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To report utilization, effectiveness, and safety of assisted reproductive technologies in 2015 and 2016. A retrospective, cross-sectional survey of 3,103 assisted reproductive technology clinics in 74 countries in 2015 and 3,249 clinics in 79 countries in 2016 that submitted cycle and pregnancy outcome data through national and regional registries. Seventy-nine countries and >3,000 assisted reproductive technology clinics. Patients undergoing assisted reproductive technology procedures. Assisted reproductive technology. Outcomes on country, regional, and global levels. Reported for 2015: 2,358,239 cycles with 548,652 infants born; for 2016: 2,807,963 cycles with 647,188 infants born. Estimated in 2015, ≥2,683,677 cycles resulted in >675,134 infants; in 2016, ≥3,100,448 cycles resulted in ≥723,026 infants. Reported cycles represent approximately 80% of global utilization. In 2015 and 2016, 27.6% and 27.8%, respectively, of women undergoing fresh autologous treatment cycles were aged ≥40 years. Frozen-thawed embryo transfer (ET) cycles accounted for 47.0% and 51.9%, respectively, of all ETs in 2015 and 2016. Oocyte donation cycles accounted for 6.7% and 7.1% of all ETs in 2015 and 2016. Intracytoplasmic sperm injection was performed in 57.7% and 56.4% of autologous aspiration cycles in 2015 and 2016, respectively. The cumulative delivery rate per aspiration cycle for fresh and frozen-thawed ET was 32.4% in 2015 and 33.1% in 2016, respectively. The average number of transferred embryos was 1.70 in 2015 and 1.69 in 2016. The proportion of single ETs in fresh autologous cycles increased from 42.1% in 2015 to 44.0% in 2016. The twin delivery rate decreased from 16.0% in 2015 to 14.7% in 2016, and the triplet rate decreased from 0.6% in 2015 to 0.4% in 2016. The proportion of single ETs in frozen-thawed ET autologous treatment cycles was 62.2% in 2015 and 64.2% in 2016, with twin and triplet rates of 10.1% and 0.3% in 2015 and 10.0% and 0.2% in 2016, respectively. Utilization of assisted reproductive technology treatment and births per cycle increased from 2015 to 2016, although multiple births were reduced. An increasing proportion of frozen-thawed ET cycles, continuing wide variation in use of intracytoplasmic sperm injection, and an increase in single ET rates are reported. [ABSTRACT FROM AUTHOR]

To evaluate in vitro fertilization (IVF) and perinatal outcomes of donor egg and autologous cycles in patients with advanced reproductive age after undergoing single frozen euploid embryo transfer. A multicenter, retrospective, cohort study. University-affiliated and private IVF centers. Patients aged 39–46 years who underwent IVF with intracytoplasmic sperm injection and preimplantation genetic testing for aneuploidy using whole-chromosome sequencing with donor (n = 278) or autologous (n = 278) oocytes between October 2017 and October 2021. Single frozen euploid embryo transfer with donor or autologous euploid embryo. The main outcome measure was the live birth rate (LBR) after the first embryo transfer, calculated per embryo transfer. The secondary outcomes included the implantation rate, ectopic pregnancy rate, miscarriage rate, and gestational age and birth weight at the time of delivery. Patients using donor or autologous oocytes had a similar likelihood of implantation (57.91% [51.87–63.78] vs. 57.19% [51.15–63.09]) and LBR (41.01% [95% confidence interval {CI}, 35.17–47.04] vs. 42.45% [95% CI, 36.56–48.49]). Furthermore, there were no significant differences in the ectopic pregnancy rate (0.72% [0.09–2.57] vs. 0.36% [0.01–1.99]), miscarriage rate (16.19% [12.06–21.05] vs. 14.39% [95% CI, 10.48–19.08]), gestational age (38.50 [38.08–38.92] vs. 39.16 [38.25–40.07] weeks), or birth weight of infants (2,982.25 [2,606.69–3,357.81] vs. 3,128.24 [2,962.30–3,294.17] kg). The univariate analysis showed no association between advanced maternal age and the LBR (relative risk, 1.03 [95% CI, 0.84–1.25]). Multivariate analysis using putative confounders for embryo competency found no associations with LBR (adjusted relative risk, 1.22 [95% CI, 0.75–1.98]). Patients with euploid blastocysts derived from donor or autologous oocytes did not reveal statistically significant differences in the LBR, implantation rate, ectopic pregnancy rate, miscarriage rate, duration of gestation, or infant birth weight. These findings suggest that age-related reproductive decline and/or poor IVF outcomes associated with women with advanced reproductive age undergoing IVF are heavily driven by embryonic aneuploidy. [ABSTRACT FROM AUTHOR]

STUDY QUESTION Can pregnancy outcomes following fresh elective single embryo transfer (eSET) in gonadotropin-releasing hormone (GnRH) antagonist protocols increase using a gonadotropin (Gn) step-down approach with cessation of GnRH antagonist on the day of hCG administration (hCG day) in patients with normal ovarian response? SUMMARY ANSWER The modified GnRH antagonist protocol using the Gn step-down approach and cessation of GnRH antagonist on the hCG day is effective in improving live birth rates (LBRs) per fresh eSET cycle. WHAT IS KNOWN ALREADY Currently, there is no consensus on optimal GnRH antagonist regimens. Studies have shown that fresh GnRH antagonist cycles result in poorer pregnancy outcomes than the long GnRH agonist (GnRHa) protocol. Endometrial receptivity is a key factor that contributes to this phenomenon. STUDY DESIGN, SIZE, DURATION An open label randomized controlled trial (RCT) was performed between November 2021 and August 2022. There were 546 patients allocated to either the modified GnRH antagonist or the conventional antagonist protocol at a 1:1 ratio. PARTICIPANTS/MATERIALS, SETTING, METHODS Both IVF and ICSI cycles were included, and the sperm samples used were either fresh or frozen from the partner, or from frozen donor ejaculates. The primary outcome was the LBRs per fresh SET cycle. Secondary outcomes included rates of implantation, clinical and ongoing pregnancy, miscarriage, and ovarian hyperstimulation syndrome (OHSS), as well as clinical outcomes of ovarian stimulation. MAIN RESULTS AND THE ROLE OF CHANCE Baseline demographic features were not significantly different between the two ovarian stimulation groups. However, in the intention-to-treat (ITT) population, the LBRs in the modified antagonist group were significantly higher than in the conventional group (38.1% [104/273] vs. 27.5% [75/273], relative risk 1.39 [95% CI, 1.09–1.77], P  =   0.008). Using a per-protocol (PP) analysis which included all the patients who received an embryo transfer, the LBRs in the modified antagonist group were also significantly higher than in the conventional group (48.6% [103/212] vs. 36.8% [74/201], relative risk 1.32 [95% CI, 1.05–1.66], P  =   0.016). The modified antagonist group achieved significantly higher implantation rates, and clinical and ongoing pregnancy rates than the conventional group in both the ITT and PP analyses (P  <   0.05). The two groups did not show significant differences between the number of oocytes retrieved or mature oocytes, two-pronuclear zygote (2PN) rates, the number of embryos obtained, blastocyst progression and good-quality embryo rates, early miscarriage rates, or OHSS incidence rates (P  >   0.05). LIMITATIONS, REASONS FOR CAUTION A limitation of our study was that the subjects were not blinded to the treatment allocation in the RCT trial. Only women under 40 years of age who had a good prognosis were included in the analysis. Therefore, use of the modified antagonist protocol in older patients with a low ovarian reserve remains to be investigated. In addition, the sample size for Day 5 elective SET was small, so larger trials will be required to strengthen these findings. WIDER IMPLICATIONS OF THE FINDINGS The modified GnRH antagonist protocol using the Gn step-down approach and cessation of GnRH antagonist on hCG day improved the LBRs per fresh eSET cycle in normal responders. STUDY FUNDING/COMPETING INTEREST(S) This project was funded by grant 2022YFC2702503 from the National Key Research & Development Program of China and grant 2021140 from the Beijing Health Promotion Association. The authors declare no conflicts of interest. TRIAL REGISTRATION NUMBER The RCT was registered in the Chinese Clinical Trial Registry; Study Number: ChiCTR2100053453. TRIAL REGISTRATION DATE 21 November 2021. DATE OF FIRST PATIENT'S ENROLLMENT 23 November 2021 [ABSTRACT FROM AUTHOR]

Summary: The aim was to explore whether the time-lapse imaging system can help day-3 single cleavage embryo transfer to obtain comparative clinical outcomes to day-4 or 5. The data of 1237 patients who underwent single embryo transfer from January 1, 2018, to September 30, 2020, in our reproductive medicine centre were retrospectively analysed. They were divided into the day-3 single cleavage-stage embryo transfer (SCT) group (n = 357), day-4 single morula transfer (SMT) group (n = 129) and day-5 single blastocyst transfer (SBT) group (n = 751) according to the different embryo transfer stage. The clinical and perinatal outcomes of the three groups were analysed and compared. The clinical pregnancy rates of the patients in the day-3 SCT group, day-4 SMT group and day-5 SBT group were 68.07, 70.54 and 72.04%, respectively. The live birth rates were 56.86, 61.24 and 60.99%, respectively. The monozygotic twin (MZT) rate in the day-3 SCT group was significantly lower than that in the day-5 SBT group (P = 0.049). Regarding perinatal outcomes, only the secondary sex ratio had a significant difference (P < 0.05). After age stratification, no improvement was found in the pregnancy outcomes of patients >35 years of age receiving blastocyst transfer. Our findings suggest that for patients with multiple high-quality embryos on day-3, prolonging the culture time can improve the pregnancy outcome to some extent, but it will bring risks. For centres that have established morphodynamic models, day-3 SCT can also achieve an ideal pregnancy outcome and reduce the rate of monozygotic twins and sex ratio. [ABSTRACT FROM AUTHOR]

