Sexual function in heterosexual couples undergoing assisted reproductive technology (ART) cycles with donor sperm.

PURPOSE: Sexuality and the desire for children are closely linked, and infertility can increase the risk of sexual dysfunction (SD). Among heterosexual infertile couples undergoing assisted reproductive technology (ART) cycles, those referred for donor sperm cycles constitute a specific subgroup, potentially different than those undergoing ART with partner's sperm, as giving up on biological parenthood can be difficult to overcome. However, the impact of donor sperm ART on infertile couples' sexuality has been hardly explored in the literature. This study aimed to describe the sexual function in couples undergoing ART with donor sperm. METHODS: This monocentric prospective observational study was conducted in heterosexual couples undergoing ART cycle with sperm donor, using the FSFI and the IIEF15 questionnaires. Seventy-nine couples were solicited to participate in the study. RESULTS: In our sample, 39.3% (n = 24) of women had sexual dysfunction (SD). Among men, 26.5% (n = 13) had erectile dysfunction (ED). No statistically significant difference was found between both groups (with or without SD) in men and women in univariate analysis. Therefore, multivariate analysis was not performed and no specific predictor of SD could be identified. CONCLUSION: Although this should be confirmed in a larger number of participants, our study demonstrates that a significant proportion of infertile patients undergoing ART with donor semen suffer from SD. No significant predictor could, however, be identified. Further research should focus on the evaluation of psychological interventions to treat or improve these disorders.

Adaptive data-driven models to best predict the likelihood of live birth as the IVF cycle moves on and for each embryo transfer.

PURPOSE: To dynamically assess the evolution of live birth predictive factors' impact throughout the in vitro fertilization (IVF) process, for each fresh and subsequent frozen embryo transfers. METHODS: In this multicentric study, data from 13,574 fresh IVF cycles and 6,770 subsequent frozen embryo transfers were retrospectively analyzed. Fifty-seven descriptive parameters were included and split into four categories: (1) demographic (couple's baseline characteristics), (2) ovarian stimulation, (3) laboratory data, and (4) embryo transfer (fresh and frozen). All these parameters were used to develop four successive predictive models with the outcome being a live birth event. RESULTS: Eight parameters were predictive of live birth in the first step after the first consultation, 9 in the second step after the stimulation, 11 in the third step with laboratory data, and 13 in the 4th step at the transfer stage. The predictive performance of the models increased at each step. Certain parameters remained predictive in all 4 models while others were predictive only in the first models and no longer in the subsequent ones when including new parameters. Moreover, some parameters were predictive in fresh transfers but not in frozen transfers. CONCLUSION: This work evaluates the chances of live birth for each embryo transfer individually and not the cumulative outcome after multiple IVF attempts. The different predictive models allow to determine which parameters should be taken into account or not at each step of an IVF cycle, and especially at the time of each embryo transfer, fresh or frozen.

Time-lapse technology improves total cumulative live birth rate and shortens time to live birth as compared to conventional incubation system in couples undergoing ICSI.

PURPOSE: The improvement of clinical outcome provided by time-lapse technology (TLT) in IVF over conventional incubation (CI) still remains controversial. This study aimed at evaluating whether the exclusive use of time-lapse technology (TLT) during whole IVF care improves total cumulative live birth rate (TCLBR) and shortens time to live birth (TTLB) as compared to the use of CI in couples undergoing ICSI. METHODS: This retrospective cohort study was conducted in couples with male infertility undergoing their first ICSI cycle in 2014-2015 and for whom embryo culture system remained the same during their whole IVF care, i.e., TLT or CI. Couples were followed up up to 2020, including all following frozen-embryo transfers and ICSI cycles (if any). Survival analysis was used to compare clinical outcome and time-related endpoints between both groups. RESULTS: A total of 151 and 250 couples underwent their whole IVF care with the exclusive use of TLT and CI, respectively. Survival analysis showed that TCLBR after whole IVF care was significantly higher in TLT than in CI group (66.9 vs 56.4%, p=0.02, log-rank test). Median live birth time was significantly shorter in TLT than CI group (464 vs 596 days, p=0.01). CONCLUSIONS: We found that TCLBR and TTLB were significantly improved with TLT over CI in couples undergoing ICSI for male factor. This study fuels the debate on the clinical benefit of using TLT. The use of time-related endpoints adds important information for both patients and practitioners.

Real-world effectiveness of Fertistartkit® treatment in women undergoing ART in French clinical practice: a retrospective multicentre study.

