Towards defining parameters for a successful single embryo transfer in frozen cycles

Extended culture of cleavage embryo to blastocyst embryo is among the good predictors of successful outcome in vitrified-thawed ICSI cycles

Background

Previous studies showed that top-quality embryo transfer (ET), number of transferred embryos, endometrial preparation with natural cycles or mild stimulation, and female BMI independently affected the outcome in frozen-thawed ET. However, the effect of culturing thawed cleavage embryos to blastocyst stage on the outcome was not sufficiently elucidated. Our objective is to evaluate the role of this extended culturing as predictor of cycle outcome in vitrified-thawed ICSI cycles.

Materials and methods

One thousand forty-two consecutive cycles of vitrified-thawed ET done in a single IVF unit [Mansoura Integrated Fertility Centre (MIFC)] were reviewed during a period from 2014 to 2017. Endometrial preparation methods were natural, stimulation by antiestrogen and/or gonadotropins, or replacement using sequential estradiol (E2) and progesterone (P4). The primary outcome was the clinical pregnancy rate while the secondary outcome was the chemical and ongoing pregnancy rate.

Results

Overall clinical pregnancy rate (CPR) is 298/1042 is 28.5%, chemical pregnancy rate (326/1042) 31.3%, and ongoing pregnancy rate (167/615) 27.2%. Comparing clinically pregnant (n = 298) and non-pregnant (n = 744) showed, respectively, the following: age 28.76 ± 5.0, 28.85 ± 5.18 (p = 0.8); BMI 31.06 ± 5.9, 32.45 ± 5.9 (p = 0.002); infertility duration 4.17 ± 3.2, 4.6 ± 3.5 (p = 0.038); endometrial thickness 10.82 ± 1.6, 10.13 ± 2.06 (p = 0.0001); and no. of ET 3.35 ± 1.5, 3.12 ± 1.60 (p = 0.035). The clinical pregnancy rate when vitrification was done on cleavage embryos was 198/502 (39.4%), and when vitrification done on blastocyst stage 100/ 536 (18.7%) (P < 0.0001); endometrial preparation: natural 72/240(29.1%), stimulated 204/680 (30.0%) replacement 17/90 (18.8%) (p = 0.09); extended culture of cleavage embryos to blastocyst stage: clinical pregnancy rate 116/194 (59.7%) chemical pregnancy rate 125/194 (64.1%), ongoing pregnancy rate 87/165 (52.7%) and non extended culture clinical pregnancy rate 182/848 (21.4%), chemical pregnancy rate 201/848 (23.7%), and ongoing pregnancy rate 80/450 (17.7%) (P < 0.0001).

Conclusion

Top-quality ET, number of transferred embryos and extended culture of cleavage embryos to blastocyst stage, cleavage embryos but not infertility duration, BMI, endometrial thickness, or hCG trigger of ovulation independently predict successful outcome in frozen cycle ET and extended culture of cleavage embryos significantly improved clinical and chemical and ongoing pregnancy rates.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The Effect of Post warming Culture Period Between Thawing and Transfer of Cryopreserved Embryos on Reproductive Outcomes After In Vitro Fertilization (IVF): A Systematic Review and Meta-analysis

Background

The purpose of this study was to evaluate the effect of post warming culture period between thawing and transfer of cryopreserved embryos on reproductive outcomes after in vitro fertilization (IVF).

Methods

An extensive literature search was performed using PubMed, EmBase, and the Cochrane library from January 2000 to August 2019. A systematic review and meta-analysis of clinical trials was performed in this manuscript. The trials represented patients with embryo transfers of at least one previously cryopreserved good quality embryo. Main outcome measures of the study included clinical pregnancy rate, live birth rate, miscarriage rate, and ectopic pregnancy rate.

Results

A total of 5338 trial/abstracts were identified through a literature search. Totally, five studies were included in the systematic review, and three in the final meta-analysis. The studies included 1717 embryo transfers, 605 after short culture, and 1112 after long culture. The clinical pregnancy rate (CPR) was the most consistent outcome reported. The CPR was slightly better after short time culture with a RR of 1.09 (0.95-1.26, 95%CI) but this difference was not statistically significant. The great heterogenicity in the results reported in the included studies made it impossible to compare all planned outcomes.