STUDY QUESTION Which clinical and embryological factors should be considered to apply double embryo transfer (DET) instead of elective single embryo transfer (eSET)? SUMMARY ANSWER No clinical or embryological factor per se justifies a recommendation of DET instead of eSET in IVF/ICSI. WHAT IS KNOWN ALREADY DET is correlated with a higher rate of multiple pregnancy, leading to a subsequent increase in complications for both mother and babies. These complications include preterm birth, low birthweight, and other perinatal adverse outcomes. To mitigate the risks associated with multiple pregnancy, eSET is recommended by international and national professional organizations as the preferred approach in ART. STUDY DESIGN, SIZE, DURATION The guideline was developed according to the structured methodology for development and update of ESHRE guidelines. Literature searches were performed in PUBMED/MEDLINE and Cochrane databases, and relevant papers published up to May 2023, written in English, were included. Live birth rate, cumulative live birth rate, and multiple pregnancy rate were considered as critical outcomes. PARTICIPANTS/MATERIALS, SETTING, METHODS Based on the collected evidence, recommendations were discussed until a consensus was reached within the Guideline Development Group (GDG). A stakeholder review was organized after the guideline draft was finalized. The final version was approved by the GDG and the ESHRE Executive Committee. MAIN RESULTS AND THE ROLE OF CHANCE The guideline provides 35 recommendations on the medical and non-medical risks associated with multiple pregnancies and on the clinical and embryological factors to be considered when deciding on the number of embryos to transfer. These recommendations include 25 evidence-based recommendations, of which 24 were formulated as strong recommendations and one as conditional, and 10 good practice points. Of the evidence-based recommendations, seven (28%) were supported by moderate-quality evidence. The remaining recommendations were supported by low (three recommendations; 12%), or very low-quality evidence (15 recommendations; 60%). Owing to the lack of evidence-based research, the guideline also clearly mentions recommendations for future studies. LIMITATIONS, REASONS FOR CAUTION The guideline assessed different factors one by one based on existing evidence. However, in real life, clinicians' decisions are based on several prognostic factors related to each patient's case. Furthermore, the evidence from randomized controlled trials is too scarce to formulate high-quality evidence-based recommendations. WIDER IMPLICATIONS OF THE FINDINGS The guideline provides health professionals with clear advice on best practice in the decision-making process during IVF/ICSI, based on the best evidence currently available, and recommendations on relevant information that should be communicated to patients. In addition, a list of research recommendations is provided to stimulate further studies in the field. STUDY FUNDING/COMPETING INTEREST(S) The guideline was developed and funded by ESHRE, covering expenses associated with the guideline meetings, the literature searches, and the dissemination of the guideline. The guideline group members did not receive payment. DPB declared receiving honoraria for lectures from Merck, Ferring, and Gedeon Richter. She is a member of ESHRE EXCO, and the Mediterranean Society for reproductive medicine and the president of the Croatian Society for Gynaecological Endocrinology and Reproductive Medicine. CDG is the past Chair of the ESHRE EIM Consortium and a paid deputy member of the Editorial board of Human Reproduction. IR declared receiving reimbursement from ESHRE and EDCD for attending meetings. She holds an unpaid leadership role in OBBCSSR, ECDC Sohonet, and AER. KAR-W declared receiving grants for clinical researchers and funding provision to the institution from the Swedish Cancer Society (200170F), the Senior Clinical Investigator Award, Radiumhemmets Forskningsfonder (Dnr: 201313), Stockholm County Council FoU (FoUI-953912) and Karolinska Institutet (Dnr 2020-01963), NovoNordisk, Merck and Ferring Pharmaceuticals. She received consulting fees from the Swedish Ministry of Health and Welfare. She received honoraria from Roche, Pfizer, and Organon for chairmanship and lectures. She received support from Organon for attending meetings. She participated in advisory boards for Merck, Nordic countries, and Ferring. She declared receiving time-lapse equipment and grants with payment to institution for pre-clinical research from Merck pharmaceuticals and from Ferring. SS-R received research funding from Roche Diagnostics, Organon/MSD, Theramex, and Gedeo-Richter. He received consulting fees from Organon/MSD, Ferring Pharmaceuticals, and Merck Serono. He declared receiving honoraria for lectures from Ferring Pharmaceuticals, Besins, Organon/MSD, Theramex, and Gedeon Richter. He received support for attending Gedeon Richter meetings and participated in the Data Safety Monitoring Board of the T-TRANSPORT trial. He is the Deputy of ESHRE SQART special interest group. He holds stock options in IVI Lisboa and received equipment and other services from Roche Diagnostics and Ferring Pharmaceuticals. KT declared receiving payment for honoraria for giving lectures from Merck Serono and Organon. She is member of the safety advisory board of EDQM. She holds a leadership role in the ICCBBA board of directors. ZV received reimbursement from ESHRE for attending meetings. She also received research grants from ESHRE and Juhani Aaltonen Foundation. She is the coordinator of EHSRE SQART special interest group. The other authors have no conflicts of interest to declare. DISCLAIMER This guideline represents the views of ESHRE, which were achieved after careful consideration of the scientific evidence available at the time of preparation. In the absence of scientific evidence on certain aspects, a consensus between the relevant ESHRE stakeholders has been obtained. Adherence to these clinical practice guidelines does not guarantee a successful or specific outcome, nor does it establish a standard of care. Clinical practice guidelines do not replace the need for application of clinical judgement to each individual presentation, nor variations based on locality and facility type. ESHRE makes no warranty, express or implied, regarding the clinical practice guidelines and specifically excludes any warranties of merchantability and fitness for a particular use or purpose (full disclaimer available at https://www.eshre.eu/Guidelines-and-Legal). [ABSTRACT FROM AUTHOR]

To prospectively examine the association between adenomyosis type, location, and severity with reproductive outcomes in patients undergoing single embryo transfer (SET) with embryos derived from donor oocytes. A prospective observational cohort study. University-affiliated in vitro fertilization center. Patients with infertility with (n = 114) and without (n = 114) adenomyosis who received their first donor oocyte transfer between January 2019 and January 2023 were included in this study. Adenomyosis was confirmed with the presence of at least one direct feature visualized by 2- or 3-dimensional transvaginal ultrasound and classified according to type (diffuse or focal), localization (inner or outer myometrium and/or junctional zone [JZ]), and uterine extension (mild, moderate, or severe). After an artificial or natural endometrial preparation cycle, patients underwent SET in the blastocyst stage. The primary outcome was the implantation rate. The secondary outcomes were the clinical pregnancy, live birth, and miscarriage rates after SET. The presence of adenomyosis did not significantly affect the implantation, clinical pregnancy, or live birth rates. However, women with adenomyosis had a significantly higher miscarriage rate than those without adenomyosis (35.4% vs. 18.1%, respectively). The multivariate analysis assessed possible risk factors for each clinical outcome considered in the study and showed that adenomyosis affected the risk of miscarriage. Specifically, transvaginal sonography detection of adenomyosis in the JZ was associated with over threefold higher relative risk of miscarriage (relative risk [RR], 3.28; 95% confidence interval [CI], 1.38–7.78). Conversely, adenomyosis features detected exclusively in the outer myometrium were associated with a higher ongoing pregnancy rate (RR, 0.30; 95% CI, 0.13–0.72). Diffuse adenomyosis in the JZ and severe adenomyosis increased the relative risk of miscarriage two-fold (RR, 2.29; 95% CI, 1.22–4.30 and RR, 2.20; 95% CI, 1.19–4.04, respectively). This study demonstrated that although adenomyosis did not significantly reduce the odds of implantation, the direct signs of adenomyosis in the JZ and disease severity are significant risk factors for miscarriage in patients receiving donor oocyte transfers. This study highlights the importance of thorough ultrasound examination and detailed adenomyosis classification in the assessment and management of patients with infertility. [ABSTRACT FROM AUTHOR]

Abstract A heterotopic pregnancy is a rare and serious pathological pregnancy. In this paper, we report a rare case of heterotopic pregnancy and perform a literature review. A 30-year-old patient with a history of left adnexectomy presented with persistent lower abdominal pain and hemorrhagic shock after single embryo transfer. Emergency laparoscopic exploration revealed a ruptured mass in the right isthmus of the fallopian tube, for which right salpingectomy was performed. After anti-inflammatory treatment and fetal preservation, the intrauterine pregnancy progressed smoothly, and a healthy baby was delivered at 39 weeks gestation. In this case, the patient’s heterotopic pregnancy was possibly due to a natural pregnancy caused by sexual intercourse during treatment, so we recommend that sexual intercourse be avoided during transfer cycles.