RESEARCH QUESTION: What is the real-world effectiveness of Fertistartkit® in women undergoing assisted reproductive technology (ART)? DESIGN: Retrospective cohort study including anonymized data of women undergoing ovarian stimulation for ART with Fertistartkit between April 2016 and November 2017 and follow-up of clinical outcomes up to February 2018. Data were collected from the electronic patient databases of 12 French ART centres. The main outcome was number of oocytes retrieved. All data were categorized according to female age (<25, 25-29, 30-34, 35-37, 38-39 and >39 years). RESULTS: A total of 1006 cycles from 914 women treated with Fertistartkit were included. At the time of first ovarian stimulation in the study, women were 34.9 ± 5.0 years old, with a median body mass index of 22.7 kg/m². Couples had been infertile for more than 4 years, with all patterns of causes of infertility. Ovarian stimulation was started with a median dose of 300 IU (interquartile range [IQR]: 150-300 IU) of Fertistartkit for 10 days (IQR: 9-11 days), so a median total dose of 2700 IU (IQR: 1800-3300 IU). The mean number of oocytes retrieved per cycle was 9.5 ± 6.8, and the mean number of mature oocytes per cycle was 7.4 ± 5.5. The obtained ongoing pregnancy per started cycle was 26.0% (95% confidence interval [CI]: 24.1-27.9) and the obtained ongoing pregnancy per puncture was 27.0% (95% CI: 25.0-29.0). CONCLUSIONS: This is the first cohort to describe Fertistartkit treatment management in real-life conditions. The real-world data show that Fertistartkit is an effective option for ovarian stimulation.

Morphokinetic parameters in chromosomal translocation carriers undergoing preimplantation genetic testing.

RESEARCH QUESTION: Can embryo morphokinetic parameters help identify unbalanced embryos in translocation carriers? DESIGN: This retrospective study was conducted in 67 translocation carriers undergoing 105 preimplantation genetic testing cycles for chromosomal structural rearrangements (PGT-SR) without aneuploidy screening (PGT-A). Using time-lapse imaging analysis, morphokinetic parameters of balanced and unbalanced embryos were compared, as well as the frequency of abnormal cellular events. The performance of a previously published prediction model of aneuploidy was also tested in this population. RESULTS: Significant differences were observed between balanced and unbalanced embryos for some morphokinetic parameters: t5 (P = 0.0067), t9+ (P = 0.0077), cc2 (P = 0.0144), s2 (P = 0.0003) and t5-t2 (P = 0.0028). Also, multinucleation at the two- or four-cell stages, abnormal division and cell exclusion at the morula stage were significantly (all P < 0.05) more frequent in unbalanced than in balanced embryos. None, however, could accurately predict embryo chromosomal status. A previously published morphokinetic prediction model for embryo aneuploidy did not adequately classify balanced and unbalanced embryos. CONCLUSIONS: No significant morphokinetic predictor of chromosomal status could be found. Time-lapse should not be used as a diagnostic tool for chromosomal status in translocation carriers.

Performance of Day 5 KIDScore™ morphokinetic prediction models of implantation and live birth after single blastocyst transfer.

PURPOSE: While several studies reported the association between morphokinetic parameters and implantation, few predictive models were developed to predict implantation after day 5 embryo transfer, generally without external validation. The objective of this study was to evaluate the respective performance of 2 commercially available morphokinetic-based models (KIDScore™ Day 5 versions 1 and 2) for the prediction of implantation and live birth after day 5 single blastocyst transfer. METHODS: This monocentric retrospective study was conducted on 210 ICSI cycles with single day 5 embryo transfer performed with a time-lapse imaging (TLI) system between 2013 and 2016. The association between both KIDScore™ and the observed implantation and live birth rates was calculated, as well as the agreement between embryologist's choice for transfer and embryo ranking by the models. RESULTS: Implantation and live birth rate were both 35.7%. A significant positive correlation was found between both models and implantation rate (r = 0.96 and r = 0.90, p = 0.01) respectively. Both models had statistically significant but limited predictive power for implantation (AUC 0.60). There was a fair agreement between the embryologists' choice and both models (78% and 61% respectively), with minor differences in case of discrepancies. CONCLUSIONS: KIDScore™ Day 5 predictive models are significantly associated with implantation rates after day 5 single blastocyst transfer. However, their predictive performance remains perfectible. The use of these predictive models holds promises as decision-making tools to help the embryologist select the best embryo, ultimately facilitating the implementation of SET policy. However, embryologists' expertise remains absolutely necessary to make the final decision.

Can time-lapse parameters predict embryo ploidy? A systematic review.

