Cumulative live birth rates following blastocyst- versus cleavage-stage embryo transfer in the first complete cycle of IVF: a population-based retrospective cohort study

Trade-off between double cleavage-stage embryos transfer and single blastocyst-stage embryo transfer in patients with few good quality embryos in antagonist cycles: a retrospective study using a propensity score matching analysis

OBJECTIVE

This study aimed to compare the per OPU clinical outcomes for transfer of Day 3 double cleavage-stage embryos (DET) and Day 5 single blastocyst-stage (SBT) in patients with five or fewer good quality embryos on day 3 per occyte pick-up cycle (OPU) in antagonist cycles with consideration of blastocyst formation failure.

METHODS

This was a retrospective, observational cohort study of 2,116 cases of OPU treated with antagonist protocol in the affiliated Chenggong Hospital of Xiamen University between January 2013 and December 2020. DET was performed in 1,811cycles and SBT was performed in 305 cycles. The DET group was matched to the SBT group by propensity score (PS) matching according to multiple maternal baseline covariates. After PS matching, there were 303 ET cycles in each group. The primary outcomes were the cumulative live birth rate (CLBR), cumulative multiple pregnancy rate(CMPR)per OPU and the number of ET to achieve live birth per OPU. Secondary outcomes were the percentage of clinical pregnancy(CPR), live birth rate(LBR), multiple pregnancy rate(MPR).

RESULTS

Following PS mating, the CLBR was slightly higher (48.8% versus 40.3% ; P = 0.041) and the CMPR was significantly higher in the DET group compared to SBT group(44.2% versus 7.9%, P < 0.001). The CPR, LBR and MPR per fresh transfer were higher in DET group compared to SBT group(50.2% versus 28.7%; 41.3% versus 21.5%;29.6% versus 0%, P < 0.001). The number of ET to achieve live birth per OPU in SBT group was obiviously more than in DET group(1.48 ± 0.578 versus 1.22 ± 0.557 ,P < 0.001).

CONCLUSION

With a marginal difference cumulative live birth rate, the lower live birth rate per fresh transfer and higher number of ET per OPU in the SBT group suggested that it might take longer time to achieve a live birth with single blastocyst strategy. A trade-off decision should be made between efficiency and safety.

Elective single versus double blastocyst-stage embryo transfer in women aged 36 years or older: a retrospective cohort study

We evaluated if elective single-blastocyst transfer (eSBT) could be adopted in women aged 36 or older. In this retrospective cohort, women aged ≥36 years received IVF ovarian stimulation cycles and had ≥ two blastocysts. A total of 240 women underwent eSBT and 189 double-blastocyst transfer (DBT) in the first transfer cycle. The subsequent frozen-thawed embryo transfer cycles were a combination of single- and double- blastocyst transfers. Analysis was stratified for patients in age groups 36-37, 38-39 and ≥40, considering the quality of the blastocyst transferred. The cumulative live birth rates (cLBR) were 74.2% (178/240) versus 63.0% (119/189) after eSBT versus DBT, respectively (aOR: 1.09 (0.68, 1.75)). Time to live birth did not vary significantly between the two groups (HR: 0.85 (0.68, 1.08)). The total number of children born was 194 after eSBT (162 singletons and 16 pairs of twins) versus 154 (84 singletons and 35 twins) after DBT. The odds ratios for preterm birth (0.37 (0.21-0.64)), and low birth weight (0.31 (0.16, 0.60)) were all lower in eSBT. In women aged ≥36 years, cLBR following single- versus double- blastocyst transfer was comparable while the odds of multiple live births and adverse perinatal outcomes were reduced.

When to Transfer Embryos if There Is Only 1 or 2?

