Frozen-thawed Blastocyst Transfer Research Articles

Combined analysis of human chorionic gonadotrophin concentrations at different time points after frozen-thawed blastocyst transfer can improve our ability to predict the pregnancy outcomes of single gestations

In this study, we conducted a retrospective single-centre study of 1664 singleton pregnancies derived from frozen-thawed blastocyst transfer between January 2017 and December 2018. Analysis showed that there were 596 early pregnancy losses and 1068 ongoing pregnancies. We compared serum HCG (human chorionic gonadotophin) concentrations on days 12, 14, 19, and 21, between the pregnancy loss group and the ongoing pregnancy group. The cut-off level of HCG at each time point was calculated to predict pregnancy outcome. Joint analysis of two single HCG levels taken one week apart was carried out to improve predictive accuracy. The levels of HCG at four time points were significantly lower in the early pregnancy loss group than in the ongoing pregnancy group. According to the area under ROC (receiver operating characteristic curve) curves, all levels of HCG taken at four time points showed good ability to predict the outcome of pregnancy. The joint analysis of two single HCG levels taken one week apart further improved the accuracy of prediction. Impact statement What is already known on this subject? Multiple studies have shown that the maternal level of serum HCG is the best parameter for predicting the course of pregnancy. What do the results of this study add? The levels of HCG on days 12, 14, 19 and 21 were significantly lower in the early pregnancy loss group than in the group of ongoing pregnancies. According to the area under ROC curves, all levels of HCG taken at four time points showed a good ability to predict the outcome of pregnancy. What are the implications of these findings for clinical practice and/or further research? The joint analysis of two single HCG levels, taken one week apart, further improved the accuracy of prediction.

Black race associated with lower live birth rate in frozen-thawed blastocyst transfer cycles: an analysis of 7,002 Society for Assisted Reproductive Technology frozen-thawed blastocyst transfer cycles

To evaluate if racial/ethnic differences in pregnancy outcomes persisted in frozen-thawed embryo transfer (FET) cycles on a national level. Retrospective cohort study. Clinic-based data. A total of 189,000 Society for Assisted Reproductive Technology FET cycles from 2014-2016 were screened, of which 12,000 cycles had available fresh cycle linkage information and ultimately, because of missing data, 7,002 FET cycles were included. Cycles were stratified by race (White, Black, Asian, and Hispanic). None. The primary outcome was live birth rate. Secondary outcomes were implantation rate, clinical pregnancy rate, multiple pregnancy rate, and clinical loss rate (CLR). Live birth rate was significantly lower in the Black vs. White and Asian, but not Hispanic group. Implantation rate was also significantly lower and CLR higher in the Black group compared with all other groups (all P<.01). Black women had a lower risk of live birth (adjusted risk ratio, 0.82; 95% confidence interval [CI], 0.73-0.92) and a higher risk of clinical loss (adjusted risk ratio, 1.59; 95%CI, 1.28-1.99) compared with White women. There was no significant difference between groups in clinical pregnancy rate or multiple pregnancy rate. When the analysis was limited to preimplantation genetic testing FET cycles, there remained a significantly lower implantation rate in the Black group compared with all other groups (all P<.01). Black race remains an independent predictor of reduced live birth rate in FET cycles, likely because of higher CLR.

L’obésité affecte les chances de naissance après transfert de blastocystes congelés

ObjectivesBoth the number of frozen-thawed embryo transfers and the incidence of obesity have increased sharply in recent years in Assisted Reproductive Technology (ART) centers. The objective of our study is therefore to evaluate the impact of female obesity on pregnancy outcomes for frozen-thawed embryo transfer at blastocyst stage. MethodsThis is a single-center retrospective study conducted between January 1, 2016, and December 31, 2019, in our Assisted Reproduction Center in Calais. All consecutive cycles of frozen embryo transfers at blastocyst stage with artificial cycle were included. A total of 296 cycles could be included corresponding to 220 cycles realized in normal Body Mass Index (BMI) patients (18.5–24.9kg/m2) and 76 in obese patients (BMI≥30kg/m2). ResultsLive birth rates and implantation rates were significantly lower in obese patients compared with patients with a normal BMI (respectively 9.2 % vs. 22.3 % and 10 % vs. 20.8 %, P=0.01 and P<0.01). ConclusionsTherefore, our study showed that obesity is associated with a lower rate of live birth and implantation following frozen-thawed blastocyst transfers in artificial cycles. This could be explained by different factors that can be both embryonic and/or extra-embryonic.

Effect of endometrial thickness changes on clinical pregnancy rates after progesterone administration in a single frozen-thawed euploid blastocyst transfer cycle using natural cycles with luteal support for PGT-SR- and PGT-M-assisted reproduction: a retrospective cohort study

BackgroundTo investigate whether the endometrial thickness change ratio from the progesterone administration day to the blastocyst transfer day is associated with pregnancy outcomes in a single frozen-thawed euploid blastocyst transfer cycle.MethodsAll patients used natural cycles with luteal support for endometrial preparation and selected a single euploid blastocyst for transfer after a biopsy for preimplantation genetic testing. The endometrial thickness was measured by transvaginal ultrasound on the progesterone administration day and the transfer day, the change in endometrial thickness was measured, and the endometrial thickness change ratio was calculated. According to the change rate of endometrial thickness, the patients were divided into three groups: the endometrial thickness compaction group, endometrial thickness non-change group and endometrial thickness expansion group. Among them, the endometrial thickness non-change and expansion groups were combined into the endometrial thickness noncompaction group.ResultsUltrasound images of the endometrium in 219 frozen-thawed euploid blastocyst transfer cycles were evaluated. The clinical pregnancy rate increased with the increase in endometrial thickness change ratio, while the miscarriage rate and live birth rate were comparable among the groups. The multiple logistic regression results showed that in the fully adjusted model a higher endometrial thickness change ratio (per 10%) was associated with a higher clinical pregnancy rate (adjusted odds ratio [aOR] 1.29; 95% confidence interval [CI], 1.01–1.64; P = .040). Similarly, when the patients were divided into three groups according to the change rate of endometrial thickness, the endometrial thickness noncompaction group had a significant positive effect on the clinical pregnancy rate compared with the endometrial thickness compaction group after adjusting for all covariates.ConclusionsIn frozen-thawed euploid blastocyst transfer cycles in which the endometrium was prepared by natural cycles with luteal support, the clinical pregnancy rate was higher in cycles without endometrial compaction after progesterone administration.

