Comparison of pregnancy outcomes between 4th day morula and 5th day blastocyst after embryo transfer: a retrospective cohort study.

BACKGROUND: This study was designed to evaluate pregnancy outcomes between morulae transferred on day 4 (D4) and blastocysts transferred on day 5 (D5). METHODS: From September 2017 to September 2020, 1963 fresh transfer cycles underwent early follicular phase extra-long protocol for assisted conception in our fertility center were divided into D4 (324 cases) and D5 (1639 cases) groups, and the general situation and other differences of patients in both groups were compared. To compare the differences in pregnancy outcomes, the D4 and D5 groups were further divided into groups A and B based on single and double embryo transfers. Furthermore, the cohort was divided into two groups: those with live births (1116 cases) and those without (847 cases), enabling a deeper evaluation of the effects of D4 or D5 transplantation on assisted reproductive outcomes. RESULTS: In single embryo transfer, there was no significant difference between groups D4A and D5A (P > 0.05). In double embryo transfer, group D4B had a lower newborn birthweight and a larger proportion of low birthweight infants (P < 0.05). The preterm delivery rate, twin delivery rate, cesarean delivery rate, and percentage of low birthweight infants were lower in the D5A group than in the D5B group (P < 0.05). Analysis of factors influencing live birth outcomes further confirmed the absence of a significant difference between D4 and D5 transplantation in achieving live birth (P > 0.05). CONCLUSION: When factors such as working life and hospital holidays are being considered, D4 morula transfer may be a good alternative to D5 blastocyst transfer. Given the in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) success rate and risk of twin pregnancy, D4 morula transfer requires an adapted decision between single and double embryo transfer, although a single blastocyst transfer is recommended for the D5 transfer in order to decrease the twin pregnancy rate. In addition, age, endometrial thickness and other factors need to be taken into account to personalize the IVF program and optimize pregnancy outcomes.

The risk of asthma in singletons conceived by ART: a retrospective cohort study.

STUDY QUESTION: Do singleton children conceived by ART have a higher asthma risk than naturally conceived (NC) singletons? SUMMARY ANSWER: The asthma risk was similar for ART-conceived singletons and NC singletons, and there were no clear differences between the various types of ART. WHAT IS KNOWN ALREADY: Whether ART increases asthma risk in offspring is questionable. The evidence is inconsistent and limited by ethnicity, geographic distribution, inadequate confounder adjustment, unsatisfactory control groups, and specific methods of ART. Furthermore, the mediating effects of obstetric and neonatal outcomes on the association between ART and asthma remain unclear. STUDY DESIGN SIZE DURATION: This observational, single-centre study was conducted at a reproductive centre of an affiliated university hospital between September 2009 and April 2023. A total of 3227 singletons aged 3-6 years conceived by IVF versus ICSI or fresh versus frozen embryo transfer were retrospectively enrolled, and a total of 1206 NC singletons of the same age were subsequently recruited. PARTICIPANTS/MATERIALS SETTING METHODS: Asthma was defined as a self-reported physician diagnosis or wheezing in the past 12 months. We performed multivariable logistic regression analyses to examine associations between asthma in offspring and ART use, adjusting for parental characteristics (age, education level, occupation type, BMI, asthma), smoking exposure, residence type, child sex, child age, and year of follow-up. Mediating effects were explored using longitudinal mediation structural equation modelling. MAIN RESULTS AND THE ROLE OF CHANCE: Asthma was reported for 51 (4.2%) of the 1206 NC singletons (median [interquartile range] age 5 [4-5] years; 48.1% females) and 169 (5.2%) of the 3227 ART-conceived singletons (5 [5-5] years; 47.6% females). We found that risks of childhood asthma in singletons conceived by ART were, overall, similar to those of NC singletons before (odds ratio [OR], 1.25 [95% CI, 0.92-1.74]; P = 0.170) and after adjustment (adjusted OR [aOR], 0.66 [95% CI, 0.44-1.03]; P = 0.126). The results were similar in multiple sensitivity analyses, and there were no clear differences in asthma risks according to the method of ART. Mediation analysis revealed a significant positive indirect effect of neonatal intensive care unit (NICU) admission (standard path coefficient, b = 0.025, P < 0.05) and a negative indirect effect of breastfeeding (b = -0.012, P < 0.05) on the association between ART and asthma in singleton offspring. LIMITATIONS REASONS FOR CAUTION: This study is limited to singletons only and cannot be generalized. The study is also limited by its retrospective observational single-centre nature and sample size. Mediation analyses were exploratory. Therefore, the findings need to be interpreted with caution. WIDER IMPLICATIONS OF THE FINDINGS: These findings can help infertile couples undergoing ART be reassured about the risk of childhood asthma in singleton offspring. Breastfeeding is recommended as a potentially feasible intervention to reduce the asthma risks in ART-conceived children who are at increased potential risk of asthma, such as those with NICU admissions. STUDY FUNDING/COMPETING INTERESTS: This work was supported by the Key Research and Development Program of Zhejiang Province (2021C03100), the National Key Research and Development Program of China (2021YFC2700603), and the Program for Key Subjects of Zhejiang Province in Medicine and Hygiene to Y. Z., the Zhejiang Province Natural Science Foundation (No. LQ22H040006) and the National Natural Science Foundation of China (No.82101759) to M.T., and the National Natural Science Foundation of China (No. 82201860) to J.Y. The authors declare no competing interests. TRIAL REGISTRATION NUMBER: ChiCTR2300069906.

Granulosa cell metabolism at ovulation correlates with oocyte competence and is disrupted by obesity and aging.