The latest reports suggest that it is better to transfer embryos to the uterus on day five of preimplantation development compared to other days of development, but it is not clear if this stands when there are only one-two embryos obtained in the cycle. Therefore, to address this issue, we performed a retrospective study of such cycles. Our study included all of the stimulated IVF/ICSI cycles performed at our institution in the period between 1 January 2004 and 31 December 2018 in which one-two embryos were obtained in the IVF/ICSI cycle and met our inclusion criteria, and we compared the data between day three and day five embryo transfer (ET). The analysis revealed that the day three ET group of patients was significantly older (p < 0.001), were administered a significantly higher dose of gonadotrophins (p = 0.015), and retrieved a lower mean number of aspirated oocytes per cycle (p < 0.001) and lower mean number of embryos (p < 0.001). The birth rate per ET was significantly higher in the day five ET group (p = 0.045) and further analysis indicated that this could be due the trend observed in a group of patients under 36 years old, while in older patients there was no such difference. To conclude, our retrospective study indicates that it might be better to perform ET on day five instead of day three when there are only one-two embryos obtained in the cycle, but probably only when patients are under 36 years old.

Higher miscarriage rate in subfertile women with endometriosis receiving unbiopsied frozen-warmed single blastocyst transfers

Background: Assisted reproductive technology treatment is recommended to overcome endometriosis-associated infertility but current evidence is controversial. Endometriosis is associated with lower antral follicle count (AFC) and oocyte yield but similar clinical outcomes compared to controls. Unaffected ovarian stimulation response and embryological outcomes but lower clinical pregnancy and live birth rates and higher miscarriage rates have been reported, implying direct impact on endometrial receptivity. With evidence emerging on the benefit of frozen-warmed and blastocyst stage transfer, we investigated ART outcomes in endometriosis using homogeneous case-control groups. Methods: This is a retrospective observational case-control study including n = 66 frozen-warmed unbiopsied single blastocyst transfers of patients with endometriosis and n = 96 of women exhibiting idiopathic sterility. All frozen-warmed transfers followed artificial endometrial preparation. Results: In control women, the mean number of oocytes recovered at oocyte pick up was higher compared to women with endometriosis (15.3 ± 7.1 vs. 12.7 ± 5.2, p = 0.025) but oocyte maturation index (mature oocytes/total oocytes at oocyte pick up) was significantly higher for endometriosis (48.2% vs. 34.0%, p = 0.005). The same was shown for the subgroup of 44 endometriosis patients after endometrioma surgery when compared with controls (49.1% vs. 34.0%, p = 0.014). Clinical pregnancy rate was not higher in endometriosis but was close to significance (47.0% vs. 32.3%, p = 0.059) while live birth rate was comparable (27.3% vs. 32.3%, p = 0.746). Miscarriage rate was higher in the endometriosis group (19.7% vs. 7.3%, p = 0.018). A significantly higher AFC was observed in the control group in comparison with the endometriosis group (16.3 ± 7.6 vs. 13.4 ± 7.0, p = 0.014). Live birth rate did not differ when comparing all endometriosis cases (p = 0.746), ASRM Stage I/II and Stage III/IV (p = 0.348 and p = 0.888) with the control group but the overall pregnancy rate was higher in ASRM Stage I/II (p = 0.034) and miscarriage rate was higher in ASRM Stage III/IV (p = 0.030) versus control. Conclusion: Blastocyst transfers in women with endometriosis originate from cycles with lower AFC but higher share of mature oocytes than in control women, suggesting that endometriosis might impair ovarian reserve but not stimulation response. A higher miscarriage rate, independent of blastocyst quality may be attributed to an impact of endometriosis on the endometrium beyond the timing of implantation.

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).

Womens’ preferences concerning IVF treatment: a discrete choice experiment with particular focus on embryo transfer policy

STUDY QUESTION

What outcomes are important for women to decide on the day of embryo transfer (ET) in IVF?

SUMMARY ANSWER

The highest cumulative live birth rate (cLBR) per treatment was the most important treatment outcome for women undergoing an IVF treatment, regardless of the number of transfers needed until pregnancy and impact on quality of life.

WHAT IS KNOWN ALREADY

Cleavage stage (Day 3) and blastocyst stage (Day 5) ETs are common transfer policies in IVF. The choice for one or the other day of ET differs between clinics. From the literature, it remains unclear whether the day of transfer impacts the cLBR. Patient preferences for the day of ET have not been examined yet.