Embryo morphology assessment performs relatively poorly in predicting implantation. Embryo aneuploidy screening (PGS) has recently improved, but its clinical value is still debated, and the development of a cheap non-invasive method for the assessment of embryo ploidy status is a highly desirable goal. The growing implementation of time-lapse devices led some teams to test the effectiveness of morphokinetic parameters as predictors of embryo ploidy, with conflicting results. The aim of this study was to conduct a comprehensive review of the literature on the predictive value of morphokinetic parameters for embryo ploidy status. A systematic search on PubMed was conducted using the following key words: time-lapse, morphokinetic, aneuploidy, IVF, preimplantation genetic screening, PGS, chromosomal status. A total of 13 studies were included in the analysis. They were heterogeneous in design, patients, day of embryo biopsy, statistical approach and outcome measures. No single or combined morphokinetic parameter was consistently identified as predictive of embryo ploidy status. In conclusion, the available studies are too heterogeneous for firm conclusions to be drawn on the predictive value of time-lapse analysis for embryo aneuploidy screening. Hence, morphokinetic parameters should not be used yet as a surrogate for PGS to determine embryo ploidy in vitro.

Ovarian reserve and response to stimulation in women undergoing fertility preservation according to malignancy type.

RESEARCH QUESTION: Does ovarian reserve and ovarian response to ovarian stimulation in women with cancer undergoing oocyte vitrification for fertility preservation vary according to the type of malignancy? DESIGN: Retrospective cohort study including 105 women aged between 18 and 40 years, who were referred for fertility preservation (oocyte vitrification) between 2013 and 2016. The women were divided into three groups: breast cancer, lymphoma or other cancer. All of them had been recently diagnosed with cancer, with gonadotoxic treatment scheduled, and had oocyte vitrification after ovarian stimulation with antagonist protocol. RESULTS: Baseline antral follicle count and anti-Müllerian hormone were no different between women with breast cancer, lymphoma or other cancer. The number of cancelled cycles for poor ovarian response was similar between the groups. The number of FSH units per mature oocyte, the number of mature oocytes (metaphase II) retrieved, and the oocyte maturity rate were not significantly different between the three groups. CONCLUSIONS: As the type of cancer does not seem to significantly affect ovarian reserve and ovarian response to ovarian stimulation, our results do not support the relevance of integrating this parameter when establishing ovarian stimulation protocol for oocyte vitrification cycle in women with cancer.

Time-lapse imaging systems in IVF laboratories: a French national survey.

PURPOSE: Although the clinical value of time-lapse imaging (TLI) systems in in vitro fertilization (IVF) cycles is still debated, its prevalence worldwide seems to be expanding. The situation of TLI in the USA has been recently surveyed, but these results might not be transposable to other countries with different IVF regulation and funding such as France. This study evaluated the TLI situation in French IVF laboratories. METHODS: An anonymous online cross-sectional survey was sent by email to 210 embryologists in September and October 2017. Laboratories, demographics, TLI clinical use, purchasing plan, and embryologists' opinions were analyzed using logistic regression to calculate odds ratio. RESULTS: Of the 210 lab directors surveyed, 78 responded (37.1%), 43 (55%) working in private IVF laboratories and 35 (45%) in public hospitals. Thirty (38.5%) were TLI users. The odds of TLI possession were not statistically different according to laboratory sector or size. Most embryologists (n = 21, 70%) used TLI for unselected patients. Cost was the main reason given by non-users for not implementing TLI (n = 24, 50%). Most respondents were convinced that TLI is superior to standard morphology (n = 52, 73.2%) and that TLI improves culture conditions (n = 62, 84.9%). However, half (n = 39, 54.9%) indicated that evidence was still lacking to assert TLI clinical usefulness. CONCLUSION: The prevalence of TLI systems and embryologists' opinion in France was slightly different from the American situation. The different regulation and funding policy might account for some differences in terms of TLI use and perception.

Adverse pregnancy and neo-natal outcomes after assisted reproductive treatment in patients with pelvic endometriosis: a case-control study.

To assess the impact of endometriosis on obstetric outcomes and to determine whether the severity, location and surgical treatment of the disease before the pregnancy had an impact on the prevalence of these disorders, a monocentric, case-control study was performed. In total, 113 pregnancies obtained by assisted reproductive treatment among patients with endometriosis were matched with control selected among assisted reproductive treatment pregnancies due to male infertility. The main result measures were pregnancy outcome at the obstetrical and neo-natal levels. The incidence of first trimester bleeding, pre-eclampsia, premature delivery threat, pelvic pain and Caesarean section was significantly higher (P < 0.05) in women with endometriosis. Except for gestational diabetes and intrauterine growth restriction (IUGR), the severity, location of lesions and surgical treatment of endometriosis did not have an impact on either pregnancy outcome or risk of obstetric complications. The IUGR is mainly due to deep locations and the revised American Fertility Society (rAFS) stages III-IV. Newborns with a mother suffering from endometriosis are at greater risk of being premature, smaller for their gestational age and more frequently hospitalized than the control group. Deep location of endometriosis is associated with more prematurity, hospitalization and smaller birthweight than ovarian locations.