REPRODUCTIVE OUTCOMES FOLLOWING FROZEN-THAWED EMBRYO TRANSFER IS SUPERIOR WITH THE TRANSFER OF BLASTOCYSTS EXPANDED ON DAY 5 THAN ON DAY 6

Abstract: To compare pregnancy and live birth rates between D5 and D6 transfer of frozen-thawed blastocysts in women undergoing ‘freeze-all’ cycles. This retrospective cohort study included 209 single autologous frozen–thawed blastocyst transfers. This cohort was divided into 2 groups based on the day of blastocyst expansion: (i) D5 blastocysts and (ii) D6 blastocysts. A ‘freeze-all’ strategy was adopted using GnRH antagonist cycles and vitrification as the method of freezing. Pregnancy rate was higher in D5 group as compared to D6 group, although not statistically significant (72.6% vs. 59.6%, respectively, p=0.078). Live birth rate was significantly higher in D5 group than in D6 group (66.9% vs. 48.1%, respectively, p=0.015). The rates of abortus, biochemical pregnancy and preterm birth were comparable between the groups. Live birth rate is superior when blastocysts expanded on D5 are used in frozen–thawed cycles, compared to those expanded on D6. The day of the blastocyst expansion appears to be an important predictor of pregnancy outcome and, thus, taken into account as well as D5 embryos should be given priority in frozen-thawed transfer cycles.

Association between endogenous LH level prior to progesterone administration and live birth rate in artificial frozen-thawed blastocyst transfer cycles of ovulatory women.

Is there an association between serum LH levels prior to progesterone administration and live birth rate (LBR) in artificial frozen-thawed embryo transfer (FET) cycles? : Low serum LH levels on the day before progesterone initiation in artificial frozen-thawed blastocyst transfer cycles of ovulatory women are associated with a lower LBR. In artificial FET cycles, exogenous oestrogen and progesterone are administered sequentially to mimic the serum hormone pattern similar to the natural cycle. In oestrogen-only phase, the supplemental oestrogen causes thickening of the endometrium and is sometimes accompanied by a rise in serum LH. However, whether the endogenous LH level in artificial FET cycles is related to clinical outcomes remains unclear. A retrospective cohort study including 3469 artificial frozen-thawed blastocyst transfer cycles was conducted at a tertiary-care academic medical centre between February 2014 and January 2020. A total of 3469 frozen blastocyst transfer cycles were stratified into four groups based on the quartiles of serum LH level before progesterone initiation: <25th percentile (LH < 8.79 mIU/ml), 25-50th percentile (8.79 ≤ LH ≤ 13.91 mIU/ml), 51-75th percentile (13.91 < LH ≤ 20.75 mIU/ml) and >75th percentile (LH > 20.75 mIU/ml). The serum LH level >75th percentile group was considered as the reference group. Patients with polycystic ovarian syndrome or other ovulatory disorders were excluded from the study. We also excluded cycles with an endometrial thickness <7 mm before progesterone initiation and patients with intrauterine adhesions and uterine abnormalities. In order to avoid the interference of BMI, all patients were divided into two categories based on the overweight threshold: BMI <25 kg/m2 and ≥25 kg/m2, and the impacts of serum LH levels on LBR were investigated separately. Univariable and multivariable logistic regression analysis were performed to adjust for potential confounders. EmpowerStats software and R-project were used to build smooth curve fitting models. Compared with the reference group, the implantation rate significantly decreased with low LH levels (<25th percentile) on the day before progesterone initiation (odds ratio [OR] = 0.74; 95% CI, 0.64-0.86; P = 0.001). Accounting for major covariates, low LH levels were associated with a relatively lower LBR (adjusted OR = 0.649; 95% CI, 0.531-0.794; P < 0.001), mainly due to a lower implantation rate, lower clinical pregnancy rate and higher pregnancy loss rate. Moreover, in the patients with BMI <25 kg/m2, low LH was associated with a lower LBR (P < 0.001); while in the overweight subgroup, LBR and LH were not correlated (P = 0.823). The main limitation of this study is its retrospective design. Owing to the relatively small number in the overweight group, the results of the overweight subgroup should be interpreted with caution. The evidence provided in this study shows the importance of serum LH levels on the day before progesterone initiation in patients undergoing artificial FET cycles. Hypothalamic dysfunction may be one of the important causes of a relatively low LH, which is related to impaired pregnancy outcomes. Serum LH levels may be used as one of the clinical indicators to predict pregnancy outcomes. No funding and no competing interest were involved in this study. NA.

Live Birth Rate of Frozen-Thawed Single Blastocyst Transfer After 6 or 7 Days of Progesterone Administration in Hormone Replacement Therapy Cycles: A Propensity Score-Matched Cohort Study.