Abstract Background The present evidence is deficient for the trade-offs between the pros and cons of single blastocyst transfer (SBT) versus double blastocyst transfer (DBT) in frozen-thawed embryo transfer cycles for women in advanced reproductive age, especially in the second cycle. The current study aimed to investigate the impact of transferred blastocyst numbers on pregnancy outcomes in the first and second embryo transfer for women ≥ 35 years. Methods This was a retrospective cohort study including 1284 frozen-thawed blastocyst transfer (FBT) cycles from two reproductive centers. We analyzed the pregnancy outcomes after SBT and DBT in the first and second FBT cycles. Moreover, stratified analysis was conducted by maternal age. Results In the first FBT cycle, the LBR was higher in the DBT group than that in the SBT group [52.3% vs. 33.9%; adjusted odds ratio (aOR), 1.65; 95% confidence interval (CI), 1.26–2.15, P

Abstract Background Several studies have demonstrated that iDAScore is more accurate in predicting pregnancy outcomes in cycles without preimplantation genetic testing for aneuploidy (PGT-A) compared to KIDScore and the Gardner criteria. However, the effectiveness of iDAScore in cycles with PGT-A has not been thoroughly investigated. Therefore, this study aims to assess the association between artificial intelligence (AI)-based iDAScore (version 1.0) and pregnancy outcomes in single-embryo transfer (SET) cycles with PGT-A. Methods This retrospective study was approved by the Institutional Review Board of Chung Sun Medical University, Taichung, Taiwan. Patients undergoing SET cycles (n = 482) following PGT-A at a single reproductive center between January 2017 and June 2021. The blastocyst morphology and morphokinetics of all embryos were evaluated using a time-lapse system. The blastocysts were ranked based on the scores generated by iDAScore, which were defined as AI scores, or by KIDScore D5 (version 3.2) following the manufacturer’s protocols. A single blastocyst without aneuploidy was transferred after examining the embryonic ploidy status using a next-generation sequencing-based PGT-A platform. Logistic regression analysis with generalized estimating equations was conducted to assess whether AI scores are associated with the probability of live birth (LB) while considering confounding factors. Results Logistic regression analysis revealed that AI score was significantly associated with LB probability (adjusted odds ratio [OR] = 2.037, 95% confidence interval [CI]: 1.632–2.542) when pulsatility index (PI) level and types of chromosomal abnormalities were controlled. Blastocysts were divided into quartiles in accordance with their AI score (group 1: 3.0–7.8; group 2: 7.9–8.6; group 3: 8.7–8.9; and group 4: 9.0–9.5). Group 1 had a lower LB rate (34.6% vs. 59.8–72.3%) and a higher rate of pregnancy loss (26% vs. 4.7–8.9%) compared with the other groups (p

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

Background: Several studies have demonstrated that iDAScore is more accurate in predicting pregnancy outcomes in cycles without preimplantation genetic testing for aneuploidy (PGT-A) compared to KIDScore and the Gardner criteria. However, the effectiveness of iDAScore in cycles with PGT-A has not been thoroughly investigated. Therefore, this study aims to assess the association between artificial intelligence (AI)-based iDAScore (version 1.0) and pregnancy outcomes in single-embryo transfer (SET) cycles with PGT-A. Methods: This retrospective study was approved by the Institutional Review Board of Chung Sun Medical University, Taichung, Taiwan. Patients undergoing SET cycles (n = 482) following PGT-A at a single reproductive center between January 2017 and June 2021. The blastocyst morphology and morphokinetics of all embryos were evaluated using a time-lapse system. The blastocysts were ranked based on the scores generated by iDAScore, which were defined as AI scores, or by KIDScore D5 (version 3.2) following the manufacturer's protocols. A single blastocyst without aneuploidy was transferred after examining the embryonic ploidy status using a next-generation sequencing-based PGT-A platform. Logistic regression analysis with generalized estimating equations was conducted to assess whether AI scores are associated with the probability of live birth (LB) while considering confounding factors. Results: Logistic regression analysis revealed that AI score was significantly associated with LB probability (adjusted odds ratio [OR] = 2.037, 95% confidence interval [CI]: 1.632–2.542) when pulsatility index (PI) level and types of chromosomal abnormalities were controlled. Blastocysts were divided into quartiles in accordance with their AI score (group 1: 3.0–7.8; group 2: 7.9–8.6; group 3: 8.7–8.9; and group 4: 9.0–9.5). Group 1 had a lower LB rate (34.6% vs. 59.8–72.3%) and a higher rate of pregnancy loss (26% vs. 4.7–8.9%) compared with the other groups (p < 0.05). The receiver operating characteristic curve analysis verified that the iDAScore had a significant but limited ability to predict LB (area under the curve [AUC] = 0.64); this ability was significantly weaker than that of the combination of iDAScore, type of chromosomal abnormalities, and PI level (AUC = 0.67). In the comparison of the LB groups with the non-LB groups, the AI scores were significantly lower in the non-LB groups, both for euploid (median: 8.6 vs. 8.8) and mosaic (median: 8.0 vs. 8.6) SETs. Conclusions: Although its predictive ability can be further enhanced, the AI score was significantly associated with LB probability in SET cycles. Euploid or mosaic blastocysts with low AI scores (≤ 7.8) were associated with a lower LB rate, indicating the potential of this annotation-free AI system as a decision-support tool for deselecting embryos with poor pregnancy outcomes following PGT-A. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effect of hatching status on predicting pregnancy outcomes in single vitrified‐warmed blastocyst transfer (SVBT) by objectively subdividing pre‐implantation blastocysts according to hatching status. Methods: This retrospective study included 817 SVBT cycles performed between January 2016 and December 2017. Transferred embryos were categorized according to their hatching status as follows: group I (n = 147), non‐hatching blastocysts; group II (n = 484), hatching blastocysts; and group III (n = 186), completely hatched blastocysts. Hatching blastocysts (group II) were then classified based on the ratio of the blastocystic diameter outside and inside the zona pellucida into early (n = 185), mid‐ (n = 103), and late (n = 196) hatching stages. Implantation rate (IR), clinical pregnancy rate (CPR), live birth rate (LBR), multiple pregnancy rate (MPR), miscarriage rate, and neonatal outcomes were evaluated. Results: For groups I, II, and III, respectively, the results were as follows: IR (28.6%, 43.6%, and 53.8%; P < 0.001), CPR (27.9%, 42.8%, and 53.2%; P < 0.001), and LBR (23.1%, 32.0%, and 42.5%; P < 0.001). Group III had better IR, CPR, and LBR. Among hatching blastocysts, late‐hatching blastocysts had the highest IR (33.5%, 46.6%, and 51.5% for early, mid‐, and late hatching, respectively; P = 0.002) and CPR (33.0%, 45.6%, and 50.5%; P = 0.002), with a tendency for a higher rate of LBR. Neonatal outcomes were not influenced by the hatching status. Conclusion: Advanced hatching status is positively associated with a higher rate of clinical pregnancy and live birth with no negative effects on neonatal outcomes. Additionally, the quantitative classification of hatching status was found to be predictive of pregnancy outcomes. Synopsis: Hatching status in single vitrified‐warmed blastocyst transfer improved clinical pregnancy and live birth rates compared with the expanded state of the blastocyst. [ABSTRACT FROM AUTHOR]

To investigate whether morphokinetic parameters differ between male and female embryos in IVF embryos resulting in live births, a retrospective cohort study was undertaken. Files of all live births resulting from a single embryo transfer (SET) cultured in time-lapse incubators between 2013 and 2019 in two tertiary care centres were reviewed. The study group consisted of 187 SETs resulted in 187 live births, of which 100 were females (53.5%) and 87 were males (46.5%). Embryo selection for transfer was based on the known implantation data (KID) score provided by the Embryoscope and morphological assessment by experienced embryologists. Neonatal sex was confirmed through live birth documentation. Morphokinetic parameters and day 3 and day 5 KID scores of male and female embryos were compared. Maternal baseline and treatment characteristics were similar between groups. Morphokinetic time-lapse parameters of male and female embryos including: pronuclei fading; cleavage timings (t2-t9); second and third cell cycle durations; synchrony of the second and third cleavages; late morphokinetic parameters and KID scores did not differ between groups. In conclusion, time-lapse morphokinetic parameters and embryo selection methods do not seem to differ between male and female embryos, and their utilization does not bias towards any neonatal sex. [ABSTRACT FROM AUTHOR]

Didelphic uterus are caused by Müllerian tube fusion failure that eventually form two uterine cavities, which is one of the rarest uterine malformations. Women with Müllerian anomalies may increase the incidence of perinatal complications and adverse outcomes of pregnancy. If Müllerian anomalies are found during pregnancy, the type of abnormality should be identified promptly, the impact on the mother and fetus should be assessed, and the frequency of prenatal care should be appropriately increased. Ovarian pregnancy as a rare ectopic gestation is often difficult to diagnose before surgery. Ovarian pregnancy seemingly has no logical relationship with the didelphic uterus. The high risk factors of ovarian pregnancy may include intrauterine device, assisted reproductive technology (ART) and intrauterine surgery history. A case of ovarian pregnancy in a woman with didelphic uterus after ART was reviewed, and the possible causes of ovarian pregnancy were summarized and analyzed. Single embryo transfer should be considered as the best transplantation strategy for those patients with didelphic uterus. Women of childbearing age should undergo a thorough pelvic examination before ART in order to make early diagnosis and proper management of congenital uterine abnormalities. [ABSTRACT FROM AUTHOR]

