 34 years old with only one good-quality embryo, having additional poor-quality embryos does not seem to help to improve ART success rates per intended embryo transfer. In conclusion, we found that simultaneous transfer of one good-quality and one poor-quality cleavage stage embryo does not improve pregnancy outcomes.

Embryo morphology and live birth in the United States

Objective

To determine the best-fit live birth rate per embryo based on maternal age, embryo stage, and embryo morphology.

Design

Retrospective data analysis.

Setting

Fertility clinics.

Patient(s)

The patients included were treated with in vitro fertilization in the United States at clinics reporting data to the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System. We analyzed live birth data of unbiopsied autologous cleavage and blastocyst stage embryos for cycles started from 2016 through 2018. The analysis included 223,377 embryo transfers with a total of 336,888 embryos.

Intervention(s)

None.

Main Outcome Measure(s)

Live birth rate per embryo and rate of multiple gestations per pregnancy.

Result(s)

At the mean maternal age of 34 years, fresh embryos produced live birth rates of 19%, 38%, 26%, and 27% for embryos aged 3, 5, 6, and 7 days, respectively. At the age 34 years, live birth rates for day 5 fresh embryos by overall morphology grade were 43% for good, 30% for fair, and 21% for poor. For the transfer of 2 fresh day 5 blastocysts, the rate of multiple gestations per pregnancy was 47% at 25 years old, 44% at 30 years old, 35% at 35 years old, and 23% at 40 years old.

Conclusion(s)

The analysis of pregnancy data in the Society for Assisted Reproductive Technology database can be used to calculate live birth rates per embryo based on maternal age, embryo age, and morphology. This information can be used for evidence-based decision making, quality control, and planning multicenter studies.

Outcomes of embryo vitrification at different developmental stages: Evaluation of 2412 warming cycles

INTRODUCTION

Advances in cell culture media have led to a shift from cleavage stage embryo transfer to blastocyst stage transfer. Extended embryo culture to the blastocyst stage provides some theoretical advantages and disadvantages. There has been controversy. This study is sought to evaluate the clinical outcomes of vitrified-warmed cleavage-stage and blastocyst-stage embryo transfers in patients undergoing Artificial Reproductive Technique treatments.

MATERIAL AND METHOD

The study was performed on 2740 women undergoing frozen embryo thawing transfer. Patients' basic situation, status of frozen embryo transfer cycle, clinical pregnancy rate, early abortion rate, sex ratio of birth, and birth weight were retrospectively analyzed. We compared the main clinical results of recovery of frozen embryo on the cleavage stage and blastocyst stage. Furthermore, we evaluated the clinical outcomes of blastocyst cryopreservation on Day 5, 6, or 7 after oocyte retrieval according to the day of blastocyst expansion were evaluated.

RESULTS

The implantation ratio of cleavage stage embryos was 21.62% compared with 43.52% on D5 (P < .05). The D5, D6, and D7 implanting rates were statistically different. The pregnancy rates were 57.56%, 51.76%, and 35.95% versus 37.79%, respectively for embryos cryopreserved on D5, D6, D7, and D3. The ectopic pregnancy rate and early abortion rate were statistically different between D5 and D3. The sex ratio, the birth weight, and birth defect were not statistically different among the four groups.

CONCLUSIONS

Blastocyst transfer achieved a higher implantation rate than vitrified cleavage stage embryo and decreased ectopic pregnancy rate. With increased incubation days before expansion blastocyst formed, the implantation rate is reduced and the early abortion rate increases.

Extended culture of cleavage-stage embryos in vitrified-thawed cycles may be an alternative to frozen and thawed blastocysts during in vitro fertilization

AIM

We compared the clinical outcomes of vitrified-thawed cycles during in vitro fertilization (IVF) for frozen and thawed blastocysts compared to cleavage-stage embryos that were frozen, thawed and extended culture to the blastocyst stage.

MATERIAL AND METHODS

Between January 2014 and December 2016, 908 frozen-thawed cycles were included in the study. After removing cycles that met exclusion criteria, clinical outcomes for 355 cleavage-stage embryos with extended blastocyst culture (Group I) were compared with 279 frozen and thawed blastocysts (Group II).