STUDY DESIGN, SIZE, AND DURATION

A discrete choice experiment (DCE) was performed to investigate female patients’ preferences and their values concerning various aspects of an IVF treatment, with a particular focus on ET policy. A multicenter DCE was conducted between May 2020 and June 2020 in which participants were asked to choose between different treatments. Each treatment was presented using hypothetical scenarios containing the following attributes: the probability of a healthy live birth per IVF treatment cycle, the number of embryos available for transfer (for fresh and frozen-thawed ET), the number of ETs until pregnancy and the impact of the treatment on the quality of life.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women (n = 445) were asked to participate in the DCE at the start of an IVF treatment cycle in 10 Dutch fertility clinics. Participating women received an online questionnaire. The attributes’ relative importance was analyzed using logistic regression analyses.

MAIN RESULTS AND THE ROLE OF CHANCE

A total of 164 women participated. The most important attribute chosen was the cLBR. The total number of embryos suitable for transfer also influenced women’s treatment preferences. Neither the number of transfers needed until pregnancy, nor the impact on quality of life influenced the treatment preferences in the aggregated data. For women in the older age group (age ≥36 years) and the multipara subgroup, the impact on quality of life was more relevant. Naive patients (patients with no prior experience with IVF treatment) assigned less value to the number of ETs needed until pregnancy and assigned more value to the cLBR than the patients who had experienced IVF.

LIMITATIONS REASONS FOR CAUTION

An important limitation of a DCE study is that not all attributes can be included, which might be relevant for making choices. Patients might make other choices in real life as the DCE scenarios presented here are hypothetical and might not exactly represent their personal situation. We tried to avoid potential bias by selecting the attributes that mattered most to the patients obtained through patient focus groups. The final selection of attributes and the assigned levels were established using the input of an expert panel of professionals and by performing a pilot study to test the validity of our questionnaire. Furthermore, because we only included women in our study, we cannot draw any conclusions on preferences for partners.

WIDER IMPLICATIONS OF THE FINDINGS

The results of this study may help fertility patients, clinicians, researchers and policymakers to prioritize the most important attributes in the choice for the day of ET. The present study shows that cLBR per IVF treatment is the most important outcome for women. However, currently, there is insufficient information in the literature to conclude which day of transfer is more effective regarding the cLBR. Randomized controlled trials on the subject of Day 3 versus Day 5 ETs and cLBR are needed to allow evidence-based counseling.

STUDY FUNDING/COMPETING INTEREST(S)

This work received no specific funding and there are no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

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.

Estimating the causal effect of embryo transfer day on clinical in vitro fertilization outcomes using propensity score matching

BACKGROUND

For women undergoing in vitro fertilization (IVF), the clinical benefit of embryo transfer at the blastocyst stage (Day 5) versus cleavage stage (Day 3) remains controversial. The purpose of this study is to compare the implantation rate, clinical pregnancy rate and odds of live birth of Day 3 and Day 5 embryo transfer, and more importantly, to address the issue that patients were chosen to receive either transfer protocol due to their underlying clinical characteristics, i.e., confounding by indication.

METHODS

We conducted a retrospective cohort study of 9,090 IVF cycles collected by Lee Women's Hospital in Taichung, Taiwan from 1998 to 2014. We utilized the method of propensity score matching to mimic a randomized controlled trial (RCT) where each patient with Day 5 transfer was matched by another patient with Day 3 transfer with respect to other clinical characteristics. Implantation rate, clinical pregnancy rate, and odds of live birth were compared for women underwent Day 5 transfer and Day 3 transfer to estimate the causal effects. We further investigated the causal effects in subgroups by stratifying age and anti-Mullerian hormone (AMH).

