Frozen-thawed Single Blastocyst Transfer Research Articles

Sex ratio shift after frozen single blastocyst transfer in relation to blastocyst morphology parameters

The sex ratio shift was observed in peoples who underwent ART treatment. Moreover, there is limited evidence on differences in sex ratio between single frozen-thawed blastocyst morphology, insemination type and transfer days. So further research is needed in this area with regard to factors possibly affecting the sex ratio. Retrospective study based on multicenter including two large assisted reproduction centers in Shanghai and Wuhan in China. A total of 6361 singleton delivery offspring after frozen-thawed blastocyst transfer. Propensity score weighting and logistic regression models were used to estimate the associations between blastocyst morphology grading and child sex ratio. The main outcome measures is singleton sex ratio. In our study, the primary outcome measure was sex ratio which was calculated as the proportion of male newborns among all live births. Higher quality blastocysts resulted in a higher sex ratio than single poor-quality frozen-thawed blastocyst transfer. Among the three blastocyst morphological parameters of trophectoderm (TE), Grade A and B were significantly associated with a higher sex ratio than Grade C. The similar trend was observed in both IVF and ICSI treated subgroups. As compared with expansion (4 + 3), expansion degree 6 achieved a higher sex ratio in overall populations and IVF treated subgroup. Transferring blastocysts of day 6 had the highest sex ratio both in IVF group and ICSI group. A 6.95% higher sex ratio in transferring blastocysts of day 5 in IVF group than those in ICSI group. No significant association between inner cell mass degree and sex ratio was observed. However, as compared with IVF treatment, all morphology parameters achieved the similar or the biased sex ratio favoring female in ICSI treated subgroup. Quality of blastocysts was positively associated with sex ratio. TE score and expansion degree rather than ICM were significantly associated with sex ratio at birth. ICSI treatment promotes the biased sex ratio favoring female.

Female obesity increases the risk of preterm birth of single frozen-thawed euploid embryos: a retrospective cohort study.

Obesity has been associated with an increased risk of reproductive failure, especially preterm birth. As preimplantation genetic testing for aneuploidies (PGT-A) is increasingly used worldwide, however, it is still unclear whether body mass index (BMI) has an effect on the preterm birth rate in patients undergoing in vitro fertilization (IVF) with PGT-A when transferring a single euploid blastocyst. This retrospective, single-center cohort study included 851 women who underwent the first cycle of frozen-thawed single euploid blastocyst transfer with PGT-A between 2015 and 2020. The primary outcome was the preterm birth rate. Secondary outcomes were clinical pregnancy, miscarriage, ectopic pregnancy, pregnancy complications, and live birth. Patients were grouped by World Health Organization (WHO) BMI class: underweight (<18.5, n = 81), normal weight (18.5-24.9, n = 637), overweight (25-30, n = 108), and obese (≥30, n = 25). There was no difference in the clinical pregnancy, miscarriage, ectopic pregnancy, pregnancy complication, and live birth by BMI category. In multivariate logistic regression analysis, preterm birth rates were significantly higher in women with overweight (adjusted odds ratio [aOR] 3.18; 95% confidence interval [CI], 1.29-7.80, p = .012) and obese (aOR 1.49; 95% CI, 1.03-12.78, p = .027) compared with the normal weight reference group. Women with obesity experience a higher rate of preterm birth after euploid embryo transfer than women with a normal weight, suggesting that the negative impact of obesity on IVF and clinical outcomes may be related to other mechanisms than aneuploidy.

Effect of development speed and quality of blastocyst on singleton birthweight in single frozen-thawed blastocyst transfer cycles.

Assisted reproductive technology (ART) has revolutionized infertility treatment, leading to a surge in ART-conceived children. Despite its success, ART-born offspring face higher risks of preterm birth (PTB), low birth weight (LBW), and small for gestational age (SGA). The mechanisms behind these outcomes remain unclear, partly attributed to multiple embryo transfers. Recent advancements advocate single blastocyst transfers for improved outcomes. However, the influence of blastocyst quality and development speed on neonatal outcomes is underexplored. This study investigated whether blastocyst development speed and quality affect singleton birthweight when the blastocyst is selected for single frozen-thawed blastocyst transfer (FBT). Data from patients who performed an FBT cycle at our center from July 2011 to June 2021 were collected and analyzed. Based on the inclusion and exclusion criteria, 420 single FBT cycles were assessed. The women were divided into four groups, Group A (day 5, good-quality blastocysts), Group B (day 5, non-good-quality blastocysts), Group C (day 6, good-quality blastocysts), and Group D (day 6, non-good-quality blastocysts) according to the developmental speed and quality of the transferred blastocyst. The birthweight was relatively the highest in Group A, which developed rapidly and transferred good quality blastocysts. However, no significant difference existed among the groups (P>0.05). The prevalence of premature birth (PTB), low birth weight (LBW), very low birth weight (VLBW), or high birth weight (HBW) was similar among the four groups (P > 0.05). No correlation existed between birth weight and blastocyst development speed or quality after adjusting for possible confounders (P > 0.05 respectively). However, the difference in the proportion of males born among the four groups was significant, especially in Group D, which was significantly lower than that in Group A (adjusted odds ratio = 0.461, 95% confidence interval: 0.230-0.921, P< 0.05). This retrospective cohort study suggests that the combined effect of blastocyst development speed and quality on neonatal birthweight is insignificant. The transfer of slow-growing, non-good-quality blastocysts increases the chance of a female baby being born.

Management strategies following implantation failure of euploid embryos.