Objective To investigate the effect of shrinkage blastocyst transfer on embryo implantation and clinical outcome. Methods The clinical data of patients with the apperance of shrinkage (the blastocyst shrinkage group) by time-lapse imaging during blastocyst culture in this center from January 2019 to April 2021 were retrospectively analyzed, and the pregnancy outcome after single blastocyst transplantation in freeze-thaw cycle was compared with that of the control group (patients without blastocyst shrinkage). Results The implantation rate (45.07%) and clinical pregnancy rate (45.07%) in the blastocyst shrinkage group were significantly lower than those of the the control group (59.93%,59.93%), and the differences were statistically significant (P＜0.05). The live birth rate (40.85%) in the blastocyst shrinkage group was lower than that of the control group (50.68%), and the abortion rate was similar to that of the control group (9.38%,13.71%), with no statistically significant difference (P＞0.05). Conclusion Blastocyst collapse is an important factor affecting embryo implantation rate and clinical pregnancy rate. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate whether elective single embryo transfer in patients with suboptimal response to ovarian stimulation is detrimental to pregnancy rates compared to double embryo transfer. Methods: A case–control retrospective study was performed in a cohort of couples undergoing IVF at the Infertility Unit of the ASST Lariana with ≤ 9 oocytes and at least 2 viable embryos. A total of 424 women were analyzed in the "double embryo transfer" group (n = 212) and elective "single embryo transfer" group (n = 212); they were matched 1:1 for female age, ovarian reserve and number of previous cycles. Cumulative clinical pregnancy rate per oocyte retrieval was the main outcome. Results: The cumulative pregnancy rate per cycle, including the fresh embryo and subsequent frozen embryo transfers, was 26% and 26%, respectively. Considering the main confounding factors, a binomial logistic model indicated that the cumulative clinical pregnancy rate was not significantly affected when a single embryo transfer was performed in women recovering up to nine oocytes. Conclusion: Live birth rate was similar between the two groups, while twin pregnancies were significantly reduced in women receiving single embryo transfer suggesting that elective single embryo transfer in patients with a limited number of embryos is not detrimental to pregnancy rates. [ABSTRACT FROM AUTHOR]

Single embryo transfer (SET) is a technique used in assisted reproductive treatment (ART) that is used to promote singleton pregnancies. To date, there are five reported cases of dizygotic twin pregnancies with mothers who underwent SET. Here, we present a sixth case of a dichorionic, diamniotic twin pregnancy with sex discordance. The patient is a 34-year-old woman with unexplained secondary infertility who underwent in vitro fertilization (IVF) and frozen-thawed embryo transfer from a SET. The ultrasonographic images from the first and second trimester scans identified dichorionic, diamniotic twin gestations. The delivery was full term and postnatal genetic testing confirmed 46, XX, and 46, XY offspring. Pathology reports of the placental and membrane findings reported diamniotic, dichorionic twins. There was no zygosity testing conducted, thus it is unknown if the twins are monozygotic or dizygotic. Two possible etiologies for sex-discordant twins, in this case, are concurrent natural conception via breakthrough ovulation at the time of SET, or discordant postzygotic nondisjunction of a single embryo. Multiple gestations may still occur in the setting of SET and zygosity testing in these instances would better elucidate our understanding of this occurrence. Moreover, improved data on the zygosity of multiple gestations following SET may enhance patient counseling.

This article details the case report of an infertile couple for more than two years. The patient has an obstetrical history of three pregnancies with two living children and her partner has no significant medical or surgical history. The first medical assessments are strictly normal. However, the semen analysis of the patient shows a severe oligoasthenoteratospermia. A pre in vitro fertilization assessment is then started. Eleven oocytes are collected from the oocyte retrieval. Ten of them are fertilized by the intracytoplasmic sperm injection (ICSI) technique. Six embryos will be obtained and frozen in L3 stage. The patient undergoes a single embryo transfer which will result in a monozygotic dichorionic-diamniotic twin pregnancy. Fertility enhancing treatments increase the prevalence of monozygotic dichorionic-diamniotic twin pregnancies compared with natural conception. This case report will allow us to approach the rare cases of monozygotic dichorionic-diamniotic twin pregnancies and to identify the factors which could explain this gap between the prevalences. [ABSTRACT FROM AUTHOR]

Single embryo transfer (SET) is a technique used in assisted reproductive treatment (ART) that is used to promote singleton pregnancies. To date, there are five reported cases of dizygotic twin pregnancies with mothers who underwent SET. Here, we present a sixth case of a dichorionic, diamniotic twin pregnancy with sex discordance. The patient is a 34-year-old woman with unexplained secondary infertility who underwent in vitro fertilization (IVF) and frozen-thawed embryo transfer from a SET. The ultrasonographic images from the first and second trimester scans identified dichorionic, diamniotic twin gestations. The delivery was full term and postnatal genetic testing confirmed 46, XX, and 46, XY offspring. Pathology reports of the placental and membrane findings reported diamniotic, dichorionic twins. There was no zygosity testing conducted, thus it is unknown if the twins are monozygotic or dizygotic. Two possible etiologies for sex-discordant twins, in this case, are concurrent natural conception via breakthrough ovulation at the time of SET, or discordant postzygotic nondisjunction of a single embryo. Multiple gestations may still occur in the setting of SET and zygosity testing in these instances would better elucidate our understanding of this occurrence. Moreover, improved data on the zygosity of multiple gestations following SET may enhance patient counseling. [ABSTRACT FROM AUTHOR]

Abstract Objective It is known that the single embryo transfer (SET) is the best choice to reduce multiples and associated risks. The practice of cryopreserving all embryos for posterior transfer has been increasingly performed for in vitro fertilization (IVF) patients at the risk of ovarian hyperstimulation syndrome or preimplantation genetic testing for aneuploidy. However, its widespread practice is still controverse. The aim of this study was to evaluate how effective is the transfer of two sequential SET procedures compared with a double embryo transfer (DET) in freeze-only cycles. Methods This retrospective study reviewed 5,156 IVF cycles performed between 2011 and 2019, and 506 cycles using own oocytes and freeze-only policy with subsequent elective frozen-thawed embryo transfers (eFET) were selected for this study. Cycles having elective SET (eSET, n = 209) comprised our study group and as control group we included cycles performed with elective DET (eDET, n = 291). In the eSET group, 57 couples who had failed in the 1st eSET had a 2nd eFET, and the estimated cumulative ongoing pregnancy rate was calculated and compared with eDET. Results After the 1st eFET, the ongoing pregnancy rates were similar between groups (eSET: 35.4% versus eDET: 38.5%; p =0.497), but the estimated cumulative ongoing pregnancy rate after a 2nd eFET in the eSET group (eSET + SET) was significantly higher (48.8%) than in the eDET group (p < 0.001). Additionally, the eSET +SET group had a 2.7% rate of multiple gestations, which is significantly lower than the eDET group, with a 30.4% rate (p < 0.001). Conclusion Our study showed the association of freeze-only strategy with until up to two consecutive frozen-thawed eSETs resulted in higher success rates than a frozenthawed DET, while drastically reducing the rate of multiple pregnancies.

Women with polycystic ovary syndrome make up the vast majority of patients with anovulatory infertility. The commonly accepted treatment guidelines recommend ovulation induction for timed intercourse as the first-line treatment. After a 2-year treatment period, the cumulative pregnancy rates with a singleton live-born baby reached 71% and 78% in two prospective studies. Despite aiming for monofollicular growth, multifollicular responses with subsequent multiple/higher order multiple pregnancies are a dreaded risk associated with ovarian induction. However, the lengthy treatment, the increase of maternal age and the psychological effects of 'obligatory intercourse' are also factors challenging the concept of ovarian induction as the first treatment approach in anovulatory infertility. Nowadays, individualized IVF treatment with cycle segmentation, freeze-all strategies and single-embryo transfers in frozen embryo transfer cycles dramatically reduces the risk of multiple pregnancies, and a cumulative pregnancy rate of 83% can be achieved over three complete cycles, thereby reducing exposure to fertility medication and time to pregnancy. Although on first sight ovarian induction might present the easier and less costly approach, efficient and individualized IVF treatments with low complication rates and the chance of preventing multiple pregnancies challenge this concept, and it seems that the time has come to abandon ovarian induction in anovulatory infertility. [ABSTRACT FROM AUTHOR]

To investigate the effect on the pregnancy rate of transfer of a good-quality embryo (GQE) and a poor-quality embryo (PQE) in comparison with a single GQE transfer. Systematic review and meta-analysis. Not applicable. Infertility patients undergoing in vitro fertilization/intracytoplasmic sperm injection- embryo transfer. Three major electronic databases (PubMed, Embase, and Cochrane Library) for studies those compared single GQE transfer to double embryo transfer of a GQE + PQE were searched. The Newcastle–Ottawa Quality Assessment Scale was used to evaluate the study quality. Random-effect meta-analysis was performed on all data for an overall analysis, followed by a subgroup analysis (fresh cleavage-stage embryos, fresh blastocysts, frozen-thawed blastocysts, and the same assessment criteria for blastocyst quality). The primary outcome was clinical pregnancy rate (CPR). A total of 17 studies with 17,612 cycles for GQE transfer and 6,431 cycles for GQE + PQE transfer were included in the meta-analysis. No significant differences were found in CPR (relative risk [RR] = 1.02; 95% confidence interval [CI], 0.91 – 1.14) and live birth rate (RR = 0.96; 95% CI, 0.87 – 1.07) between GQE + PQE and GQE transfers. However, the transfer of GQE + PQE increased multiple pregnancy rate (RR = 0.14; 95% CI, 0.09–0.20) and multiple birth rate (RR = 0.08; 95% CI, 0.06 – 0.12), when compared with the patients undergoing a single GQE transfer. Subgroup analyses by type of embryo for transfer and assessment criteria for embryo quality showed similar trends. Double embryo transfer with GQE + PQE does not result in increased or decreased CPR and live birth rate when compared with a single GQE transfer but leads to a higher multiple pregnancy rate and multiple birth rate. Prospero CRD42022296681 (https://www.crd.york.ac.uk/prospero/display%5frecord.php?RecordID=296681) registered on January 7, 2022. [ABSTRACT FROM AUTHOR]