STUDY QUESTION: Is oocyte developmental competence associated with changes in granulosa cell (GC) metabolism? SUMMARY ANSWER: GC metabolism is regulated by the LH surge, altered by obesity and reproductive aging, and, in women, specific metabolic profiles are associated with failed fertilization versus increased blastocyst development. WHAT IS KNOWN ALREADY: The cellular environment in which an oocyte matures is critical to its future developmental competence. Metabolism is emerging as a potentially important factor; however, relative energy production profiles between GCs and cumulus cells and their use of differential substrates under normal in vivo ovulatory conditions are not well understood. STUDY DESIGN, SIZE, DURATION: This study identified metabolic and substrate utilization profiles within ovarian cells in response to the LH surge, using mouse models and GCs of women undergoing gonadotropin-induced oocyte aspiration followed by IVF/ICSI. PARTICIPANTS/MATERIALS, SETTING, METHODS: To comprehensively assess follicular energy metabolism, we used real-time metabolic analysis (Seahorse XFe96) to map energy metabolism dynamics (mitochondrial respiration, glycolysis, and fatty acid oxidation) in mouse GCs and cumulus-oocyte complexes (COCs) across a detailed time course in the lead up to ovulation. In parallel, the metabolic profile of GCs was measured in a cohort of 85 women undergoing IVF/ICSI (n = 21 with normal ovarian function; n = 64 with ovarian infertility) and correlated with clinical parameters and cycle outcomes. MAIN RESULTS AND THE ROLE OF CHANCE: Our study reveals dynamic changes in GC energy metabolism in response to ovulatory LH, with mitochondrial respiration and glycolysis differentially affected by obesity versus aging, in both mice and women. High respiration in GCs is associated with failed fertilization (P < 0.05) in a subset of women, while glycolytic reserve and mitochondrial ATP production are correlated with on-time development at Day 3 (P < 0.05) and blastocyst formation (P < 0.01) respectively. These data provide new insights into the cellular mechanisms of infertility, by uncovering significant associations between metabolism within the ovarian follicle and oocyte developmental competence. LIMITATIONS, REASONS FOR CAUTION: A larger prospective study is needed before the metabolic markers that were positively and negatively associated with oocyte quality can be used clinically to predict embryo outcomes. WIDER IMPLICATIONS OF THE FINDINGS: This study offers new insights into the importance of GC metabolism for subsequent embryonic development and highlights the potential for therapeutic strategies focused on optimizing mitochondrial metabolism to support embryonic development. STUDY FUNDING/COMPETING INTEREST(S): National Health and Medical Research Council (Australia). The authors have no competing interests. TRIAL REGISTRATION NUMBER: N/A.

Fertility clinics have a duty of care towards patients who do not have children with treatment.

In medically assisted reproduction (MAR) success has mostly been measured in terms of achieving (healthy) livebirths. We argue this focus is too narrow and that success should be measured in terms of alleviating patient suffering caused by an unfulfilled child wish. The major implication is that clinics must better tailored care to effectively support patients who do not have child(ren) with treatment. First, we argue that clinics have a duty of care towards patients for whom MAR does not result in children because this is a common treatment outcome, because treatment is burdensome and creates new losses for patients, and because the field has the necessary expertise to provide support and it is part of patient-centred care. Then, we examine concerns about the adequacy of addressing the possibility that treatment may end without children, namely, that this may hinder patients' hope and put them off doing treatment, and that it may be perceived as a sign of clinical incompetence, as well as concerns about the required skill set. We end with a set of research-informed recommendations to promote healthy adjustment to ending fertility treatment without children. These focus on the need to reconceptualize 'success' and 'failure' in MAR, to promote open discussion about the possibility of treatment not resulting in children and encourage patients to develop 'plan(s) B', to support patients who end treatment without children, and to create the organizational structures needed to support clinics and healthcare professionals in this endeavour.

First case report of a successful delivery of a healthy boy by preimplantation genetic testing for Beckwith-Wiedemann syndrome.

PURPOSE: To showcase the successful use of ICSI with PGT-M to overcome Beckwith-Wiedemann syndrome (BWS)-related reproductive challenges, resulting in the birth of a healthy baby boy. By targeting the maternally inherited CDKN1C pathogenic gene variant, this report highlights the genetic interventions in BWS reproductive risk management. METHODS: This case report describes a 41-year-old woman seeking fertility assistance after a previous pregnancy revealed a fetal anomaly related to BWS. Families with BWS recurrence face challenges, as maternally inherited CDKN1C pathogenic variants contribute to approximately 40% of genetic alterations, with a potential recurrence risk as high as 50%. Genetic analysis identified a pathogenic variant in the CDKN1C gene of the fetus that was maternally inherited. The pregnancy was terminated due to the fetal anomalies. The couple underwent intra-cytoplasmic sperm injection (ICSI) combined with preimplantation genetic testing for monogenic diseases (PGT-M) and preimplantation genetic testing for aneuploidy (PGT-A). RESULTS: Two embryos from IVF with low-risk PGT-M and euploid status. One transferred via frozen embryo transfer (FET) in February 2023 resulted in the successful birth of a healthy baby boy. This study reports the first successful delivery of a healthy boy after PGT-M for the CDKN1C gene variant c.79_100delinsGTGACC, contributing to the limited literature on successful outcomes for BWS. CONCLUSION: Utilizing PGT-M in combination with IVF can lead to favorable outcomes in managing BWS-associated reproductive challenges, offering insights into potential genetic interventions and successful birth.

Diverse impacts of female chromosomal polymorphisms on assisted reproduction outcomes: a retrospective cohort study.