RESULTS

Cryo-survival rate of the two groups were similar (96.7% versus 95.0%). Implantation rates (28.9% versus 22.4%, p = .04) and clinical pregnancy rates (37.2% versus 27.9%, p = .03) were higher in Group I. Pregnancy, live birth and abortus rates were similar in both groups. Although overall abortus rates were similar in both groups, abortus rates before 12 weeks of gestation were higher in Group I, and chemical abortus rates were higher in Group II (p = .03, p = .04). Weeks of gestation at birth and birth weight were similar in both groups.

CONCLUSIONS

The use of extended blastocyst culture of cleavage-stage embryos was not inferior to frozen and thawed blastocysts. Freezing at the cleavage-stage can provide similar cryo-survival rates than blastocyst vitrification. Vitrifying surplus or all embryos for storage at the cleavage-stage allows higher implantation and clinical pregnancy rates. But after abortus, live birth rates were similar in both groups.

Increased male live-birth rates after blastocyst-stage frozen-thawed embryo transfers compared with cleavage-stage frozen-thawed embryo transfers: a SART registry study

Objective

To investigate whether there is a difference in live-birth gender rates in blastocyst-stage frozen-thawed embryo transfers (FETs) compared with those in cleavage-stage FETs.

Design

Retrospective cohort study.

Setting

Academic medical center.

Patient(s)

All women with recorded live births who underwent FET at either the blastocyst or cleavage stage, reported to the Society for Assisted Reproductive Technology during 2004–2013.

Intervention(s)

None.

Main Outcome Measure(s)

The primary outcome was live-birth gender rates. Demographic criteria were also collected. The chi-square analyses were used for bivariate associations, and multiple logistic regression models were used for adjusted associations, with all two-sided P<.05 considered statistically significant.

Result(s)

A statistically significant increase was noted in the number of live male births after blastocyst-stage FET compared with that after cleavage-stage FET (51.9% vs. 50.5%). After controlling for potential confounders including age (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.03, 1.08), body mass index (OR, 1.08; 95% CI, 1.04, 1.12), and male factor infertility (OR, 1.06; 95% CI, 1.03, 1.08), the increase in male live births after blastocyst-stage FET remained statistically significant.

Conclusion(s)

In patients undergoing FETs, blastocyst-stage transfers are associated with higher male gender live-birth rates compared with cleavage-stage transfers.

Perinatal outcomes in singleton live births after fresh blastocyst-stage embryo transfer: a retrospective analysis of 67 147 IVF/ICSI cycles

STUDY QUESTION

Are perinatal outcomes different between singleton live births conceived from fresh blastocyst transfer and those following the transfer of fresh cleavage-stage embryos?

SUMMARY ANSWER

Fresh blastocyst transfer does not increase risks of preterm birth (PTB), low/high birth weight or congenital anomaly and does not alter the sex ratio at birth or prejudice the chance of having a healthy baby.

WHAT IS KNOWN ALREADY

Extended embryo culture is currently considered the best option for embryo selection, but concerns have been raised about increased risks of preterm delivery and large-for-gestational-age (LGA) babies.