Conclusion

There are no differences in reproductive outcomes if cryopreserved embryos are transferred after overnight culture or after two hours of culture following thawing. Due to small number and the poor quality of trials reported on this topic, the results of this review should be treated with caution.

Do different culture intervals (2 × 24 hours) after thaw of cleavage stage embryos affect pregnancy rates? A randomized controlled trial

The aim of the study was to evaluate whether selecting embryos for transfer after prolonged culture after thaw (18-24 h) has better pregnancy rates than selecting embryos for transfer after short culture after thaw (2-5 h). We performed a double-blinded, randomized, controlled trial, evaluating 388 patients submitted to ART treatment who had embryos frozen on day-2 and subsequently transferred. All patients received the same endometrial priming with estradiol valerate followed by vaginal progesterone. Patients were randomized for Frozen embryo transfer 2-5 h after thaw (Group D2) or 18-24 h after thaw (Group D2/D3). The main Outcome Measure was ongoing pregnancy rate (OPR) at 20 weeks' gestation per embryo transfer. A total of 179 patients had embryos transferred 2-5 h after thaw and 209 patients had embryos transferred 18-24 h after thaw. The mean age in group D2 was 36 ± 4.4 and 36 ± 5.4 in group D2/D3. Ongoing pregnancy rate was 28% and 33.5% (p = 0.2) for groups D2 and D2/D3, respectively. These results suggest that increasing the culture time of embryos in one day to improve selection before transfer does not increase ongoing pregnancy rate. CLINICAL TRIAL REGISTRATION NUMBER: NCT03381001.

Does Overnight Culture of Cleaved Embryos Improve Pregnancy Rate in Vitrified-Warmed Embryo Transfer Programme?

Background

Vitrification is a routine procedure in assisted reproductive technique (ART) lab. However, there is widespread variability between protocols of different centres. The aim of this study was to compare the chemical pregnancy, clinical pregnancy and live birth rates between one-day embryo culture and immediate transfer for frozen-thawed embryo transfer (FET) cycles.

Methods

In this cohort retrospective study, 366 FET cycles were divided into two groups: Group A, the embryos were warmed one day before transfer, and were cultured overnight; Group B, the embryos were warmed on the same day of transfer, at least were cultured 1 h before embryo transfer (ET). Chemical and clinical pregnancy and live birth rates were compared between two groups.

Results

The chemical pregnancy was higher in group A than B (37.9% versus 28.9%), but this difference was not significant (P = 0.07). Clinical pregnancy (30.8% versus 24.1%) and live birth (19.8% versus 22.05%) were similar in group A and B, (P = 0.15), and (P = 0.8). Conclusion: In conclusion, overnight culture and confirmation of mitosis resumption was not essential for FET cycles in vitrification method.

Improvement of pregnancy outcome by extending embryo culture in IVF-ET during clinical application

PURPOSE

The purpose of this study is to investigate the application value of the extended embryo culture for 7-8 h in day 3 morning during IVF-ET process.

METHODS

Embryos were retrospectively assessed during 08:00-09:00 on the morning of day 3 in the control group, and were assessed once again at 16:00 in the afternoon in the extended culture (EC) group. The embryos with good developmental potential were preferentially selected to transfer. The cumulative pregnancy outcomes were analyzed in one oocyte retrieval cycle.

RESULTS

Similar proportions were found in the rates of cumulative clinical pregnancy, cumulative live birth, and the perinatal/neonatal outcomes per oocyte retrieval cycle (P > 0.05). But higher total clinical pregnancy rate, higher total implantation rate, and lower total abortion rate were obtained in the EC group (P < 0.05). After EC, 53.58% of the embryos were able to continue to develop. The transferred embryos were mainly composed of ≥ 8-cell embryos (75.90%) in the EC group and ≤ 8-cell embryos (82.92%) in the control group. Interestingly, the implantation rates were increasingly improved with the increasing blastomere number up to 56.31% at the morula stage in the EC group, while they were limited to 32.33% at 8-cell stage in the control group.

CONCLUSIONS

The extended culture of day 3 embryos for 7-8 h not only reduced the risk of IVF-ET treatment compared to blastocyst culture through another 2-3 days, but also improved the clinical outcomes and the efficiency of every transferred cycle and every transferred embryo.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

Retrospectively registered on December 15, 2015 NCT02639715 .

