Elective Single Embryo Transfer Research Articles

IVF and obstetrics outcomes among women of very advanced maternal age (45+) using donor egg

Research QuestionDoes very advanced maternal age (VAMA, aged 45+) influence obstetric outcomes among women using donor oocytes in in vitro fertilization (IVF)? DesignThis retrospective cohort study analysed data from a nationwide IVF registry in Taiwan, focusing on IVF cycles involving women aged 45 or older using donated oocytes between 2007 and 2016. The study assessed cumulative live birth rates (CLBR) and secondary outcomes such as clinical pregnancy, miscarriage, live birth, and twin pregnancy rates, alongside perinatal outcomes like caesarean section rates, preeclampsia, gestational diabetes, and birth weight. ResultsThe study included 1,718 embryo transfer cycles from 745 women, with a stable live birth rate of about 40% across the study period. The CLBR was slightly lower in women over 50 (54.2%) compared to those aged 45-46 (58.0%), but these differences were not statistically significant (p=0.647). Secondary outcomes and perinatal outcomes did not significantly differ across age groups. Regression analysis suggested a non-significant decrease in live birth rates and birth weight with increasing maternal age. The study also found that single embryo transfer (SET) minimized the risk of twin pregnancies without significantly affecting live birth rates. ConclusionsIVF with donor oocytes remains a viable option for women of VAMA, with consistent live birth rates across age groups. However, the study underscores the importance of elective SET to reduce the risk of twin pregnancies and associated adverse outcomes. Further research is needed to explore the impact of other factors such as paternal age and embryo development stage on IVF success in this population.

Multifetal Pregnancy After Implementation of a Publicly Funded Fertility Program

A publicly funded fertility program was introduced in Ontario, Canada, in 2015 to increase access to fertility treatment. For in vitro fertilization (IVF), the program mandated an elective single-embryo transfer (eSET) policy. However, ovulation induction and intrauterine insemination (OI/IUI)-2 other common forms of fertility treatment-were more difficult to regulate in this manner. Furthermore, prior epidemiologic studies only assessed fetuses at birth and did not account for potential fetal reductions that may have been performed earlier in pregnancy. To examine the association between fertility treatment and the risk of multifetal pregnancy in a publicly funded fertility program, accounting for both fetal reductions and all live births and stillbirths. This population-based, retrospective cohort study used linked administrative health databases at ICES to examine all births and fetal reductions in Ontario, Canada, from April 1, 2006, to March 31, 2021. Mode of conception: (1) unassisted conception, (2) OI/IUI, or (3) IVF. The main outcome was multifetal pregnancy (ie, a twin or higher-order pregnancy). Modified Poisson regression generated adjusted relative risks (ARRs) and derived population attributable fractions (PAFs) for multifetal pregnancies attributable to fertility treatment. Absolute rate differences (ARDs) were used to compare the era before eSET was promoted (2006-2011) with the era after the introduction of the eSET mandate (2016-2021). Of all 1 724 899 pregnancies, 1 670 825 (96.9%) were by unassisted conception (mean [SD] maternal age, 30.6 [5.2] years), 24 395 (1.4%) by OI/IUI (mean [SD] maternal age, 33.1 [4.4] years), and 29 679 (1.7%) by IVF (mean [SD] maternal age, 35.8 [4.7] years). In contrast to unassisted conception, individuals who received OI/IUI or IVF tended to be older, reside in a high-income quintile neighborhood, or have preexisting health conditions. Multifetal pregnancy rates were 1.4% (95% CI, 1.4%-1.4%) for unassisted conception, 10.5% (95% CI, 10.2%-10.9%) after OI/IUI, and 15.5% (95% CI, 15.1%-15.9%) after IVF. Compared with unassisted conception, the ARR of any multifetal pregnancy was 7.0 (95% CI, 6.7-7.3) after OI/IUI and 9.9 (95% CI, 9.6-10.3) after IVF, with corresponding PAFs of 7.1% (95% CI, 7.1%-7.2%) and 13.4% (95% CI, 13.3%-13.4%). Between the eras of 2006 to 2011 and 2016 to 2021, multifetal pregnancy rates decreased from 12.9% to 9.1% with OI/IUI (ARD, -3.8%; 95% CI, -4.2% to -3.4%) and from 29.4% to 7.1% with IVF (ARD, -22.3%; 95% CI, -23.2% to -21.6%). In this cohort study of more than 1.7 million pregnancies in Ontario, Canada, a publicly funded IVF program mandating an eSET policy was associated with a reduction in multifetal pregnancy rates. Nevertheless, ongoing strategies are needed to decrease multifetal pregnancy, especially in those undergoing OI/IUI.

IMPACT OF TIME INTERVAL FROM CESAREAN DELIVERY TO FROZEN EMBRYO TRANSFER ON REPRODUCTIVE AND NEONATAL OUTCOMES

To evaluate differences in reproductive and neonatal outcomes based on the time interval from cesarean delivery to subsequent frozen embryo transfer (FET) DESIGN: Retrospective cohort SUBJECTS: Women undergoing autologous elective single embryo transfer (eSET) FET following prior cesarean delivery EXPOSURE: Time from prior cesarean delivery to subsequent FET MAIN OUTCOME MEASURES: Live birth RESULTS: A total of 6,556 autologous eSET FET cycles were included. FET cycles were divided into eight groups based on the time interval from prior cesarean delivery to subsequent FET in months. Time was also evaluated as a continuous variable. The proportion of live births did not differ significantly across all time interval groups and over continuous time (range: 40.0% - 45.6%, adjusted (adj) p = 0.572, continuous adj p = 0.599). Mean gestational age at the time of delivery did not significantly differ as the time between prior cesarean delivery and subsequent FET increased (range: 37.3 - 38.4 weeks, adj p = 0.87, continuous adj p = 0.06). When time was evaluated continuously, the proportion of preterm births was higher with a shorter time between cesarean delivery and subsequent FET (p = 0.02). Mean birth weight ranged from 3181 grams to 3470 grams, with a statistically significant increase over time (continuous adj p = 0.01). However, the proportions of extremely low birth weight, very low birth weight, and low birth weight did not significantly differ. There were no significant differences in reproductive outcomes based on the time interval from cesarean delivery to FET, including live birth. The proportion of preterm deliveries decreased with a longer time between cesarean delivery and FET. Differences in mean neonatal birth weight were not clinically significant, as the proportion of low-birth-weight neonates was not significantly different over time. While large, this sample cannot address all outcomes associated with short interpregnancy intervals, particularly rarer outcomes such as uterine rupture. When counseling patients, the timing of FET following cesarean delivery must be balanced against the risks of increasing maternal age on reproductive and neonatal outcomes.