Euploid blastocyst implantation failure may result from embryonic factors undetectable by preimplantation genetic testing for aneuploidy (PGT-A); however, various nonembryonic factors can also intricately interfere with implantation. This review seeks to clarify evidence-based testing and treatments for implantation failure after euploid embryo transfer. We conducted a review of the literature on implantation failure after euploid embryo transfer or multiple embryo transfer cycles, which mainly included systematic reviews and meta-analyses. The recommended tests for implantation failure include (1) hysteroscopy, (2) endometrial CD138 immunohistochemistry and bacterial culture, (3) serum 25-hydroxyvitamin D3, and (4) thrombophilia screening. Based on diagnostic findings, the following treatments have been recommended: (1) antibiotics for chronic endometritis, (2) vitamin D replacement, (3) lifestyle modification, and (4) low-dose aspirin starting from the postimplantation period for thrombophilia. Moreover, frozen-thawed single euploid blastocyst transfer using assisted hatching and hyaluronan-enriched transfer medium may support embryo implantation. To ensure a successful pregnancy in subsequent embryo transfers, simple, inexpensive, and evidence-based tests and treatments should be selected.

#193 : Comparison of the Different Expression of OCT-4, GATA-3 and Clinical Pregnancy Outcome Between the Day 5 and Day 6 Blastocysts

Background and Aims: In common experience of in vitro-fertilization (IVF) cycle, blastocysts formed at Day 5 (D5) are regarded as higher quality and are more desirable for embryo transfer compared with those formed at Day 6 (D6). How those delayed D6 embryo differs from D5 embryo is less discussed. This study aimed to elucidate the cell content distinguished by immunofluorescent (IF) staining between the same grade of D5 and D6 blastocysts that might link to the clinical pregnancy outcome in frozen–thawed embryo from different day of blastocyst formation. Method: The retrospective study included 1327 frozen-thawed single blastocyst transfer (SBT) cycles in the Taipei Fertility Center during March 2020 to December 2022. All D5 (D5-SBT) and D6 (D6-SBT) frozen-thawed SET cycles (n=1327) were separated to non-PGS (n=671) and PGS-euploid (n=656) groups, then assigned to high grade (AA, AB, BA, BB) and low grade (BC, CB, CC). Aneuploidy and mosaicism embryo are excluded. For cell content analysis, pluripotent marker OCT-4 initially expressed in all blastomeres but restricted to the inner cell mass (ICM) of the blastocyst and downregulated in the trophectoderm (TE). GATA-3 is a TE specific marker which increases during pre-implantation embryo development. The cell number, OCT-4 and GATA-3 expression of same grade frozen-thawed D5 (n=14) and D6 (n=14) blastocysts were analyzed with IF staining. D5 extensively cultured to D6 (n=10) were used as the control group of regularly development. Cell numbers of TE and ICM region were examined by OCT-4 and GATA-3 IF detection. The total cell number was visualized with DAPI staining. Results: According to staining results, there were no significant differences in total cell number, TE and ICM cell number between the same grade D5 and D6 blastocysts. However, TE cell number significantly increased in D5 extensively cultured blastocysts, indicating higher proliferative capacity in TE cells from D5 blastocysts. In the clinical data of the non-PGS group, chemical pregnancy rate (HCG+) and clinical pregnancy rate (SAC+) of high grade D5-SBT were significantly increased compared with high grade D6-SBT (HCG+: 69.1% versus 47.0%, P&lt;0.001; SAC+: 63.0% versus 43.4%, P=0.001). In the PGS-euploid group, the chemical pregnancy rate (HCG+) showed significantly increased in high grade D5-SBT compared with high grade D6-SBT (69.5% versus 60.0%, P=0.047). The clinical pregnancy rate (SAC+) was significantly higher in high grade D5-SBT compared with high grade D6-SBT (65.5% versus 52.5%, P=0.009). The ongoing pregnancy rate was significantly higher in high grade D5-SBT compared with high grade D6-SBT (57.6% versus 43.3%, P=0.005). Conclusion: According to the IF data in this study, we demonstrated that the number of GATA3-positive TE cells were significantly decreased in D6 blastocyst compared with D5 extensively cultured blastocysts. Due to decreased proliferative capacity in high grade D6 blastocyst, transfer of high grade D5 blastocyst would exhibit higher ongoing pregnancy rate than D6 blastocyst.

#276 : Impact of Previous Cesarean Delivery on Pregnancy and Neonatal Outcomes of Subsequent In Vitro Fertilization/Intracytoplasmic Sperm Microinjection and Single Frozen-Thawed Embryo Transfer

Background and Aims: Cesarean delivery (CD) rates continue to rise worldwide. Prior studies have indicated that CD is associated with not only various gynaecological symptoms and obstetric complications but also lower probability of subsequent fertility. However, the recognition about impact of CD on clinical outcomes in subsequent IVF/ICSI-FET is very limited. The purpose was to investigate the effects of previous CD on pregnancy and neonatal outcomes in single frozen-thawed embryo transfer (FET) cycles so that women with a previous cesarean delivery can be given detailed fertility counseling during the ART process. Methods: This is a large retrospective cohort study including a total of 5,750 patients who desired to transfer single vitrified-thawed blastocyst from the same oocyte retrieval cycle as their last live birth between January 2011 and January 2021 in a center for reproductive medicine in Shandong, China, comprising FET cycles of 3,853 previous single CD and 1,897 previous single vaginal delivery (VD). Results: Women with a previous CD had significantly lower rates of biochemical pregnancy (64.52% vs. 71.48% before propensity score matching (PSM), P&lt;0.001; and 65.58% vs. 71.49% after PSM, P&lt;0.001), clinical pregnancy (58.16% vs. 65.79% before PSM, P&lt;0.001; and 59.22% vs. 66.17% after PSM, P&lt;0.001) and live birth (48.17% vs. 55.82% before PSM, P&lt;0.001; and 49.29% vs. 56.10% after PSM, P&lt;0.001) than those with a previous VD. Meanwhile, the CD rate was significantly higher in the CD group (97.85% vs. 18.53% before PSM, P&lt;0.001; and 98.02% vs. 20.51% after PSM, P&lt;0.001). The rates of multiple pregnancy, miscarriage, ectopic pregnancy, multiple live birth, labor complications and preterm and neonatal outcomes were comparable between the two groups. Conclusion: Compared to VD, a previous CD is associated with a significant reduction in the rates of biochemical pregnancy, clinical pregnancy and live birth in patients undergoing subsequent single frozen-thawed blastocyst transfer.