BACKGROUND: The effects of female chromosomal polymorphisms (FCPs) on various aspects of reproductive health have been investigated, yet the findings are frequently inconsistent. This study aims to clarify the role of FCPs on the outcomes of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). METHODS: This retrospective cohort study comprised 951 couples with FCPs and 10,788 couples with normal karyotypes who underwent IVF/ICSI treatment at Peking University Third Hospital between 2015 and 2021. The exposure was FCPs. The embryological outcomes and clinical outcomes were compared. RESULTS: The FCPs, as a whole, compromised the oocyte maturation rate (76.0% vs. 78.8%, P = 0.008), while they did not adversely affect other IVF/ICSI outcomes. Further detailed analyses showed that every type of FCPs contributed to the lower oocyte maturation rate, particularly the rare FCPs (69.0% vs. 78.8%, P = 0.008). The female qh + was associated with a higher normal fertilization rate (63.0% vs. 59.2%, adjusted P = 0.022), a higher clinical pregnancy rate (37.0% vs. 30.7%, adjusted P = 0.048), and a higher live birth rate (27.0% vs.19.0%, adjusted P = 0.003) in couples undergoing IVF. Conversely, in couples undergoing ICSI, female qh + was found to be related to a lower normal fertilization rate (58.8% vs. 63.8%, P = 0.032), a comparable clinical pregnancy rate (25.7% vs. 30.9%, P = 0.289), and a comparable live birth rate (19.8% vs. 19.2%, P = 0.880) compared to the control group. Additionally, an increased risk of preterm birth was observed in women undergoing IVF with multiple polymorphisms (62.5% vs. 16.9%, adjusted P <  0.001) and in women undergoing ICSI with pstk+ (36.4% vs. 15.4%, P = 0.036). CONCLUSIONS: Our research unravels the diverse impacts of various FCPs on IVF/ICSI outcomes, highlighting the detrimental effects of FCPs on oocyte maturation and the risk of preterm birth.

Impacts of male chromosomal polymorphisms on semen quality and IVF/ICSI outcomes: A retrospective cohort study.

OBJECTIVE: The study aims to elucidate the impacts of different types of male chromosomal polymorphisms (MCPs) on various outcomes of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) treatment. METHODS: This retrospective cohort study included 1442 couples with normal karyotypes, 1442 couples with MCPs, 42 couples with male chromosomal rearrangements (MCRs), and 42 couples with MCRs combined with MCPs who underwent IVF/ICSI treatment at Peking University Third Hospital from 2015 to 2021. The semen quality, embryological outcomes, and clinical outcomes of different groups stratified by karyotypes were compared. RESULTS: For couples undergoing IVF, male inv(9) was associated with a significantly lower sperm viability rate (29.41% vs 34.49%, P = 0.030), a lower progressive motility rate (25.13% vs 30.50%, P = 0.013), and a lower normal fertilization rate (52.41% vs 59.84%, P = 0.014). Male 9qh + was related to a lower sperm viability rate (27.56% vs 34.49%, P = 0.028). No MCPs were observed to compromise clinical outcomes in couples undergoing IVF. For couples undergoing ICSI, no MCPs exhibited an association with poorer semen quality and embryological outcomes. However, Yqh + and DGpstk+ were found to be significantly correlated with an increased likelihood of preterm birth (23.3% vs 9.2%, P = 0.003; 20.0% vs 9.2%, P = 0.041, respectively). In couples with MCRs, the presence of MCPs significantly reduced the sperm viability rate (19.99% vs 30.97%, P = 0.017) and progressive motility rate (8.07% vs 27.85%, P = 0.018). CONCLUSION: Our study provides detailed evidence for the impacts of various MCPs on IVF/ICSI outcomes, reveals the complexity and heterogeneity of these impacts, and highlights the adverse effects of male inv(9).

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

STUDY QUESTION: Do embryos with longer telomere length (TL) at the blastocyst stage have a higher capacity to survive after frozen-thawed embryo transfer (FET)? SUMMARY ANSWER: 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. WHAT IS KNOWN ALREADY: 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. STUDY DESIGN SIZE DURATION: 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. PARTICIPANTS/MATERIALS SETTING AND METHODS: 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. MAIN RESULTS AND THE ROLE OF CHANCE: 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. LIMITATIONS REASONS FOR CAUTION: 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. WIDER IMPLICATIONS OF THE FINDINGS: 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. STUDY FUNDING/COMPETING INTERESTS: 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. TRIAL REGISTRATION NUMBER: N/A.

The endometrial transcriptome of infertile women with and without implantation failure.

INTRODUCTION: Implantation failure after transferring morphologically "good-quality" embryos in in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) may be explained by impaired endometrial receptivity. Analyzing the endometrial transcriptome analysis may reveal the underlying processes and could help in guiding prognosis and using targeted interventions for infertility. This exploratory study investigated whether the endometrial transcriptome profile was associated with short-term or long-term implantation outcomes (ie success or failure). MATERIAL AND METHODS: Mid-luteal phase endometrial biopsies of 107 infertile women with one full failed IVF/ICSI cycle, obtained within an endometrial scratching trial, were subjected to RNA-sequencing and differentially expressed genes analysis with covariate adjustment (age, body mass index, luteinizing hormone [LH]-day). Endometrial transcriptomes were compared between implantation failure and success groups in the short term (after the second fresh IVF/ICSI cycle) and long term (including all fresh and frozen cycles within 12 months). The short-term analysis included 85/107 women (33 ongoing pregnancy vs 52 no pregnancy), excluding 22/107 women. The long-term analysis included 46/107 women (23 'fertile' group, ie infertile women with a live birth after ≤3 embryos transferred vs 23 recurrent implantation failure group, ie no live birth after ≥3 good quality embryos transferred), excluding 61/107 women not fitting these categories. As both analyses drew from the same pool of 107 samples, there was some sample overlap. Additionally, cell type enrichment scores and endometrial receptivity were analyzed, and an endometrial development pseudo-timeline was constructed to estimate transcriptomic deviations from the optimum receptivity day (LH + 7), denoted as ΔWOI (window of implantation). RESULTS: There were no significantly differentially expressed genes between implantation failure and success groups in either the short-term or long-term analyses. Principal component analysis initially showed two clusters in the long-term analysis, unrelated to clinical phenotype and no longer distinct following covariate adjustment. Cell type enrichment scores did not differ significantly between groups in both analyses. However, endometrial receptivity analysis demonstrated a potentially significant displacement of the WOI in the non-pregnant group compared with the ongoing pregnant group in the short-term analysis. CONCLUSIONS: No distinct endometrial transcriptome profile was associated with either implantation failure or success in infertile women. However, there may be differences in the extent to which the WOI is displaced.

Cut-off point of mature oocyte for routine clinical application of rescue IVM: a retrospective cohort study.

