Frozen-thawed Blastocyst Transfer Research Articles

High serum progesterone levels on the day of embryo transfer in patients undergoing artificial frozen-thawed blastocyst transfer: Is there a ceiling effect?

To evaluate the potential ceiling effect of high serum progesterone levels on the day of embryo transfer for pregnancy outcomes in patients undergoing artificial frozen-thawed blastocyst transfer (FET) cycles. This retrospective cohort study included 595 patients who underwent artificial FET cycles. We evaluated progesterone levels and found that 40.6 ng/mL corresponded to the 90th percentile and 23.9 ng/mL corresponded to the 50th percentile. Based on these findings, we categorized progesterone levels as <20 ng/mL (n=220, 37.0%), 20-40 ng/mL (n=312, 52.4%), and ≥40 ng/mL (n=63, 10.6%). The primary outcome measures were the clinical pregnancy rate (CPR) and live birth rate (LBR). Blastocyst morphology grades, including expansion, trophectoderm, and inner cell mass grades, were significantly associated with clinical pregnancy (p<0.001 for all). Progesterone levels between 20 and 40 ng/mL were associated with higher CPR (p=0.043). In the multivariate analysis, only blastocyst expansion and inner cell mass grades were independently and significantly associated with CPR [p=0.011, odds ratio (OR)=1.6, (confidence interval) CI 95%=1.13-2.39, and p=0.007, OR=1.65, CI 95%=1.14-2.39, respectively]. The progesterone level and trophectoderm grade were not statistically significant. Regarding LBR, only blastocyst expansion grades 4 and trophectoderm grades A or B were significantly associated. Based on these data, we speculate that if serum progesterone levels exceed 40 ng/mL on the day of embryo transfer in patients undergoing artificial FET cycles, there is no need to reduce the progesterone dose.

Use of hCG for luteal support in natural frozen-thawed blastocyst transfer cycles: a cohort study.

In the realm of natural frozen-thawed embryo transfer (FET) cycles, the application of luteal phase support (LPS) is a prevalent practice, primarily due to its beneficial impact on reproductive outcomes. Among the various LPS medications, human chorionic gonadotropin (hCG) is one that exerts its function on both the corpus luteum and the endometrium. To evaluate the effect of hCG administration as LPS on reproductive outcomes in natural FET cycles. This study was a retrospective cohort analysis conducted at a tertiary care hospital. It included women who underwent natural FET treatment from January 2018 to December 2022. Participants were divided into the hCG LPS group and the non-hCG LPS group on the basis of whether they used hCG as LPS after blastocyst transfer. The primary outcome was the clinical pregnancy and live birth rates. The secondary outcomes included the early miscarriage rate (before 12th gestational week) and total miscarriage rate. A total of 4762 women were included in the analysis, and 1910 received hCG LPS and 2852 received no hCG LPS (control group). In the general cohort, the clinical pregnancy and live birth rates in the hCG LPS group were significantly lower than those in the control group (63.82% vs 66.41%, aOR 0.872, 95% CI 0.765-0.996, P=0.046; 53.98% vs 57.15%, aOR 0.873, 95% CI 0.766-0.991, P=0.035, respectively). The early miscarriage and total miscarriage rates were similar between the two groups. In a subgroup analysis, in women who received an hCG trigger, there was no significant difference in the clinical pregnancy rate or live birth rate between the two groups. However, in women who ovulated spontaneously, the clinical pregnancy and live birth rates in the hCG LPS group were significantly lower than those in the control group (60.99% vs 67.21%, aOR 0.786, 95% CI 0.652-0.946, P=0.011; 50.56% vs 57.63%, aOR 0.743, 95% CI 0.619-0.878, P=0.001, respectively). Among women undergoing natural cycle frozen-thawed blastocyst transfer, hCG LPS is associated with lower clinical pregnancy and live birth rates. Additionally, the adverse effect of hCG LPS is more pronounced in women who ovulate spontaneously.

O-029 Atosiban in women with previous single implantation failure undergoing frozen-thawed blastocyst transfer: a placebo-controlled randomized trial

Abstract Study question Does the administration of Atosiban before frozen-thawed blastocyst transfer improve the live birth rate in women with a history of a single implantation failure? Summary answer In women with a single implantation failure undergoing frozen-thawed blastocyst transfer, Atosiban did not improve the ongoing pregnancy rate. What is known already Uterine peristalsis preceding embryo transfer is believed to adversely impact the success rates of IVF. Atosiban can reduce uterine peristalsis and act as a role of oxytocin antagonist. The effectiveness of Atosiban in the general population of IVF patients has not been conclusively shown by randomised clinical trials or meta-analyses. It has been suggested that women with previous implantation failure may potentially benefit from the use of Atosiban, particularly in the presence of uterine peristalsis. We aim to evaluate if Atosiban before embryo transfer increases live birth rate in women undergoing frozen-thawed blastocyst transfer? Study design, size, duration We conducted a single-centre, double-blind placebo randomised controlled trial (RCT) in women with previous single implantation failure undergoing frozen-thawed blastocyst transfer. Between July 2019 and June 2023, we randomised 1,100 participants to either Atosiban or placebo. The primary outcome was live birth (≥20 weeks of gestation) in the first FET after randomization. In this abstract, we present results on ongoing pregnancy. Data on live birth will be available at the conference. Participants/materials, setting, methods We randomised women with a history of one failed fresh or frozen blastocyst, with at least one cryopreserved blastocyst into two groups on the day of transfer. In the Atosiban group, women were administered 37.5mg of Atosiban intravenously 30-min prior to FET. In the placebo group, women received a saline infusion for the same duration. Uterine peristalsis was measured using transvaginal ultrasound prior to administration of study drugs. The analysis was done based on intention-to-treat. Main results and the role of chance The ongoing pregnancy rates were 50.46% (277/549) and 46.82% (258/551) in the Atosiban and control groups, respectively (RR 1.08, 95% CI 0.95 to 1.22, P = .23). Uterine peristalsis was measured in 720 (65%) of all participants. Within this cohort, of the 163 (22%) women with abnormal contractions, the ongoing pregnancy rates were 51.9% and 41.7%, respectively (RR 1.25, 95% CI 0.90 to 1.73, P = .19). Among 208 women (29%) with peristalsis but without abnormal contraction waves, ongoing pregnancy rates were 50.9% and 48.0% (RR 1.06, 95% CI 0.81 to 1.40, P = .67). In 349 women (48%) without peristalsis, the ongoing pregnancy rates were 48.6% in the Atosiban group versus 50.6% in the control group (RR 0.96, 95% CI 0.78 to 1.19, P = .71). Limitations, reasons for caution Our study only included women with previous blastocyst implantation failure. Uterine peristalsis was not initially assessed, resulting in only 65% (720/1,100) of the participants having peristalsis measured. In this abstract, we only report on the ongoing pregnancy rate. We will present data on live birth at the congress. Wider implications of the findings In unselected women undergoing frozen-thawed blastocyst transfer with previous single implantation failure, Atosiban does not enhance the ongoing pregnancy rate. Future research regarding Atosiban in IVF should assess uterine peristalsis and focus on women with abnormal contractions. Trial registration number ChiCTR1900022333