STUDY DESIGN, SIZE, DURATION

We conducted a retrospective cohort study based on data from the Human Fertilisation and Embryology Authority (HFEA) anonymised and cycle-based dataset in the UK between 1999 and 2011.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Baseline characteristics were compared between in vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) blastocyst-stage and cleavage-stage embryo transfer cycles using the χ2 test for categorical/dichotomised covariates and the Mann-Whitney test for continuous covariates. Statistical significance was set at <0.005. Poisson regression and multinomial logistic regression were used to establish relationships between perinatal outcomes and blastocyst-stage embryo transfer or cleavage-stage embryo transfer. Risk ratios (RRs), adjusted risk ratios (aRRs) and their 99.5% confidence intervals (CIs) were calculated as a measure of strength of associations. Results were adjusted for clinically relevant covariates. A sub-group analysis included women undergoing their first IVF/ICSI treatment. The level of significance was set at <0.05, and 95% CIs were calculated in the sub-group analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Of a total of 67 147 IVF/ICSI cycles, 11 152 involved blastocyst-stage embryo(s) and 55 995 involved cleavage-stage embryo(s). The two groups were comparable with regards to the risk of PTB (aRR, 1.00; 99.5% CI, 0.79-1.25), very-preterm birth (VPTB) (aRR, 1.00; 99.5% CI, 0.63-1.54), very-low birth weight (VLBW) (aRR, 0.84; 99.5% CI, 0.53-1.34), low birth weight (LBW) (aRR, 0.92; 99.5% CI, 0.73-1.16), high birth weight (HBW) (aRR, 0.94; 99.5% CI, 0.75-1.18) and very-high birth weight (VHBW) (aRR, 1.05; 99.5% CI, 0.66-1.65). The risk of congenital anomaly was 16% higher in the blastocyst-stage group than in the cleavage-stage group, but this was not statistically significant (aRR, 1.16; 99.5% CI, 0.90-1.49). The chance of having a healthy baby (born at term, with a normal birth weight and no congenital anomalies) was not altered by extended culture (aRR, 1.00; 99.5% CI, 0.93-1.07). Extended culture was associated with a marginal increase in the chance having a male baby in the main cycle-based analysis (aRR, 1.04; 99.5% CI, 1.01-1.09) but not in the sub-group analysis of women undergoing their first cycle of treatment (aRR, 1.04; 95% CI, 1.00-1.08). In the sub-group analysis, the risk of congenital anomalies was significantly higher after blastocyst-stage embryo transfer (aRR, 1.42; 95% CI, 1.12-1.81).

LIMITATIONS, REASONS FOR CAUTION

This study is limited by the use of observational data and inability to adjust for key confounders, such as maternal smoking status and body mass index (BMI), which were not recorded in the HFEA dataset. As the main analysis was cycle-based and we were unable to link cycles within women undergoing more than one IVF/ICSI cycle, we undertook a sub-group analysis on women undergoing their first treatment cycle.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings should reassure women undergoing blastocyst-stage embryo transfer. For the first time, we have shown that babies born after blastocyst transfer have a similar chance of being healthy as those born after cleavage-stage embryos transfer.

STUDY FUNDING/COMPETING INTEREST(S)

The research activity of Dr Nicola Marconi was funded by the scholarship 'A. Griffini-J. Miglierina', Fondazione Comunitaria del Varesotto, Provincia di Varese, Italy. The authors do not have any competing interests to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Impact of Transferring a Poor Quality Embryo Along with a Good Quality Embryo on Pregnancy Outcomes in IVF/ICSI Cycles: a Retrospective Study

Background The number and the quality of embryos transferred are important predictors of success in in vitro fertilization (IVF) cycles. In the presence of more than one good quality embryo on the transfer day, double-embryo transfer (DET) can be performed with these embryos, but generally, different quality embryos are present in the available transfer cohort. We aimed to investigate the effect of transferring a poor quality embryo along with a good quality embryo on IVF outcomes. Methods In this study, 2298 fresh IVF/intracytoplasmic sperm injection (ICSI) cycles with two good quality embryos (group A), one good and one poor quality embryo (group B), and single good quality embryo (group C) transfers were examined. All groups were divided into two subgroups according to the transfer day as cleavage or blastocyst stage. Clinical pregnancy and live birth rates were the primary outcomes. Results In the cleavage stage transfer subgroups, the clinical pregnancy rates were lower in the single-embryo transfer (SET) subgroup compared with DET subgroups, but the difference was not statistically significant compared with DET with mixed quality embryos. The live birth rates were comparable between the three groups. In the blastocyst transfer subgroups, the clinical pregnancy and live birth rates were significantly higher in DET with two good quality embryos than DET with mixed quality embryos and SET groups. Multiple pregnancy rates were higher in both DET groups in terms of transfer day (p = 0.001). Conclusion DET with mixed quality embryos results with lower clinical pregnancy and live birth rates compared with DET with two good quality embryos at the blastocyst stage. At cleavage stage transfer, there is no difference in live birth rates between the two groups.