BackgroundProgesterone administration before transfer in hormone replacement treatment (HRT) is crucial to pregnancy outcomes in frozen-thawed blastocyst transfer (FET), but the optimal progesterone duration is inconsistent. The objective of this study was to investigate live birth rate (LBR) of different progesterone duration before blastocyst transfer in HRT–FET cycles.MethodIn this retrospective cohort study, patients underwent first HRT–FET (including suppression HRT) from January 2016 to December 2019 were included. Logit-transformed propensity score matching (PSM) was performed to assess covariates. The primary outcome was live birth rate after 28 weeks’ gestation. Basing on different duration of progesterone before transfer, patients were classified into P6-protocol (blastocyst transfer performed on the sixth day), or P7-protocol (blastocyst transfer performed on the seventh day). Subgroup analyses were conducted as follows: age stratification (–35, 35–38, 38–), development days of blastocyst (D5 or D6), blastocyst quality (high-quality or poor-quality), and endometrial preparation protocols (HRT or suppression HRT).ResultAfter case matching with propensity score methods, a total of 1,400 patients were included finally: 700 with P6-protocol and 700 with P7-protocol. Significantly higher live birth rate (38.43% versus 31.57%, respectively, P = 0.01) and clinical pregnant rate (50.43% versus 44.14%, respectively, P = 0.02) were observed in P6-protocol than those of P7-protocol. First-trimester abortion rates (18.13% versus 20.71%, P = 0.40) and ectopic pregnancy rates (2.27% versus 1.94%, P = 0.77) were similar between P6- and P7-groups. Preterm birth rate, low birth weight rate, newborn sex proportion, neonatal malformation rate were comparable between groups. Significantly higher LBRs were observed in patients with: age under 35, D5 blastocyst transfer, high-quality blastocyst transfer, and undergoing HRT cycles combined P6-protocol.ConclusionFrozen-thawed blastocyst transfer on the sixth day of progesterone administration in first HRT cycle is related to higher live birth rate compared with transfer on the seventh day, especially among patients aged under 35, D5 blastocyst and/or high-quality blastocyst transfer.

P–760 Cycle outcomes in frozen-thawed single blastocyst transfers in overweight and obese women

Abstract Study question Are cycle outcomes different in frozen embryo transfer in obese and overweight women compared to normal weight cases? Summary answer As BMI increases, although implantation rates are similar, miscarriage rates increase and live birth rates decrease, especially in cases whose BMI value is above 30. What is known already Obesity has adverse effects on the reproductive system. Obesity causes ovulatory dysfunction and menstrual cycle disorders, thus reducing fertility. As BMI increases, the implantation, pregnancy and ongoing pregnancy rates decrease and the rate of clinical losses increases. In donor oocyte cycles, the BMI of the recipient has a statistically significant detrimental effect on obstetrics outcomes such as pregnancy rate and live birth rate. However, very few studies evaluate the impact of BMI on frozen-thawed single blastocyst transfer. Study design, size, duration This retrospective study was conducted at Istanbul Memorial Hospital, ART and Reproductive Center between 2011 and 2020. A total of 5642 frozen-thawed single blastocyst transfer cycles were examined. Patients were grouped according to the World Health Organisation BMI classification system: Group I (BMI 25–29.9) (n = 1663); Group II (BMI 30–34.9) (n = 598); Group III (BMI 35–39.9) (n = 150); Group IV (BMI&amp;gt;40) (n = 30); Control Group (BMI 18.5–24.9) (n = 3201). Participants/materials, setting, methods: Patients between 17–42 years old were included. Preimplantation genetic diagnosis (PGD) was performed for patients &amp;gt;37 years old. Exclusion criteria were: repeated pregnancy losses, Mullerian abnormalities, intrauterine adhesions, endometrial thickness &amp;lt;7mm during frozen embryo transfer (FET) cycle. For endometrial preparation, modified natural cycle or artificial cycle were used. Single top/good quality blastocysts were transferred. Main results and the role of chance A total of 5642 FET cycles were analyzed. There was no significant difference in patient characteristics in terms of mean age, endometrial thickness on embryo transfer day and Anti Mullerian Hormone levels between the groups. Cycle outcomes were analysed according to the BMI groups. Mean age of groups were 32.1(17–42), 32(18–42), 32.6(20–42), 32.8(23–42) in groups I to IV respectively and 32(18–42) in the control group. Pregnancy rates were 70.9%(n = 1180) 70.7%(n = 423), 76%(n = 114) and 54.8%(n = 17) in groups I to IV respectively and 72.4% in the control group(n = 2321) (p &amp;gt; 0,05). Clinical pregnancy losses rates were 18.9%(n = 196), 23.9%(n = 86), 23.1%(n = 22) and 23%(n = 3) in groups I to IV respectively and 15.1% in the control group(n = 316) (p &amp;lt; 0,05). The live birth rates were 49.9%(n = 830) 45.1%(n = 270), 47.3%(n = 71) and 33.3%(n = 10) in groups I to IV, respectively and 54.9% (n = 1759) in the control group (p &amp;lt; 0,05). There was no statistically significant difference in implantation rates between the groups but clinical pregnancy losses rates were higher in obese patients (groups II-III-IV) whereas live birth rates were lower compared to group I (overweight) and the control group. Limitations, reasons for caution The limitation of the study is its retrospective nature. Wider implications of the findings: Our study shows that, there is a significantly higher risk of negative cycle outcomes in obese patients. Pre-treatment counselling is therefore needed to increase patient awareness of the risks and to provide advice on weight loss. Trial registration number Not applicable

P–691 How predictive is endometrial thickness for live birth after fresh and frozen-thawed embryo transfer when no cut-off is employed?