P-039 Parthenogenetic chimeras may be the cause of the development of a case of 46, XX/46, XY chimeras complicated by severe oligozoospermia

Abstract Study question How did the 46,XX/46,XY chimeric case of severe oligozoospermia arise? Summary answer DNA analysis suggested the possibility of monogenetic chimerism as a mechanism for the development of this case. What is known already Sex-chromosome discordant chimerism in humans(XX/XY chimerism)is a rare chromosomal abnormality. Although the first case was described in 1962, its incidence is still unknown. The XX/XY chimera manifests variable genital phenotypes. The XX/XY chimera is classified into subtypes; tetragametic chimeras, parthenogenetic chimeras, androgenetic chimeras and sesquizygotic twinning chimeras. Genotyping of XX/XY chimeras is important no only to clarify its developmental mechanism but also for diagnosis and treatment. As a result, patients occasionally present with infertility. We present a case of a parthenogenetic chimera with a karyotype of XX/XY in relation to infertility. Study design, size, duration case research. We researched from July 2023 to December 2023. Participants/materials, setting, methods A 38-year-old man diagnosed with azoospermia by his previous physician presented to our clinic with primary infertility for 1 year and 6 months. At 28 years old, he presented with left testicular inflammation and subsequent atrophy. He has no sexual problems. He has an older sister and a younger sister, both married with children. Main results and the role of chance Physical findings: BH 163 cm, BW 53 kg, BMI 19.95, external genitalia: male. Semen analysis: severe oligozoospermia: mostly immobile sperm with some sperm moving slightly in situ. Morphology (Kurger strict criteria): no abnormal sperm morphology. Left testicular hypoplasia: USG: 12 ml right testis, 1 ml left, no other problems. Abdominal MRI: no abnormalities in the kidney to the bladder. No uterus or ovaries. Prostate and seminal vesicles normal; AMH 3.34ng/ml (0.77-14.5) Testosterone 6.55ng/ml (1.95-7.63), DHEA-S 199 μg/dl(106-464),LH 6.2, FSH 7.5, E2 32.5, PRL 12.43, blood type A, Rh+, RH-Hr:CcDee, HLA-A, B, C, DR: all undetermined, Y chromosome SRY (FISH): SRY signal numbers 0 and 1 were observed. Chromosome analysis (G band): 46, XX[22]/46, XY[8]. SNP microarray chromosome examination: presumptive parthenogenic chimerism Treatment: His wife underwent oocyte pick up and intracytoplasmic sperm injection(ICSI) was performed using his frozen sperm. One blastocyst was frozen, but one frozen-thawed blastocyst transfer during an HRT cycle failed to result in pregnancy. The use of assisted reproductive technology(ART) is currently ongoing. Limitations, reasons for caution DNA analysis of both parents was necessary to determine the cause of the problem, but the patient refused to have her parents tested. Wider implications of the findings By accumulating and studying a large number of cases like this one, it may be possible to correctly treat patients with 46, XX/46, XY chimeric infertility. Trial registration number not applicable

P-656 Comparative clinical outcome following individualized follitropin delta dosing in Japanese women undergoing progestin-primed ovarian stimulation for in vitro fertilization /intracytoplasmic sperm injection