• Stable IVF outcomes can be achieved for women aged 45+ years using donor eggs. • Single-embryo transfer minimizes twin pregnancies and optimizes safety. • Cumulative live birth rates remain over 50% for very advanced maternal age. • These results are from a nationwide Taiwan IVF registry analysis of advanced maternal age. Does very advanced maternal age (VAMA; age ≥45 years) influence obstetric outcomes among women using donor oocytes in IVF? This retrospective cohort study analysed data from a nationwide IVF registry in Taiwan, focusing on IVF cycles involving women aged 45 years and 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 such as Caesarean section rates, pre-eclampsia, gestational diabetes and birthweight. The study included 1226 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 aged 50 years and older (54.2%) compared with those aged 45–46 years (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 trend towards a decrease in live birth rate and birthweight 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. IVF 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. [ABSTRACT FROM AUTHOR]

The increased use of gestational carriers has expanded family-building opportunities for people and couples unable to carry pregnancies on their own. National American Society of Reproductive Medicine guidelines for gestational carriers have changed over time to reflect advances in reproductive technology and mounting evidence supporting the medical benefits associated with singleton gestations. Assess changes in gestational carrier cycle practice patterns and resultant pregnancy outcomes in the United States in relation to changing national American Society of Reproductive Medicine guidelines, which changed in 2013 and 2017. This retrospective study used data from the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System and included all cycles that were reported from 2014–2020 involving an embryo transfer to a gestational carrier. Binomial regression models evaluated trends in preimplantation genetic testing for aneuploidy, American Society of Reproductive Medicine guideline adherence, number of embryos transferred, and pregnancy outcomes over time. Of the 40,177 gestational carrier transfer cycles from 2014–2020, there was a significant increase in frozen-thawed cycles (41.3% increase), use of assisted hatching (53.4% increase), intracytoplasmic sperm injection (50.0% increase), and preimplantation genetic testing for aneuploidy (155.7% increase). The likelihood of preimplantation genetic testing for aneuploidy was higher in 2020 than in 2014 for autologous oocyte transfers to gestational carriers, both for those aged ≥38 years (adjusted relative risk, 2.38 [95% confidence interval, 2.11–2.70]) and than those aged <38 years (adjusted relative risk, 2.85 [95% confidence interval, 2.58–3.15]). As preimplantation genetic testing for aneuploidy usage increased, single embryo transfer rose for both autologous (adjusted relative risk, 2.22 [95% confidence interval, 1.94–2.50]) and donor cycles (relative risk, 1.91 [95% confidence interval, 1.81–2.02]). This shift toward single embryo transfer corresponded with a decrease in multiple embryo transfer by 79.2% and subsequent decreases in multiple gestations by 68.8% in donor and 73.6% in autologous oocyte cycles from 2014–2020. Gestational carrier cycles remained highly adherent to changing American Society of Reproductive Medicine guidelines throughout the study period. Among live births, there was a 19.4% and 7.9% increase in term deliveries among donor and autologous oocyte cycles, respectively, from 2014 to 2020. Practice patterns have drastically changed throughout the study period, with major increases in the use of preimplantation genetic testing for aneuploidy, intracytoplasmic sperm injection, assisted hatching, and frozen transfers. In response to changing American Society of Reproductive Medicine guidelines, the use of multiple embryo transfers has decreased for gestational carrier cycles with subsequent decreases in multiple gestations and miscarriages and slight increases in live birth rates. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Background Evidence referring to the trade-offs between the benefits and risks of single embryo transfer (SET) versus double embryo transfer (DET) following assisted reproduction technology are insufficient, especially for those women with a defined embryo quality or advanced age. Methods A systematic review and meta-analysis was conducted according to PRISMA guidelines. PubMed, EMBASE, Cochrane Library and ClinicalTrials.gov were searched based on established search strategy from inception through February 2021. Pre-specified primary outcomes were live birth rate (LBR) and multiple pregnancy rate (MPR). Odds ratio (OR) with 95% confidence interval (CI) were pooled by a random-effects model using R version 4.1.0. Results Eighty-five studies (14 randomized controlled trials and 71 observational studies) were eligible. Compared with DET, SET decreased the probability of a live birth (OR = 0.78, 95% CI: 0.71–0.85, P

BACKGROUND: Although a recent study reported that the pregnancy outcomes in the first trimester were more correlated with endometrial thickness on the day of the trigger than with endometrial thickness on the day of single fresh-cleaved embryo transfer, it remains unclear whether endometrial thickness on the day of the trigger can predict live birth rate after a single fresh-cleaved embryo transfer. OBJECTIVE: This study aimed to examine whether endometrial thickness on the trigger day is associated with live birth rates and whether modifying the single fresh-cleaved embryo transfer criteria to reflect endometrial thickness on the trigger day improved the live birth rate and reduced maternal complications in a clomiphene citrate–based minimal stimulation cycle. STUDY DESIGN: This was a retrospective study of the outcomes of 4440 treatment cycles of women who underwent single fresh-cleaved embryo transfer on day 2 of the retrieval cycle. From November 2018 to October 2019, single fresh-cleaved embryo transfer was performed when endometrial thickness on the day of single fresh-cleaved embryo transfer was ≥8 mm (criterion A). From November 2019 to August 2020, single fresh-cleaved embryo transfer was conducted when endometrial thickness on the day of the trigger was ≥7 mm (criterion B). RESULTS: A multivariate logistic regression analysis revealed that increased endometrial thickness on the trigger day was significantly associated with an improvement in the live birth rate after single fresh-cleaved embryo transfer (adjusted odds ratio, 1.098; 95% confidence interval, 1.021–1.179). The live birth rate was significantly higher in the criterion B group than in the criterion A group (22.9% and 19.1%, respectively; P=.0281). Although endometrial thickness on the day of single fresh-cleaved embryo transfer was sufficient, the live birth rate tended to be lower when endometrial thickness on the trigger day was

BACKGROUND: A clinical pregnancy prediction model was developed by implementing machine learning technology that uses a combination of static images and medical data to calculate the outcome of an in vitro fertilization cycle.OBJECTIVE: To provide a system that can accurately and sufficiently assist with decision making that is critical to in vitro fertilization cycles, primarily embryo selection.STUDY DESIGN: Historical medical data, which consist of clinical information and a complete transferred embryo image dataset, of 697 patients who underwent unique in vitro fertilization were collected. Various techniques of machine learning were used, namely decision tree, random forest, and gradient boosting; each technique used the same data configuration for performance comparison and was subsequently optimized using genetic algorithm.RESULTS: A prediction model with a peak accuracy of approximately 65% was achieved. Significant differences in the performances of the 3 selected algorithms were apparent. Nonetheless, additional metric measurements, such as receiver operating characteristic, area under the receiver operating characteristic curve score, accuracy, and loss, suggested that the gradient boosting model performed the best in predicting clinical pregnancy.CONCLUSION: This study served as a stepping stone toward the application of in vitro fertilization prediction models that use machine learning techniques. However, additional validation steps are required to boost the model's performance for its implementation in the clinical setting.

PurposeThis study investigated the relationship between the vitamin D [25(OH)D] level in individual follicles and oocyte developmental competence.MethodsA prospective cohort study in a private infertility center. Infertile women (N = 198) scheduled for intracytoplasmic sperm injection (ICSI) and a single embryo transfer (SET) provided serum samples and 322 follicular fluid (FF) specimens, each from a single follicle on the day of oocyte retrieval.ResultsFFs corresponding to successfully fertilized oocytes (following ICSI) contained significantly lower 25(OH)D level compared with those that were not fertilized (28.4 vs. 34.0 ng/ml, P = 0.001). Top quality embryos on the third day after fertilization, when compared to other available embryos, developed from oocytes collected from follicles containing significantly lower 25(OH)D levels (24.56 vs. 29.59 ng/ml, P = 0.007). Positive hCG, clinical pregnancy, and live birth rates were achieved from embryos derived from oocytes that grew in FF with significantly lower 25(OH)D levels than in follicles not associated with subsequent pregnancy. The concentration of 25(OH)D in FF in women with negative hCG was 32.23 ± 20.21 ng/ml, positive hCG 23.62 ± 6.09 ng/ml, clinical pregnancy 23.13 ± 6.09 ng/ml, and live birth 23.45 ± 6.11 ng/ml (P

Background: Many guidelines have been issued regarding the number of embryos to be transferred after in vitro fertilization (IVF), but patients and clinicians may be reluctant to accept or offer a single embryo transfer due to the expected lower chance of pregnancy or live birth. This study was aimed to provide additional information on cycle outcome according to the number and quality of thawed transferred blastocysts. Methods: A retrospective cohort study was designed to collect the data of 505 patients who performed the first frozen blastocysts transfer at Tam Anh General Hospital from June 2018 to September 2019. One good-quality embryo was transferred for 121 patients (Group 1), two good for 214 patients (Group 2), one good and one poor for 112 patients (Group 3), one good and two poor for 25 patients (Group 4), and one or two poor for 33 patients (Group 5). Results: The pregnancy rate was 71.9%, 74.8%, 69.4%, 84.0%, and 39.4% in Group 1–5, respectively. The multiple pregnancy rate was 36.9%, 16.9%, and 32.0% in Groups 2–4, respectively, higher than Group 1 (4.9%). The live birth rate was 55.6%, 50.9%, and 60.0% in Group 2–4, respectively, but not significantly different from the Group 1 (47.9%). Conclusions: Transferring an additional good or poor embryo, along with a good embryo, does not increase the live birth rate while the incidence of multiple pregnancies rises significantly.