Blastocyst telomere length predicts successful implantation after frozen-thawed embryo transfer.

Do embryos with longer telomere length (TL) at the blastocyst stage have a higher capacity to survive after frozen-thawed embryo transfer (FET)? Digitally estimated TL using low-pass whole genome sequencing (WGS) data from the preimplantation genetic testing for aneuploidy (PGT-A) process demonstrates that blastocyst TL is the most essential factor associated with likelihood of implantation. The lifetime TL is established in the early cleavage cycles following fertilization through a recombination-based lengthening mechanism and starts erosion beyond the blastocyst stage. In addition, a telomerase-mediated slow erosion of TL in human fetuses has been observed from a gestational age of 6-11 weeks. Finally, an abnormal shortening of telomeres is likely involved in embryo loss during early development. Blastocyst samples were obtained from patients who underwent PGT-A and FET in an IVF center from March 2015 to May 2018. Digitally estimated mitochondrial copy number (mtCN) and TL were used to study associations with the implantation potential of each embryo. In total, 965 blastocysts from 232 cycles (164 patients) were available to investigate the biological and clinical relevance of TL. A WGS-based workflow was applied to determine the ploidy of each embryo. Data from low-pass WGS-PGT-A were used to estimate the mtCN and TL for each embryo. Single-variant and multi-variant logistic regression, decision tree, and random forest models were applied to study various factors in association with the implantation potential of each embryo. Of the 965 blastocysts originally available, only 216 underwent FET. While mtCN from the transferred embryos is significantly associated with the ploidy call of each embryo, mtCN has no role in impacting IVF outcomes after an embryo transfer in these women. The results indicate that mtCN is a marker of embryo aneuploidy. On the other hand, digitally estimated TL is the most prominent univariant factor and showed a significant positive association with pregnancy outcomes (P < 0.01, odds ratio 79.1). We combined several maternal and embryo parameters to study the joint effects on successful implantation. The machine learning models, namely decision tree and random forest, were trained and yielded classification accuracy of 0.82 and 0.91, respectively. Taken together, these results support the vital role of TL in governing implantation potential, perhaps through the ability to control embryo survival after transfer. The small sample size limits our study as only 216 blastocysts were transferred. The number was further reduced to 153 blastocysts, where pregnancy outcomes could be accurately traced. The other limitation of this study is that all data were collected from a single IVF center. The uniform and controlled operation of IVF cycles in a single center may cause selection bias. We present novel findings to show that digitally estimated TL at the blastocyst stage is a predictor of pregnancy capacity after a FET cycle. As elective single-embryo transfer has become the mainstream direction in reproductive medicine, prioritizing embryos based on their implantation potential is crucial for clinical infertility treatment in order to reduce twin pregnancy rate and the time to pregnancy in an IVF center. The AI-powered, random forest prediction model established in this study thus provides a way to improve clinical practice and optimize the chances for people with fertility problems to achieve parenthood. This study was supported by a grant from the National Science and Technology Council, Taiwan (MOST 108-2321-B-006-013 -). There were no competing interests. N/A.

ESHRE guideline: number of embryos to transfer during IVF/ICSI†.

ESHRE guideline: number of embryos to transfer during IVF/ICSI†.

A pilot study to investigate the clinically predictive values of copy number variations detected by next-generation sequencing of cell-free deoxyribonucleic acid in spent culture media

To investigate the positive predictive value and false positive risk of copy number variations (CNV's) detected in cell free deoxyribonucleic acid (DNA) from spent culture media for nonviable or aneuploid embryos. Diagnostic/prognostic accuracy study. Patients aged 35 and younger with an indication for IVF-ICSI and elective single frozen embryo transfer at a single, private IVF center. Embryo selection was performed according to the conventional grading, blinded to noninvasive preimplantation genetic testing for aneuploidy (niPGT-A) results. After clinical outcomes were established, spent culture media samples were analyzed. Prognostic accuracy of CNVs according to niPGT-A results to predict nonviability or clinical aneuploidy. One hundred twenty patients completed the study. Interpretations of next-generation sequencing (NGS) profiles were as follows: 7.5% (n = 9) failed quality control; 62.5% (n = 75) no CNVs detected; and 30% (n = 36) abnormal copy number detected. Stratification of abnormal NGS profiles was as follows: 15% (n = 18) whole chromosome and 15% (n = 18) uncertain reproductive potential. An intermediate CNV was evident in 27.8% (n = 5) of the whole chromosome abnormalities. The negative predictive value for samples with no detected abnormality was 57.3% (43/75). Whole chromosome abnormality was associated with a positive predictive value of 94.4% (17/18), lower sustained implantation rate (5.6%, 1/18), and higher relative risk (RR) for nonviability compared with no detected abnormalities (RR 2.21, 95% CI: 1.66-2.94). No other CNVs were associated with significant differences in the sustained implantation or RRs for nonviability. Unequal sex chromosome proportions suggested that maternal contamination was not uncommon. A secondary descriptive analysis of 705 supernumerary embryos revealed proportions of NGS profile interpretations similar to the transferred cohort. Significant median absolute pairwise differences between certain subcategories of CNV abnormalities were apparent. Whole chromosome abnormalities were associated with a high positive predictive value and significant RR for nonviability. Embryos associated with other CNVs had sustained implantation rates similar to those with no abnormalities detected. Further studies are required to validate the clinical applicability of niPGT-A. clinicaltrials.gov (NCT04732013).