BACKGROUND: The rescue in vitro mature(Rescue IVM) technique allows the use of immature oocytes collected in conventional COH to obtain more mature oocytes for fertilization through in vitro maturation. Some studies have shown that Rescue IVM could improve clinical outcomes in patients undergoing IVF/ICSI, but the effectiveness and the indications for the clinical application of this technique remain controversial. It remains to be studied whether Rescue IVM should be universally applied in all conventional IVF/ICSI cycles. METHOD: This is a large retrospective cohort study that included a total of 22,135 female patients undergoing their first IVF treatment cycles. The effect of the number of mature oocytes(metaphaseII[MII]) on the cumulative live birth rate was investigated in a population with routine IVF/ICSI first. The receiver operating characteristic curve(ROC) analysis was used to explore the cut-off point of the number of MII affecting CLBR. Secondly, Patients undergoing ICSI with Rescue IVM were included in the analysis with those who underwent ICSI only during the same period, grouped according to the MII cut-off values. Multi-factor binary logistic regression and inverse probability weighting (IPW) were used to investigate whether Rescue IVM influenced the final cumulative live birth rate(CLBR). RESULTS: The CLBR increased with the number of MIIoocytes (P < 0.001). The ROC analysis showed the cut-off point for the number of MIIoocytes to have a significant effect on CLBR was 9 (sensitivity 0.715, specificity 0.656). Furthermore, 912 patients who underwent ICSI with Rescue IVM were included and compared to those who underwent ICSI only during the same period, and found Rescue IVM significantly increased the number of available MIIoocytes. For patients with MII numbers < 9, Rescue IVM significantly improves their clinical pregnancy rate(55.6% vs. 46.7%, P = 0.001) and CLBR(65.4% vs. 48.1%, P < 0.001), but not for those patients with MII numbers ≥ 9. CONCLUSION: This study further clarifies the candidates for the application of Rescue IVM technique: patients with an MII oocytes < 9 in a conventional IVF/ICSI cycle. In contrast, it is not necessary for patients who already have sufficient mature oocytes(≥ 9), to avoid over-medication.

Long-term healthcare utilization and costs of babies born after assisted reproductive technologies (ART): a record linkage study with 10-years' follow-up in England.

STUDY QUESTION: Is the long-term health care utilization of children born after ART more costly to the healthcare system in England than children born to mothers with no fertility problems? SUMMARY ANSWER: Children born after ART had significantly more general practitioner (GP) consultations and higher primary care costs up to 10 years after birth, and significantly higher hospital admission costs in the first year after birth, compared to children born to mothers with no fertility problems. WHAT IS KNOWN ALREADY: There is evidence that children born after ART are at an increased risk of adverse birth outcomes and a small increased risk of rare adverse outcomes in childhood. STUDY DESIGN, SIZE, DURATION: We conducted a longitudinal study of 368 088 mother and baby pairs in England using a bespoke linked dataset. Singleton babies born 1997-2018, and their mothers, who were registered at GP practices in England contributing data to the Clinical Practice Research Datalink (CPRD), were identified through the CPRD GOLD mother-baby dataset; this data was augmented with further linkage to the mothers' Human Fertilisation and Embryology Authority (HFEA) Register data. Four groups of babies were identified through the mothers' records: a 'fertile' comparison group, an 'untreated sub-fertile' group, an 'ovulation induction' group, and an ART group. Babies were followed-up from birth to 28 February 2021, unless censored due to loss to follow-up (e.g. leaving GP practice, emigration) or death. PARTICIPANTS/MATERIALS, SETTING, METHODS: The CPRD collects anonymized coded patient electronic health records from a network of GPs in the UK. We estimated primary care costs and hospital admission costs for babies in the four fertility groups using the CPRD GOLD data and the linked Hospital Episode Statistics (HES) Admitted Patient Care (APC) data. Linear regression was used to compare the care costs in the different groups. Inverse probability weights were generated and applied to adjust for potential bias caused by attrition due to loss to follow-up. MAIN RESULTS AND THE ROLE OF CHANCE: Children born to mothers with no fertility problems had significantly fewer consultations and lower primary care costs compared to the other groups throughout the 10-years' follow up. Regarding hospital costs, children born after ART had significantly higher hospital admission costs in the first year after birth compared to those born to mothers with no fertility problems (difference = £307 (95% CI: 153, 477)). The same pattern was observed in children born after untreated subfertility and ovulation induction. LIMITATIONS, REASONS FOR CAUTION: HFEA linkage uses non-donor data cycles only, and the introduction of consent for data use reduced the availability of HFEA records after 2009. The fertility groups were derived by augmenting HFEA data with evidence from primary care records; however, there remains some potential misclassification of exposure groups. The cost of neonatal critical care is not captured in the HES APC data, which may cause underestimation of the cost differences between the comparison group and the infertility groups. WIDER IMPLICATIONS OF THE FINDINGS: The findings can help anticipate the financial impact on the healthcare system associated with subfertility and ART, particularly as the demand for these treatments grows. STUDY FUNDING/COMPETING INTEREST(S): C.C. and this work were funded by a UK Medical Research Council Career Development Award [MR/L019671/1] and a UK MRC Transition Support Award [MR/W029286/1]. X.H. is an Australia National Health and Medical Research Council (NHMRC) Emerging Leadership Fellow [grant number 2009253]. The authors declare no competing interest. TRIAL REGISTRATION NUMBER: N/A.

Predicting the likelihood of live birth: an objective and user-friendly blastocyst grading system.