Abstract Study question Is ovarian stimulation with follitropin delta (FD) in its individualized regimen as efficacious as follitropin alfa and human menopausal gonadotropin (FAHMG)? Summary answer Ovarian stimulation with individualized FD dosing resulted in a significantly higher fertilization rate and number of blastocysts with good quality compared to conventional FAHMG dosing. What is known already Previous randomized controlled trials conducted in Japan, China, Europe, and both North and South America have demonstrated that ovarian stimulation using the individualized FD dosing regimen, which is based on serum anti-Müllerian hormone (AMH) levels and body weight, effectively modulated the ovarian response without compromising pregnancy and live birth rates. Study design, size, duration A retrospective study was conducted by reviewing the medical records of 1,720 IVF/ICSI cycles in 1,272 Japanese patients. The primary endpoint of the study was the ongoing pregnancy rate, assessed at 8 weeks of gestation, in the frozen-thawed embryo transfer. Participants/materials, setting, methods The FD treatment consisted of a fixed daily dose individualized according to each patient’s initial AMH level and body weight (AMH &amp;lt;2.04 ng/ml: 12 μg; AMH ≥2.04 ng/ml: 0.19 to 0.10 μg/kg; min-max 6–12 μg). The FAHMG dose was determined by the antral follicle count (AFC), with the following protocol: for AFC &amp;lt;25, 300 IU/day; for 40&amp;gt; AFC ≥25, 225 IU/day; and for AFC ≥40: 150 IU/day). A progestin-primed ovarian stimulation (PPOS) protocol was applied. Main results and the role of chance Multiple regression analyses (MRA) showed that the use of FD was negatively correlated with the number of oocytes retrieved (NOR) (P = 0.001), and positively correlated with the fertilization rate (FR) (P = 0.02). NOR was comparable between FD and FAHMG (10.9 ± 6.4 versus 11.8 ± 7.8) when the Mann-Whitney test (MW) was applied (P = 0.111), but significantly higher in FAHMG when the patient is younger than 40 years old with AMH ≥2 ng/ml (P &amp;lt; 0.01). The total gonadotropin use was significantly (P &amp;lt; 0.001) reduced from an average of 167.1 ± 46.9 μg (2789.9 ± 782.9 IU) FAHMG to 102.6 ± 31.6 μg FD. FR was significantly higher in FD compared with FAHMG (78.7% versus 74.1%, P &amp;lt; 0.05) on MW. Additionally, MW indicated a significantly higher number of good-quality blastocysts in FD (2.9±2.6) versus with FAHMG (2.4±2.5) (P &amp;lt; 0.05). The blastocysts obtained from FD also showed a significantly higher implantation rate (50.1% versus 39.7%, P &amp;lt; 0.01) and a comparable ongoing pregnancy rate (28.7% versus 25.7%, P = 0.292) compared to those from FAHMG as determined by chi-square test. The higher implantation rate in FD may be attributed to the greater number of good-quality blastocysts obtained compared with FAHMG. Limitations, reasons for caution This study only covered the clinical outcome of women undergoing PPOS protocol with frozen-thawed blastocyst transfers. Wider implications of the findings The present study shows that FD in its individualized fixed-dose regimen has the potential to improve the success rate in frozen-thawed embryo transfer across all ages and with a lower gonadotropin consumption compared to conventional FAHMG dosing. Trial registration number not applicable

P-328 Uterine Fluid microbiome composition in fertile controls and infertile women

Abstract Study question Is the microbiome of the Uterine Fluid (UF) related to outcomes of frozen-thawed blastocyst transfer? Summary answer Microbiome of UF collected by double-sheated catheter shows Lactobacilli as the most abundant species but does not relate to outcomes of frozen-thawed blastocyst transfer. What is known already The microbiome of UF has been described to be largely dominated (&amp;gt;90%) by Lactobacilli and has been shown to be markedly associated with the outcomes of embryo transfer. Nonetheless, previous reports have not collected UF by avoiding vaginal/cervical contamination through a double-sheated catheter. Study design, size, duration Observational study conducted at Fondazione IRCCS Ca’Granda Ospedale Maggiore Policlinico and IRCCS Ospedale San Raffaele, Milan, Italy. n = 13 fertile controls underwent UF sampling in the pre-receptive (LH + 2) and receptive (LH + 7) phase of a monitored natural cycle and n = 48 infertile women underwent UF sampling on day LH + 7 of the monitored natural cycle preceding that of their first frozen-thawed blastocyst transfer. UF was sampled by aspiration with a double-sheated catheter (commonly used for embryo transfer. Participants/materials, setting, methods Microbiome analysis was conducted following the Illumina protocol for V3-V5 regions of the 16S rRNA and using the Illumina MiSeq instrument. Raw sequencing data processing encompassed quality controls, and QIIME 2 scripts were employed to obtain taxonomic abundances (taxonomic levels L2-L7). Alpha (within sample), and beta (among samples) diversity and differential expression at taxonomic level (using limma, Bioconductor library) were calculated. Main results and the role of chance UF microbiome analysis showed lack of separation between samples from the two Centres, confirming the reproducibility of the technique. UF microbiome was also found to be stable throughout the menstrual cycle, with no diversity observed between LH + 2 and LH + 7 samples in the population of fertile controls (p = 0.9, Adonis test on beta diversity; confirmed by differential abundance tests based on linear regression models at taxonomic levels). UF of fertile controls showed Lactobacillus Helveticus as the most abundant species (16.2%), followed by other Lactobacilli (unspecified) (12.1 %), Lactobacillus Iners (11.8%), Streptococcus (unspecified) (6.8%), Bifidobacterium (4.7%) and Gardnerella (1.9 %). In women who achieved successful implantation after FET, the most abundant species was L. Helveticus (58.1%) followed by L. Iners (9.8%), Acinetobacter lwoffii (5.9%) and other Lactobacilli (unspecified) (4.0%). No statistically significant differences were found in linear regression comparisons at taxonomic level with UF of women with failed implantation, in whom most abundant species were L. Helveticus (50.4%, p = 0.11), L. Iners (15.8%, p = 0.95), other Lactobacilli (unspecified) (13.7%, p = 0.17) and Garnderella (6.5%, p = 0.19). The proportion of Lactobacillus- dominated (&amp;gt;90%) samples was 50% (n = 10/20) in infertile women achieving successful implantation and 46% (n = 13/28) in infertile women with failed implantation (p = 0.8). Limitations, reasons for caution These results are preliminary and only include the first n = 48 patients of the total n = 249 patients that will be enrolled. A larger sample is required to further investigate possible relations between UF microbiome composition and implantation outcomes. Wider implications of the findings As UF microbiome was found to be stable between cycle phases and it is non-invasively collected, it could be analysed in the same cycle in which ET is scheduled. This might increase accuracy compared to current tests for endometrial receptivity, that have to be performed in the cycle before ET. Trial registration number RF-2019-12369460

P-129 Transferring blastocysts derived from frozen-thawed cleavage embryos versus frozen-thawed blastocysts: A comparative analysis of pregnancy outcomes