Chronic Infection in Recurrent Pregnancy Loss

In the present study, the effects of chronic endometritis (CE) on implantation and pregnancy outcomes, the effects of CE on endometrial function, and the effects of progesterone as a treatment for CE were examined. It was found that the pregnancy rate and live birth rate were significantly lower in CE patients in a prospective study. When patients were diagnosed with CE, not only were the pregnancy rate and live birth rate significantly lower, but the miscarriage rate was higher in a retrospective study. Next, the presence of chronic deciduitis (CD) in the miscarriage specimen was determined in patients diagnosed with or without CE before pregnancy. CD was determined when the presence of clusters of plasma cells or five or more plasma cells in the decidua. CD was found in more than half of CE, but not found in Non-CE before pregnancy. In in vitro study, we revealed the secretions of TNF[Formula: see text], IL1[Formula: see text], and IL6 per cell were significantly higher in CE. The rate of Th1 was greater and it of Th2 was significantly lower in CE, and those of Tregs and Th17 were not different. Both PRL and IGFBP1, decidualized markers, showed significant decreases in secretion with CE, and conversely, the number of cells was significantly higher in the CE group. Based on the results of bench studies, we hypothesized that an altered administration route and increased dosage of progestogen may improve clinical outcomes. The clinical outcomes of patients who underwent single frozen-thawed blastocyst transfer were examined for each hormone replacement therapy. It was found that using a progesterone vaginal suppository in combination with an oral progestin for hormone replacement improved the live birth rate, but not the miscarriage rate in CE patients when compared with using an oral progestin alone.

Tubal superfetation following frozen-thawed single-embryo transfers in two separate cycles: Case report and literature review.

Superfetation is a very rare occurrence. In the context of assisted reproduction, it has been reported only as an intrauterine pregnancy after ovarian stimulation and/or embryo transfer in the presence of an undiagnosed ectopic pregnancy. Here we report a case of a 27-year-old anovulatory patient, gravida 1 para 1, who underwent two frozen-thawed single-blastocyst transfers in separate cycles. The patient reported that 12 days after the first transfer, she had menstrual bleeding and stopped her estradiol and progesterone supplementation without undergoing a blood human chorionic gonadotropin (βhCG) test. At her request, a second cycle was immediately initiated, with endometrial thickness measuring 4 mm. Eleven days after the second transfer, the βhCG value was inappropriately high. A right tubal pregnancy corresponding to 8 gestational weeks was diagnosed. Laparoscopy revealed a prominent right tubal pregnancy in addition to a significantly smaller left tubal pregnancy. The discordant tubal pregnancies were confirmed histologically. To our knowledge, superfetation involving a second ectopic pregnancy coexistent with a first, contralateral ectopic pregnancy consequent to consecutive in vitro fertilization procedures has not previously been described in the medical literature. This case emphasizes the importance of routine βhCG testing after every IVF cycle, even if apparently unsuccessful.

Effects of embryo characteristics in frozen-thawed single euploid blastocyst transfers on pregnancy outcomes: a retrospective cohort study

Objectives: Our study examined the effects of the trophectoderm biopsy (TB) day and the presence of necrotic foci (NF) or separate blastomeres (SB) within euploid embryos on in vitro fertilization (IVF) pregnancy outcomes. Methods: This retrospective cohort study was conducted from January 2017 to September 2021 at Memorial Sisli Hospital, Istanbul, Turkey. The study comprised a total of 2758 frozen-thawed euploid embryo transfer cycles. After thawing, blastocysts were graded using Gardner's classification Top-Quality (TQ), Good-Quality (GQ), Moderate-Quality (MQ), Poor-Quality (PQ) and further divided into groups according to the presence of NF and/or SB and evaluated for pregnancy outcomes. Results: There were significant correlations between pregnancy outcomes and the degree of blastocoele expansion, as well as the presence of NF or SB in the euploid embryo. Ongoing pregnancy rates were lower in the group with NF in the inner cell mass (ICM) or trophectoderm (TE) than in the group without NF. The presence of SB decreased the rates of ongoing pregnancy and increased the rates of miscarriage. Embryos with expansion grades ≤ 3 had lower rates of ongoing pregnancy and higher rates of miscarriage compared to embryos with expansion grades&amp;gt; 3. TQ and GQ embryos had a higher rate of ongoing pregnancy and a lower rate of miscarriage than MQ and PQ embryos. Conclusions: When selecting the embryo to be transferred to a patient, careful consideration should be given to the morphological grade of the embryo as well as whether or not it contains NF and SB.

Dynamic peripheral blood microRNA expression landscape during the peri-implantation stage in women with successful pregnancy achieved by single frozen-thawed blastocyst transfer.