RESULTS

Our analyses uncovered an evidence of a significant difference in implantation rate (p=0.04) favoring Day 5 transfer, and showed that Day 3 and Day 5 transfers made no difference in both odds of live birth (p=0.27) and clinical pregnancy rate (p=0.11). With the increase of gestational age, the trend toward non-significance of embryo transfer day in our result appeared to be consistent for subgroups stratified by age and AMH, while all analyses stratified by age and AMH were not statistically significant.

CONCLUSIONS

We conclude that for women without strong indications for Day 3 or Day 5 transfer, there is a small significant difference in implantation rate in favor of Day 5 transfer. However, the two protocols have indistinguishable outcomes on odds of live birth and clinical pregnancy rate.

Cumulative live birth rate after IVF: trend over time and the impact of blastocyst culture and vitrification

STUDY QUESTION

Has cumulative live birth rate (CLBR) improved over time and which factors are associated with such an improvement?

SUMMARY ANSWER

During an 11-year period, 2007–2017, CLBR per oocyte aspiration increased significantly, from 27.0% to 36.3%, in parallel with an increase in blastocyst transfer and cryopreservation by vitrification.

WHAT IS KNOWN ALREADY

While it has been shown that live birth rate (LBR) per embryo transfer (ET) is higher for fresh blastocyst than for fresh cleavage stage embryo transfer, CLBR per oocyte aspiration, including one fresh ET and all subsequent frozen embryo transfers (FET), does not seem to differ between the two culture strategies.

STUDY DESIGN, SIZE, DURATION

A national register study including all oocyte aspirations performed in Sweden from 2007 to 2017 (n = 124 700 complete IVF treatment cycles) was carried out. Oocyte donation cycles were excluded.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Data were retrieved from the Swedish National Registry of Assisted Reproduction (Q-IVF) on all oocyte aspirations during the study period where autologous oocytes were used. CLBR was defined as the proportion of deliveries with at least one live birth per oocyte aspiration, including all fresh and/or frozen embryo transfers within 1 year, until one delivery with a live birth or until all embryos were used, whichever occurred first. The delivery of a singleton, twin, or other multiples was registered as one delivery. Cryopreservation of cleavage stage embryos was performed by slow freezing and of blastocyst by vitrification.

MAIN RESULTS AND THE ROLE OF CHANCE

In total, 124 700 oocyte aspirations were performed (in 61 313 women), with 65 304 aspirations in women <35 years and 59 396 in women ≥ 35 years, resulting in 38 403 deliveries with live born children. Overall, the CLBR per oocyte aspiration increased significantly during the study period, from 27.0% to 36.3% (odds ratio (OR) 1.039, 95% CI 1.035–1.043) and from 30.0% to 43.3% if at least one ET was performed (adjusted OR 1.055, 95% CI 1.050–1.059). The increase in CLBR was independent of maternal age, number of oocytes retrieved and number of previous IVF live births. The CLBR for women <35 and ≥35 years both increased significantly, following the same pattern. During the study period, a substantially increasing number of blastocyst transfers was performed, both in fresh and in FET cycles. Other important predicting factors for live birth, such as number of embryos transferred, could not explain the improvement. An increased single embryo transfer rate was observed with time.

LIMITATIONS, REASONS FOR CAUTION

The retrospective design implicates that other confounders of importance for CLBR cannot be ruled out. In addition, some FET cycles might be performed later than 1 year post oocyte aspiration for the last year (2017) and are, thus, not included in this study. In addition, no data on ‘dropouts’, i.e. patients that do not continue their treatment despite having cryopreserved embryos, are available, or if this drop-out rate has changed over time.

WIDER IMPLICATIONS OF THE FINDINGS

The results suggest that blastocyst transfer, particularly when used in FET cycles and in combination with vitrification, is an important contributor to the improved live birth rates over time. This gives a possibility for a lower number of oocyte aspirations needed to achieve a live birth and a shortened time to live birth.

STUDY FUNDING/COMPETING INTERESTS

The study was financed by grants from the Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement (ALFGBG-70940) and by Hjalmar Svensson’s research foundation. None of the authors declares any conflict of interest.