RESEARCH QUESTION: Can day-5 blastocysts be ranked according to their likelihood of live birth using an objective and user-friendly grading system? DESIGN: A retrospective multicentre study conducted between 2017 and 2019, including 1044 day-5 blastocysts. Blastocyst expansion degree, trophectoderm and inner cell mass quality were assessed morphologically and morphometrically. Several analyses were conducted: the association between the qualitative and quantitative assessment for the blastocyst expansion degree and the number of trophectoderm cells; the effect of the embryo quality on day 3 and the contribution of the three blastocyst parameters to live birth, with logistic regression; and a decision tree with the most significant variables to create the new scoring system. RESULTS: Cut-off points were found to discriminate between expanding and expanded blastocysts (165 µm for blastocyst diameter) and between trophectoderm grades (A: ≥14 cells; B: 11-13 cells; C: ≤10 cells). When the embryos reached the blastocyst stage, their quality on day 3 did not add predictive value for implantation and live birth. In the logistic regression analysis, the only parameter capable of significantly predicting the live birth likelihood was the trophectoderm grade: A versus C (OR 1.95, 95% CI 1.26 to 3.0); B versus C (OR 1.71, 95% CI 1.22 to 2.4). The decision tree supported the finding that the trophectoderm grade had the highest predictive value for a live birth, followed by the blastocyst expansion degree in a second step. CONCLUSIONS: This new method makes objective blastocyst assessment feasible, allowing for standardization and exportation to other laboratories worldwide.

The effect of hCG day progesterone in 1318 cycles on pregnancy outcomes: ongoing discussion.

OBJECTIVES: To investigate the effect of human chorionic gonadotropin day progesterone (hCG-P) level on pregnancy outcomes in in vitro fertilization (IVF) cycles. MATERIAL AND METHODS: This study is an analysis of a cohort of 1318 fresh IVF- embryo transfer cycles, including 579 agonists and 739 antagonists, performed at a single IVF center between 2007 and 2018. For fresh cycles, we performed Receiver Operating Characteristic analysis (ROC) to calculate the threshold value of hCG-P, which affects pregnancy outcomes. We divided patients below and above the determined threshold value into two groups, then, correlation analysis and we performed logistic regression analysis. RESULTS: According to ROC curve analysis of hCG-P,AUC was 0.537 (95% CI: 0.510-0.564, p < 0.05) for LBR, and the threshold value for P was 0.78. The hCG-P threshold value of 0.78 proved to be significant in relation to BMI, type of drug used during induction, the hCG day E2, the total number of oocytes, the number of oocytes and the subsequent pregnancy outcome between the two groups (p < 0.05). However, the model we built, which accounted for hCG-P, total number of oocytes, age, BMI, induction protocol, total dose of gonadotropin used in induction did not prove significant in terms of its effect on LBR. CONCLUSIONS: The threshold value of hCG-P that we found to have an effect on LBR was quite low compared with the P-value generally recommended in the literature. Therefore, further studies are needed to determine an accurate P-value that reduces success in managing fresh cycles.

Early pregnancy outcomes of IVF cycles using donor versus partner sperm: analysis of 1 376 454 cycles recorded by the Human Fertilisation and Embryology Authority (1991-2016).

STUDY QUESTION: Are the early pregnancy outcomes of IVF pregnancies conceived with donor sperm different to those conceived with partner sperm? SUMMARY ANSWER: Pregnancies conceived with donor sperm have a lower odds of early pregnancy loss and ectopic pregnancy compared to pregnancies conceived with partner sperm. WHAT IS KNOWN ALREADY: The number of cycles using donor sperm has risen significantly in recent years. Adverse early pregnancy outcomes have a negative impact on women and their partners. The evidence available to date regarding early pregnancy outcomes for pregnancies conceived with IVF donor sperm is limited by low numbers and lower-quality studies. STUDY DESIGN, SIZE, DURATION: This is a retrospective cohort study of 1 376 454 cycles conceived with either donor or partner sperm between 1991 and 2016 as recorded in the Human Fertilisation and Embryology Authority (HFEA) Register. PARTICIPANTS/MATERIALS, SETTING, METHODS: The HFEA has recorded data on all fertility treatments carried out in the UK from 1991 onwards, and it publishes this data in an anonymized form. This study assessed the outcomes of all pregnancies conceived with donor sperm and compared them to those conceived with partner sperm among IVF cycles recorded in the HFEA anonymized dataset from 1991 to 2016. Cycles that included intrauterine insemination, donor oocytes, preimplantation genetic testing, oocyte thaw cycles and alternative fertility treatments were excluded. The outcomes of interest were biochemical pregnancy, miscarriage, ectopic pregnancy, stillbirth and live birth. Logistic regression was used to adjust for confounding factors including age of the female partner, cause of infertility, history of previous pregnancy, fresh or frozen cycle, IVF or ICSI, number of embryos transferred, and year of treatment. Results are reported as adjusted odds ratios (aOR) and 95% CIs. MAIN RESULTS AND THE ROLE OF CHANCE: This study found reductions in the odds of biochemical pregnancy (aOR 0.82, 95% CI 0.78-0.86), miscarriage (aOR 0.93, 95% CI 0.89-0.97), and ectopic pregnancy (aOR 0.77, 95% CI 0.66-0.90) among pregnancies as a result of the use of donor sperm as opposed to partner sperm. LIMITATIONS, REASONS FOR CAUTION: This study is retrospective and limited by the constraints of routinely collected data. No data were available for maternal characteristics such as BMI, smoking and partner age, which could all be potential confounders. Clustering of multiple pregnancies within women could not be accounted for as the data are reported only at the cycle level with no maternal identifiers. WIDER IMPLICATIONS OF THE FINDINGS: This study has demonstrated that there are no increased risks of adverse pregnancy outcome with donor sperm pregnancies. The reduction in miscarriage in pregnancies using donor sperm suggests that sperm could have a role in miscarriage, as the selection process for being accepted as donor is stringent. STUDY FUNDING/COMPETING INTEREST(S): No external funding was sought for this study. C.A. has received funding from Ferring to attend a UK meeting for trainees in reproductive Medicine. A.M. has received funding from Ferring, Cook, Merck Serono, Geodon Ritcher, and Pharmasure for speaking at, or attending, meetings relating to reproductive medicine. She has also participated in a Ferring advisory board. S.B. has received grants from Tenovus and the UK Medical Research Council. She has also been supported with a Medical Research Scotland PhD studentship. TRIAL REGISTRATION NUMBER: N/A.

Assisted reproductive technologies in Africa: The African Network and Registry for ART, 2018 and 2019.