Analysis of embryo intactness and developmental potential following slow freezing and vitrification

The aim of this study was to identify the parameters that are related to intactness and developmental potential of a day 3 embryo after warming to improve the selection criteria used to cryopreserve and transfer embryos. We also sought to compare slow freezing and vitrification methods of cryopreservation and to evaluate the viability of non-intact embryos. Embryos warmed following slow freezing (n=220) or vitrification (n=522) were divided into 3 groups according to the proportion of surviving blastomeres (I<50%; II=50-99%; and III=100%). The developmental potential of embryos, including the mitosis resumption rate, blastocyst formation rate, and formation rate of grade A blastocysts (i.e., fully expanded blastocysts with an inner cell mass and grade A or B trophectoderm) were retrospectively assessed in embryos. Cleavage-stage embryos with <50% blastomere survival were analyzed using next-generation sequencing (NGS). Logistic regression analysis showed that vitrification and grade 1 were independent predictive factors of embryo intactness and developmental potential (all p<0.05). On day 3, embryos with 4-6 cells or blastomere damage had lower developmental potential than those with 7-9 cells or intact blastomeres (all p<0.05). NGS results showed that the chromosomal status was completely normal in 8 embryos that developed into expanded blastocysts, whereas 4 out of 5 embryos in which development was arrested were abnormal. The results of this study suggest that vitrification is a better choice than slow freezing for embryo cryopreservation. Embryos showing poor quality (fragmentation >30% and/or a non-stage-specific cell size) and lower cell numbers (4-6 cells) on day 3 should be cultured to the blastocyst stage and then vitrified if they develop into good-quality blastocysts. The developmental potential of non-intact embryos is lower than that of intact embryos; however, after they are cultured to the fully expanded blastocyst stage, embryos with <50% blastomere survival appear to be better candidates for transfer. Abbreviations ART: assisted reproductive technology; grade A blastocyst: fully expanded blastocyst with an inner cell mass and grade A or B trophectoderm; NGS: next-generation sequencing; IVF: in vitro fertilization; ICSI: intracytoplasmic sperm injection; FET: frozen-thawed embryo transfer.

Prognostic factors for patients undergoing vitrified-warmed human embryo transfer cycles: a retrospective cohort study

We examined the prognostic factors for pregnancy in 210 vitrified-warmed embryo transfer (ET) cycles in 121 patients. The univariate analysis showed that age, gravida, the number of cycles associated with infertility caused by endometriosis, the number of previous assisted reproductive technology (ART) treatment cycles, and the number of ICSI procedures were significantly lower in pregnant cycles compared with non-pregnant cycles. The percentages of ET using at least one intact embryo and of ET using at least one embryo that had developed further after warming were significantly higher in pregnant cycles compared with non-pregnant cycles. Multivariate logistic regression analysis showed that previous ART treatment cycles, ET with at least one intact embryo, and ET using at least one embryo that had developed further were independent prognostic factors for pregnancy in vitrified-warmed ET cycles. We conclude that fewer previous ART treatment cycles, ET using at least one intact embryo, and ET with embryos that have developed further after warming might be favourable prognostic factors for pregnancy in vitrified-warmed ET cycles.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

Retrospectively registered NCT02639715 .

Influence of post-thaw culture on the developmental potential of human frozen embryos

PURPOSE

Apart from freezing/thawing related cryodamage, several additional factors have been identified as major players in the reduction of success rates after frozen embryo transfers. The post-thaw culture is particularly relevant as it may amplify environmental influences over a stressed embryo. In the present study the influence of the post-thaw culture duration on the implantation and developmental potential of cleavage stage embryos was evaluated.

METHODS

In this retrospective evaluation, that spanned an 8-year period, 631 frozen-thawed embryos were allocated to one of two study groups, depending on their post-thaw culture period: 1) the long (18-24 h), or 2) the short (2-5 h) culture group. Groups were compared regarding implantation rate and live birth rate per embryo transferred. This comparison was corrected for the most common confounding factors such as maternal age at oocyte pick-up, number of transferred embryos, developmental day at freezing, blastomere survival after thawing, catheter used for transfer and year of procedure.

RESULTS

Implantation and live birth rate per embryo transferred were inversely related to the duration of the post-thaw culture, as diminishing this period significantly increased both rates. Moreover, no advantage could be found for a long post-thaw culture period, even for embryos with observed mitotic activity.