Abstract Study question Does endometrial thickness (EMT) predict live birth (LB) after fresh and frozen-thawed embryo transfer (ET) and is there a lower EMT cut-off for ET? Summary answer Once intracavitary pathology and inadvertent progesterone exposure is excluded, EMT is not predictive for LB. EMT is not linearly associated with probability of LB. What is known already EMT is commonly used as a marker of endometrial receptivity and in turn, assisted reproductive technology treatment success. ET is often cancelled or postponed if EMT is below an arbitrary cut-off. However, the available evidence on the relationship between EMT and LB rates is conflicting and too dubious to hold such strong stance. An overwhelming majority of the studies on the subject are retrospective, they use different arbitrary cut off values ranging between 6 to 9 mm with heterogeneous stimulation and transfer protocols. Study design, size, duration Records of all women who underwent fresh or frozen-thawed ET in Koc University Hospital Assisted Reproduction Unit between October 2016 - August 2019 were retrospectively screened. All women who underwent fresh or frozen-thawed blastocyst transfer during the study period were included. Every woman contributed to the study with only one transfer cycle for each category, i.e., fresh ET and frozen-thawed ET. Participants/materials, setting, methods After ruling out endometrial pathology, EMT was measured on the day of ovulation trigger for fresh ET cycles, and on the day of progesterone commencement for frozen-thawed ET. ET was carried out, regardless of EMT, if there was no suspicion of inadvertent progesterone exposure, i.e., due to follicular phase progesterone elevation in fresh or premature ovulation in frozen ET cycles. Main results and the role of chance 560 ET cycles, 273 fresh and 287 frozen-thawed, were analyzed. EMT varied from 4mm to 18mm. EMT were similar between women who achieved a LB and who did not after fresh ET [10.5 (9.2 – 12.2) mm and 9 (8 – 11) mm, respectively, p = 0.11]. Ovarian stimulation characteristics and proportion of women who received a single embryo were similar (69% vs 68.3%, respectively, p = 0.91). Women who achieved a LB was significantly younger than those who did not [35 (32–38) and 37 (33–41), respectively, p &amp;lt; 0.01]. Women who had a LB and who did not after frozen-thawed ET had similar EMT of 8.4 (7.4 – 9.7) mm and 9 (8 – 10) mm, respectively (p = 0.38). Women who achieved a LB were significantly younger than those who did not [32 (29–35) vs 34 (30–38) years, p = 0.04]. The proportion of women who received a single ET was similar between women who achieved a LB and who did not after a FET [86/95 (90.5%) vs 181/192 (94.3%), respectively, p = 0.26]. Area under curve values of EMT for predicting LB in fresh, frozen-thawed and all ET were 0.56, 0.47 and 0.52, respectively. EMT and LB rate were not linearly correlated in fresh or frozen-thawed ET cycles. Limitations, reasons for caution Although our study is retrospective, no women was denied ET due to EMT in our center. Only patients undergoing ET were included in the analysis, which may introduce bias due to the selection of couples who were competent enough to produce at least one blastocyst fit for transfer. Wider implications of the findings: Since women with thin endometrium had reasonable chance for LB even in the absence of a cut-off for EMT in this unique dataset, delaying or denying ET for any given EMT value alone does not seem justified. Further studies in which ET is carried out regardless of EMT are needed. Trial registration number Not applicable

P–264 Clinical relevance of re-expansion after blastocyst thawing

Abstract Study question Are there any differences in clinical outcomes after SET of re-expanded versus non-re-expanded blastocysts? Summary answer The transfer of re-expanded thawed blastocysts is associated with improved clinical outcomes. What is known already Improvements in embryo culture conditions, endometrial receptivity protocols and vitrification as a revolutionary cryopreservation technique have allowed the expansion of blastocyst stage transfers (Lieberman and Tucker, 2006; Stanger et al., 2012; Rienzi et al., 2017), increasing clinical pregnancy and implantation rates in IVF cycles. The re-expansion of thawed blastocyst at the time of transfer has been considered as a good prognosis factor, but not always thawed embryos re-expand. To evaluate the relevance of this event, we compared the clinical results of the re-expanded embryos versus the collapsed ones after their thawing and transfer. Study design, size, duration A total number of 1.125 frozen-thawed blastocyst transfers were included in this retrospective observational study between January 2018 and December 2020. Seven hundred and eighty-six thawed blastocyst were fully expanded at the time of the transfer and 339 thawed blastocysts were non-re-expanded when they were transferred. Participants/materials, setting, methods 1.125 single frozen-thawed blastocyst embryo transfer (SET) cycles (802 from donated and 319 from autologous oocytes) were divided in two groups (re-expanded vs non-re-expanded). Positive beta human chorionic gonadotrophin (bHCG), pregnancy rate (PR), early miscarriage rate (EMR) and live birth rate (LBR) were compared between the two groups. Blastocysts were thawed using an Irvine Scientific® Thaw kit, Irvine Scientific® and were transferring in culture medium (Global® Total® LP, CooperSurgical®). Main results and the role of chance During 2018, 190 re-expanded blastocyst and 94 non-re-expanded were transferred. Statistical significant differences were found in the percentage of positive bHCG (48.4% vs 30.9%, p &amp;lt; 0,0048) and PR (39.5% vs 25.5%, p &amp;lt; 0,0203), respectively. In 2019, statistical differences were found in the LBR between 307 re-expanded blastocyst and 124 non-re-expanded (30.6% vs 12.9%; p &amp;lt; 0,00001). Differences were also found in positive bHCG (50.2% vs 21.8%, p &amp;lt; 0,00001) and PR (40.7% vs 15.3%, p &amp;lt; 0,00001), respectively. Finally, in 2020, 289 re-expanded blastocyst and 121 non-re-expanded were transferred, and significant differences were obtained in the percentage of positive bHCG (46.8% vs 22.3%, p &amp;lt; 0,00001) and PR (32.9% vs 15.7%, p &amp;lt; 0,00001), respectively. Globally, all the variables analysed were statistically significant in favour of the re-expanded embryo group: positive bHCG (48.7% vs 24.5%; p &amp;lt; 0,00001), PR (37.5% vs 18.3%; p &amp;lt; 0,00001) and LBR (20.1% vs 9.5%; p &amp;lt; 0,00001), except for EMR. Limitations, reasons for caution The inherent limitations to a retrospective design. Larger studies are warranted in order to reach robust conclusions on the subject. Wider implications of the findings: Transfer of re-expand blastocyst could be a positive indicator of clinical outcomes. In case of non-re-expand embryos, transfer of two could be reasonable. Trial registration number NONE

P–772 Blastocyst quality and perinatal outcomes in women undergoing single blastocyst transfer in frozen cycles