What are the dynamic expression features of plasma microRNAs (miRNAs) during the peri-implantation period in women with successful pregnancy via single frozen-thawed blastocyst transfer? There is a significant change in the plasma miRNA expression profile before and after blastocyst transfer, during the window of implantation. The expression of miRNAs in peripheral blood has indicative functions during the peri-implantation period. Nevertheless, the dynamic expression profile of circulating miRNAs during the peri-implantation stage in women with a successful pregnancy has not been studied. Seventy-six women treated for infertility with a single frozen-thawed blastocyst transfer in a natural cycle were included in this study. Among them, 57 women had implantation success and a live birth, while 19 patients experienced implantation failure. Peripheral blood samples were collected at five different time points throughout the peri-implantation period, including D0 (ovulation day), D3, D5, D7, and D9 in this cycle of embryo transfer. The plasma miRNAs in women with blastocyst transfer were isolated, sequenced, and analyzed. Peripheral blood samples were collected in EDTA tubes and stored at -80°C until further use. miRNAs were isolated from blood, cDNA libraries were constructed, and the resulting sequences were mapped to the human genome. The plasma miRNAs were initially analyzed in a screening cohort (n = 34) with successful pregnancy. Trajectory analysis, including a global test and pairwise comparisons, was performed to detect dynamic differentially expressed (DE) miRNAs. Fuzzy c-means clustering was conducted for all dynamic DE miRNAs. The correlation between DE miRNAs and clinical characteristics of patients was investigated using a linear mixed model. Target genes of the miRNAs were predicted, and functional annotation analysis was performed. The expression of DE miRNAs was also identified in a validation set consisting of women with successful (n = 23) and unsuccessful (n = 19) pregnancies. Following small RNA sequencing, a total of 2656 miRNAs were determined as valid read values. After trajectory analysis, 26 DE miRNAs (false discovery rate < 0.05) were identified by the global test, while pairwise comparisons in addition identified 20 DE miRNAs. A total of seven distinct clusters representing different temporal patterns of miRNA expression were discovered. Nineteen DE miRNAs were further identified to be associated with at least one clinical trait. Endometrium thickness and progesterone level showed a correlation with multiple DE miRNAs (including two of the same miRNAs, hsa-miR-1-3p and hsa-miR-6741-3p). Moreover, the 19 DE miRNAs were predicted to have 403 gene targets, and there were 51 (12.7%) predicted genes likely involved in both decidualization and embryo implantation. Functional annotation for predicted targets of those clinically related DE miRNAs suggested the involvement of vascular endothelial growth factor and Wnt signaling pathways, as well as responses to hormones, immune responses, and cell adhesion-related signaling pathways during the peri-implantation stage. The raw miRNA sequence data reported in this article have been deposited in the Genome Sequence Archive (GSA-Human: HRA005227) and are publicly accessible at https://ngdc.cncb.ac.cn/gsa-human/browse/HRA005227. Although the RNA sequencing results revealed the global dynamic changes of miRNA expression, further experiments examining the clinical significance of the identified DE miRNAs in embryo implantation outcome and the relevant regulatory mechanisms involved are warranted. Understanding the dynamic landscape of the miRNA transcriptome could shed light on the physiological mechanisms involved from ovulation to the post-implantation stage, as well as identifying biomarkers that characterize stage-related biological process. The study was funded by the Major clinical research project of Tangdu Hospital (2021LCYJ004) and the Discipline Platform Improvement Plan of Tangdu Hospital (2020XKPT003). The funders had no influence on the study design, data collection, and analysis, decision to publish, or preparation of the article. There are no conflicts of interest to declare.

The effect of chronic endometritis on the clinical outcomes of patients with failure of first embryo transfer

Objective: To investigate the effect of chronic endometritis (CE) on the clinical outcomes of patients with failure of first embryo transfer. Methods: A total of 5 605 cycles of frozen-thawed single blastocyst transfer in the reproductive center of the Third Affiliated Hospital of Zhengzhou University from January 2017 to June 2021 were retrospectively collected. After the failure of first embryo transfer, all patients underwent hysteroscopy, and when necessary, endometrial pathology and immunohistochemistry were combined to diagnose CE. Patients were divided into two groups: non-CE group (5 033 cycles) and CE treatment group (572 cycles). The main outcome was live birth rate and the secondary outcomes included clinical pregnancy rate and early abortion rate. The quantitative data were represented by Median (Q1, Q3). The rank sum test was used for comparison between groups. The factors related to live birth rate were analyzed by binary logistic regression model. Results: The incidence of CE was 10.21% (572 cycles) in patients with the failure of first embryo transfer. The maternal age in the non-CE group was 31.0 (29.0, 34.0) years old, and that in the CE treatment group was 31.0 (29.0, 34.0) years old (P<0.001). There was a statistically significant difference in endometrial preparation between the two groups (P=0.010). The endometrial thickness in the CE group was 9.0 (8.2, 10.3) mm on progesterone transformation day, which was higher than that of [9.5 (8.6, 11.0) mm] in the non-CE group (P<0.001). There was no significant difference in clinical pregnancy rate (60.3% (3 035 cycles) vs 63.1% (361 cycles), P=0.193), early abortion rate (17.1% (520 cycles) vs 20.5% (74 cycles), P=0.112) and live birth rate (49.2% (2 477 cycles) vs 49.3% (282 cycles), P=0.969) between the non-CE group and the CE treatment group. The maternal age, endometrial thickness on progesterone transformation day and blastocyst grade were related factors of the live birth rate, and the OR(95%CI) were 0.94 (0.93-0.96), 1.10 (1.06-1.14) and 2.07 (1.84-2.32)), respectively (all P<0.001). Compared with the non-CE group, the CE treatment group did not affect the live birth rate after transplantation, the aOR (95%CI) was 0.99 (0.82-1.18), P=0.882. Conclusions: For patients who underwent the failure of first embryo transfer, hysteroscopy is recommended before single frozen blastocyst transfer, and if necessary, combined with immunohistochemical screening for CE. After standardized treatment, CE patients could obtain similar clinical pregnancy rate, early miscarriage rate and live birth rate as non-CE patients.

Adverse maternal and neonatal outcomes of preimplantation genetic testing with trophectoderm biopsy: a retrospective cohort study of 3373 intracytoplasmic sperm injection single frozen-thawed blastocyst transfer cycles.