RESEARCH QUESTION: What were the utilization, practices and outcomes of assisted reproductive technology (ART) in Africa in 2018 and 2019? DESIGN: Cycle-based data (CBD) and retrospective summary data were collected cross-sectionally from voluntarily participating ART centres. RESULTS: During 2018, 43,958 ART procedures were reported by 67 centres in 16 countries, increasing to 45,185 procedures reported by 70 centres in 18 countries in 2019. Autologous fresh procedures predominated at 70%, whereas autologous frozen embryo transfers (FET) increased from 21.2% to 23.1% and oocyte donation cycles remained below 10%. In 2019, the mean age of women undergoing autologous fresh embryo transfer was 33.9 years and received a mean number of 2.4 embryos per transfer. The clinical pregnancy rate (CPR) per fresh embryo transfer was 42.8% in 2018 and 38.4% in 2019, with corresponding rates of 38.3% and 31.8% after FET. In both years, most ART procedures, excluding single embryo transfer (SET), were associated with a multiple delivery rate above 20%, reaching over 30% after elective dual embryo transfer in autologous cycles and after fresh oocyte donation. Multiples were predominantly born preterm with a substantially increased perinatal mortality rate. The CBD for both years showed that elective SET (eSET) achieved a high CPR without compromising safety. CONCLUSION: This third report of The African Network and Registry for Assisted Reproductive Technology documents the prevailing practice of multiple embryo transfers in a cohort of relatively young women while highlighting the importance of disaggregating eSET, non-eSET and double embryo transfer. The high CPR after eSET and the increase in cryopreservation cycles are encouraging trends towards decreasing the number of embryos transferred without compromising effectiveness. Improved follow-up of ART pregnancies is required.

Outcomes after assisted reproductive technology in women with cancer: a systematic review and meta-analysis.

STUDY QUESTION: What are the associations between a history of cancer and outcomes after ART? SUMMARY ANSWER: Compared to women without cancer, on average, women with cancer had a lower return for embryo transfer and a lower likelihood of clinical pregnancy and live birth after ART. WHAT IS KNOWN ALREADY: Small, single-institution studies have suggested that cancer and its treatment may negatively affect ART outcomes. STUDY DESIGN, SIZE, DURATION: We conducted a systematic review with meta-analysis of studies comparing ART outcomes between women with and without cancer. PubMed, Embase and Scopus were searched for original, English-language studies published up to June 2021. PARTICIPANTS/MATERIALS, SETTING, METHODS: Inclusion criteria required reporting of ART outcomes after controlled ovarian stimulation (COS) among women with a history of cancer compared to women without cancer who used ART for any indication. Outcomes of interest ranged from duration of COS to likelihood of live birth after embryo transfer. Random-effects meta-analysis was used to calculate mean differences and odds ratios (ORs) with 95% CIs and 95% prediction intervals (PIs). We assessed heterogeneity by age-adjustment, referent group indication for ART, study location and among women with breast cancer and women who initiated ART before cancer treatment. We used visual inspection, Egger's test and the trim-and-fill method to assess funnel plot asymmetry. MAIN RESULTS AND THE ROLE OF CHANCE: Of 6094 unique records identified, 42 studies met inclusion criteria, representing a median per study of 58 women with cancer (interquartile range (IQR) = 159) and 114 women without cancer (IQR = 348). Compared to women without cancer, on average, women with cancer had a lower return for embryo transfer (OR: 0.22; 95% CI: 0.07, 0.74; 95% PI: 0.00, 64.98); lower likelihood of clinical pregnancy (OR: 0.51; 95% CI: 0.35, 0.73; 95% PI: 0.19, 1.35); and lower likelihood of live birth (OR: 0.56; 95% CI: 0.38, 0.83; 95% PI: 0.19, 1.69). Substantial among-study heterogeneity was observed for COS duration, gonadotropin dose, cycle cancellation, total oocytes and mature oocytes. Fertilization percentage showed less heterogeneity, but study-specific estimates were imprecise. Similarly, number of embryos showed less heterogeneity, and most studies estimated minimal differences by cancer history. Funnel plot asymmetry was observed for estradiol peak and oocyte maturation percentage. LIMITATIONS, REASONS FOR CAUTION: Appreciable confounding is possible in 11 studies that lacked adequate control for group differences in age, and among-study heterogeneity was observed for most outcomes. Lack of data limited our ability to assess how cancer clinical factors (e.g. cancers other than breast, cancer stage and treatment) and ART cycle characteristics (e.g. fresh versus frozen embryo transfers and use of gestational carriers) may affect outcomes. WIDER IMPLICATIONS OF THE FINDINGS: Women with cancer may be less likely to achieve pregnancy and live birth after embryo transfer. Further examination of reproductive outcomes and sources of heterogeneity among studies is warranted to improve evidence of the expected success of ART after a cancer diagnosis. STUDY FUNDING/COMPETING INTEREST(S): This research was supported in part by R01 CA211093 and P30 ES010126. C.M. was supported by the University of North Carolina Lineberger Cancer Control Education Program (T32 CA057726) and the National Cancer Institute (F31 CA260787). J.A.R.-H. was supported by the National Cancer Institute (K08 CA234333, P30 CA016672). J.A.R.-H. reports receiving consulting fees from Schlesinger Group and Guidepoint. The remaining authors declare no competing interests. REGISTRATION NUMBER: N/A.

Antral follicle count measured at down-regulation as predictor of ovarian response and cumulative live birth: single center analysis including 2731 long agonist IVF cycles.