Purpose: Specific serum beta human chorionic gonadotropin (β-hCG) parameters that can predict live birth after an embryo transfer have yet to be defined. Methods: We performed a retrospective cohort study of 1,028 patients with a detectable β-hCG who underwent a single embryo transfer between 2002 and 2019 at a large academic center. Two β-hCG parameters were examined in relation to live birth: 1) "doubling" defined as β-hCG doubling over 48 h and 2) "reaching 100" defined as a β-hCG ≥ 100 mIU/mL by 15 days after oocyte retrieval (AOR). Results: One thousand three hundred forty cycles involving a single embryo were analyzed. Two thirds were frozen embryos and 86% were blastocyst transfers. Preimplantation genetic testing was performed in almost 30% of cycles. When β-hCG levels "doubled," a live birth occurred in 80.7% of cycles and when β-hCG levels "reached 100" by 15 days AOR, live birth occurred in 81.6% of cycles. When β-hCG levels both doubled and reached 100 by 15 days, AOR 85.4% cycles resulted in live birth. A multiple logistic regression model to control for patient and cycle level factors revealed a live birth odds ratio (OR) of 8.0 (95% CI 5.7–11.1) when β-hCG "doubled" and an OR of 21.2 (95% CI 14.3–31.5) when β-hCG "reached 100." When both these latter parameters were met, the OR was 12.5 (95% CI 8.9–17.8). Conclusion: β-hCG parameters of "doubling" and "reaching 100" by 15 days AOR are robust predictors of live birth and can aid in patient counseling regarding pregnancy outcomes soon after single embryo transfer. [ABSTRACT FROM AUTHOR]

Does the COVID-19 vaccination affect endometrial receptivity after single euploid embryo transfer, measured by sustained implantation rate? A retrospective cohort study analysing two groups of single euploid embryo transfers using own oocytes: one historical cohort of 3272 transfers 1 year before the pandemic; and one comprising 890 transfers in women previously vaccinated with mRNA vaccines against severe acute respiratory syndrome coronavirus 2. The main outcomes were clinical pregnancy rate (CPR) and sustained implantation rate (SIR) per embryo transfer. These outcomes were compared between non-vaccinated and vaccinated women, and women who had received one and two doses. Lastly, vaccinated women were divided into quartiles according to the time from last dose to embryo transfer. Similar CPR and SIR were found between non-vaccinated and vaccinated women, and the odds ratio for both outcomes was not statistically significant after being controlled for potential confounders (OR 0.937, 95% CI 0.695 to 1.265 and OR 0.910, 95% CI 0.648 to 1.227 respectively). Within the vaccinated group, women who had received one or two doses also had similar outcomes. In addition, no differences were found according to the time interval from vaccination to embryo transfer. The administration of mRNA vaccines against COVID-19 had no effect on endometrial receptivity and embryo implantation, regardless of the number of doses and time interval from vaccination to embryo transfer. The potential negative effect of the vaccine on endometrial receptivity and reproductive outcomes is reassuring for patients in the process of undergoing assisted reproductive treatment. [ABSTRACT FROM AUTHOR]

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Research Question: What is the effect of embryo morphology score on 14-day β-HCG levels and 14-18-day β-HCG doubling values, and do they have differences in day-3 embryo or day-5 blastocyst transfers?, Design: Retrospective analysis of 4434 fresh cycles of single embryo transfers (SET) with β-HCG ≥15 mIU/ml on day 14 after transfer via IVF and ICSI. The correlation between embryo morphology score and 14-day β-HCG was examined. Doubling of 14-18 day β-HCG was analysed in 2628 cycles to determine correlations with embryo morphology score., Results: In day-3 SET, number of embryonic cells was positively correlated with 14-day post-transfer β-HCG values (R = 0.076; P = 0.013). No significant correlation was observed between the grade of the transferred embryos and the 14-18-day serum β-HCG doubling values. In day-5 single blastocyst transfers, the degree of blastocyst expansion, trophoblast cell and inner cell mass (ICM) grades demonstrated a significant positive correlation with 14-day post-transfer β-HCG (P < 0.001, P = 0.014, P = 0.003). Degree of blastocyst expansion was significantly correlated with 14-18-day β-HCG doubling values (R = -0.051, P = 0.027). Grades of the ICM and trophoblast cells showed no significant correlation with 14-18-day β-HCG doubling values., Conclusion: In fresh SET, embryo morphology score influences 14-day β-HCG values in day-3 embryos and day-5 blastocyst transfers. Embryo morphology score in day-3 SET does not affect 14-18-day β-HCG doubling values. Degree of blastocyst expansion significantly affects 14-18-day β-HCG doubling values in day-5 blastocyst transfers., (Copyright © 2024 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.)

Study Question: Do obstetric and perinatal complications vary according to different blastocyst developmental parameters after frozen-thawed single-blastocyst transfer (SBT) cycles?, Summary Answer: Pregnancies following the transfer of a blastocyst with a grade C trophectoderm (TE) were associated with an increased risk of placenta previa compared to those with a blastocyst of grade A TE., What Is Known Already: Existing studies investigating the effect of blastocyst morphology grades on birth outcomes have mostly focused on fetal growth and have produced conflicting results, while the risk of obstetric complications has rarely been reported. Additionally, growing evidence has suggested that the appearance of TE cells could serve as the most important parameter for predicting implantation and live birth. Given that the TE ultimately develops into the placenta, it is plausible that this independent predictor may also impact placentation., Study Design, Size, Duration: This retrospective cohort study at a tertiary-care academic medical center included 6018 singleton deliveries after frozen-thawed SBT cycles between January 2017 and December 2021., Participants/materials, Setting, Methods: Singleton pregnancies were grouped into two groups according to blastocyst developmental stage (Days 5 and 6), 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). The main outcomes included pregnancy-induced hypertension, preeclampsia, gestational diabetes mellitus, preterm premature rupture of membrane, placenta previa, placental abruption, placenta accreta, postpartum hemorrhage, preterm birth, low birth weight, small for gestational age, and birth defects. Multivariate logistic regressions were performed to evaluate the effect of blastocyst developmental stage, embryo expansion stage, ICM grade, and TE grade on measured outcomes adjusting for potential confounders., Main Results and the Role of Chance: No association was found between blastocyst developmental stage and obstetric or perinatal outcomes both before and after adjusting for potential confounders, and similar results were found with regard to embryo expansion stage and ICM grade. Meanwhile, the incidence of placenta previa derived from a blastocyst with TE of grade C was higher compared with those derived from a blastocyst with TE of grade A (1.7%, 2.4%, and 4.0% for A, B, and C, respectively, P = 0.001 for all comparisons). After adjusting for potential covariates, TE grade C blastocysts had 2.81 times the likelihood of resulting in placenta previa compared to TE grade A blastocysts (adjusted odds ratio 2.81, 95% CI 1.11-7.09). No statistically significant differences were detected between any other measured outcomes and TE grades both before or after adjustment., Limitations, Reasons for Caution: The study is limited by its retrospective, single-center design. Additionally, although the sample size was relatively large for the study group, the sample size for certain subgroups was relatively small and lacked adequate power, particularly the ICM grade C group. Therefore, these results should be interpreted with caution., Wider Implications of the Findings: The study extends our knowledge of the potential downstream effect of TE grade on placental abnormalities., Study Funding/competing Interest(s): This study was supported by the National Key Research and Development Program of China (2023YFC2705500, 2023YFC2705501, 2023YFC2705505, 2019YFA0802604); National Natural Science Foundation of China (82130046, 82320108009, 82371660, 32300710); Shanghai leading talent program, Innovative research team of high-level local universities in Shanghai (SHSMU-ZLCX20210201, SHSMU-ZLCX20210200, SHSMU-ZLCX20180401), Shanghai Jiaotong University School of Medicine Affiliated Renji Hospital Clinical Research Innovation Cultivation Fund Program (RJPY-DZX-003), Science and Technology Commission of Shanghai Municipality (23Y11901400), Shanghai's Top Priority Research Center Construction Project (2023ZZ02002), and Three-Year Action Plan for Strengthening the Construction of the Public Health System in Shanghai (GWVI-11.1-36). The authors have no conflicts of interest to declare., Trial Registration Number: N/A., (© The Author(s) 2024. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Purpose: Several studies investigated endometrial patterns, with respect to pregnancy rates following the transfer of embryos but did not distinguish between single- and multiple-blastocyst procedures. We clarified how the endometrial pattern imaged to transfer a frozen embryo is associated with pregnancy outcomes in single-blastocyst frozen-embryo transfer (sbFET)., Methods: Patients ≤35 years who underwent sbFET on the hormone replacement protocol. We analyzed endometrial patterns' associations with pregnancy outcomes in relation to blastocyst grade and pregnancy-related factors., Results: Of the 1383 cycles, 483 were Lf, 840 were partial-Lf, and 60 were non-Lf. Leaf pattern (Lf): central echogenic line present and continuous. Overall, decreasing distinctness of the central echogenic line was associated with significantly lower rates of clinical pregnancy (Lf: 70.4%; partial-Lf: 58.1%; non-Lf: 28.3%) and live birth (56.3%, 45.5%, and 15.0%) and a higher miscarriage rate (20.0%, 21.7%, and 47.1%). Logistic regressions showed pregnancy and live birth to be significantly more likely and miscarriage less likely in Lf than non-Lf: OR (95% CI): 6.07 (3.24-11.37), 7.43 (3.47-15.39), and 0.20 (0.07-0.57)., Conclusions: Non-Lf presentation was associated with lower rates of pregnancy and live birth, suggesting it signals unsuitable conditions for embryo transfer. We provide information on the pregnancy outcomes of sbFET for endometrial patterns., Competing Interests: The authors declare that there are no conflicts of interest., (© 2024 The Author(s). Reproductive Medicine and Biology published by John Wiley & Sons Australia, Ltd on behalf of Japan Society for Reproductive Medicine.)