CONCLUSION

This retrospective analysis indicates that a short post-thaw culture period is associated with higher implantation and live birth rates per embryo. This study supports selection of frozen-thawed embryos strictly based on blastomere cryosurvival and raises the hypothesis that environmental factors may have an important role on embryo implantation and developmental potential during post-thaw culture.

[Frozen embryo transfer protocol: does spontaneous cycle give good results?]

OBJECTIVE

Frozen embryos' transfer optimize the pregnancy rates per retrieval. In France, 60% of transfer cycles occur in stimulated cycles. The aim of this study was to evaluate the outcomes of frozen embryo transfers in spontaneous, substituted and stimulated cycle.

PATIENTS AND METHODS

This retrospective study includes patients who are 18-43 years old and had a frozen embryo transfer between 1st January 2008 and 31st December 2008. Three transfer protocols have been used: the spontaneous cycle (group 1), substituted cycle (group 2), and stimulated cycle (group 3). The characteristics of couples, embryonic parameters and data transfer cycles, and their outcomes were evaluated.

RESULT(S)

Among the 333 patients, 132 were included in the first group, 24 in the second group and 177 in the third group. After checking the homogeneity of the three groups, we found pregnancy rates (respectively 20.49 vs 13.04% and 11.32%, P=0.0348), and deliveries (respectively 13.93 vs 8,7 and 6.29%, P=0.0314), significantly higher in spontaneous cycles.

DISCUSSION AND CONCLUSION

Currently there is no consensus on the best technique for endometrial preparation for frozen embryo transfer. Our results support transfers in spontaneous cycle for normo-ovulating patients. Natural cycles can achieve good pregnancy rates while minimizing the costs and side effects.

Cryopreservation of blastocysts is the most feasible strategy in good responder patients

OBJECTIVE

To assess on which day to cryopreserve and transfer thawed embryos in good-responder patients by comparing the cycle outcomes of day 3 transfers vs blastocysts formed through extended culture before or after cryopreservation.

DESIGN

Retrospective clinical study.

SETTING

Private IVF center.

PATIENT(S)

Frozen-thawed cycles (n = 2,531) who had ETs at day 3, 5, and 6 and post-thawed extended culture of day 3 until day 5 or 6.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Primary outcomes were implantation and delivery rates. Secondary outcomes were clinical pregnancy and miscarriage rates.

RESULT(S)

In thawing cycles, embryos developing to blastocysts on day 5 through extended culture before or after cryopreservation yielded higher rates of implantation (51.1% and 51.3%, respectively), clinical pregnancy (69.9% and 62.2%, respectively), and delivery per thawing cycle (56.7% and 51%, respectively) accompanied by lower miscarriage rates (15.2%, 16.4%, respectively) compared with day 3 transfers (28.3%, 55.3%, 42.5%, 20.1%, respectively). Late-developing embryos formed before or after cryopreservation resulted in compromised implantation (44.7% and 44.2%, respectively), clinical pregnancy (59.9% and 45.9%, respectively), delivery per thawing cycle (42.8% and 32.4%, respectively) and higher miscarriage rates (25.7% and 23.5%, respectively) than day 5 embryos.

CONCLUSION(S)

The feasible strategy in good responder patients appears to be the cryopreservation of blastocysts in the fresh cycle. Retardation in development results in a compromised outcome because of reduced inherent capacity of embryos.

Frozen-thawed embryo transfer cycles: clinical outcomes of single and double blastocyst transfers

PURPOSE

To evaluate clinical outcomes of frozen-thawed embryo transfer cycles when one or two blastocysts are transferred.

METHODS

Retrospective chart review

RESULTS

Two hundred forty-three frozen blastocyst transfer (FBT) cycles were analyzed. Clinical pregnancy rate (50.4% vs. 34.7%), live birth rate (45.8% vs. 30.6%), and twin live birth rate (19.3% vs. 0) were significantly higher in the double versus single FBT group, respectively (p < 0.05). Prior fresh cycle success with same-cohort embryos did not predict outcome of FBT cycle. When the fresh cycle was unsuccessful, there still was a significant increase in twinning when two frozen-thawed blastocysts were transferred.