Abstract Study question Is the morphological grading systems of a blastocyst associated with perinatal outcomes in women undergoing frozen-thawed single blastocyst transfer (SBT)? Summary answer Preferential transfer of a blastocyst based on their morphological grading systems appears to be supported by observed differences in perinatal outcomes. What is known already The transfer of a morphologically good quality blastocyst is associated with higher implantation and pregnancy rates as compared with a poor quality blastocyst. However to date, the association of the morphologic parameters of the blastocyst (developmental stage, inner cell mass (ICM), and trophectoderm (TE)) with the perinatal outcomes after blastocyst transfer remains unknown. Study design, size, duration A retrospective cohort study including 21,648 frozen-thawed SBT cycles from January 2013 to March 2019. Participants/materials, setting, methods 6037 women with singleton delivery in Peking University Third Hospital were eligible for analysis. Multivariate logistic regression was used to test the risk of factors with the expression of crude odds ratios (OR) and adjusted OR (aOR) with 95% confidence intervals (CI). Main results and the role of chance Transfer of a blastocyst with grading lower than 3BB was associated with a higher chance of female baby (49% vs 43%, aOR = 1.27 (1.12, 1.43)) and a higher rate of cesarian section (C-section) (69% vs 65%, aOR = 1.17 (1.03, 1.34)). Compared with stage 4 blastocyst, transfer of a stage 3 blastocyst was associated with a higher chance of preterm delivery (PTD) (aOR = 1.77 (1.08, 2.90)). Both stage 3 and stage 6 blastocyst transfer was associated with a lower chance of female baby (aOR = 0.68 (0.48, 0.97), 0.66 (0.47, 0.93), respectively). Compared with grade A ICM blastocyst transfer, Grade B ICM and grade C ICM blastocyst transfer was associated with a lower chance of a female baby (adjusted OR = 0.84 (0.73, 0.96), 0.63 (0.48, 0.83), respectively) and a higher risk of large for gestational age (LGA) (aOR = 1.20 (1.01, 1.42), 1.46 (1.07, 1.98), respectively). Grade C ICM blastocyst transfer was associated with an increased risk of macrosomia (aOR = 1.66 (1.14, 2.42)).Grade B TE and grade C TE blastocyst transfer had a lower risk of gestational diabetes mellitus (GDM) (aOR = 0.76 (0.60, 0.98), 0.69 (0.50, 0.94), respectively) than grade A TE blastocyst transfer. Limitations, reasons for caution The main limitations of this study were its retrospective nature and the relative subjectivity of blastocyst scoring. The follow-up was conducted through a phone call and some patients might not report their obstetrical and neonatal outcomes, leading to a relatively lower rate of several obstetrical outcomes. Wider implications of the findings: Transfer of a poor quality blastocyst is associated with a higher rate of C-section. The association between ICM grading and LGA and macrosomia would suggest that blastocysts with grade A ICM grading should be transferred preferentially and supports the use of current morphological grading systems for embryo prioritisation. Trial registration number N/A

P–254 The outcome of artificial reproductive technologies (ART) cycles with transfer of frozen-thawed blastocysts depending on whether expanded on day 5 or day 6

Abstract Study question Is there a difference in ART cycle results after frozen embryo transfer (FET), depending on whether blastocysts were cryopreserved on day 5 or 6? Summary answer There’s no statistical difference in the clinical pregnancy rate (CPR), life birth rate (LBR), miscarriage rate (MR) between embryos frozen on day 5 and 6. What is known already Currently, opinions differ regarding this topic. Previous studies demonstrated no difference in ongoing pregnancy rates between embryos frozen on day 5 (group A) or day 6 (group B) after FET. However, metanalysis (2019) suggested higher CPR and LBR after transferring embryos from group A rather than group B. It has also been established that ovarian stimulation leads to endometrial changes that result in deleterious effects on the implantation window and endometrial receptivity. Consequently, fresh transfers were excluded. Due to hormonal priming of endometrial receptivity, the same pregnancy outcomes should be expected with frozen-thawed blastocysts (day 5 vs 6). Study design, size, duration Retrospective cohort study was conducted between January 2015 and December 2018 with selected group of patients under 40 years of age. Group A consisted of 2275 cryotransfers of blastocyst expanded on day 5; group B included 170 cryotransfers of blastocyst on day 6. Both groups had an average of 1,52 embryos transferred per patient. Participants/materials, setting, methods Embryos were vitrified and warmed with Cryotop method (Kitazato, BioPharma). Blastocysts were scored according to Gardner and Schoolcraft grading system. Only expanded on day or 6 blastocysts of excellent and good (AA, AB, BA, BB) quality were selected. The embryos were cultured in CSC medium (Irvine Scientific) for 2–4 hours prior intrauterine transfer. The cycles with donor gametes, surrogacy and preimplantation genetic testing (PGT) were excluded. Statistical validity was assessed by Pearson’s chi-squared test. Main results and the role of chance The rates of the CPR, the ongoing pregnancy rate (OPR) and the LBR between group A and B were 50,8% (1157/2275) vs 46,5% (79/170) (p = 0,26), 37,4% (852/2275) vs 37,0% (63/170) (p = 0,91), 36,5% (832/2275) vs 35,2% (60/170) (p = 0,73) respectively and no significant differences were found in each category. Moreover, similarly there were no significant differences in the miscarriage rate 26,0% (301/1157) and 21,5% (17/79) (p = 0,37) as well Limitations, reasons for caution The study is limited due to uneven distribution of patients in both groups and by a low number of participants. The grading of blastocysts’ quality is also subjected to a human factor. Wider implications of the findings: This study confirms that frozen-thawed blastocysts do not seem to exhibit a difference in the CPR, OPR, LBR and MR whether they were expanded on day 5 or day 6. The cryopreservation of day 6 blastocyst can increase the chances of the patient for the positive outcome. Trial registration number Not applicable

P–032 Assessment of embryonic developmental outcome of direct unequal cleavage in patients with non-obstructive azoospermia and/or obstructive azoospermia