In this multicenter, non-inferiority, randomized trial, we randomly assigned 992 women undergoing in-vitro fertilization (IVF) with a good prognosis (aged 20-40, ≥3 transferrable cleavage-stage embryos) to strategies of blastocyst-stage (n = 497) or cleavage-stage (n = 495) single embryo transfer. Primary outcome was cumulative live-birth rate after up to three transfers. Secondary outcomes were cumulative live-births after all embryo transfers within 1 year of randomization, pregnancy outcomes, obstetric-perinatal complications, and livebirths outcomes. Live-birth rates were 74.8% in blastocyst-stage group versus 66.3% in cleavage-stage group (relative risk 1.13, 95%CI:1.04-1.22; P non-inferiority  < 0.001, P superiority  = 0.003) (1-year cumulative live birth rates of 75.7% versus 68.9%). Blastocyst transfer increased the risk of spontaneous preterm birth (4.6% vs 2.0%; P = 0.02) and neonatal hospitalization >3 days. Among good prognosis women, a strategy of single blastocyst transfer increases cumulative live-birth rates over single cleavage-stage transfer. Blastocyst transfer resulted in higher preterm birth rates. This information should be used to counsel patients on their choice between cleavage-stage and blastocyst-stage transfer (NCT03152643, https://clinicaltrials.gov/study/NCT03152643 )., (© 2024. The Author(s).)

Introduction: The incidence of ectopic pregnancy is up to four times higher after in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) than in spontaneous pregnancies, and the risk of ectopic pregnancy is increased by tubal factor infertility and the transfer of multiple embryos. However, the effect of embryo quality on the probability of ectopic pregnancy has not been investigated until now and it is not clear whether ovarian stimulation parameters affect the incidence of ectopic pregnancy. Material and Methods: An historical cohort study of 15 006 clinical pregnancies (diagnosed by ultrasound at 6–8 gestational weeks) after non‐donor IVF/ICSI with fresh embryo transfer (n = 8952) or frozen–thawed embryo transfer (n = 6054). Treatments were performed during 2000–2017 in Finland. A total of 9207 (61.4%) single and 5799 (38.6%) double embryo transfers of no more than one top‐quality embryo were evaluated. We analyzed the effects of multiple factors on ectopic pregnancy by logistic regression, including type of cycle (fresh vs frozen embryo transfer), female age, number and quality of embryos transferred, tubal factor infertility and factors of ovarian response to gonadotropin stimulation. Results: Ectopic pregnancy was observed in 2.3% of cycles. There was no significant difference in ectopic pregnancy rate after fresh embryo transfer and frozen embryo transfer (2.2% vs 2.4%, p = 0.3). The ectopic pregnancy rate was lower in cycles with top‐quality embryo transfer (1.9%) than of those where only non‐top quality embryos were transferred (2.7%, p < 0.0001). Tubal factor infertility was diagnosed more often in ectopic pregnancy than in intrauterine pregnancies (21.2% vs 11.0%, p < 0.0001). Logistic regression revealed lower odds for ectopic pregnancy after a top‐quality embryo transfer than after transfer of a non‐top quality embryo (odds ratio [OR] 0.72, 95% confidence interval [CI] 0.56–0.92, p = 0.007). Transfer of two vs one embryo (OR 1.35, 95% CI 1.05–1.70, p = 0.02) and tubal factor infertility (OR 2.21, 95% CI 1.68–2.91, p < 0.0001) significantly increased the risk of ectopic pregnancy. Conclusions: Transfer of non‐top quality embryos is associated with a higher rate of ectopic pregnancy. This is particularly important to keep in mind in treatments with only non‐top embryos available even in the absence of tubal factor infertility. To minimize the risk of ectopic pregnancy, the number of embryos transferred should be as low as possible. [ABSTRACT FROM AUTHOR]

Objective: To date, evidence regarding the effectiveness and safety of two consecutive cycles of single embryo transfer (2SETs) compared with one cycle of double embryo transfer (DET) has been inadequate, particularly considering infertile women with different prognostic factors. This study aimed to comprehensively summarize the evidence by comparing 2SETs with DET. Methods: PubMed, Embase, Cochrane Library databases, ClinicalTrails.gov, and the WHO International Clinical Trials Registry Platform were searched up to March 22, 2022. Peer-reviewed, English-language randomized controlled trials (RCTs) and observational studies (OS) comparing the outcomes of 2SETs with DET in infertile women with their own oocytes and embryos were included. Two authors independently conducted study selection, data extraction, and bias assessment. The Mantel–Haenszel random-effects model was used for pooling RCTs, and a Bayesian design-adjusted model was conducted to synthesize the results from both RCTs and OS. Main Results: Twelve studies were finally included. Compared with the DET, 2SETs were associated with a similar cumulative live birth rate (LBR; 48.24% vs. 48.91%; OR, 0.97; 95% credible interval (CrI), 0.89–1.13, τ2 = 0.1796; four RCTs and six observational studies; 197,968 women) and a notable lower cumulative multiple birth rate (MBR; 0.87% vs. 17.72%; OR, 0.05; 95% CrI, 0.02–0.10, τ2 = 0.1036; four RCTs and five observational studies; 197,804 women). Subgroup analyses revealed a significant increase in cumulative LBR (OR, 1.33; 95% CrI, 1.29–1.38, τ2 = 0) after two consecutive cycles of single blastocyst transfer compared with one cycle of double blastocyst transfer. Moreover, a lower risk of cesarean section, antepartum hemorrhage, preterm birth, low birth weight, and neonatal intensive care unit admission but a higher gestational age at birth and birth weight were found in the 2SETs group. Conclusion: Compared to the DET strategy, 2SETs result in a similar LBR while simultaneously reducing the MBR and improving maternal and neonatal adverse outcomes. The 2SETs strategy appears to be especially beneficial for women aged ≤35 years and for blastocyst transfers. [ABSTRACT FROM AUTHOR]

Abstract Background The KIDScore™ Day 5 (KS-D5) model, version 3, is a general morphokinetic prediction model (Vitrolife, Sweden) for fetal heartbeat prediction after embryo transfer that was developed based on a large data set that included implantation results from a range of clinics with different patient populations, culture conditions and clinical practices. However, there was no study to comparing their pregnancy and live birth prediction ability among different maternal age. The aim of this study is to analyze the performance of KS-D5 in predicting pregnancy and live birth in various maternal age groups after single vitrified-warmed blastocyst transfer (SVBT). Methods A total of 2486 single vitrified-warmed blastocyst transfer (SVBT) cycles were analyzed retrospectively. Confirmed fetal heartbeat positive (FHB+) and live birth (LB+) rates were stratified by Society for Assisted Reproductive Technology (SART) maternal age criteria (

ObjectiveTo date, evidence regarding the effectiveness and safety of two consecutive cycles of single embryo transfer (2SETs) compared with one cycle of double embryo transfer (DET) has been inadequate, particularly considering infertile women with different prognostic factors. This study aimed to comprehensively summarize the evidence by comparing 2SETs with DET.MethodsPubMed, Embase, Cochrane Library databases, ClinicalTrails.gov, and the WHO International Clinical Trials Registry Platform were searched up to March 22, 2022. Peer-reviewed, English-language randomized controlled trials (RCTs) and observational studies (OS) comparing the outcomes of 2SETs with DET in infertile women with their own oocytes and embryos were included. Two authors independently conducted study selection, data extraction, and bias assessment. The Mantel–Haenszel random-effects model was used for pooling RCTs, and a Bayesian design-adjusted model was conducted to synthesize the results from both RCTs and OS.Main ResultsTwelve studies were finally included. Compared with the DET, 2SETs were associated with a similar cumulative live birth rate (LBR; 48.24% vs. 48.91%; OR, 0.97; 95% credible interval (CrI), 0.89–1.13, τ2 = 0.1796; four RCTs and six observational studies; 197,968 women) and a notable lower cumulative multiple birth rate (MBR; 0.87% vs. 17.72%; OR, 0.05; 95% CrI, 0.02–0.10, τ2 = 0.1036; four RCTs and five observational studies; 197,804 women). Subgroup analyses revealed a significant increase in cumulative LBR (OR, 1.33; 95% CrI, 1.29–1.38, τ2 = 0) after two consecutive cycles of single blastocyst transfer compared with one cycle of double blastocyst transfer. Moreover, a lower risk of cesarean section, antepartum hemorrhage, preterm birth, low birth weight, and neonatal intensive care unit admission but a higher gestational age at birth and birth weight were found in the 2SETs group.ConclusionCompared to the DET strategy, 2SETs result in a similar LBR while simultaneously reducing the MBR and improving maternal and neonatal adverse outcomes. The 2SETs strategy appears to be especially beneficial for women aged ≤35 years and for blastocyst transfers.