OBJECTIVE: Evaluate antral follicle count measured after pituitary suppression (AFCaps) with a GnRH agonist as predictor of ovarian response and cumulative live birth (CLB). METHODS: This study is a large cohort analysis of retrospective data between January 2011 and September 2020 in a tertiary-care university hospital. All first initiated IVF/ICSI cycles in women under 43 years of age for whom AFCaps was registered in our database were included. To evaluate CLB rates (CLBRs), only finalized cycles were analyzed (at least one live birth and/or all embryos transferred), excluding PGT cycles and severe male factor requiring testicular sperm extraction. RESULTS: AFCaps showed a good predictive ability in predicting ovarian response to ovarian stimulation. Predicting poor response, AFCaps presented an area under the receiver-operating characteristic curve (AUCROC) of 0.85 (95% CI 0.83-0.87), for high response prediction, the AUCROC was 0.80 (95% confidence interval [CI] 0.77-0.83).Although AFCaps was statistically higher in patients who achieved at least one live birth (13.6 ± 6.05 vs. 9.79 ± 6.33) and CLBRs per started cycle significantly increase between AFCaps quartiles (15.9%, 36.2%, 45.1% and 52.9%) its ability to predict CLBR was modest, with an AUCROC of 0.67 (95% CI 0.65-0.69). CONCLUSIONS: Women undergoing their first IVF/ICSI cycle following a long agonist GnRH protocol can be counseled with AFCaps measurement about their probability of achieving poor/high response. Based on this marker physicians can personalize ovarian stimulation with the aim of optimizing ovarian response and minimizing its risks. However, AFCaps has failed to predict CLB per started IVF cycle as an isolated marker.

Accuracy of endometrial length measurement in predicting IVF/ICSI outcome.

This study aimed to evaluate if endometrial length (EL) affects the likelihood of a positive pregnancy test in individuals who had in vitro fertilization/intra cytoplasmic sperm injection (IVF/ICSI). Between December 2020 and June 2021, 100 women from those referred to the High Institute for Infertility Diagnosis and Assisted Reproductive Technologies, Al-Nahrain University, for IVF/ICSI were selected. These women were 20-40 years old with primary type sub-fertility and met the inclusion criteria. Controlled ovarian hyperstimulation (antagonist protocol), followed by transvaginal sonography (TVS), was used to measure the endometrial length (EL) from the internal ostium to the fundus on the day of ovum collection. Afterwards, the association between endometrial length and the outcome was examined. The data were analyzed using the Statistical Package for Social Sciences (SPSS). The data show an important link between EL and treatment success. Endometrial length of ≥39 mm was considered a good cut-off point for IVF/ICSI pregnancy rates with a sensitivity of 75%, a specificity of 68%, a positive predictive value of 57%, and a negative predictive value of 83, and area under the curve of 0.81. An endometrial length of 39 mm can be used as an appropriate cut-off point in IVF/ICSI to predict a greater pregnancy rate. Vaginal sonography could be used in the ART cycle to measure the endometrial length and thickness and to determine endometrial receptiveness.

Mental health and behavioural problems in adolescents conceived after ART.

STUDY QUESTION: Does mental health and behaviour differ between those conceived with and those conceived without ART? SUMMARY ANSWER: Our study observed less externalizing behaviour (delinquent/aggressive), and more parent-reported internalizing behaviour, as well as more (clinical) depression at age 14 years, in adolescents conceived after ART compared to their non-ART counterparts. WHAT IS KNOWN ALREADY: Health outcomes of ART-conceived offspring may differ from those conceived without ART, and previous studies have reported differences in behaviour and mental health, particularly in childhood. STUDY DESIGN, SIZE, DURATION: The Growing Up Healthy Study (GUHS) is a prospective cohort study, investigating the long-term health of offspring conceived after ART (aged 14, 17 and 20 years), in the two operational fertility clinics in Western Australia 1991-2001 (n = 303). Their long-term health outcomes were compared to those of offspring conceived without ART from the Raine Study Generation 2 (Gen2) born 1989-1991 (n = 2868). Both cohorts are representative of the local adolescent population. PARTICIPANTS/MATERIALS, SETTING, METHODS: Mental health parameters and behaviour were assessed at ages 14 and 17 years, through the parent completed 'Child Behaviour Checklist' (CBCL; ART versus non-ART: age 14 years: N = 150 versus N = 1781, age 17 years: N = 160 versus N = 1351), and the adolescent completed equivalent 'Youth Self-Report' (YSR; age 14 years: by N = 151 versus N = 1557, age 17 years: N = 161 and N = 1232). Both tools generate a T-score (standardized for age and sex) for internalizing (withdrawn, somatic complaints, anxious/depressed), externalizing (delinquent/aggressive behaviour) and total behaviour. Adolescents also completed the 'Beck Depression Inventory for Youth' (BDI-Y; age 14 years: N = 151 versus N = 1563, age 17 years: N = 161 versus N = 1219). Higher scores indicate poorer mental health and behaviour on all the above tools. Parent-reported doctor-diagnosed conditions (anxiety, behavioural problems, attention problems and depression) were also univariately compared between the cohorts. In addition, univariate comparisons were conducted between the GUHS adolescents and Gen2 adolescents born to subfertile parents (time to pregnancy >12 months), as well as between offspring born to subfertile versus fertile parents within the Gen2 cohort. A subgroup analysis excluding offspring born preterm (<37 weeks' gestation) or at low birthweight (<2500 g) was also performed. Generalized estimating equations that account for correlated familial data were adjusted for the following covariates: non-singleton, primiparity, primary caregiver smoking, family financial problems, socio-economic status and both maternal and paternal ages at conception. MAIN RESULTS AND THE ROLE OF CHANCE: At both 14 and 17 years of age, ART versus non-ART-conceived adolescents reported lower mean T-scores for externalizing problems (age 14 years: 49 versus 51, P = 0.045, age 17 years: 49 versus 52, P < 0.001). A similar effect was reported by parents, although not significant (age 14 years: P = 0.293, age 17 years: P = 0.148). Fewer ART-conceived adolescents reported a T-score above the clinical cut-off for externalizing behaviour (≥60; age 14 years: 7.3% versus 16.3%, P = 0.003, age 17 years: 8.1% versus 19.7%, P < 0.001). At both ages, no differences in internalizing behaviour were reported by adolescents (age 14 years: P = 0.218, age 17 years: P = 0.717); however, higher mean scores were reported by parents of the ART-conceived adolescents than by parents of the non-ART conceived adolescents (age 14 years: 51 versus 48, P = 0.027, age 17 years: 50 versus 46, P < 0.001). No differences in internalizing behaviour above the clinical cut-off (T-score ≥ 60) were observed. At age 17 years, parents who conceived through ART reported higher total behaviour scores than those parents who conceived without ART (48 versus 45, P = 0.002). At age 14 years, ART versus non-ART-conceived adolescents reported significantly higher mean scores on the BDI-Y (9 versus 6, P = 0.005); a higher percentage of adolescents with a score indicating clinical depression (≥17; 12.6% versus 8.5%, aOR 2.37 (1.18-4.77), P = 0.016), as well as more moderate/severe depression (≥21; 9.3% versus 4.0%, P = 0.009). At age 17 years, no differences were reported on the BDI-Y. There was also a higher percentage of parent-reported doctor-diagnosed anxiety in the ART cohort (age 14 years: 8.6% versus 3.5%, P = 0.002, at age 17 years: 12.0% versus 4.5%, P < 0.001). Removing adolescents born preterm or at low birthweight did not alter the above results. Comparing outcomes between GUHS adolescents and Gen2 adolescents born to subfertile parents, as well as between those born to subfertile versus fertile parents within Gen2, did not alter results for CBCL and YSR outcomes. Those born to subfertile parents showed higher rates of clinical depression than those born to fertile parents at age 14 years (13.7% versus 6.9%, P = 0.035). LIMITATIONS, REASONS FOR CAUTION: The main limitation of the study is the time difference between the GUHS and Gen2 assessments. Even though we have adjusted for covariates, additional socio-economic and lifestyle factors affecting behaviour and mental well-being could have changed. We were unable to differentiate between different types of ART (e.g. IVF versus ICSI), owing to the low number of ICSI cycles at the time of study. Fertility sub-analyses need to be replicated in larger cohorts to increase power, potentially using siblingship designs. Lastly, selection bias may be present. WIDER IMPLICATIONS OF THE FINDINGS: The reported lower prevalence of externalizing behaviour (delinquent/aggressive), and higher prevalence of internalizing behaviour, as well as more (clinical) depression at age 14 years, in ART versus non-ART-conceived adolescents, is in line with some previous studies, mostly conducted in childhood. It is reassuring that differences in the rates of depression were not observed at age 17 years, however, these findings require replication. As the use of ART is common, and mental health disorders are increasing, knowledge about a potential association is important for parents and healthcare providers alike. STUDY FUNDING/COMPETING INTEREST(S): This project was funded by an NHMRC Grant (Hart et al., ID 1042269). R.J.H. is the Medical Director of Fertility Specialists of Western Australia and a shareholder in Western IVF. He has received educational sponsorship from MSD, Merck-Serono and Ferring Pharmaceuticals. P.B. is the Scientific Director of Concept Fertility Centre, Subiaco, Western Australia. J.L.Y. is the Medical Director of PIVET Medical Centre, Perth, Western Australia. TRIAL REGISTRATION NUMBER: N/A.