To investigate whether trophectoderm biopsy increases the risk of adverse maternal and neonatal outcomes in intracytoplasmic sperm injection (ICSI) single frozen-thawed blastocyst transfer cycles. This respective cohort study enrolled 3373 ICSI single frozen-thawed blastocyst transfer cycles with and without trophectoderm biopsy. Statistical methods including univariate logistic regression analysis, multivariate logistic regression analysis, and stratified analyses were performed to explore the impact of trophectoderm biopsy on adverse maternal and neonatal outcomes. The rates of adverse maternal and neonatal outcomes were comparable between the two groups. Univariate analysis showed that the live birth rate (45.15% vs. 40.75%; P = 0.010) in the biopsied group was statistically higher than that in the unbiopsied group, and the rates of miscarriage (15.40% vs. 20.00%; P = 0.011) and birth defects (0.58% vs. 2.16%; P = 0.007) were statistically lower in the biopsied group. After adjusting for confounding factors, the rates of miscarriage (aOR = 0.74; 95% CI = 0.57-0.96; P = 0.022) and birth defects (aOR = 0.24, 95% CI = 0.08-0.70, P = 0.009) in the biopsied group were significantly lower than those in the unbiopsied group. Stratified analyses showed that the birth defects rate after biopsy was significantly reduced in the subgroups of age < 35years old, BMI ≥ 24kg/m2, artificial cycle with downregulation, poor-quality blastocysts, and Day 5 poor-quality blastocysts. Preimplantation genetic testing (PGT) with trophectoderm biopsy does not increase the risk of adverse maternal and neonatal outcomes in ICSI single frozen-thawed blastocyst transfer cycles, and PGT can effectively reduce the rates of miscarriage and birth defects.

P-362 Pregnancy outcomes of frozen-thawed single euploid blastocyst transfers after endometrial preparation with natural cycle, letrozole use, or programmed cycle

Abstract Study question Is natural cycle the best protocol for endometrial preparation in frozen-thawed single euploid blastocyst transfers? Summary answer Clinical and ongoing pregnancy were comparable between endometrial preparation methods although programmed cycle was associated with a higher risk of miscarriage compared to natural cycle. What is known already Utilization of frozen-thawed single euploid embryo transfers based on PGT-A have been substantially increased recently, but there are still no firm conclusions on the optimal protocol in frozen-thawed embryo transfers (FETs). Even so, significant concerns have been raised about maternal and fetal safety associated with the programmed cycles and several favorable outcomes of natural cycles and letrozole use in FETs have been suggested in recent years. Pregnancy outcomes after endometrial preparation with natural cycle, letrozole use, programmed cycles have not been compared in euploid blastocyst FETs. Study design, size, duration This was a retrospective cohort study at a single center including FET cycles from January 2019 to October 2021. Participants/materials, setting, methods A total of 708 frozen-thawed single euploid blastocyst transfer cycles were analyzed. Endometrial preparation was performed using natural cycle with hCG trigger (n = 60), ovulation induction with letrozole (n = 32), or programmed cycle (n = 616) at the discretion of each attending physician. Pregnancy outcomes including clinical pregnancy, ongoing pregnancy, and miscarriage were calculated using multivariable logistic regression. Main results and the role of chance The three groups were similar for age, BMI, basal FSH, TSH, AMH levels, PGT-A indications, presence of ovulatory dysfunction, endometrial thickness on the starting day of progesterone supplementation, and the proportion of good quality embryo transferred. The crude clinical pregnancy rate, ongoing pregnancy rate, and miscarriage rate were not different among the groups (55.0% vs. 68.9% vs. 61.9%, p = 0.40; 51.7% vs. 59.4% vs. 50.0%, p = 0.58; 6.1% vs. 13.6% vs. 20.4%, p = 0.11, respectively). After adjusting for confounders, clinical pregnancy and ongoing pregnancy outcomes of natural cycle were similar to that of letrozole cycle and programmed cycle. However, programmed cycle was associated with significantly higher odds of miscarriage compared to natural cycle (aOR 4.33, 95% CI 1.01-18.58). Limitations, reasons for caution This was not an intention-to-treat study due to its retrospective design. Another limitation of this study includes a small sample size and risk of patient selection bias for indication of PGT-A. Wider implications of the findings Natural cycle and ovulation induction with letrozole may be safely and effectively carried out for endometrial preparation in patients undergoing single euploid FETs. Trial registration number not applicable

P-269 trophectoderm grade is associated with the risk of placenta previa in frozen-thawed single blastocyst transfer cycles