CONCLUSIONS

Transferring two blastocysts during an FBT cycle resulted in higher live birth and twin live birth rates. Single FBT provided acceptable pregnancy rates for couples seeking to avoid a multiple pregnancy or for those having a single blastocyst stored. Interestingly, the outcome of fresh cycle with same-cohort embryos did not influence the outcome of frozen-thawed cycle.

Correlation between embryological factors and pregnancy rate: development of an embryo score in a cryopreservation programme

PURPOSE

To establish which embryo parameters, in frozen thawed embryo transfers, have the highest prognosis value in the establishment of pregnancy. The relative importance of different embryo parameters is used to develop an embryo score.

METHODS

Retrospective analysis of the implantation rate in 356 frozen/thawed single embryo transfers. A logistic regression model is used to establish an embryo score.

RESULTS

A direct correlation is established between the implantation rate and fresh embryo development (number of blastomeres and their symmetry), survival rate after thawing and mitosis resumption after overnight culture.

CONCLUSIONS

An embryo score is developed to determine the implantation potential of frozen/thawed embryos.

The number of blastomeres in post-thawing embryos affects the rates of pregnancy and delivery in freeze-embryo-transfer cycles

PURPOSE

To observe the differences in pregnancy rates (PRs), delivery rates, and abortion rates associated with frozen-embryo-transfer (FET)-based use of post-thawing embryos with different numbers of blastomeres.

METHODS

959 FET cycles and 361 successful FET cycles performed between January 2007 and December 2007. Compare the PRs and abortion rates in post-thawing embryos with 8 blastomeres (8c), 7c, 6c, 5c, 4c,and 3c.

RESULTS

1. The total PRs of post-thawing 8c, 7c, 6c, 5c, 4c, and 3c embryos were 44.1%, 41.0%, 34.4%, 23.8%, 12.5%, and 0%, respectively (p < 0.05). 2. The abortion rates for the transferred embryos of the 8c, 7c, 6c, 5c, and 4c groups were 17.92%, 19.35%, 27.69%, 24%, 20%, respectively (p < 0.05).

CONCLUSION

The number of blastomeres in the post-thawing embryos is an important factor influencing the occurrence of pregnancy in FET procedures; however, the criterion that post-thawing embryos with 50% intact blastomeres will lead to pregnancy may not be valid.

Impact of cleavage-stage embryo biopsy in view of PGD on human blastocyst implantation: a prospective cohort of single embryo transfers

BACKGROUND

Human embryo biopsy is performed for preimplantation genetic diagnosis (PGD). The impact of 1- or 2-cell removal at cleavage-stage on future embryo development and implantation capacity is highly debated.

METHODS

In order to explore this issue further, a cohort of Day 5 single embryo transfers was analysed prospectively for embryological and clinical outcome. All transferred embryos resulted from 8-cell embryos on Day 3, from which subsequently either one cell (group I, n = 182) or two cells (group II, n = 259) were removed, or on which no invasion by means of embryo biopsy was performed (group III, control group, n = 702). RESULTS Blastocyst formation was significantly better in group III compared with group II, and similar to group I. Group I and group II did not differ in Day 3 nor in Day 5 embryo development. The overall live birth rate was significantly higher in group I (37.4%, CI 29.0-47.4%) than in group II (22.4%, CI 17.0-28.9%), and comparable to the reference ICSI population (35.0%, CI 30.8-39.7%).

CONCLUSIONS

The clinical outcome of 1-cell biopsy was significantly better than that of 2-cell biopsy, even when adjusted for availability of genetically transferable embryos.

Transfer of two versus three embryos in women less than 40 years old undergoing frozen transfer cycles

OBJECTIVE

To compare outcomes of frozen embryo transfer (FET) cycles when two or three embryos were transferred in women aged <40 years.

DESIGN

Retrospective chart review.

SETTING

A university-affiliated IVF program.

PATIENT(S)

Women undergoing FET cycles between January 2004 and December 2005.

INTERVENTION(S)

Transfer of two or three embryos.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy rate (PR), multiple pregnancy rate (MPR), and live birth rate (LBR).

RESULT(S)

In patients aged <35 (n = 145), two versus three embryo group had similar PR and LBR, but the MPR was significantly higher in the three-embryo group (41% for three embryos vs. 9.4% for two embryos). Clinical pregnancy in the fresh cycle from which the frozen embryos were obtained did not affect the PR, and an increase in MPR was still observed. In patients aged 35 to 39 (n = 93), there were no differences in the PR, MPR, or LBR between the two groups.