The effect of laser-assisted hatching on vitrified/warmed blastocysts: the ALADDIN randomized controlled trial

ObjectiveTo evaluate whether laser-mediated assisted hatching (AH) performed on vitrified/warmed blastocysts before embryo transfer can improve live birth rate. DesignThe “pArtiaL zonA pelluciDa removal by assisteD hatchINg of blastocysts (ALADDIN)” is a 2-center comparative study with a parallel randomized controlled design. SubjectsParticipants were recruited between September 2018 and November 2021. They were aged 18 to 39 years, underwent non-donor IVF cycles, and were scheduled for elective single embryo transfer with vitrified/warmed blastocysts. Those with uterine abnormalities, BMI >35 kg/m2, severe male factor infertility, or performing preimplantation genetic testing were excluded. InterventionAssisted hatching was performed using a 1480 nm diode laser, removing approximately one-third of the zona pellucida with continuous 0.2 ms pulses applied from the 1 to 5 o’clock positions. Main Outcome MeasuresThe primary outcome was the live birth rate. Secondary endpoints included clinical pregnancy, miscarriage, multiple pregnancies, preterm births, obstetrical and neonatal complications, and congenital anomalies. ResultsOverall, 698 participants met the inclusion criteria and were randomized: 352 patients were assigned to the AH arm and 346 to the control arm. One-hundred and five (29.8%) and 101 (29.2%) participants achieved a live birth following treatment, respectively (p=0.87). The relative risk of live birth in patients with vitrified/warmed blastocysts treated with AH was 1.02 (95%CI: 0.86-1.19). Exploratory subgroup analyses for women’s age, recruiting centers, indications for IVF, method of insemination, blastocyst quality, and days of blastocyst development failed to highlight any clinical situation that could benefit from AH in thawed blastocysts. ConclusionIn patients undergoing frozen embryo transfer with vitrified/warmed blastocysts, laser AH does not improve the live birth rate. Further studies are required to rule out milder but potentially interesting benefits in specific subgroups of patients.

Multiple Gestation after Elective Single-Embryo Transfer: A State-of-the-Art Review of Literature and Suggested Mechanisms.

Elective single-embryo transfers are being increasingly used to curb the increase in multiple gestation rates. However, it has been documented that single-embryo transfers could still result in twins and on rarer occasions in triplet pregnancies. Main Body. A literature review was done to highlight the possible mechanisms leading to embryonic splitting. In this review, the incidence of zygotic splitting was addressed and the notion of chorionicity was explained. Risk factors for zygotic splitting and suggested mechanisms for both twin and higher order pregnancies were suggested and discussed. The hypotheses that we have so far remain unproven due to the rarity of zygotic splitting as well as the ethicolegal considerations of human embryo research. The presence of such incidents necessitates extensive counselling of the couple.

Morphological assessment of oocyte quality during assisted reproductive technology cycle.

Following the advancement of medically assisted reproduction (MAR) technology, and the rationale to extend the culture to the blastocyst stage, performing elective single embryo transfer (eSET), gamete quality and assessment have acquired large relevance in ART. Embryo quality is strictly correlated with gametes quality and culture conditions. Oocyte maturity assessment is therefore imperative for fertilization and embryo evolution. Mature oocytes at the metaphase II stage result in a higher fertilization rate compared to immature oocytes. Indeed, oocyte morphology evaluation represents an important and challenging task that may serve as a valuable prognostic tool for future embryo development and implantation potential. Different grading systems have been reported to assess human embryos, however, in many cases, it is still a major challenge to select the single embryo to transfer with the highest implantation potential. Further, eSET has conferred a challenge to embryologists, who must try to enhance embryo culture and selection to provide an adequate success rate, whilst reducing the overall number of embryos transferred. Above the standard morphological assessment, there are several invasive or non-invasive approaches for embryo selection such as preimplantation genetic testing, time-lapse technology, proteomics and metabolomics, as well as oxygen utilization and analysis of oxidative stress in culture medium. This short review is not designed to be a comprehensive review of all possible features that may influence oocyte quality. It does give, however, a brief overview and describes the prognostic value of the morphological characteristics of human oocytes on their developmental capacity following ART treatments.

Optimising Ovulation Induction in PCOS

Biochemical, Metabolic and Endocrine changes in PCOS result in reproductive impairment in women with PCOS. Controlled ovarian stimulation (COS) may be associated with • Unpredictable response • Response may be slow • Hyper-response - OHSS • Risk of Cyst Formation • Poor oocyte quality • Miscarriage • Cycle cancellation So, the ovulation induction protocol should be efficacious and safe resulting in a singleton live birth, minimising complications, and risks like ovarian hyperstimulation syndrome (OHSS), multiple pregnancies and cancellation of cycles. For this special consideration should be given to prediction of response, pre-treatment, choosing the right ovulation induction (OI) protocol with right dose and analogue, using GnRH agonist trigger instead of hCG, preventing late follicular phase rise in progesterone, or following the segmentation protocol. We can maximize the success rates by stimulation individualization based on age, AMH, AFC and amended further for BMI. AMH is considered as more sensitive marker to define follicle excess than AFC as it appraises more follicle classes - preantral and early antral. One should probably use mild stimulation protocols where gonadotropins are given in combination with oral ovulogens or the low dose step up protocol. It is essential that we use GnRH antagonist protocol and administer GnRH agonist if there is risk of OHSS. If segmentation protocol is used one could also use the progesterone primed ovarian stimulation instead of GnRG antagonist. One could reduce the incidence of OHSS by laparoscopic ovarian drilling and use of Metformin and aspirin before assisted reproduction. If the patient is at risk of developing OHSS during stimulation then one could administer cabergoline, intravenous infusion of calcium gluconate or albumin and methylprednisolone. But freezing all embryos and transferring them in a subsequent cycle increase the efficacy and reduce complications of ART in PCOS women. Elective single embryo transfer(eSET) should be the norm to reduce the multiple pregnancy rate. Conclusion Thus, in all ART cycles individualised COS with freeze all and eSET could help in increasing the success of ART and reducing stress and anxiety and complications in these women.