Ran Kim,1 Seung-Ah Choe,2 Eun A Park,1 Myung Joo Kim,1 Young-Sang Kim,1 You Shin Kim1 1Department of Obstetrics and Gynecology, CHA Fertility Center Seoul Station, CHA University School of Medicine, Seoul, 04637, Korea; 2Department of Preventive Medicine, Korea University College of Medicine, Seoul, 02841, KoreaCorrespondence: Seung-Ah ChoeDepartment of Preventive Medicine, Korea University College of Medicine, Department of Epidemiology & Health Informatics, Graduate School of Public Health, Korea University, 73 Goryeodae-ro, Seongbuk-gu, Seoul, 02841, KoreaTel +82-2-2286-1344Email seungah@korea.ac.krPurpose: To assess the impact of additional embryo transfer (ET) on pregnancy in young women, we used a natural-experiment approach.Patients and Methods: The design was based on the national policy of South Korea limiting the number of embryos transferred in vitro fertilization (IVF):≦2 embryos on day 2– 4 or one on day 5– 6 for patients aged < 35, with one extra embryo allowed for patients aged ≥ 35. Using the data from 1909 ET cycles of 1287 women aged ≥ 34 and ≤ 35, we calculated adjusted risk ratios (RRs) for pregnancy.Results: Half of cycles were undertaken by women aged 35, and additional ET was performed in 68.7% of them. Intrauterine pregnancy (45.2% vs 51.3%) and multiple gestation (30.5% vs 6.9%) were more common in women aged 35 than in those aged 34. The RR for intrauterine pregnancy was 1.34 (95% confidence interval: 1.12– 1.59) when comparing double ET to single ET in frozen day 5– 6 cycles.Conclusion: We observed no evidence of a higher probability of pregnancy with additional ET in fresh or frozen day 3– 4 ET, or in fresh day 5– 6 ET of women aged 35. Additional ET may not increase the successful pregnancy rate in the 35-year-old group, unless it is a frozen day 5– 6 ET cycle.Keywords: in vitro fertilization, single embryo transfer, pregnancy rate, multiple pregnancy

Objective: To study the influence of the previous cesarean section on the pregnancy outcomes and perinatal outcomes in single embryo transfer (SET) cycles in an in vitro fertilization/intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET) setting compared to those with previous vaginal delivery (VD). In addition, the association between fertility outcomes and different cesarean scar defect (CSD) sizes was studied. Method: This was a retrospective cohort study conducted in the Reproductive Center of the First Affiliated Hospital of Nanjing Medical University. A total of 4,879 patients with previous delivery history undergoing SET were included between January 2015 and April 2019. Patients were divided into the VD group and cesarean delivery (CD) group according to different modes of previous delivery. The primary outcome was live birth rate. The pregnancy outcomes of CD were analyzed as a subgroup and the relationship between pregnancy outcomes as well as the different sizes of CSD were explored by logistic regression analysis. Results: There were no significant differences in live birth rate, clinical pregnancy rate, and miscarriage rate between the CD group and VD group. The incidence rates of pregnancy complications such as pregnancy hypertension, gestational diabetes mellitus, placenta abnormalities, premature rupture of membrane, and postpartum hemorrhage were similar in the two groups. Live birth rate was significantly lower in the CSD group (23.77% vs 37.01%, aOR: 0.609, 95% CI: 0.476-0.778) comparing to patients without CSD. There were also significant differences in clinical pregnancy rate (37.52% vs 47.64%, aOR: 0.779, 95%CI: 0.623-0.973) and miscarriage rate (34.55% vs 20.59%, aOR: 1.407, 95%CI:1.03-1.923). Large size CSD significantly decreased live birth rate (13.33% vs 26.29%, aOR: 0.422, 95%CI: 0.197-0.902) and clinical pregnancy rate (25.33% vs 40.09%, aOR: 0.503, 95%CI: 0.272-0.930) compared with small size CSD. Conclusion: For women with previous cesarean sections, the pregnancy outcomes were similar to those with previous VD without increased perinatal complications following SET. The presence of CSD was associated with a marked reduction in live birth rate, especially in patients with large size CSD. [ABSTRACT FROM AUTHOR]

Reflecting the current trends, the utilization of frozen-thawed transfer cycles has been steadily increasing worldwide; outcome predictors of these cycles are therefore a major research goal. Our aim was to investigate whether the outcome of a fresh single blastocyst transfer (SBT) can serve as a prognostic factor for the subsequent vitrified–warmed SBT originating from the same cohort. A retrospective cohort study was performed at a single unit. Non-donor fresh cycles were analyzed as predictors of the following vitrified–warmed cycle. Only SBTs were included. Cycles designated to a freeze-all policy and cycles involving pre-implantation genetic analysis were excluded. A total of 1127 vitrified–warmed single blastocyst cycles were included. The indications for artificial reproductive technologies were comparable across the study groups. Vitrified–warmed cycles following a live birth outcome in the fresh cycle were more likely to result in a clinical pregnancy than those following a fresh cycle, which failed to reach a live birth. The same trend was observed for live birth rate following vitrified–warmed transfer in the fresh cycle. After correcting for possible confounders, age and embryo quality were significantly correlated with the chance for a live birth, but the previous fresh cycle did not affect the results. We therefore conclude that after adjustment for age, embryo quality and number of previous oocyte retrieval cycles, the fresh cycle outcome was not a significant influential factor for the following vitrified–warmed cycle. [ABSTRACT FROM AUTHOR]

Study Question: Can use of a commercially available time-lapse algorithm for Day 5 blastocyst selection improve pregnancy rates compared with morphology alone?Summary Answer: The use of a time-lapse selection model to choose blastocysts for fresh single embryo transfer on Day 5 did not improve ongoing pregnancy rate compared to morphology alone.What Is Known Already: Evidence from time-lapse monitoring suggests correlations between timing of key developmental events and embryo viability. No good quality evidence exists to support improved pregnancy rates following time-lapse selection.Study Design, Size, Duration: A prospective multicenter randomized controlled trial including 776 randomized patients was performed between 2018 and 2021. Patients with at least two good quality blastocysts on Day 5 were allocated by a computer randomization program in a proportion of 1:1 into either the control group, whereby single blastocysts were selected for transfer by morphology alone, or the intervention group whereby final selection was decided by a commercially available time-lapse model. The embryologists at the time of blastocyst morphological scoring were blinded to which study group the patients would be randomized, and the physician and patients were blind to which group they were allocated until after the primary outcome was known. The primary outcome was number of ongoing pregnancies in the two groups.Participants/materials, Setting, Methods: From 10 Nordic IVF clinics, 776 patients with a minimum of two good quality blastocysts on Day 5 (D5) were randomized into one of the two study groups. A commercial time-lapse model decided the final selection of blastocysts for 387 patients in the intervention (time-lapse) group, and blastocysts with the highest morphological score were transferred for 389 patients in the control group. Only single embryo transfers in fresh cycles were performed.Main Results and the Role Of Chance: In the full analysis set, the ongoing pregnancy rate for the time-lapse group was 47.4% (175/369) and 48.1% (181/376) in the control group. No statistically significant difference was found between the two groups: mean difference -0.7% (95% CI -8.2, 6.7, P = 0.90). Pregnancy rate (60.2% versus 59.0%, mean difference 1.1%, 95% CI -6.2, 8.4, P = 0.81) and early pregnancy loss (21.2% versus 18.5%, mean difference 2.7%, 95% CI -5.2, 10.6, P = 0.55) were the same for the time-lapse and the control group. Subgroup analyses showed that patient and treatment characteristics did not significantly affect the commercial time-lapse model D5 performance. In the time-lapse group, the choice of best blastocyst changed on 42% of occasions (154/369, 95% CI 36.9, 47.2) after the algorithm was applied, and this rate was similar for most treatment clinics.Limitations, Reasons For Caution: During 2020, the patient recruitment rate slowed down at participating clinics owing to coronavirus disease-19 restrictions, so the target sample size was not achieved as planned and it was decided to stop the trial prematurely. The study only investigated embryo selection at the blastocyst stage on D5 in fresh IVF transfer cycles. In addition, only blastocysts of good morphological quality were considered for transfer, limiting the number of embryos for selection in both groups: also, it could be argued that this manual preselection of blastocysts limits the theoretical selection power of time-lapse, as well as restricting the results mainly to a good prognosis patient group. Most patients were aimed for blastocyst stage transfer when a minimum of five zygotes were available for extended culture. Finally, the primary clinical outcome evaluated was pregnancy to only 6-8 weeks.Wider Implications Of the Findings: The study suggests that time-lapse selection with a commercially available time-lapse model does not increase chance of ongoing pregnancy after single blastocyst transfer on Day 5 compared to morphology alone.Study Funding/competing Interest(s): The study was financed by a grant from the Swedish state under the ALF-agreement between the Swedish government and the county councils (ALFGBG-723141). Vitrolife supported the study with embryo culture dishes and culture media. During the study period, T.H. changed his employment from Livio AB to Vitrolife AB. All other authors have no conflicts of interests to disclose.Trial Registration Number: ClinicalTrials.gov registration number NCT03445923.Trial Registration Date: 26 February 2018.Date Of First Patient’s Enrolment: 11 June 2018. [ABSTRACT FROM AUTHOR]