Temporal patterns of gene regulation and upstream regulators contributing to major developmental transitions during Rhesus macaque preimplantation development

The preimplantation period of life in mammals encompasses a tremendous amount of restructuring and remodeling of the embryonic genome and reprogramming of gene expression. These vast changes support metabolic activation and cellular processes that drive early cleavage divisions and enable the creation of the earliest primitive cell lineages. A major question in mammalian embryology is how such vast, sweeping changes in gene expression are orchestrated, so that changes in gene expression are exactly appropriate to meet the developmental needs of the embryo over time. Using the rhesus macaque as an experimentally tractable model species closely related to the human, we combined high quality RNA-seq libraries, in-depth sequencing and advanced systems analysis to discover the underlying mechanisms that drive major changes in gene regulation during preimplantation development. We identified the major changes in mRNA population and the biological pathways and processes impacted by those changes. Most importantly, we identified 24 key upstream regulators that are themselves modulated during development and that are associated with the regulation of over 1000 downstream genes. Through their roles in extensive gene networks, these 24 upstream regulators are situated to either drive major changes in target gene expression or modify the cellular environment in which other genes function, thereby directing major developmental transitions in the preimplantation embryo. The data presented here highlight some of the specific molecular features that likely drive preimplantation development in a nonhuman primate species and provides an extensive database for novel hypothesis-driven studies.

Pregnancy outcomes of fresh IVF conceived pregnancies after embryo transfer at different stages of early embryonic development

Objective: To compare pregnancy outcomes between pregnancies following day 2, day 3, and days 5/6 fresh embryo transfer (ET).Methods: A retrospective cohort study including all pregnancies following fresh IVF/intracytoplasmic sperm injection (ICSI) ET cycles performed between January 2014 and December 2015 at Fertility and In Vitro Fertilization (IVF) Unit of the tertiary Soroka University Medical Center. The study groups consisted of 48, 72, 120, and 144 hours embryos. Pregnancies were confirmed by a serum beta-human chorionic gonadotropin measurement. Data regarding patients' medical history, infertility workup, fertility treatment characteristics, and outcome, as well as obstetrical outcome, were collected from patients' medical records and IVF Laboratory database. Multiple regression models were constructed to control for confounders. Patients who underwent fertility preservation treatment, cycles of oocyte donation or in vitro maturation oocytes, and cases of preimplantation genetic testing were excluded.Results: A total of 534 pregnancies following fresh IVF/ICSI ET on day 2 (n = 189, 35.4%), day 3 (n = 200, 37.5%), and days 5 or 6 (n = 145, 27.2%) were included. Live birth rate demonstrated a linear association to the developmental stage at ET with the highest rates in blastocysts and gradually lower in day 3 and day 2 ET (79.2, 65.8, and 60.6%, respectively, p = .001). A positive linear association was also observed between ET age and clinical pregnancy rate (77.3, 87.5, and 90.3% for days 2, 3, and 5/6, respectively, p = .002), as well as with combined pregnancy complication rate (29, 37.3, and 43.3%, p = .026). However, using multivariate logistic regression model controlling for ET age, maternal age, smoking, obesity, initial HCG level and peak E2 level, live birth rate was comparable between the study groups regardless of ET age. Pregnancy complications were comparable between the groups; however, a composite pregnancy complications variable was higher in the blastocyst pregnancies compared to cleavage embryos pregnancies.Conclusions: The common approach of blastocyst transfer, as high quality of the embryo, has not proven beneficial in terms of live birth rate. Moreover, cleavage stage embryos were not associated with adverse perinatal outcomes. The current data suggest maternal age has an independent effect on live birth.

Cleavage Stage versus Blastocyst Stage Embryo Transfer in Oocyte Donation Cycles

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

Can repeated IVF-ICSI-cycles be avoided by using blastocysts developing from poor-quality cleavage stage embryos?