The POPI-Plus tool: prediction model of outcome of pregnancy in in vitro fertilization from a large retrospective cohort

To create a tool that accurately predicts live birth chances after a positive pregnancy test after elective single embryo transfer (ET). Retrospective cohort. CHUM hospital and Ovo clinic in Montreal, Canada. Patients with a positive pregnancy test result who underwent their first single ET after invitro fertilization (IVF) at the CHUM hospital and Ovo clinic in Montreal, Canada, from 2012 to 2016 were selected. A total of 1,995 patients were included in this study. The data from both centers were combined and divided into training (70%, n = 1,398) and validation (30%, n = 597) sets. The predictive model was developed using backward selection method for the following variables: age of patient at egg retrieval; log β-human chorionic gonadotropin (β-hCG) (β-hCG) 1; log β-hCG 2; and IVF treatment type. Moreover, the classification tree, random forest, and neural network models were generated. The measured outcomes were live birth (live fetus ≥24 weeks of gestation) and nonviable pregnancies. The performance of all models was evaluated by area under the receiver operating characteristic curve (AUC). Advancing age was negatively correlated with live birth. The odds ratio (OR) of age of patient at the time of egg retrieval was 0.95 (95% confidence interval [CI], 0.91-0.99). The log β-hCG 1 and log β-hCG 2 were positively correlated with live birth in the univariate analysis (OR, 4.15 [95% CI, 3.19-5.39], and OR, 3.84 [95% CI, 2.99-4.93], respectively). The β-hCG 1 level needed for a successful pregnancy was lower in frozen ET and modified natural IVF than in simulated IVF (OR, 0.55 [95% CI, 0.34-0.91], and OR, 0.49 [95% CI, 0.26-0.95], respectively). The best performance in terms of the AUC was the updated logistic model: POPI-Plus. The AUC values were 0.76 (95% CI, 0.73-0.79) and 0.78 (95% CI, 0.74-0.82) for the training and validation data, respectively. The other models (classification tree, random forest, and neural network) also performed adequately, with an AUC of ≥0.7, but remained below POPI-Plus. An open-access calculator was generated and can be found on the website of the University of Montreal on the following link: https://deptobsgyn.umontreal.ca/departement/divisions/medecine-et-biologie-de-la-reproduction/the-popi-plus-tool/. The POPI-Plus tool offers individualized counseling for patients after an initial positive β-hCG test result. Future studies will assess its impact on patient anxiety while awaiting viability ultrasound and perform prospective validation on new patients.

Primary omental pregnancy after in vitro fertilization complicated by hemoperitoneum—how to manage it laparoscopically

To report an uncommon case of primary OP treated laparoscopically. Ectopic pregnancy (EP) is the leading cause of maternal mortality during the first trimester and the incidence increases with assisted reproductive techniques, occurring in approximately 1.5%-2.1% of patients undergoing invitro fertilization.1 Omental pregnancy (OP) is an extremely rare form of EP accounting for less than 1% of all EPs. OP can be classified as primary or secondary on the basis of Studdiford's criteria2. The preoperative diagnosis of OP is complex and usually occur in acute circumstances during a throughout intraoperative evaluation of the abdomen.3-5 A delayed diagnosis poses a serious threat to the survival of the patient; therefore, it is important to remark that EP can exist in unusual locations and prompt surgical intervention may be necessary. A step-by-step narrated video of a rare clinical case and description of the surgical procedure. Tertiary Level Academic Hospital "IRCCS Azienda Ospedaliero - Universitaria di Bologna" Bologna, Italy. A 36-year-old woman was referred to our emergency room because of acute abdominal pain and nausea for 2 hours with no signs of hemodynamic instability. The patient also complained that poor vaginal bleeding appeared during the last 24 hours. The patient has undergone a cycle of invitro fertilization with an elective single frozen embryo transfer of a blastocyst on day 5, 2 months before. She had no relevant clinical or surgical history. Diffuse abdominal tenderness and a painful uterus at mobilization were appreciated at clinical examination. A massive hemoperitoneum was diagnosed using transvaginal-transabdominal ultrasound, and no uterine or adnexal lesions were identified. The β-human chronic gonadotropin level was 43.861 mIU/mL, and the hemoglobin value was 10.5 g/dL. On suspicion of a ruptured EP, after detailed counseling and the acquisition of informed consent, a laparoscopic exploration was planned. First, the hemoperitoneum was evacuated to allow visualization of the abdominal cavity. At pelvic inspection, no EP was found. Throughout the exploration of the abdominal cavity, a 4-cm bluish cystic mass of friable consistency was detected infiltrating the omentum and the mesentery. According to Studdiford's criteria, the diagnosis of a primary OP was established. A careful and complete excision of the ectopic implant was performed with an ultrasonic system and required a considerable hemostatic effort using bipolar energy, endoscopic clips, and mechanical compression. The postoperative course was uneventful. The β-human chronic gonadotropin levels gradually decreased to negative values within 29 days after surgery. Omental ectopic pregnancy can be successfully managed with a laparoscopic approach even in an emergency setting. Omental pregnancy can easily be overlooked, even by skilled surgeons, during laparoscopic exploration. It is mandatory that all peritoneal surfaces and the omentum be carefully inspected during surgery in patients without other signs of pelvic EP.We confirm that the patient included in this video gave consent for publication of the video and posting of the video online, including on social media, the journal website, scientific literature websites, and other applicable sites.