Abstract Study question Does direct unequal cleavage (DC) affect embryonic development after ICSI with testicular sperm (TESE-ICSI) in patients with non-obstructive azoospermia (NOA) and/or obstructive azoospermia (OA)? Summary answer The incidence of DC at the first cleavage (DC1) was extremely high and DC1 negatively affected embryonic development in NOA patients. What is known already It has been reported that the blastocyst development of embryos with direct cleavage (DC) was significantly lower than that without DC, but the clinical pregnancy rate after blastocyst transfer was not different with or without DC. The incidence of DC has been reported to be significantly higher after ICSI with testicular sperm (TESE-ICSI) than ICSI with ejaculated sperm (Ej), but to our knowledge, there are few reports investigating that the embryos with DC after TESE-ICSI affect embryonic development. Study design, size, duration We conducted a retrospective cohort study using time-lapse incubators (Geri, Genea Biomedx, Australia) from September 2018 to November 2020. Of 1033 two-pronuclear (2PN) embryos from TESE-ICSI, 486 and 547 embryos were from OA (35.9±5.5 years) and NOA (33.7±5.2 years), respectively. As an age matched control, we chose 581 embryos from ICSI using Ej (36.5±4.4 years). Participants/materials, setting, methods DC embryos were classified as DC1 (DC at first cleavage), DC2 (DC at second cleavage), and non-DC (without DC). The incidences of DC1 or DC2 and blastocyst development rates were compared among OA, NOA and Ej groups. In TESE-ICSI group, we compared blastocyst development rates with or without DC between good and poor quality embryos on day 3. Good quality embryos were defined as 8 cells with G3 or more by the Veeck’s classification. Main results and the role of chance DC1 incidence was significantly higher in NOA (37.3%) than OA (27.8%) and Ej (22.7%) (P &amp;lt; 0.01), whereas DC2 incidence was not statistically different among three groups; NOA (15.7%), OA (15.0%) and Ej (13.4%). Blastocyst development rates in DC1 were 17.8%, 19.5% and 25.8% for NOA, OA and Ej, respectively, which were significantly lower compared to non-DC in corresponding three groups (65.1%, 67.7%, and 68.5%, respectively, P &amp;lt; 0.01). In TESE-ICSI group, good-quality embryo rate on day 3 was significantly lower in DC1 (34.5%, P &amp;lt; 0.01) than DC2 (60.9%) or non-DC (54.2%). Additionally, blastocyst development rates in DC1 and DC2 were significantly lower than non-DC regardless of embryonic grades on day 3 (35.1%, 51.0%, and 81.6% for good-quality embryos on day 3, 10.1%, 27.0%, and 49.1% for poor-quality embryos on day 3, respectively, P &amp;lt; 0.05). When immotile sperm was used for TESE-ICSI, DC1 incidence was 40.0% (6/15), which did not show statistically differences. When performing single frozen-thawed blastocyst transfers, no pregnancies resulted from either DC1 (n = 13) or DC2 (n = 3) embryos in TESE-ICSI group. Limitations, reasons for caution We had a few data about the pregnancy rates after blastocyst transfers with DC, because embryos with DC were seldom transferred due to those lower priority. Although DC might be influenced by the sperm, we did not analyze the incidence of DC by taking the semen factors into account. Wider implications of the findings: The incidence of DC1 was extremely high and DC1 negatively affected embryonic development in NOA patients. Therefore, it is important to observe embryos using time-lapse incubator in order to recognize embryos with/without pregnancy potential, especially for embryos with DC1 in NOA patients. Trial registration number Not applicable

P–627 Optimal timing of day 6 blastocyst transfer in artificially prepared frozen-thawed embryo transfer cycles

Abstract Study question When is the optimal timing of day 6 (D6) blastocyst transfer between the 6thday (P6)and the 7th(P7) day of progesterone administration in artificially prepared frozen-thawed embryo transfer(FET) cycle Summary answer When transferring D6 blastocysts in artificially prepared FET cycles, live birth rate tended to be higher in P6 group than in P7 group. What is known already Blastocyst transfer in FET cycles has increased due to several reasons including convenience for optimization of endometrial synchronization, improvement of laboratory techniques and preimplantation genetic testing. Meanwhile, D6 blastocyst which cryopreserved on day 6 after being developed to the full blastocyst stage, presented lower pregnancy outcomes in FET cycle than D5 blastocysts. However, there have been few studies on the optimal duration of progesterone administration when transferring D6 blastocysts. Study design, size, duration This was a retrospective cohort study including patients who underwent frozen-thawed blastocyst transfer in artificially prepared cycles from January 2000 to May 2020. Patients with D6 blastocyst transfer on the 6th day of progesterone administration were included in D6-P6 group, and patients with D6 blastocyst transfer on the 7th day of progesterone administration were included in D6-P7 group. Participants/materials, setting, methods Increasing dose of estradiol valerate was administered from the 3rd day of menstruation: 4 mg/day for the first four days, 6 mg/day for next four days, and then 8 mg/day until the confirmation of pregnancy. Progesterone was administered from the 14th day of menstruation if the endometrial thickness reached ≥7 mm. The independent t-test or Mann-Whitney test, chi-square test, and logistic regression analysis were performed. Main results and the role of chance A total of 50 patients were included, and 13 patients underwent FET on P6 and 37 patients underwent FET on P7. Live birth rate was comparable between the P6 group and the P7 group (18.9% vs. 15.4%, p = 0.775). Live birth rate was higher in the D6-P6 group than in the D6-P7 group after adjusting for age, AMH, endometrial thickness on the starting day of progesterone administration and good embryo rate transferred with statistical significance (OR: 6.716, p = 0.005). Limitations, reasons for caution Limitations of the present study is the retrospective design and the small sample size. Caution is needed in extrapolating results of this study because only intramural and vaginal progesterone supplementations were included in this study. Wider implications of the findings: Even if the duration of blastocyst formation was delayed, frozen-thawed D6 blastocyst may need to be considered for on P6 rather than P7. The difference of live birth rate is not statistically significant. This study should be acknowledged for the underestimation of the difference because of the small sample size. Trial registration number Not applicable

The perinatal outcomes of frozen-thawed blastocyst transfer are better than fresh blastocyst transfer: a systematic review and meta-analysis.