Abstract Study question Dose obstetric and perinatal complications differ among different blastocyst developmental parameters after frozen-thawed single blastocyst transfer (SBT) cycles? Summary answer Blastocysts with grade C trophectoderm (TE) were associated with an increased risk of placenta previa compared to those with grade A TE. What is known already Existing studies investigating the effect of blastocyst morphology grades on birth outcomes have mostly focused on fetal growth and have produced conflicting results, while the risk of obstetric complications has rarely been reported. Additionally, growing evidence have suggested that the appearance of TE cells could serve as the most important parameter for predicting implantation and live birth. Given that the TE ultimately develops into the placenta, it is plausible that this independent predictor may also impact placentation. Study design, size, duration This was a retrospective cohort study conducted at a single tertiary-care academic reproductive center. A total of 6168 patients who underwent frozen-thawed SBT and resulted in singleton delivery beyond 20 weeks of gestation between January 2017 and December 2021 were analyzed. Participants/materials, setting, methods Main outcomes included placenta previa, placental abruption, placenta accreta, pregnancy-induced hypertension (PIH), preeclampsia, preterm birth (PTB), low birth weight (LBW) and small for gestational age (SGA). Multivariate logistic regressions were performed to evaluate the effect of blastocyst developmental stage (day 5 and 6), embryo expansion stage (stages 3, 4, 5 and 6), inner cell mass (ICM) grade (A, B and C), and TE grade (A, B and C) on measured outcomes adjusting for potential confounders. Main results and the role of chance The overall rates of placenta previa, placental abruption, placenta accreta, PIH, preeclampsia, PTB, LBW and SGA was 2.8% (n = 173), 0.4% (n = 26), 1.3% (n = 83), 5.3% (n = 328), 4.3% (n = 267), 6.8% (n = 417), 3.7% (n = 230), and 2.8% (n = 172), respectively. Specifically, the incidence of placenta previa derived from blastocyst with TE of grade C was higher compared with those derived from blastocyst with TE of grade A (1.8%, 2.5% and 3.9% for A, B and C, respectively, P = 0.003 for all comparisons). No such differences were observed for any other outcomes. After adjusting for potential covariates (maternal age, maternal BMI, maternal education, duration of infertility, gravidity, parity, previous caesarean section, infertility diagnosis, IVF or ICSI, previous embryo transfer, and type of endometrial preparation), TE grade C blastocyst had 2.58 times the likelihood of resulting in the risk of placenta previa compared to TE grade A blastocysts (adjusted odds ratio [AOR] 2.58, 95% confidence interval [CI] 1.05-6.31). No statistically significant associations were detected between any other measured outcomes and blastocyst developmental parameters. Furthermore, when restricted to pregnancies above 28 gestational weeks, the risk of placenta previa remained significantly higher with TE of grade C (AOR 2.56, 95% CI 1.05-6.27) than with TE of grade A. Limitations, reasons for caution The retrospective design, lack of controlling for residual confounding factors, and inter-observer variability limited this study. Wider implications of the findings The study extends our knowledge of the potential downstream effect of TE grade on placental abnormalities. Trial registration number not applicable

P-729 Factors affecting live birth rates in frozen-thawed single euploid blastocyst transfer cycles

Abstract Study question What are the factors affecting the rates of live birth in frozen-thawed euploid embryo transfer cycles? Summary answer Some demographic characteristics, frozen embryo transfer (FET) cycle parameters, and embryo characteristics of patients affect live birth rates in euploid embryo transfer cycles. What is known already The aim of assisted reproductive techniques (ART) is to achieve live birth as soon as possible. Preimplantation genetic testing (PGT) is an embryo selection technique recommended to shorten the live birth time. In addition, PGT reduces the number of failed ART cycles by eliminating embryos with chromosomal abnormalities that will not implant or will cause miscarriage. Despite these, the live birth rate after euploid embryo transfer cycles is still not at the expected level. Study design, size, duration This retrospective cohort study was conducted between January 2011 and May 2021 at the IVF and Reproductive Genetics Centre, Memorial Sisli Hospital, Istanbul, Turkey. The study involved a total of 2783 frozen-thawed euploid embryo transfer cycles. Participants/materials, setting, methods 2873 euploid FET cycles were analysed in the study to determine factors affecting live birth rates. 30 parameters thought to affect live birth were identified and analysed by logistic regression analysis on the effects of live birth. These parameters include patients' demographics, fresh cycle and FET cycle characteristics, and embryo-related parameters on live birth effects in euploid embryo transfer cycles. Main results and the role of chance 53% of 2783 euploid embryo transfer cycles have resulted in a live birth. The birth rate was 0,5 times less in the group with a body mass index (BMI) of higher than 29 compared to the group with a BMI of less than 25 (p &amp;lt; 0.05). In cycles in which embryos of good-to-moderate-to-poor quality were transferred, the chance of live birth was lower than in cycles in which embryos of top quality were transferred (OR:0.837 OR:0.515 OR:0.528, respectively). The live birth rate was higher in cases where endometrial preparation was performed in natural cycles than in artificial cycles (OR:1.67, p &amp;lt; 0.05). Embryo transfers without separate blastomeres had a higher live birth rate than embryo transfers with separate blastomeres (OR:1.416, p &amp;lt; 0.006). The live birth rate was 0.7 times lower in the group that did not undergo embryo re-expansion 4 hours after thawing (p &amp;lt; 0.04). Embryo transfer on the sixth day was associated with a lower live birth rate than embryo transfer on the fifth day. (OR:0.6, p &amp;lt; 0.02). The group with a history of recurrent implantation failure (RIF) had a lower live birth rate than the group without a history of RIF (OR:0.5) Limitations, reasons for caution This study is a retrospective study. Wider implications of the findings In euploid embryo transfer cycles, clinicians and embryologists must know the parameters affecting live birth to guide treatment and select the embryo to be transferred first. In addition, the patient should be informed and guided about these factors. Trial registration number Not applicable

P-192 Blastocyst collapse during embryonic development is a marker of low pregnancy potential, independent of other blastocyst evaluation criteria