Increased incidence of live births in implanted day 5 versus day 6 blastocysts following single embryo transfers with PGT-A

Elective single-embryo transfers of euploid or low-level mosaic blastocysts were analyzed in this retrospective study to determine the correlations of live birth (LB) probability with embryonic developmental features of implanted day 5 (D5, n = 245) or day 6 (D6, n = 73) blastocysts using time-lapse (TL) monitoring. According to the logistic regression analyses (adjusted odds ratio [OR] = 0.341, 95% confidence interval [CI] = 0.169–0.685, P < 0.05), the LB probability was negatively associated with the D6 group. The LB rate of the D5 group was higher than the D6 group (88.2% vs. 75.3%; P < 0.05). Compared with the D5 blastocysts, the D6 blastocysts exhibited comparable dysmorphisms except for the multinucleation at the 4-cell stage (10.9% vs. 2.9%, P < 0.05). Moreover, D6 blastocysts had considerably slower developmental kinetics and poorer blastocyst morphologies. Further analysis confirmed that the LB rate was not associated with developmental kinetics or dysmorphisms but rather with blastocyst morphology (inner cell mass [ICM] grade ≤ C vs. ICM grade A, adjusted OR = 0.155, 95% CI = 0.04–0.596, P < 0.05; trophectoderm [TE] grade ≤ C vs. TE grade A, adjusted OR = 0.157, 95% CI = 0.032–0.760, P < 0.05). In conclusion, D6 implanted blastocysts have a considerably lower LB rate than D5 implanted blastocysts. As determined by TL monitoring, the diminished blastocyst morphology can be one of the primary reasons underlying the decreased likelihood of LB.

Guideline No. 315: Prevention of Ovarian Hyperstimulation Syndrome

Summary Statements1.The particular follicle-stimulating hormone formulation used for ovarian stimulation does not affect the incidence of ovarian hyperstimulation syndrome. (I)2.Coasting may reduce the incidence of severe ovarian hyperstimulation syndrome. (III)3.Coasting for longer than 3 days reduces in vitro fertilization pregnancy rates. (II-2)4.The use of either luteinizing hormone or human chorionic gonadotropin for final oocyte maturation does not influence the incidence of ovarian hyperstimulation syndrome. (I)5.There is no clear published evidence that lowering the human chorionic gonadotropin dose will result in a decrease in the rate of ovarian hyperstimulation syndrome. (III)6.Cabergoline starting from the day of human chorionic gonadotropin reduces the incidence of ovarian hyperstimulation syndrome in patients at higher risk and does not appear to lower in vitro fertilization pregnancy rates. (II-2)7.Avoiding pregnancy by freezing all embryos will prevent severe prolonged ovarian hyperstimulation syndrome in patients at high risk. (II-2)8.Pregnancy rates are not affected when using gonadotropin-releasing hormone (GnRH) agonists in GnRH antagonist protocols for final egg maturation when embryos are frozen by vitrification for later transfer. (II-2) Recommendations1.The addition of metformin should be considered in patients with polycystic ovarian syndrome who are undergoing in vitro fertilization because it may reduce the incidence of ovarian hyperstimulation syndrome. (I-A)2.Gonadotropin dosing should be carefully individualized, taking into account the patient’s age, body mass, antral follicle count, and previous response to gonadotropins. (II-3B)3.Cycle cancellation before administration of human chorionic gonadatropin is an effective strategy for the prevention of ovarian hyperstimulation syndrome, but the emotional and financial burden it imposes on patients should be considered before the cycle is cancelled. (III-C)4.Gonadotropin-releasing hormone (GnRH) antagonist stimulation protocols are recommended in patients at high risk for ovarian hyperstimulation syndrome (OHSS). The risk of severe OHSS in patients on GnRH antagonist protocols who have a very robust ovarian stimulation response can be reduced by using a GnRH agonist as a substitute for human chorionic gonadotropin to trigger final oocyte maturation. (I-B)5.A gonadotropin-releasing hormone (GnRH) antagonist protocol with a GnRH agonist trigger for final oocyte maturation is recommended for donor oocyte and fertility preservation cycles. (III-C)6.Albumin or other plasma expanders at the time of egg retrieval are not recommended for the prevention of ovarian hyperstimulation syndrome. (I-E)7.Elective single embryo transfer is recommended in patients at high risk for ovarian hyperstimulation syndrome. (III-C)8.Progesterone, rather than human chorionic gonadotropin, should be used for luteal phase support. (I-A)9.Outpatient culdocentesis should be considered for the prevention of disease progression in severe ovarian hyperstimulation syndrome. (II-2B)

P-713 Preimplantation DNA methylation screening (PIMS) illustrates the outcome of assisted reproductive technology

Abstract Study question It is unknown whether using DNA methylation can improve the outcome of ART and can exclude the imprinted gene diseases. Summary answer Our study provides a criterion on selecting blastocyst according to DNA methylome, which can improve live birth rate and decrease birth defect rate. What is known already How to select the embryos is one key factor that can determine the successful rate of ART. As aneuploidy exists in 20-30% of blastocysts, preimplantation genetic screening (PGS) has been widely used, which increases the live birth rate. Unfortunately, the live birth rate remains around 50% even with the help of PGS. DNA methylation is known to play important function during embryogenesis. Previous study has shown that a large proportion of human embryos have abnormal DNA methylome. However, whether DNA methylation pattern can affect the clinical outcome of ART has not been investigated in clinics. Study design, size, duration To determine whether PIMS method can increase live birth rate during ART, the whole genome DNA methylation of 3-5 biopsied cells from trophectoderm were measured. The methylation level and chromosome copy number variation (CNV) were analyzed by using the methylome data. elective single embryo transfer (eSET) will be performed for embryos with euploid chromosome. The live birth rate, pregnant rate and abortion rate will be examined. 182 families including 800 blastocysts were enrolled in PIMT. Participants/materials, setting, methods Eligible couples include advanced maternal age, recurrent pregnancy loss with unknown reason, recurrent implantation failure with unknown reason, severe oligoteratozoospermia. Eligible couples must have two or more good-quality blastocysts. We call a blastocyst as good quality if the blastocyst is 4BC or better according to the Gardner morphologic criteria on day 5-6 of embryo culture. Main results and the role of chance No one has ever performed clinical trial to investigate the impact of DNA methylation of blastocyst on the outcome of artificial assisted reproductive (ART). Here, we performed PIMS using the biopsied trophectoderm of 800 blastocysts. Chromosome copy number variation and DNA methylation pattern were analyzed by using methylome data. 162 of euploid embryos were transferred. Our data show that significant variation of DNA methylation level of blastocysts can be observed in both younger women (£37 years old) and older women (&amp;gt;37 years). Blastocysts with global methylation level around 0.26 have the highest birth and pregnancy rate, but the lowest abortion rate. The higher the difference methylation value from 0.26 is, the lower the birth rate becomes. Furthermore, by using artificial intelligence method according to different methylated regions between the embryos succeeding in live-birth and those failing in live-birth, we can robustly predict the clinical outcome of blastocysts. PIMS method can find the abnormality of DNA methylation states in the imprinted control regions which can cause the imprinted diseases. Our study provides a criterion on selecting blastocyst according to DNA methylome during ART, which can potentially improve the live birth rate and decrease the birth defect rate. Limitations, reasons for caution Because of the low coverage of single cell DNA methylome, PIMS method cannot cover all imprinted control regions. Wider implications of the findings PIMS method can potentially find more human diseases which is caused by DNA methylation mutation. Trial registration number NCT03642574

P-525 A second euploid embryo transfer is more likely to succeed if there was a previous confirmed euploid implantation.