Abstract Study question Is there an enhancement in pregnancy outcomes when cleavage-stage embryos are thawed, cultured for transfer as blastocysts, as opposed to transferring thawed blastocysts? Summary answer The strategy of culturing frozen-thawed cleavage embryos for 2 days and transferring them as blastocysts is not inferior to the transfer of frozen-thawed blastocysts. What is known already Embryo cryopreservation in IVF has many advantages, allowing couples to postpone pregnancy for personal reasons and reducing the risk of ovarian hyperstimulation syndrome. In the past, the common practice involved freezing and transferring cleavage embryos. However, a current trend favors single-embryo transfers at the blastocyst stage, promoting potential self-selection during extended culture. Several studies have raised concerns about potential damage during blastocyst vitrification, prompting investigation into whether cryopreserving cleavage-stage embryos for subsequent culturing to blastocysts yields superior outcomes compared to direct transfer of thawed blastocysts. Study design, size, duration This observational study was conducted at Hung Vuong Hospital from January 2022 to December 2023. We included 509 patients who underwent IVF followed by FET cycles. The D3-5 group (n = 167) comprised embryos that were frozen and thawed at the cleavage stage, subsequently extended two more days of culturing to the blastocyst stage for transfer. The D5 group (n = 342) involved frozen and thawed blastocysts. We excluded donor cycles, surrogacy, and cycles with preimplantation genetics testing. Participants/materials, setting, methods We used vitrification method for embryo cryopreservation. The freezing and thawing process were performed using either Kitazato or Cryotec medium kit, following manufacture’s instruction. Regarding the D3-5 group, thawed cleavage embryos were cultured for two more days until blastulation and transfer. Regarding the D5 group, blastocysts transfer was performed at least 2 hours after warming. The embryo transfer procedure was performed under abdominal ultrasonographical guidance. Pregnancy results were recorded and compared between two groups. Main results and the role of chance Regarding the D3-5 group, a noteworthy proportion of 65.3% cycles were unfortunately cancelled. The primary reason for cycle cancellations was the absence of developed blastocysts for transfer (85.3%). The remaining 14.7% of cancellations were attributed to other reasons. Fertilization rates were comparable between the two groups, with 80.8% in the D3-5 group and 81.5% in the D5 group (p = 0.464). However, the blastulation rate in the D3-5 group (40.1%) was lower than in the D5 group (46.4%), (p = 0.016). Patients in the D5 group demonstrated slightly better pregnancy outcomes compared to the D3-5 group: implantation rate (59.9% versus 51.7%, p = 0.302), clinical pregnancy rate (52.3% versus 44.8%, p = 0.36), ongoing pregnancy rate (37.7% versus 34.5%, p = 0746), live birth rate (33.9% versus 31%, p = 0.78), and miscarriage rate (26.3% versus 20.7%, p = 0.46). However, these differences were not statistical significance. Limitations, reasons for caution This is an observational study, we observed that thawing the cleavage-stage embryos then subsequently culture to the blastocyst stage may lead to the lower blastulation rate or even absence of developed blastocysts for transfer. This approach also increases the workload for embryologists. Wider implications of the findings Culturing frozen-thawed cleavage embryos for 2 days and transferring them as blastocysts increases workload for embryologists and poses a risk of cycle cancellation. We propose that the use of frozen-thawed blastocysts may be a more efficient and patient-friendly option. Trial registration number not applicable

P-608 Cumulative live birth rates after 3 consecutive embryo transfers in freeze-all cycles following gonadotropin-releasing hormone antagonist protocol versus progesterone-primed ovarian stimulation

Abstract Study question Do cumulative live birth rates in freeze-all cycles differ between gonadotropin-releasing hormone (GnRH) antagonist protocol and progesterone-primed ovarian stimulation (PPOS)? Summary answer GnRH antagonist and PPOS protocols have similar cumulative live birth rates in freeze-all cycles. What is known already GnRH antagonists and progesterone have been used for pituitary suppression in ovarian stimulation cycles. While PPOS protocol has the advantage of oral usage and lower cost, data regarding the laboratory and clinical outcome is limited and confounding. Freeze-all cycles might provide a better model to assess the impact of PPOS protocol and GnRH antagonist protocol on laboratory, clinical outcomes and cumulative live birth rates. Study design, size, duration A retrospective cohort study on IVF cycles performed (n = 568) between January 2020 and May 2022.The entire cohort of embryos were cryopreserved at the blastocyst stage.Inclusion criteria were 18-42 years of age,ICSI for severe male factor infertility.Exclusion criteria were PGD and severe endometriosis.Indications for cryopreservation in the antagonist group were high ovarian response (n:102),endometrial polyps (n:34),high follicular phase P4(n:48) and elective purposes(n:260).PPOS was used due to a transient shortage of GnRH antagonist in the market (n:124). Participants/materials, setting, methods 568 women (GnRH antagonist:444; PPOS:124) were included in the analysis.The primary outcome was the cumulative live birth rate (CLBR) after 3 consecutive embryo transfer cycle, and the secondary outcome parameters were the number of M-II oocytes, fertilization rate and blastocyst utilization rate. Student’s t-test was used for normally distributed continuous data and Fisher’s exact tests for categorical data were used. A generalized estimating equation model and logistic regression analysis were performed to adjust for confounding factors. Main results and the role of chance The mean age of the GnRH antagonist group was 34.1 ± 5.3 and 34.5 ± 5.7 years in PPOS group (p = 0.38). The baseline characteristics including BMI, serum AMH levels, duration of infertility, duration of stimulation and gonadotropin ampules used were similar in both groups. Estradiol and progesterone levels at the time of ovulation trigger were higher in GnRH antagonist cycles (2383.5 ± 1375.4 vs 2034.5 ± 1218.3, p = 0.02 and 0.7 ± 0.6 vs 0.5 ± 0.4, p = 0.01, respectively) The mean number of cumulus-oophorus complexes (12.9 ± 7.4 vs 11.5± 10.0, p = 0.61), M-II oocytes (10.0± 6.1 vs 9.1± 6.1, p = 0.14), frozen blastocysts (4.8± 3.5 vs 4.7± 3.6, p = 0.71) were similar between GnRH antagonist and PPOS groups, respectively. Fertilization rates (84.4% vs 87.2%, p = 0.12) and blastocyst utilization rates (63.4% vs 65.9%, p = 0.34) were also similar between GnRH antagonist and PPOS groups, respectively. The number of transferred embryos and the number of unused blastocysts were similar between groups. The CLBRs after one IVF cycle and 3 consecutive frozen-thawed blastocyst transfers were comparable in GnRH antagonist and PPOS cycles (56.8% and 53.2%, p = 0.37, respectively). Limitations, reasons for caution This was a retrospective study with relatively small sample size performed at a single fertility center, which may limit the generalizability of our findings. Wider implications of the findings If the fresh embryo transfer is not intended, PPOS protocol can be used in all patient types with cost-effective and patient-friendly manner. Trial registration number 2024.013.IRB2.012