Transfer of cryopreserved-warmed blastocysts is common in the practice of in vitro fertilization. The purpose of the study is to examine the available evidence and determine whether cryopreservation of blastocysts and subsequent frozen blastocyst transfer (BT) result in better outcomes than fresh BT. Related studies comparing outcomes of in vitro fertilization (IVF) cycles between fresh and frozen BTs were retrieved from Medline, Cochrane Central Register of Clinical Trials, EMBASE, DARE, and CINAHL through March 2020. The outcomes of interest were preterm birth, extremely preterm birth, small for gestational age, large for gestational age, low birth weight, extremely low birth weight, caesarean section, perinatal mortality and preeclampsia. The analysis was performed using Rev Man 5.1 software. Risk ratios (RRs) and risk differences were calculated with 95% confidence intervals, to evaluate the results of each outcome. The quality of the referenced studies was assessed using the Newcastle-Ottawa scale (NOS) checklists. Nine studies with 42,342 women incorporated in this meta-analysis. The incidence of preterm birth (RR = 0.89, 95% CI: 0.82, 0.97) and small for gestational age (RR = 0.55, 95% CI 0.41-0.74) was low in frozen BT group. There was no significant difference in the risk of low birth weight (RR = 0.89, 95% CI: 0.67, 1.19) and perinatal mortality (RR = 1.47, 95% CI: 0.85, 2.55) between frozen-thawed and fresh BT. Singleton pregnancy after frozen BT was associated with higher large for gestational age (RR = 1.47, 95% CI: 1.37, 1.57), caesarean section rates (RR = 1.24, 95% CI: 1.13, 1.36) and preeclampsia compared with fresh BT (RR = 1.85, 95% CI: 1.22, 2.82). The frozen BT results in better perinatal outcomes compared with that of fresh BT. Furthermore, comprehensive randomized clinical trials comparing freeze-all with fresh BT cycles are needed to draw sound conclusions.

Endometrial preparation does not affect the risk of hypertensive disorders of pregnancy in low-risk women undergoing frozen embryo transfer

Objective Frozen embryo transfer (FET) is associated with a higher risk of hypertensive disorders in pregnancy. The objective of the present study is to evaluate the effect of different protocols of endometrial preparation on the risk of these disorders. Methods We conducted a retrospective cohort study on 594 singleton pregnancies achieved by embryo transfer of single frozen-thawed blastocysts. Women with preexisting risk factors for hypertensive disorders were excluded. Women were divided into two groups according to the endometrial preparation protocol: either natural cycle (n = 495) or programming cycle with hormonal replacement therapy (n = 97). The primary outcome was the frequency of hypertensive disorders in pregnancy: specifically, gestational hypertension and preeclampsia. Results No differences emerged between women following the natural cycle and those following the programming cycle in the frequency of gestational hypertension (5 vs. 4%) and preeclampsia (1.1 vs. 1.2%). No impact emerged also after multivariate analyses. Conclusions Women receiving hormonal replacement therapy have the same risk of gestational hypertension and preeclampsia as women following natural cycles when considering low-risk singleton pregnancies.

Development and frozen-thawed transfer of non-pronuclear zygotes-derived embryos in IVF cycles

ObjectiveTo explore the development and pregnancy potential of non-pronuclear (0PN) zygote-derived embryos in conventional in vitro fertilization (IVF) cycles. Study designEmbryonic development in 1039 oocyte retrieval cycles and clinical outcomes of 659 frozen-thawed blastocyst transfer cycles were retrospectively studied. ResultsDevelopmental potential of embryos with different blastomere numbers on day 3 were inconsistent in 0PN and 2PN groups. For 0PN-derived embryos, blastocyst rate of fast developing embryos (75.4%) was similar to that of intermediately developing embryos (72.9%), but good quality blastocyst rate of the former (49.2%) was significantly higher than that of the later (39.6%). In 2PN group, intermediately developing embryos had the highest blastocyst rate (77.9%) and good quality blastocyst rate (51.5%) (statistically significant). Comparison of frozen-thawed transfer was carried out between 0PN- and 2PN-derived blastocysts. For both single (SBT) and double blastocyst transfer (DBT) groups, no statistical differences existed between 0PN- and 2PN-derived blastocysts in clinical pregnancy rates (45.2% and 49.1% in SBT group, 64.7% and 66.4% in DBT group), implantation rates (45.2% and 49.1% in SBT group, 41.2% and 47.7% in DBT group) and live birth rates (35.5% and 36.8% in SBT group, 52.9% and 51.2% in DBT group). ConclusionThe developmental characteristic of 0PN-derived embryos was different from that of 2PN-derived embryos in IVF cycles. 0PN-derived blastocysts could obtain acceptable clinical pregnancy and live birth, but more studies are needed to confirm the safety..

Association between serum estradiol levels prior to progesterone administration in artificial frozen-thawed blastocyst transfer cycles and live birth rate: a retrospective study.