Abstract Study question Does the outcome of the first, euploid transfer affect the success rate of the second PGT-A transfer cycle? Summary answer Live birth rate is higher in the second euploid transfer if the first euploid transfer results in at least a biochemical pregnancy versus no implantation. What is known already There is limited evidence on counselling patients for a second euploid embryo transfer based on previous outcomes. The existing literature is reassuring showing very high implantation rates even following two or more successive failed euploid transfers. Achieving implantation is a major step towards success. The association between a PGT-A embryo transfer cycle where implantation was achieved (at least biochemical pregnancy, miscarriage or live birth) with the outcome of the subsequent embryo transfer is interesting to explore and incorporate in patient counselling. Study design, size, duration This is a retrospective analysis of patients who underwent PGT-A treatment in a single centre from 2015-2021. Live birth rate was the main outcome of interest. Pregnancy rate and miscarriage rate were secondary outcomes. Means and standard deviations were used for demographic parameters. Embryos were biopsied at blastocyst stage for PGT-A and next generation sequencing was used. Embryo transfers were performed with uniform protocols by different, experienced clinicians. Participants/materials, setting, methods Patients who had their second euploid embryo transfer were included in the analysis. Outcomes were assessed in relation to the outcome of the first euploid cycle; whether at least a biochemical pregnancy was achieved versus a negative pregnancy test. Patients with uterine anomalies / suboptimal endometrial thickness were excluded. Protocols for endometrial preparation and add-ons were individualised and were not uniform for the two cycles. Protocols included both medicated cycles and ovulatory cycles. Main results and the role of chance 331 women were included in the analysis undergoing their second euploid embryo transfer cycle. 152 had one previous euploid implantation (the first cycle resulted in a biochemical pregnancy, miscarriage, or live birth) (group 1) and 179 had one previous failed implantation of a euploid embryo (the first cycle resulted in a negative pregnancy test) (group 2). There was no significant difference between the two groups in patient demographic characteristics including age, body mass index and age at egg collection. No significant difference was documented for embryo quality, day 5 versus day 6 embryos or endometrial thickness. More cycles were medicated in group 1 compared to group 2. All patients had an elective single embryo transfer. Live birth rate was significantly higher for group 1 versus group 2, 58% vs 44%, p = 0.013, OR 1.75 (1.12-2.70). No significant difference was observed for pregnancy rate or miscarriage rate. Limitations, reasons for caution This is a retrospective analysis in a single fertility centre, therefore prone to bias and results cannot be generalised unless validated by larger prospective multi-centre studies. There are multiple possible cofounders such as background and duration of subfertility, endometrial preparation protocols and add-on interventions which cannot be accounted for. Wider implications of the findings These findings suggest that the first euploid transfer outcome is important for future euploid transfer cycles. Women who achieved at least a positive pregnancy test in the first cycle seem to have higher success rates in subsequent PGT-A transfer. Further research is warranted to explore this association for patient counselling. Trial registration number not applicable

P-128 Morphokinetics and blastocyst biomarkers of twin and triplet monozygotic pregnancy using artificial intelligence

Abstract Study question Can AI reduce the rate of twin and triplet monozygotic pregnancies following elective single embryo transfer (eSET)? Summary answer AI can automatically annotate morphokinetic developments and other biomarkers. Embryos leading multiple monozygotic pregnancies have slower cell divisions and larger ICM than monoamniotic embryos. What is known already Monozygotic twin (MZT) and monozygotic triplet (MTP) pregnancies are a rare phenomenon in spontaneous pregnancies, but the incidence increases significantly when pregnancies are achieved by assisted reproductive technology (ART); 0.4% vs. 1.56% MZTs, and 0.004% vs. 0.048% MTPs. It is unclear what mechanisms cause an embryo to split into two or three, although several have been proposed such as culture to blastocyst, decompacting ICMs, frozen-warmed embryo transfers, assisted hatching and even ICSI. In order to study this split phenomenon, time-lapse imaging has been used to discover any signs of embryo division. Study design, size, duration This is a retrospective assessment of a total of 8 embryos from 2018 to 2022 that led to single pregnancy (n = 4), twin pregnancy (n = 3) and triple pregnancy (n = 1) following a fresh single embryo transfer. All embryos were inseminated using the ICSI technique and assisted hatching was performed before fresh transfer. Participants/materials, setting, methods Using CHLOE (Fairtility, Tel Aviv) we automatically assessed the morphokinetics, blastocyst biomarkers and scores. Singletons and multiple pregnancies were compared in terms of morphokinetics (t-test) and surface area of ICM, ICM diameter, ICM area/embryo area ratio, ICM shape and CHLOE embryo quality score were compared using the ANOVA test. Main results and the role of chance Embryos that led to multiple pregnancies had slower embryo development than embryos that led to singletons (single vs multiple: t2: 22.1+-2 vs 25.2+-2, p = 0.04; t3: 32.56+-2.65 vs 36.98 +-1.48, p = 0.01; t5: 44.09+-4.84 vs 50.37+−0.69, p = 0.02; t6: 47.26+-3.87 vs 53.59+-2.40, p = 0.01; t7: 48.76+-4.04 vs 55.15+-3, p = 0.02; t8: 50.18+-4.27 vs 57.55+-1.5, p = 0.008; t9: 63.27+-3.76 vs 73.04+-5.33, p = 0.03). Embryos leading to triplets were slower than twins which were, in turn, slower than singletons (single vs twins vs triplets: t4: 33.86+-3.41 vs 37.69+-1.61 vs 48.95, p = 0.007; t8: 50.18+-4.27 vs 58.07+-1.29 vs 55.96, p = 0.04; t9: 63.27+-3.76 vs 71.23+-4.81 vs 78.44, p = 0.01). Embryos that led to multiple pregnancies had a larger ICM to embryo surface area ratio (single vs multiple: 0.14+−0.08 vs 0.27+−0.06, p = 0.04) and smaller embryo diameter (single vs multiple: 177.2+-16.5 vs 138.15+-8.25, p = 0.003). We didn’t find statistically significant differences between the groups in CHLOE EQ score (single vs multiple: 0.97 vs 0.76, p = 0.36), Blast score (single vs multiple: 0.87+−0.06 vs 0.78+−0.13, p = 0.26), CHLOE Rank, Trophectoderm quality, ICM Area (single vs multiple: 3629+-1361 vs 4151 +- 569, p = 0.48) and ICM shape (single vs multiple: 1.64+−0.45 vs 1.27+−0.12, p = 0.15). Limitations, reasons for caution The main limitation of this study is the number of cases included in the study, as we studied one triplet, 3 twins and 4 single pregnancies. Wider implications of the findings This might be the first time that AI has been used to analyse the behaviour of embryos resulting in multiple pregnancies. The transfer of a slowly dividing embryo and/or with a large ICM could result in a multiple pregnancy. Trial registration number not applicable