P-153 Optimizing clinical outcomes in single vitrified-thawed blastocyst transfer cycles: impact of blastocyst re-expansion status

Abstract Study question is the blastocyst re-expansion status according to the thawing-transfer time interval related to the clinical outcomes in a single frozen-thawed blastocyst transfer cycles? Summary answer The post-thawing blastocyst shrinkage is linked to lower clinical outcomes, and minimizing the time between thawing and transfer optimizes outcomes especially for shrunken blastocysts. What is known already • A reduced ART outcome was observed with the use of shrunken post-warming blastocysts (Ito et al., 2023) • The spontaneous blastocyst shrinkage observed during in vitro embryonic development is considered as a negative prognosis factor for implantation (Sciorio et al., 2020) • The blastocyst’s re-expansion level after thawing proves to be the best post-thaw parameter for the prediction of live birth (The Vienna consensus., 2017. Ahlstrom et al., 2013). • The fast blastocele re-expansion seems to have a predictive value for implantation in frozen-thawed blastocyst transfer cycle (Shu et al., 2009). Study design, size, duration This was a retrospective study of 577 single frozen-thawed blastocyst transfer cycles from January 2022 to April 2023. Participants/materials, setting, methods Only B4 and B5 blastocyst quality obtained in day-5 were included in this study. The morphological characteristics were evaluated: after thawing (T0) and at Transfer time (TR). Blastocysts with 50% reduction of blastocele were classified “Shrunken”, the rest are “re-expanded”. and categorized into Group-1: re-expanded at T0 (n = 173); Group-2: shrunken at T0 and re-expanded at TR (n = 135); Group-3: shrunken at T0 and TR (n = 199). Statistical tests: chi-square, T-test and Mann-Whitney. (Statistical significance p &amp;lt; 0.05*). Main results and the role of chance Clinical outcomes of re-expanded blastocysts comparing to shrunken blastocysts at TR were respectively 42.21% versus 32.71% for pregnancy rate (PR) (p &amp;lt; 0.007),39.61% versus 30.48% for implantation rate (IR) (p &amp;lt; 0.02) and 35.71% versus 22.30% for life birth rate (LBR) (p &amp;lt; 0.004), a significantly higher outcomes were observed for re-expanded blastocysts. The miscarriage rate decreased from 25.00% to 9.23% (p &amp;lt; 0.001). The transfer of shrunken blastocysts in an interval of time within 1 hour or less comparing to more than 1 hour between T0 and TR showed the following results: PR = 40.82% versus 28.07% (p &amp;lt; 0.032), IR = 39.81% to 25.10%, (p &amp;lt; 0.02) and LBR = 26.53% versus 19.88% (p &amp;lt; 0.2). a significantly higher clinical outcomes were observed for shrunken blastocysts transferred within 1 hour or less. Group analysis: the PR, IR and LBR significantly increased for Group-1 comparing to Group 2. For Group-3, shrunken blastocysts at TR had the lower outcomes. (respectively p = 0.003; 0.017; 0.0002) Limitations, reasons for caution It is an ongoing retrospective observational study. Blastocysts with a low quality (B3 or less) were excluded from this study how limit our ability to extend the findings to low morphology degrees not covered by this research. Wider implications of the findings The management of frozen blastocyst transfers in IVF laboratories have to take into consideration in addition to the classic morphological evaluation, the blastocoele re-expansion state and the time interval between thawing and transfer to optimize the transfer outcomes. Trial registration number not applicable

P-588 Serum Luteinizing Hormone levels before progesterone supplementation are significantly associated with live birth rate in single euploid frozen embryo transfers performed in hormonal replacement cycles