Women's preferences concerning IVF treatment: a discrete choice experiment with particular focus on embryo transfer policy.

STUDY QUESTION: What outcomes are important for women to decide on the day of embryo transfer (ET) in IVF? SUMMARY ANSWER: The highest cumulative live birth rate (cLBR) per treatment was the most important treatment outcome for women undergoing an IVF treatment, regardless of the number of transfers needed until pregnancy and impact on quality of life. WHAT IS KNOWN ALREADY: Cleavage stage (Day 3) and blastocyst stage (Day 5) ETs are common transfer policies in IVF. The choice for one or the other day of ET differs between clinics. From the literature, it remains unclear whether the day of transfer impacts the cLBR. Patient preferences for the day of ET have not been examined yet. STUDY DESIGN SIZE AND DURATION: A discrete choice experiment (DCE) was performed to investigate female patients' preferences and their values concerning various aspects of an IVF treatment, with a particular focus on ET policy. A multicenter DCE was conducted between May 2020 and June 2020 in which participants were asked to choose between different treatments. Each treatment was presented using hypothetical scenarios containing the following attributes: the probability of a healthy live birth per IVF treatment cycle, the number of embryos available for transfer (for fresh and frozen-thawed ET), the number of ETs until pregnancy and the impact of the treatment on the quality of life. PARTICIPANTS/MATERIALS SETTING METHODS: Women (n = 445) were asked to participate in the DCE at the start of an IVF treatment cycle in 10 Dutch fertility clinics. Participating women received an online questionnaire. The attributes' relative importance was analyzed using logistic regression analyses. MAIN RESULTS AND THE ROLE OF CHANCE: A total of 164 women participated. The most important attribute chosen was the cLBR. The total number of embryos suitable for transfer also influenced women's treatment preferences. Neither the number of transfers needed until pregnancy, nor the impact on quality of life influenced the treatment preferences in the aggregated data. For women in the older age group (age ≥36 years) and the multipara subgroup, the impact on quality of life was more relevant. Naive patients (patients with no prior experience with IVF treatment) assigned less value to the number of ETs needed until pregnancy and assigned more value to the cLBR than the patients who had experienced IVF. LIMITATIONS REASONS FOR CAUTION: An important limitation of a DCE study is that not all attributes can be included, which might be relevant for making choices. Patients might make other choices in real life as the DCE scenarios presented here are hypothetical and might not exactly represent their personal situation. We tried to avoid potential bias by selecting the attributes that mattered most to the patients obtained through patient focus groups. The final selection of attributes and the assigned levels were established using the input of an expert panel of professionals and by performing a pilot study to test the validity of our questionnaire. Furthermore, because we only included women in our study, we cannot draw any conclusions on preferences for partners. WIDER IMPLICATIONS OF THE FINDINGS: The results of this study may help fertility patients, clinicians, researchers and policymakers to prioritize the most important attributes in the choice for the day of ET. The present study shows that cLBR per IVF treatment is the most important outcome for women. However, currently, there is insufficient information in the literature to conclude which day of transfer is more effective regarding the cLBR. Randomized controlled trials on the subject of Day 3 versus Day 5 ETs and cLBR are needed to allow evidence-based counseling. STUDY FUNDING/COMPETING INTERESTS: This work received no specific funding and there are no conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.