Abstract Study question Is evaluation of blastocyst collapse during embryonic development an independent marker for ongoing pregnancy in single frozen-thawed blastocyst transfer cycles? Summary answer Collapse of blastocyst more than 20.4% of the area may be a marker of low ongoing pregnancy potential, independent of other evaluation criteria. What is known already Time-lapse monitoring revealed that a section of the extended trophectoderm (TE) is ruptured during development. This TE rupture causes an efflux of blastocoel fluid and a reduction in embryonic volume. This phenomenon is described as collapse. Several studies have reported that the collapse results in a low clinical and ongoing pregnancy potential for the blastocyst. However, the collapsed blastocysts were associated with poor morphological quality. Previous studies have not evaluated whether collapse is an independent predictor of pregnancy based on other blastocyst evaluation criteria. Therefore, it is necessary to determine whether blastocyst collapse is an independent predictor of ongoing pregnancy. Study design, size, duration This retrospective, single-center study was conducted at the TAKAHASHI WOMEN'S CLINIC from January, 2018 to December, 2020. All blastocysts were derived from the ICSI cycles. Time-lapse monitoring using Embryoscope + (Vitrolife) was used to observe the presence and degree of collapse. The degree of collapse was calculated from the embryonic volume at the maximum expansion and the lowest volume after collapse. We analyzed the relationship between 904 cycles of single vitrified-warmed blastocyst transfer and ongoing pregnancy. Participants/materials, setting, methods The ongoing pregnancy rates of collapsed and non collapsed blastocysts were compared using chi-squared test. The cut-off value of the degree of collapse for ongoing pregnancy was calculated using receiver operating characteristic (ROC) curve analysis. The effect of collapse above the cut-off value on ongoing pregnancy was examined using multivariate logistic regression analysis, including confounding factors (patient age, body mass index, inner cell mass (ICM) grade, TE grade, day of blastocyst formation, and expansion stage). Main results and the role of chance During the study period, 329 of the 904 transferred blastocysts exhibited collapse during time-lapse monitoring, and the degree of collapse ranged from 2.10% to 75.90%, with a median of 30.70%. In total, 575 transferred blastocysts were determined to be non collapsed. The mean patient age ( ± standard division) was 36.89 ± 4.77 years in the collapsed blastocyst group and 36.52 ± 4.42 years in the non collapsed blastocyst group (p = 0.151). The proportion of blastocysts with poor morphological grade (&amp;lt;BB ) was higher in the collapsed blastocysts group than in the non collapsed blastocysts group (32.5% vs. 17.91%, p &amp;lt; 0.0001). The ongoing pregnancy rate was significantly lower in the collapsed blastocysts group than in the non collapsed blastocysts group (45.4% vs. 34.0%, p = 0.0009). ROC curve analysis showed that the cut-off value for the degree of collapse for low pregnancy potential was 20.4%. Multivariate logistic analysis with confounding factors revealed that blastocyst collapse above the cut-off value (≥20.4%) had an effect on ongoing pregnancy (adjusted odds ratio: 0.53, 95% confidence interval: 0.34–0.82, p = 0.005) independent of ICM and TE grades, day of blastocyst formation, and expansion stage. Limitations, reasons for caution This retrospective study was conducted at a single fertility center. In addition, the analyzed blastocysts were derived only from the ICSI cycles. Therefore, it is necessary to analyze the effects of collapse in blastocysts derived from C-IVF cycles. Wider implications of the findings Our results demonstrate that ≥20.4% collapse may be an additional marker to consider when selecting blastocysts for transfer. If the blastocysts are of the same grade, it is better to select non collapsed embryos. Trial registration number not affect

P-201 Developmental analysis of blastocysts with blastomere exclusion during compaction and its relationship to pregnancy outcomes and preimplantation genetic testing for aneuploidy results

Abstract Study question What effects do blastocysts with blastomere exclusion during compaction have on embryo morphokinetics, morphology grade, genetic testing for aneuploidy (PGT-A) results, and pregnancy outcomes? Summary answer Blastocysts with blastomere exclusion leads to delay blastulation and poor morphology grade, but does not affect pregnancy outcomes and euploidy in PGT-A. What is known already It has been reported that aneuploid blastomeres are excluded during compaction, which is a mechanism for chromosome repair in blastocysts through the exclusion of aneuploid cells.Furthermore, in this phenomenon, it is known that the first cleavage of embryos is often abnormal, in which three or more cells originate from a single cell division event.However, this phenomenon has not been reported in the evaluation of embryo morphokinetics, artificial intelligence (AI) scores, or PGT-A results. Study design, size, duration In this retrospective study, we analyzed clinical medical reports at the Takahashi Women’s Clinic in Japan. We included 934 blastocysts cultured in a time-lapse incubator (EmbryoScope) after intracytoplasmic sperm injection (ICSI) from January 2018 to June 2021. Participants/materials, setting, methods Blastocysts cultured using a time-lapse incubator (EmbryoScope) after ICSI were classified into a control group (N = 515) with blastomere compaction or a BE group (N = 419) with blastomere exclusion during compaction. The first type of cleavage, AI score (IDAScore), embryo morphokinetics, and single frozen-thawed blastocyst transfer outcome were evaluated.Logistic regression analysis was performed to compare the two groups, considering patient age, blastocyst grade (Gardner classification), culture days, body mass index, and basal anti-Müllerian hormone level. Main results and the role of chance Comparing the control and BE groups, the first cleavage abnormality rate was 16.9% vs. 67.3% (P &amp;lt; 0.001), the percentage with good embryo grade (Gardner criteria ≧BB) was 93.4% vs. 61.0% (P &amp;lt; 0.001), and the mean score by AI analysis was 8.3 ± 1.3 vs. 6.4 ± 1.9 (P &amp;lt; 0.001), respectively. The BE group had a higher rate of abnormal cleavage and a significantly worse embryo grade and AI score than the control group.In the evaluation of embryo morphokinetics, the time to morula was 84.2 ± 7.0 h vs. 89.0 ± 8.5 h (P &amp;lt; 0.05) and time to blastocyst was 105.9 ± 9.4 h vs. 114.7 ± 11.4 h (P &amp;lt; 0.05). The BE group significantly delayed blastulation compared to the control group.The euploidy, mosaicism, and aneuploidy rates of PGT-A were 13.6% (9/66), 9.1% (6/66), and 77.3% (51/66) in the control group vs. 13.2% (5/38), 13.2% (5/38), and 73.7% (28/38) in the BE group, respectively. There was no significant difference in the PGT-A results between the two groups. Furthermore, the single-blastocyst transfer pregnancy rates (gestational sac with heart activity) in the control and BE groups were 47.1% (147/312) and 32.6% (60/184), respectively. Pregnancy rate was lower in the BE group, but was not significantly different from that of the control group. Limitations, reasons for caution The study was conducted at a single in vitro fertilization center. Embryo transfer results were based on ongoing pregnancies, while live birth data for all pregnancies are not yet available. Wider implications of the findings Although the BE group was graded worse, statistical analysis considering the grade showed no significant difference in PGT-A and pregnancy rates between the two groups.These results suggest that blastocysts with blastomere exclusion can be useful as transferable embryos if they grow to a transferable grade. Trial registration number not applicable

Pregnancy Outcomes for Day 5 Versus Day 6 Single Frozen-thawed Blastocyst Transfer with Different Qualities of Embryos: A Large Matched-cohort Study.