Abstract Study question Do luteinizing hormone (LH) levels measured prior to initiating progesterone supplementation influence live birth rate (LBR) in artificial frozen-thawed single euploid blastocyst transfer cycles? Summary answer Serum LH levels, measured prior to progesterone initiation in artificial frozen-thawed single euploid blastocyst transfer cycles, are significantly associated with LBR. What is known already In the absence of a dominant follicle, estrogen supplementation in artificial endometrial preparation for frozen embryo transfer (FRET) can lead to a rise in endogenous LH levels, as observed in a natural cycle. Since the LH rise is a key feature in natural conception and the embryo, the endometrium, and the myometrium display receptors for LH, the rise observed during FRET preparation may have an impact on the clinical outcomes of the treatment. Previous studies found contradictory results hence none of them excluded embryo aneuploidy by implementation of preimplantation genetic testing for aneuploidies and the transfer of euploid embryos. Study design, size, duration Retrospective analysis of 639 frozen-thawed single euploid blastocyst transfer cycles performed in a tertiary referral IVF center from January 2018 to August 2023. Cycles with hormonal pre-treatment or pituitary suppression were excluded. Participants/materials, setting, methods Single euploid FRET cycles were included. Oral estradiol administration commenced on cycle-day 2/3. Estradiol, progesterone, and LH were measured at the start of endometrial preparation and up to 3 days before progesterone initiation, and the slope of LH was calculated. Patients were stratified in groups according to their LH values before progesterone administration, and the impact of LH on LBR and implantation rate was assessed. Logistic regression analysis was performed to adjust for potential confounders. Main results and the role of chance In total 639 cycles were included. Patients’ characteristics (mean+/-SD) were: age 33.2±5.9 years; BMI 27.5±4.9 kg/m2. The median duration of estrogen administration was 15 days (range: 11-27 days). The overall implantation rate and LBR were 65.9% (421/639) and 46.9% (300/639), respectively. Patients were stratified into six groups according to their LH levels prior to progesterone supplementation: &amp;lt;10th percentile (≤6mIU/ml, n = 57), p10th-p25th (&amp;gt;6 to ≤ 8.5mIU/ml, n = 81), p25th-p50th (&amp;gt;8.5 to ≤ 12.4mIU/ml, n = 176), p50th-p75th (&amp;gt;12.4 to ≤ 18.1mIU/ml, n = 180), p75th-p90th (&amp;gt;18.1 to ≤ 25.0mIU/ml, n = 91) and &amp;gt;p90th (&amp;gt;25.0mIU/ml, n = 54). A significant trend for higher LBR with increasing serum LH levels was observed (Cochran-Armitage Test, P = 0.041) but not for implantation rate (P = 0.158). Those with higher basal serum estradiol levels before estrogen supplementation had a steeper LH increase from basal to progesterone-supplementation day (0.40 mIU/mL higher per 10pmol/L increase in basal estradiol, P = 0.027). Regression analysis identified as independent predictors of LBR BMI (OR 0.96, 95%CI: 0.93-0.99) and embryo quality (CC vs. AA p &amp;lt; 0.001, CB vs. AA p = 0.027, BC vs. AA p = 0.013). Patients with steeper LH increases from estrogen to progesterone-supplementation day had higher LBR in both univariable (OR:1.27, 95%CI: 1.00–1.63, P = 0.052) and multivariable analyses (OR:1.26, 95%CI: 0.97–1.64, P = 0.085) but the difference didn’t reach statistical significance. Limitations, reasons for caution The retrospective design of the study is a limitation. Results should be interpreted with caution due to the small number of patients in the lowest and highest LH percentile groups. Wider implications of the findings The results of this study suggest that serum LH levels measured before progesterone supplementation may have an impact on the clinical outcome of artificial frozen-thawed blastocyst transfer cycles. Further studies with a higher sample size are necessary to confirm or refute our findings. Trial registration number not applicable

Trophectoderm biopsy is associated with lower risks of moderate to extreme prematurity and low birthweights: a national registry cohort study of singleton livebirths from frozen-thawed blastocyst transfers

BackgroundTrophectoderm biopsy has become the mainstay assisted reproductive technique performed for preimplantation genetic testing, accounting for 43.8% of embryo transfer cycles in the US in 2019 alone. Despite its prevalence, data on the obstetric and perinatal outcomes post trophectoderm biopsy remains sparse and mixed. ObjectiveThis study aimed to examine the risks of adverse perinatal outcomes in birth weights and prematurity after transfers of vitrified-thawed blastocyst with trophectoderm biopsy for preimplantation genetic testing. Study DesignThis was a retrospective observational cohort study of 45,712 singleton live births resulting from autologous vitrified-thawed blastocyst transfer cycles with or without trophectoderm biopsy for preimplantation genetic testing, reported by participating member clinics to the Society for Assisted Reproductive Technology national registry between 2014 and 2017. Adverse perinatal outcomes of preterm births and low birth weights were analyzed. Multivariable regression analyses were performed to control for covariates. Comparing the trophectoderm biopsy (n=21,584) and no trophectoderm biopsy (n=24,128) groups, adjusted odds ratios were calculated for the outcomes of small for gestational age, large for gestational age, low birth weight < 2,500 g, very low birth weight < 1,500 g, extremely low birth weight < 1,000 g, late preterm births < 37 weeks, moderate preterm births < 34 weeks, and extremely preterm births < 28 weeks. ResultsWomen in the trophectoderm biopsy group were older and more likely to have prior pregnancies, deliveries, and history of spontaneous abortions. Tobacco use, diminished ovarian reserve, and recurrent pregnancy loss were also more prevalent in the trophectoderm biopsy group. Trophectoderm biopsy was not associated with small-for-gestational-age (aOR 0.97, 95% CI 0.85-1.12, p-value 0.72) or large-for-gestational-age newborns (aOR 1.10, 95% CI 0.99-1.22, p-value 0.09). Risks of preterm births < 37 weeks gestation were similar between the biopsy and non-biopsy groups (aOR 0.93, 95% CI 0.85-1.02, p-value 0.11). Trophectoderm biopsy was associated with a significantly lower risk of low birthweight < 2,500 g (aOR 0.80, 95% CI 0.70-0.92, p-value <0.001), very low birthweight < 1,500 g (aOR 0.62, 95% CI 0.46-0.83, p-value <0.001), extremely low birthweight < 1,000 g (aOR 0.48, 95% CI 0.31-0.74, p-value <0.001), moderate preterm birth < 34 weeks (aOR 0.76, 95% CI 0.64-0.91, p-value 0.003), and extreme preterm birth < 28 weeks (aOR 0.63, 95% CI 0.43-0.92, p-value 0.017). ConclusionTrophectoderm biopsy is not associated with increased risks of small for gestational age, large for gestational age, or late preterm birth. Risks of low birthweight, very low birthweight, and extremely low birthweight from moderate and extreme preterm births are lower after trophectoderm biopsy, possibly by selecting against confined placental mosaicism or inducing placental epigenetic changes, the mechanisms of which warrant further investigation.