CONCLUSION(S)

Transfer of two instead of three frozen embryos in patients <35 years old resulted in a significant decrease in MPR without compromising PR or LBR. Transferring additional embryos when a patient had an unsuccessful fresh cycle was not warranted. In the age group 35-39 years, transferring two instead of three embryos did not decrease PR or LBR, and had no effect on the risk of high-order multiples.

Predictive factors for live birth in cryopreservation single embryo transfer cycles

IVF cryopreservation cycles are known to be less successful than fresh cycles. The objective of this study was to investigate what variables, maternal and embryonic, that independently predict the live birth rate in cryopreservation single embryo transfers (SET). A retrospective analysis was performed on 622 cryopreservation SET originating from 371 consecutive patients performing 410 fresh cycles. Maternal and embryonic variables were analysed using logistic regression. The overall pregnancy and live birth rates were 22 and 16% respectively. Blastomere survival rate, number of previous fresh cycles and IVF as fertilization method compared with intracytoplasmic sperm injection (ICSI), were positive predictors of live birth. Number of embryos thawed to obtain one transfer was negatively associated with pregnancy rate but not with live birth rate. No statistical difference in live birth rate was found whether the couple had performed one, two or three failed cryopreservation cycles previously from the same egg retrieval. Knowledge of certain predictors for live birth contributes to the estimation of prognosis in cryopreservation SET, and is important when deciding whether to perform single or double embryo transfer in cryopreservation cycles. However, despite being independently associated with live birth and pregnancy, the predictive value of identified variables was low.

Serum progesterone on the day of human chorionic gonadotropin administration predicts clinical pregnancy of sibling frozen embryos

OBJECTIVE

To evaluate patient characteristics and fresh in vitro fertilization (IVF) cycle parameters that influence success of sibling frozen-thawed embryo transfer (FET) cycles.

DESIGN

Retrospective study.

SETTING

Academic infertility practice.

PATIENT(S)

Infertile women undergoing FET cycles using embryos cryopreserved on day 3 after insemination after an initial fresh IVF cycle.

INTERVENTION(S)

90 FET cycles.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy (CP).

RESULT(S)

The likelihood of CP after FET was statistically significantly higher in women who had achieved CP in the preceding fresh IVF cycle (71.4% vs. 40.6%). Multivariable logistic regression analysis confirmed that patients achieving CP after the fresh IVF cycle were more likely to achieve CP after FET (OR 5.5; 95% CI, 1.2-25.3) after adjusting for age, number, and cleavage status of embryos transferred. Additionally, higher serum levels of progesterone on the day of human chorionic gonadotropin administration emerged as predictive of CP after FET at a statistically significant level.

CONCLUSION(S)

The outcome of the fresh embryo transfer cycle is the foremost predictor of CP after FET of the sibling embryos. The relationship between serum progesterone on the day of human chorionic gonadotropin administration in the fresh cycle and the outcome of subsequent FET is noteworthy and merits further investigation.

Viability of frozen-thawed human embryos with one-two blastomeres lysis

OBJECTIVE

To assess the impact of one-two blastomeres lysis on the viability of thawed day 3 human embryos.

METHODS

A retrospective analysis was performed on 248 frozen-thawed embryo replacement cycles in which all embryos were frozen at day 3 at the seven-eight cell stage with <or=10% fragmentation.

RESULTS

Outcomes of transfer cycles with fully intact embryos (intact group) were compared with those in which all transferred embryos have lost one-two blastomeres (damage group). Comparable pregnancy rates (38.46% vs 38.64%), birth rates (34.62% vs 36.36%) and implantation rates (26.31% vs 26.25%) were obtained in intact and damage groups. These results were also not significantly different from mixed transfer cycles in which one intact embryo and one damaged embryo were transferred together.

CONCLUSION

The developmental potential of partially damaged cryopreserved human embryos with less than 25% cells loss is comparable to that of fully intact embryos. Presence of one-two lysed blastomeres in the thawed day 3 embryo does not appear to have a negative influence on the further development of the sibling intact cells.

The relationship between endometrial thickness and outcome of medicated frozen embryo replacement cycles

OBJECTIVE

To examine the relationship between endometrial thickness and outcome of medicated frozen-thawed embryo replacement (FER) cycles.