This study aimed to determine whether the day of blastocyst expansion affects pregnancy outcomes in frozen-thawed blastocyst transfer (FBT) cycles. A retrospective match-cohort study was conducted. Patients who underwent blastocyst transfer in frozen-thawed cycles at day 5 or 6 were matched for potential confounding factors. A total of 2207 matched pairs of FBT cycles were included from January 2016 to December 2019 in our Reproductive Medicine Center. The clinical pregnancy rate (CPR) and live birth rate (LBR) were significantly increased in day 5 blastocyst transfers when compared to day 6 blastocyst transfers, in terms of the same embryo quality. For FBT cycles with good-quality embryo, the CPR at day 5 and 6 was 61.30% and 57.56%, respectively (P=0.045), and the LBR was 44.79% and 36.16%, respectively (P<0.001). For FBT cycles with poor-quality embryo, the CPR at day 5 and 6 was 48.61% and 40.89%, respectively (P=0.006), and the LBR was 31.71% and 25.74%, respectively (P=0.019). The CPR for FBT cycles with good-quality embryo was statistically higher at day 6 than that at day 5 with poor-quality embryo transferred (57.56% vs. 48.61%, P=0.001). Maternal age, anti-Müllerian hormone (AMH), endometrial thickness, embryo quality, and the day of blastocyst expansion were independently correlated with the CPR and LBR. The FBT cycles at day 5 had significantly higher CPR (adjusted odds ratio [OR]=1.246, 95% confidence intervals [CI]: 1.097-1.415, P=0.001) and LBR (adjusted OR=1.435, 95% CI: 1.258-1.637, P<0.001) than those at day 6. The embryo quality is the primary indicator for FBT cycles. Day 5 blastocysts should be preferred when the quality of embryo at day 5 is the same as that at day 6.

Association between endometrial blood and clinical outcome in frozen single blastocyst transfer cycles.

Background: The success of embryo transfer cycle depends mainly on the quality of embryo and endometrial receptivity. Ultrasound examination is still the most widely used non-invasive evaluation method for its advantages of convenience, non-invasiveness and repeatability. Ultrasound-measured endometrial blood flow is one of the important evaluation indicators of morphology. Aims: To investigate the effect of the number of endometrial blood flow branches on pregnancy outcome of frozen-thawed embryo transfer cycles which have undergoing hormone replacement therapy (HRT-FET). Material and methods: A retrospective cohort study was performed looking at a total of 1390 HRT-FET cycles from our reproductive medicine center between January 2017 to December 2021, which transferred one blastocyst frozen on day 5 with good quality in morphology. Associations between endometrial blood flow branches and pregnancy outcomes were evaluated with multivariable linear regression analysis. Results: The number of endometrial blood flow branches was independently associated with clinical pregnancy (OR 1.10; 95% CI 1.02-1.20). After adjusting for potential confounders, the effect size (odds ratio) was 1.09 (95% CI 1.00-1.19), and the results showed that the clinical pregnancy rate and live birth rate of T2 and T3 groups were significantly higher than those in group T1 (p < 0.05). Subgroup analysis showed that a consistent association between the endometrial blood flow branches and clinical pregnancy in all subgroups. Conclusion: Our study provided evidence for the influence of endometrial blood flow on pregnancy outcomes. There may be an independent association between the number of endometrial blood flow branches and pregnancy outcomes in frozen-thawed single blastocyst transfer cycles.

Trophectoderm biopsy is associated with adverse obstetric outcomes rather than neonatal outcomes

BackgroundWith the wide application of preimplantation genetic testing (PGT) with trophectoderm (TE) biopsy, the safety of PGT has always been a concern. Since TE subsequently forms the placenta, it is speculated that the removal of these cells was associated with adverse obstetrical or neonatal outcomes after single frozen-thawed blastocyst transfer (FBT). Previous studies report contradictory findings with respect to TE biopsy and obstetric and neonatal outcomes.MethodsWe conducted a retrospective cohort study including 720 patients with singleton pregnancies from single FBT cycles who delivered at the same university-affiliated hospital between January 2019 and March 2022. The cohorts were divided into two groups: the PGT group (blastocysts with TE biopsy, n = 223) and the control group (blastocysts without biopsy, n = 497). The PGT group was matched with the control group by propensity score matching (PSM) analysis at a ratio of 1:2. The enrolled sample sizes in the two groups were 215 and 385, respectively.ResultsPatient demographic characteristics were comparable between the groups after PSM except for the proportion of recurrent pregnancy loss, which was significantly higher in the PGT cohort (31.2 vs. 4.2%, P < 0.001). Patients in the PGT group had significantly higher rates of gestational hypertension (6.0 vs. 2.6%, adjusted odds ratio (aOR) 2.91, 95% confidence interval (CI) 1.18–7.18, P = 0.020) and abnormal umbilical cord (13.0 vs. 7.8%, aOR 1.94, 95% CI 1.08–3.48, P = 0.026). However, the occurrence of premature rupture of membranes (PROM) (12.1 vs. 19.7%, aOR 0.59, 95% CI 0.35–0.99, P = 0.047) was significantly lower in biopsied blastocysts than in unbiopsied embryos. There were no significant differences in regard to other obstetric and neonatal outcomes between the two groups.ConclusionsTrophectoderm biopsy is a safe approach, as the neonatal outcomes from biopsied and unbiopsied embryos were comparable. Furthermore, PGT is associated with higher risks of gestational hypertension and abnormal umbilical cord but may have a protective effect on PROM.