Clinical Outcomes of Frozen-Thawed Single Blastocyst Transfers in Relation to Blastocyst Diameter and Timing of Cryopreservation

Background: It is important to select blastocysts based on their likelihood of leading to pregnancy. The purpose of this study was to focus on expansion time and blastocyst diameter as simple factors to assess blastocysts relative to clinical outcomes. Methods: This study is based on 1,514 cycles in women [Formula: see text] years who underwent frozen-thawed blastocyst transfer (FBT) between November 2017 and February 2021. Blastocysts were classified according to the time they reached [Formula: see text]m inner diameter (116, 120, and 140[Formula: see text]h). Furthermore, blastocyst diameter at freezing was classified into three groups: groups S (under 167[Formula: see text][Formula: see text]m), M (167–181[Formula: see text][Formula: see text]m), and L (over 181[Formula: see text][Formula: see text]m), based on tertile values. We compared the clinical outcomes (including the clinical pregnancy rate [CPR]) of FBT. Results: CPR was significantly higher in groups M and L than in group S at 116[Formula: see text]h ([Formula: see text]). At 120[Formula: see text]h, CPR in group L was significantly higher than in group S ([Formula: see text]). However, at 140[Formula: see text]h, there were no significant differences among the three groups. There were no significant differences in miscarriage rates at 116, 120, and 140[Formula: see text]h. When only good quality embryos were compared, group L resulted in a significantly higher CPR than group S at 116[Formula: see text]h ([Formula: see text]). At 120[Formula: see text]h, both groups M and L had significantly higher CPR than group S ([Formula: see text]). There were no significant differences at 140[Formula: see text]h. Conclusion: These results suggest that when multiple embryos are frozen at the same time on day 5 of culture, a higher pregnancy rate can be obtained by selecting embryos with larger blastocyst diameters. In addition, it is important to confirm sufficient blastocyst expansion before cryopreservation.

In vitro Fertilization Outcomes of Frozen-thawed Embryo Transfer with Hatched Blastocysts versus with Hatching Blastocysts.

This study aimed to elucidate the effect of hatching status on in vitro fertilization (IVF) outcomes in frozen-thawed blastocyst transfer cycles. Frozen-thawed embryo transfer (FET) cycles performed at a single fertility center between 2016 and 2021 were retrospectively assessed. Analyses were restricted to 6,821 frozen-thawed blastocyst transfers in women aged 24-47 years. For optimal comparability, double embryo transfer (ET) cycles consisting of one hatching and one hatched blastocyst were excluded. The implantation and pregnancy rates were evaluated and compared between the hatching and hatched blastocyst transfer groups based on patients' age (<38 vs. ≥38 years), blastocyst grade (good vs. bad grade), and the number of transferred embryos (single ET vs. double ET). Hatched blastocyst transfer was associated with higher implantation and clinical pregnancy rates in the single ET group (15.7% and 15.6%, respectively; p<0.001). The transfer of two hatched blastocysts had higher implantation and clinical pregnancy rates compared to the transfer of two hatching blastocysts (19.5% and 20.4%, respectively; p<0.001) in the double ET group. In the hatched blastocyst transfer group, the clinical pregnancy and implantation rates were higher, regardless of each woman's age and embryo quality. The IVF treatment outcomes were improved when the blastocysts were hatched during FET cycles. Hence, hatched blastocyst transfer in FET cycles could be considered a superior method in IVF practice.

Impact of double trophectoderm biopsy on reproductive outcomes following single euploid blastocyst transfer

ObjectivesTo study the effect of double trophectoderm biopsy on clinical outcomes following single euploid blastocyst transfer. Study designRetrospective cohort study of 2046 single euploid frozen-thawed blastocyst transfers from January 2015 to June 2022 in a single centre.All patients undergoing a frozen-thawed embryo transfer (FTET) cycle with euploid blastocysts, biopsied for any indication, were included. The outcomes were compared for blastocysts which were biopsied and vitrified once (Group 1, n = 1684), biopsied once but vitrified twice (Group 2, n = 312) and biopsied and vitrified twice (Group 3n = 50). We adjusted for confounders and performed subgroup analysis for PGT-A, PGT-M and PGT-SR cycles. The primary outcome was live birth rate. Secondary outcomes included pregnancy, clinical pregnancy, birthweight and sex ratio. ResultsAfter adjusting for confounders (previous failed euploid implantations, embryo quality and day of biopsy), embryos which were biopsied twice had lower OR for clinical pregnancy (0.48, CI 0.26–0.88, p = 0.019) and for live birth (0.50 CI 0.27–0.92, p = 0.025) compared to controls. Embryos which were biopsied once but vitrified twice had no different ORs for all reproductive outcomes compared to controls. No significant difference was observed for neonatal birthweight or sex ratio amongst the three groups. This is a retrospective single centre study with inherent bias and results may not be transferable to all settings. ConclusionThis study is the largest to date assessing the outcomes of FTET cycles following double trophectoderm biopsy. The results are in keeping with the existing literature and can be incorporated into patient counselling. Whilst double biopsy seems to adversely impact LBR, it is only one of the many factors that can affect success rates. The subfertility background and embryo characteristics should not be overlooked. This study provides reassuring evidence since double biopsied embryos still result in live births with no difference in sex ratio or birthweight. However, long term follow up of the off-springs is lacking and should be reported in future studies.

Female smoking does not affect live birth rate after frozen thawed blastocyst transfer cycle

PurposeThe development of vitrification and blastocyst culture have recently led to a rapidly growing number of single frozen thawed blastocyst transfer (FBT) cycles worldwide. Although the impact of female smoking on spontaneous fertility is well established, its effect on assisted reproductive technologies (ART) outcome is still controversial, and no study has specifically evaluated its effect on FBT cycles’ outcome. MethodsThis retrospective study was conducted in all consecutive FBT cycles conducted between 2012 and 2021 in a single University-based ART centre. Endometrial preparation was standard and based on hormonal replacement therapy. One or two blastocysts were transferred according to couple's history and embryo quality. Female smoking status was recorded for each cycle, and the association between female smoking status and Live Birth Rate (LBR) after FBT cycle was evaluated with univariate and multivariate analysis. ResultsA total of 1537 FBT cycles performed in non-smoking women and 397 FBT cycles performed in smoking women were included in the analysis. No independent association between female smoking status and LBR in FBT cycles was found after logistic regression (OR=1.07 [0.79–1.45], p = 0.649). ConclusionOur study suggests that female smoking might not impair endometrial receptiveness in non-stimulated FBT cycles. Further studies should nevertheless consider assessing more precisely the current smoking exposure.