In many clinics, good-quality embryos are selected for embryo transfer and cryopreservation at the cleavage stage, and poor-quality embryos are discarded. The aim of this retrospective study was to examine how many repeated IVF cycles could be avoided by culturing the cleavage stage poor-quality embryos to blastocyst stage and transferring them after vitrification and warming (604 IVF and intracytoplasmic sperm injection [IVF-ICSI] cycles were included). Poor-quality cleavage stage embryos not eligible for transfer or cryopreservation were cultured until day 5 or 6, and those developing to the blastocyst stage were vitrified. The rate of vitrified blastocysts and clinical pregnancy and delivery rate of the warmed blastocysts was evaluated. The effect of the extended culture on the cumulative delivery rate, and the number of avoided new treatment cycles was calculated. The surplus blastocysts resulted in clinical pregnancy, spontaneous abortion and delivery rates of 24.6%, 27.3% and 17.2% respectively. The use of surplus blastocysts raised cumulative delivery rate from 43% to 47% and 53 repeated new cycles were avoided. This study shows that the cumulative delivery rate can be increased, and repeated IVF-ICSI treatments avoided by using blastocysts developing from poor-quality cleavage stage embryos, which otherwise would have been discarded.

Blastocyst transfer ameliorates live birth rate compared with cleavage-stage embryos transfer in fresh in vitro fertilization or intracytoplasmic sperm injection cycles: reviews and meta-analysis

PURPOSE

Blastocyst transfer has been recommended to raise the implantation rate without affecting the pregnancy rate. The objective of this meta-analysis is to systematically evaluate whether the live birth rate and other pregnancy outcomes can be improved by blastocyst transfer compared with cleavage-stage embryos transfer.

MATERIALS AND METHODS

EMBASE and MEDLINE databases were searched for papers published between March 2004 and March 2013. An extensive range of the electronic databases yielded initially 317 studies from which seven trials met the inclusion criteria for further analysis. Our outcome measures were the live birth rate, clinical pregnancy rate, implantation rate, ongoing pregnancy rate, multiple pregnancy rate, first trimester miscarriage rate and ectopic pregnancy rate. Fixed effects models were chosen to calculate the odds ratio (OR).

RESULTS

Seven trials (n=1446 cases) were finally analyzed. Compared with cleavage-stage embryos transfer, the blastocyst transfer was statistically significantly associated with an increase in clinical pregnancy rate [OR 1.43; 95% confidence interval (CI), 1.15-1.78], implantation rate (OR 1.38; 95% CI, 1.09-1.74) and ongoing pregnancy rate (OR 2.15; 95% CI, 1.57-2.94), and also a reduction in the probability of first trimester miscarriage rate (OR 0.51; 95% CI, 0.30-0.87). The improvement in the live birth rate was also observed (OR 1.77; 95% CI, 1.32-2.37). Moreover, there was no evidence of difference in multiple pregnancy and ectopic pregnancy rates.

CONCLUSION

The available evidences suggest that live birth and other pregnancy outcomes after fresh in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) are significantly improved following blastocyst transfer as compared to cleavage-stage embryo transfer.

The prognostic significance of day 3 embryo cleavage stage on subsequent blastocyst development in a sequential culture system

PURPOSE

To determine prognostic significance of blastomere number on Day 3 of culture upon subsequent blastocyst (BL) development.

METHODS

A retrospective analysis was conducted in 37 IVF subjects undergoing standard protocols and BL transfer after sequential embryo culture in P1 and BL media.

RESULTS

Of Day 3 embryos containing 7 or more blastomeres, 68.9% (186/270) developed into BL compared to embryos containing 4-6 blastomeres, 38.1% (56/147), P < 0.0001. The majority of BL, 68.9% (168/244), were observed on Day 5. Extended Day 6 culture represented 31.1% (76/244) of all BLs.

CONCLUSIONS

The observation of 7 or more blastomeres on Day 3 yielded a significantly greater likelihood of BL development. Embryos containing 4-6 blastomeres are still relatively likely to progress to a BL. Extended culture to Day 6 still yields a significant proportion of BL. Cell cleavage stage on Day 3 appears to be a useful prognostic indicator of subsequent BL development.