DESIGN

A retrospective observational study.

SETTING

Assisted conception unit at a university hospital.

PATIENT(S)

All patients who underwent an FER cycle between 1997 and April 2006 and met the inclusion criteria.

INTERVENTION(S)

For endometrial preparation, a daily dose of 6 mg of oral E(2) valerate was started on menstrual day 1, and P pessaries (800 mg daily) were administrated when the endometrial thickness had reached 7 mm or more, with ET taking place 2-3 days later. The FER cycles were categorized according to endometrial thickness measurement on the day of P supplementation.

MAIN OUTCOME MEASURE(S)

Implantation, clinical pregnancy, ongoing pregnancy, and live birth rates.

RESULT(S)

In all, 768 consecutive medicated FER cycles were analyzed. The lowest pregnancy rates were associated with endometrial thickness <7 mm (n = 13) and >14 mm (n = 12; 7% in both groups). Significantly higher implantation (19% vs. 12%), clinical pregnancy (30% vs. 18%), ongoing pregnancy (27% vs. 16%), and live birth (25% vs. 14%) rates were achieved in cycles where endometrial thickness was 9-14 mm (n = 386), compared with those in which endometrial thickness was 7-8 mm (n = 357). These differences remained significant after adjusting for confounding variables (adjusted odds ratio [OR] = 1.83 [confidence interval {CI} = 1.3-2.6] for clinical pregnancy, 1.8 [CI = 1.2-2.6] for ongoing pregnancy and 1.9 [CI = 1.3-2.8] for live birth).

CONCLUSION(S)

In medicated FER cycles, an endometrial thickness of 9-14 mm measured on the day of P supplementation is associated with higher implantation and pregnancy rates compared with an endometrial thickness of 7-8 mm.

Embryonic factors affecting outcome from single cryopreserved embryo transfer

Multiple pregnancy minimization by single embryo transfer is becoming more prevalent, but is less common in the case of cryopreserved embryos. This study defines embryonic characteristics in single cryopreserved embryo transfers associated with success rates equivalent to those achieved when transferring two cryopreserved embryos. In a retrospective analysis of 6916 cryopreserved day-2 embryo transfer procedures, transfer of two cryopreserved embryos resulted in higher clinical pregnancy rates when compared with transfer of a single thawed embryo but was also associated with elevated multiple pregnancy rates (26.7% in women under 36). Optimal outcome (implantation rate of 30.9%) from single cryopreserved embryo transfer (SCET) in women under 36 was associated with cryopreservation at the 4-cell stage, loss of fewer than two blastomeres and subsequent cleavage of at least two surviving blastomeres. In comparison, transfer of two cryopreserved embryos in women under 36 resulted in pregnancy and implantation rates of 25.5 and 16.1% respectively. Interestingly, in cryopreserved 4-cell stage embryos, loss of a single blastomere did not reduce implantation potential and cleavage of only a single post-thaw blastomere was not indicative of increased implantation potential. Establishment of these critical thresholds provides a rational basis for SCET.

Cumulative impact of adding frozen–thawed cycles to single versus double fresh embryo transfers

Randomized control trials have shown that single embryo transfer (SET) results in lower live birth rates than double embryo transfer (DET), while observational, retrospective studies find no decrease in overall live birth rate when using a SET policy. The cumulative (fresh transfer followed by frozen - thawed transfers of embryos from the same stimulated cycle) live birth rate after the first and the second stimulated cycle of SET and DET respectively has been analysed. All couples who received their first fresh embryo transfer at Sahlgrenska University Hospital during 2003 and 2004 were included (n = 689). The live birth rates after DET versus SET in the first and second fresh cycles were 29.7 (47/158) versus 23.9% (127/531) and 30.8 (41/133) versus 22.0% (45/205). The cumulative live birth rate per patient after the addition of frozen-thawed embryo transfers were similar: 33.5 (53/158) and 34.8% (185/531) for DET and SET respectively after the first cycle and 32.3 (43/133) versus 32.2% (66/205) after the second cycle. A logistic regression analysis showed no significant correlation for SET or DET with cumulative live birth. Thus, cumulative live birth rates are similar after SET and DET in a routine IVF programme with a majority of SET transfers, although a higher number of frozen-thawed cycles were needed in the SET group.