Effect of post-vitrification cryopreservation duration on singleton birth-weight in frozen-thawed blastocysts transfer cycles.

This study aimed to explore the effect of cryopreservation duration after blastocyst vitrification on the singleton birth-weight of newborns to assess the safety of long-term preservation of frozen-thawed blastocyst transfer (FBT) cycles. This was a retrospective observational study conducted at the Gynecological Endocrinology and Assisted Reproduction Center of the Peking Union Medical College Hospital. Patients who gave birth to singletons between January 2006 and December 2021 after undergoing FBT cycles were included. Five groups were formed according to the duration of cryopreservation of embryos at FBT: Group I included 274 patients with a storage time < 3 months. Group II included 607 patients with a storage time of 3-6 months. Group III included 322 patients with a storage time of 6-12 months. Group IV included 190 patients with a storage time of 12-24 months. Group V included 118 patients with a storage time of > 24 months. Neonatal outcomes were compared among the groups. Multivariate linear regression analysis was performed to evaluate birth-weights and other birth-related outcomes. A total of 1,511 patients were included in the analysis. The longest cryopreservation period was 12 years. The birth-weights of neonates in the five groups were 3344.1 ± 529.3, 3326.1 ± 565.7, 3260.3 ± 584.1, 3349.9 ± 582.7, and 3296.7 ± 491.9 g, respectively (P > 0.05). The incidences of preterm birth, very preterm birth, low birth-weight, and very low birth-weight were similar in all groups (P > 0.05). The large-for-gestational-age and small-for-gestational-age rates did not differ significantly among the groups (P > 0.05). After adjusting for confounding factors that may affect neonatal outcomes, a trend for an increased risk of low birth-weight with prolonged cryopreservation was observed. However, cryopreservation duration and neonatal birth-weight were not significantly correlated (P > 0.05). The duration of cryopreservation after blastocyst vitrification with an open device for more than 2 years had no significant effect on the birth-weight of FBT singletons; however, attention should be paid to a possible increase in the risk of low birth-weight.

Which factors affect the live birth outcome of the first single euploid frozen-thawed blastocyst transfer in couples with balanced chromosomal translocations?

The objective of this study is to investigate the factors that influence the live birth rate (LBR) of the first single euploid frozen-thawed blastocyst transfer (FBT) cycles after preimplantation genetic testing for structural rearrangements (PGT-SR) in couples with balanced chromosomal translocations (BCT). Single center, retrospective and observational study. A total of 336 PGT-SR and the first single euploid FBT cycles between July 2016 and December 2022 were included in this study. The patients were divided into two groups according to the live birth outcomes. The parameters of the study population, controlled ovarian stimulation cycles, and FBT cycles were analyzed. Multivariable binary logistic regression was performed to find the factors that affected the LBR. The percentage of blastocysts at developmental stage Day 5 compared to Day 6 (51.8% vs. 30.8%; P<0.001) and with morphology ≥BB compared to <BB (49.7% vs. 32.2%; P=0.001) was significantly different between the group that resulted in live births (n=193) and the group that did not (n=143). The results of the multivariable binary logistic regression analysis indicated that the developmental stage (adjusted OR: 2.068, 95%CI 1.291-3.313; P=0.003) and morphology (adjusted OR: 1.697, 95%CI 1.039-2.773; P=0.035) of the blastocyst were significantly correlated with live birth. Patients with blastocysts that reached the developmental stage at Day 5 and had a morphology of ≥BB had a higher likelihood of having a live birth. The developmental stage and morphology of blastocyst affect the live birth outcome of the first single euploid FBT in BCT carriers undergoing PGT-SR.

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.

Single versus double blastocyst transfer in first and second frozen-thawed embryo transfer cycle in advance-aged women: a two-center retrospective cohort study.

The present evidence is deficient for the trade-offs between the pros and cons of single blastocyst transfer (SBT) versus double blastocyst transfer (DBT) in frozen-thawed embryo transfer cycles for women in advanced reproductive age, especially in the second cycle. The current study aimed to investigate the impact of transferred blastocyst numbers on pregnancy outcomes in the first and second embryo transfer for women ≥ 35 years. This was a retrospective cohort study including 1284 frozen-thawed blastocyst transfer (FBT) cycles from two reproductive centers. We analyzed the pregnancy outcomes after SBT and DBT in the first and second FBT cycles. Moreover, stratified analysis was conducted by maternal age. In the first FBT cycle, the LBR was higher in the DBT group than that in the SBT group [52.3% vs. 33.9%; adjusted odds ratio (aOR), 1.65; 95% confidence interval (CI), 1.26-2.15, P < 0.001]. However, the LBR of the DBT group showed no remarkable difference compared with that of the SBT group in the second cycle of FBT (44.3% vs. 33.3%; aOR, 1.30; 95% CI, 0.81-2.08; P = 0.271). Furthermore, stratified analysis by age showed a higher LBR for the DBT group than the SBT group in patients aged 38-42 years (43.1% vs. 33.9%; aOR, 2.27; 95% CI, 1.05-4.90; P = 0.036). The present study demonstrated that the SBT regimen is a better choice for both, the first and second frozen-thawed embryo transfer cycles, for women aged 35-37 years. Additionally, the DBT regimen is still recommended to achieve a high LBR in women aged 38-42 years in the second FBT cycle. These findings may be beneficial for deciding the embryo transfer regimens in women of advanced reproductive age.

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.