P-222 Early blastulation on day 4 predicts ongoing pregnancy in fresh transfer cycles

Abstract Study question Do embryos with early blastulation (EB) on D4 show higher implantation potential compared to top D5 blastocysts in fresh elective single embryo transfer (eSET) cycles? Summary answer Fresh EB transfer with time start to blastulation (tSB)&amp;lt;96.6h and time of expanded blastocyst (tEB)&amp;lt;100h post-insemination is predictive of ongoing pregnancy for patients &amp;lt;35. What is known already Expansion and hatching of blastocysts are correlated to implantation potential in fresh single transfers. Thanks to time-lapse morphokinetics, several time-points can be analyzed during embryonic growth. Embryos with faster growing speed are correlated to euploid status. The tSB of &amp;lt; 96.6h, day 4 post-insemination, is reported to have significant predictive value of euploid embryos, which are found to be associated not only with higher expansion scores, but also with shorter tSB, full expansion, and hatching. A study reported that significantly more embryos that reached the tSB by 100h implanted compared to those that did not. Study design, size, duration Prospective observational study in a single private hospital during 2022. In 160 cycles (n = 81 cIVF and n = 79 ICSI) an EB on D4 was observed. 48 patients (n = 28 ICSI and n = 20 cIVF) underwent a fresh eSET with an embryo showing EB on day 4. Participants/materials, setting, methods Patients with EB on D4 (tSB&amp;lt;96.6h, tEB&amp;lt;100h post-insemination) were enrolled regardless of indication, female age, attempt’s rank or technique. Those with a fresh eSET on D4 were included in this study. Gardner’s classification was used to rate the blastocysts in Embryoscope + (Vitrolife). The outcome data of transfer for D4 blastocysts (B3/B4 AA-AB-BA) were compared to eSET with top D5 (B4/B5 AA) of reference group (female age ≤35). The statistical analyses were performed by SPSS software. Main results and the role of chance In the study group, all the transferred embryos were graded according to Gardner’s classification as B3AA, or B3AB, or B3BA, or B4AA, or B4AB, or B4BA. In the reference group, we chose only the fresh transfer cycles with ultra-top grade D5 embryos classified as B4AA or B5AA. The results obtained in the overall population (n = 48) were compared to those obtained in the reference group (n = 92): age 34.0 ± 3.8 vs 31.8 ± 2.3, oocyte maturity (OM) 79.8% vs 80.3%, fertilization rate (FR) 80.0% vs 77.0%, overall blastulation rate (OBR) 78.1% vs 74.3%, top blastulation rate (TBR) 59.1% vs 54.4%, total pregnancy rate (PR) 75.5% vs 61.4%, implantation rate (IR) 58.3 vs 51.2% and ongoing pregnancy rate (OPR) 58.6% vs 47.1%, and showed a statistical difference only in PR (p&amp;lt;0.05). The results obtained in younger patients with age 32.1 ± 3.2 (n = 34) were also compared to reference group: OM 75.1% vs 80.3%, FR 85.0% vs 77.0%, OBR 78.1% vs 74.3%; TBR 58.7% vs 54.4% were comparable between the groups. A statistical difference was observed for PR (88.0% vs 61.4%, p&amp;lt;0.01) IR (70.6% vs. 51.2%, p&amp;lt;0.05) and OPR (70.6% vs 47.1%, p&amp;lt;0.05). Limitations, reasons for caution The small size of the sample needs to be expanded in order to confirm the encouraging findings in a larger population, especially in older patients yielding more aneuploid embryos. The study will continue during 2023 and will compel the live birth rate. Wider implications of the findings When a D4 embryo with EB is available, the best option is the fresh transfer on D4. The increased implantation with EB seems to correlate with embryo euploidy and the advanced endometrial receptivity in stimulated cycles. Higher IR and OPR are reported even in patients with lower rate of aneuploidy. Trial registration number not applicable

P-262 Comparative ability of iDAScore and embryo morphology grade to predict clinical pregnancy: Retrospective cohort study of 1510 fresh and frozen elective single embryo transfers