To study whether serum estradiol (E2) levels prior to progesterone administration in the artificial endometrial preparation (AEP) of frozen-thawed blastocyst transfer affect the live birth rate. Retrospective cohort study. Tertiary-care academic medical centre. A total of 3857 frozen-thawed blastocyst transfer cycles were divided into three groups: <200 pg/ml (n = 1676); 200-399 pg/ml (n = 1296); and ≥400 pg/ml (n = 885), based on the 25th (182.3 pg/ml) and 75th percentile (390.2 pg/ml) of serum E2 level prior to progesterone administration. Univariable and multivariable logistic regression analysis was performed. The primary outcome of the study was the live birth rate and the secondary outcomes included clinical pregnancy rate, pregnancy loss rate, neonatal birthweight, Z-score, and small for gestational age (SGA). Compared with the reference group, accounting for major covariates, the live birth rate significantly decreased in the '≥400 pg/ml' group (adjusted OR 0.71, 95% CI 0.59-0.85). Compared with the reference group, there was an association between the E2 level in the '≥400 pg/ml' group and a decrease in the clinical pregnancy rate (adjusted OR 0.74, 95% CI 0.61-0.89). Compared with the reference group, the pregnancy loss rate significantly increased in the '≥400 pg/ml' group (adjusted OR 1.45, 95% CI 1.08-1.93). The E2 levels did not affect neonatal birthweight, Z-score, and SGA among singletons. High serum E2 levels prior to progesterone administration in AEP are associated with a decreased live birth rate after frozen-thawed blastocyst transfer. High serum E2 levels prior to progesterone administration in artificial FET are associated with a decreased live birth rate after frozen-thawed blastocyst transfer.

Advanced trophectoderm quality increases the risk of a large for gestational age baby in single frozen-thawed blastocyst transfer cycles.

Does trophectoderm (TE) quality affect birthweight after single frozen-thawed blastocyst transfer? Transfer of single blastocyst with advanced TE quality was associated with higher birthweight and increased risk of a large for gestational age (LGA) baby. Transfer of blastocysts with advanced TE quality results in higher ongoing pregnancy rates and a lower miscarriage risk. However, data on the relationship between TE quality and birthweight are still lacking. This retrospective cohort study at a tertiary-care academic medical center included 1548 singleton babies born from single frozen-thawed blastocyst transfer from January 2011 to June 2019. Babies were grouped into four groups according to embryo expansion (Stages 3, 4, 5 and 6), three groups according to inner cell mass (ICM) quality (A, B and C), and three groups according to TE quality (A, B and C). Main outcomes included absolute birthweight, Z-scores adjusted for gestational age and gender, and adverse neonatal outcomes. Multivariable linear and logistic regression analyses were performed to investigate the association of neonatal outcomes with expansion stage, ICM quality and TE quality. As TE quality decreased, birthweight (3468.10 ± 471.52, 3357.69 ± 522.06, and 3288.79 ± 501.90 for A, B and C, respectively, P = 0.002), Z-scores (0.59 ± 1.07, 0.42 ± 1.04, and 0.27 ± 1.06 for A, B and C, respectively, P = 0.002) and incidence of LGA (28.9%, 19.7% and 17.4% for A, B and C, respectively, P = 0.027) decreased correspondingly. After adjusting for confounders, compared with the Grade A group, blastocysts with TE Grade B (standardized coefficients (β): -127.97 g, 95% CI: -234.46 to -21.47, P = 0.019) and blastocysts with TE grade C (β: -200.27 g, 95% CI: -320.69 to -79.86, P = 0.001) resulted in offspring with lower birthweight. Blastocysts with TE grade C brought babies with lower Z-scores than TE Grade A (β: -0.35, 95% CI: -0.59 to -0.10, P = 0.005). Also, embryos with TE Grade B (adjusted odds ratio (aOR):0.91, 95% CI: 0.84 to 0.99, P = 0.033) and embryos with TE Grade C (aOR : 0.89, 95% CI: 0.81 to 0.98, P = 0.016) had lower chance of leading to a LGA baby than those with TE Grade A. No association between neonatal outcomes with embryo expansion stage and ICM was observed (all P > 0.05). The retrospective design, lack of controlling for several unknown confounders, and inter-observer variation limited this study. The study extends our knowledge of the down-stream effect of TE quality on newborn birthweight and the risk of LGA. This study was funded by National Key R&D Program of China (2018YFC1003000), National Natural Science Foundation of China (81771533 to Y.P.K. and 31200825 to L.S.) and Innovative Research Team of High-level Local Universities in Shanghai (SSMU-ZLCX20180401), Shanghai Sailing Program(21YF1423200) and the Fundamental research program funding of Ninth People's Hospital affiliated to Shanghai Jiao Tong university School of Medicine (JYZZ117). The authors declare no conflict of interest in this present study. N/A.

Which factors affect the likelihood of miscarriage after single euploid blastocyst transfer?

Research questionWhich parameters affect the likelihood of miscarriage after single euploid frozen–thawed blastocyst transfer (FBT)? DesignIn this retrospective study, clinical and laboratory data from 1051 single euploid FBTs were evaluated. Exclusion criteria were endocrine or systemic pathologies, uterine anomalies or pathologies, unilateral or bilateral hydrosalpinx, karyotypic abnormalities (either maternal or paternal) or thrombophilia. Patients were divided into two groups according to pregnancy outcome: live birth and miscarriage. ResultsBody mass index (BMI) (25.98 ± 0.5 versus 24.36 ± 0.21, P = 0.019), duration of infertility (6.62 ± 0.54 versus 4.92 ± 0.18, P = 0.006) and number of previous miscarriages (1.36 ± 0.13 versus 0.79 ± 0.05, P < 0.001) were significantly higher in the miscarriage group (n = 100) than in the live birth group (n = 589). Although the trophectoderm and inner cell mass (ICM) percentage scores were not statistically different among the miscarriage and live birth groups, the percentage of day-6 biopsied embryos was significantly higher in the miscarriage group. Binary logistic regression analysis revealed that BMI (OR 1.083, 95% CI 1.013 to 1.158, P = 0.02) and number of previous miscarriages (OR 1.279, 95% CI 1.013 to 1.158, P = 0.038) were independent factors for miscarriage. Patients with elevated BMI and a higher number of miscarriages were at increased risk of miscarriage. ConclusionAfter a single euploid FBT, BMI and number of previous miscarriages are predictors of miscarriage. Lifestyle interventions before FBT may decrease miscarriage rates.