Abstract Study question Can iDAScore predict ongoing clinical pregnancy (CP) with a sensitivity and specificity equivalent to that associated with manual morphology assessment and grading? Summary answer The fully automated iDAScore was able to predict CP with equivalent performance to manual morphology assessment and grading in this retrospective cohort study. What is known already iDAScore is an artificial intelligence (AI) based algorithm developed by applying machine learning to morphokinetic time laps (TL) image data of embryos with a known treatment outcome. Embryos are automatically assessed on day 5 of culture and ranked according iDAScore, ranging from 1 to 9.9. Embryos may be prioritised for transfer based on highest sore. Along with other published AI algorithms, iDAScore has been proposed to optimise the chance of CP following ET by improving objectivity of embryo assessment compared with manual scoring systems. The fully autonomous assessment of embryos by AI algorithms has beneficial implications for laboratory workload. Study design, size, duration Retrospective audit of 787 fresh and 723 frozen single embryo transfer cycles which took place from April 2019 to September 2022. All recipient, surrogacy, warmed oocyte, embryo biopsy, cleavage stage and slow thaw frozen ET cycles were excluded. Participants/materials, setting, methods Selection for transfer was based on blastocyst morphology grade. iDAScores were obtained retrospectively. The area under the receiver operator characteristic (AUROC) curve and sensitivity and specificity for CP prediction of both iDAScore and blastocyst morphology grade was compared overall and in two stratified analyses. The first assessed fresh and frozen cycles separately, the second compared their performance in female age groups of ≤ 35 and &amp;gt;35 years. CP was defined by ultrasound detection of foetal heartbeat. Main results and the role of chance The mean grading of blastocysts by iDA was 8.34 ± 1.4, with a strong correlation to classic morphological scoring (r = 0.69, P &amp;lt; 0.001). The clinical pregnancy rate for fresh and frozen embryo transfer was 31.0% (95%CI 27.9-34.3) and 44.0% (95%CI 40.8-48.0) respectively. iDA score was positively associated with clinical pregnancy rates in both fresh (adjOR 1.69, 95%CI 1.44-1.99) and frozen embryo transfers (adjOR 1.45, 95%CI 1.26-1.67), independent of maternal age. There was no difference in the AUROC for iDA (AUC 0.64, 95%CI 0.62-0.67) versus conventional morphology (AUROC 0.63, 95CI 0.61-0.66) when all eSETs were considered, or when fresh eSETS (AUROC for fresh iDA 0.66 95%CI 0.62-0.70 vs morphology 0.65 95%CI 0.62-0.69) or frozen iDA 0.63 95%CI 0.59-0.67 vs morphology 0.61 95%CI 0.57-0.64) eSETS were considered separately. The iDA score exhibited slightly better performance in the age stratified analyses, with a higher AUROC in women &amp;gt;35 years; iDA 0.68 95%CI 0.64-0.71 vs morphology 0.64 95%CI 0.60-0.67, p = 0.021) but no difference was observed in younger women. This age difference in iDA performance was primarily driven by frozen embryo transfers (p = 0.002). For women &amp;gt;35years an iDA score of 8.75 was associated with an AUROC of 0.63 and 67% sensitivity and 60% specificity for prediction of clinical pregnancy. Limitations, reasons for caution This was a retrospective single centre study and the performance of iDA needs to be confirmed prospectively in a multi-centre trial. That selection of embryos for transfer was based on morphology, may have contributed to overestimation of model performance. Wider implications of the findings The application of AI based embryo ranking algorithms to embryo selection for transfer, has the potential to maintain clinical pregnancy rates while reducing the time burden associated with conventional morphology / morphokinetic assessments. Trial registration number Nil

P-216 Evaluation of embryo quality and morphokinetics following short exposure of oocytes to spermatozoa

Abstract Study question Does embryo quality and morphokinetics following short exposure of oocytes to spermatozoa differ from conventional long exposure? Summary answer No statistical differences were found in embryo quality and morphokinetics following short exposure. Short exposure technique enables better monitoring of the embryos and easier handling. What is known already Overnight exposure of oocytes to spermatozoa may lead to toxic effects associated with reactive oxygen species. In short exposure, the duration of oocyte incubation with the sperm is reduced to 2-4 hours. Few studies showed that embryo morphology as well as pregnancy rates improved by short exposure, however, this remains controversial. Embryo morphokinetics in a time-lapse incubator yielding more accurate information on embryo quality, has not been reported for embryos derived by the short exposure technique. Study design, size, duration A retrospective study (2013-2019) 536 IVF cycles were included: 110 short exposure and 426 conventional IVF (long exposure). All embryos were cultured in the EmbryoScope. Short and long exposure cycles were compared for the average embryo scores of general and adapted laboratory in-house models. Groups were analyzed according to 2, 3 and 5 days of culture and maternal age. Moreover, differences of KID (Known implanted data) embryos morphokinetics were compared for cell division timings. Participants/materials, setting, methods IVF patients with mechanical factor, normal sperm counts. In conventional IVF, the oocytes were inseminated 6-7 hours post retrieval and mechanically denuded after 18-20 hours of incubation. In short exposure, the oocytes were inseminated and denuded 2-3 hours post retrieval and immediately placed in the EmbryoScope, for accurate annotation. In both methods oocytes were washed, incubated in EmbryoScope and cultured till the day of transfer. Women were divided by age groups: &amp;lt;35, 35-40 and &amp;gt;40. Main results and the role of chance No statistical difference was found in embryo cleavage rates and number of transferred embryos per cycle between long and short exposure in all three maternal age groups. The clinical pregnancy rate was slightly higher in the short exposure compared to the long exposure group but did not reach statistical significance (37.5% vs 32.5, p = NS). In women younger than 35y, elective single embryo transfer resulted in a statistically significant higher clinical pregnancy rate in the short exposure group compared to the long (p = 0.037). No significant differences were found in the average embryo morphokinetic score according to the general model and the adapted in-house model between the two groups. Moreover, no difference was found in embryo morphokinetics between short and long exposure in 272 KID negative and 116 KID positive embryos. Limitations, reasons for caution Since the study was retrospective and the short exposure group was smaller than the conventional IVF group, additional studies are needed to support our results. Wider implications of the findings Short exposure is more convenient and easier to perform. It is as good as long exposure in terms of clinical pregnancy rates and may be beneficial in patients younger than 35 years old. Trial registration number 0015-20-CMC