Sexual transmission of Zika virus in an entirely asymptomatic couple returning from a Zika epidemic area, France, April 2016.

The current Zika virus outbreak and its potential severe health consequences, especially congenital fetal syndrome, have led to increased concern about sexual transmission, especially in pregnant women and women of reproductive age. Here we report a case of Zika virus sexual transmission, likely male-to-female, in a totally asymptomatic couple.

Does sperm origin affect embryo morphokinetic parameters?

PURPOSE: The purpose of our study was to use time-lapse in order to evaluate the impact of sperm origin (fresh ejaculate or surgically retrieved) on embryo morphokinetic parameters and clinical outcome in intracytoplasmic sperm injection (ICSI) cycles. METHODS: This retrospective monocentric study was conducted in 485 unselected couples undergoing 604 ICSI cycles with embryo culture in the Embryoscope®. Among them, 445 couples underwent ICSI cycle with fresh ejaculated sperm and 40 with surgically retrieved sperm (26 with testicular sperm and 14 with epididymal sperm). Embryo morphokinetic parameters and clinical cycle outcome were compared between fresh ejaculated sperm and surgically retrieved sperm. A subgroup analysis was also conducted between testicular and epididymal sperm ICSI cycles. RESULTS: Clinical outcome was comparable between groups according to sperm origin. Although most early morphokinetic parameters were comparable between ejaculated and surgical sperm groups, a few parameters were significantly different between both groups, but with a considerable overlap in their distribution. Late cellular events occurred significantly later in the surgical sperm group than in the ejaculated sperm group. CONCLUSIONS: Morphokinetic analysis did not allow us to identify clinically relevant differences between fresh ejaculate and surgically retrieved sperm groups. Further studies are needed, especially concerning the relationship between sperm origin and late morphokinetic parameters, such as blastocyst development.

Morphokinetic parameters of ICSI tripronucleated embryos observed using time lapse.

Time-lapse analysis of tripronucleated zygotes obtained in ICSI cycles showed that 75.4% cleaved into embryos. These embryos subsequently demonstrated slower developmental kinetics than normally fertilized embryos.

Proficiency in oocyte retrieval assessed by the learning curve cumulative summation test.

The number of procedures required for a trainee to reach proficiency in oocyte retrieval and the criteria applied to define performance are not well defined. To evaluate the learning curve of oocyte retrieval, this study prospectively evaluated three trainees over 6 months. Oocyte retrieval was monitored by the learning curve-cumulative summation test (LC-CUSUM), a specific statistical tool designed to indicate when a predefined level of performance is reached. Oocytes were retrieved from one ovary by the trainee and from the second ovary by a senior operator in a randomized manner. The main outcome measure was the ratio of oocytes collected and follicles aspirated. A trainee's ratio of ≥ 80% of the senior operator's defined success. From 17 to >50 procedures were necessary for the trainees to reach the predefined level of performance. Cumulative summation tests implemented after the learning phase confirmed that performance was maintained. The present study confirms the large variability in acquiring proficiency for surgical procedures. It provides an exportable model for a quantitative tailored monitoring of the learning curve and for continuous monitoring of performance in oocyte retrieval.

Determining the cost-effectiveness of follitropin alfa biosimilar compared to follitropin alfa originator in women undergoing fertility treatment in France.

Objective: The study assessed cost-effectiveness of follitropin alfa biosimilar versus the originator in terms of cost per cumulative live-birth (CLB) for the French healthcare system based on real-world evidence. Follitropin alfa biosimilars have been shown to have comparable clinical outcomes to the originator, in both clinical studies and real-world settings, in terms of oocyte retrieval and cumulative live-birth rate (CLBR). Previous health economic studies comparing the cost-effectiveness of follitropin alfa biosimilars against the originator utilised clinical trial data, leaving ambiguity over cost-effectiveness in real-world settings. Additionally, previous cost-effectiveness analysis has been performed for live-births following only fresh embryo transfers, whereas, fresh and frozen transfers are common in clinical practice. This study investigates the cost per CLB, which more closely models clinical practice. Study design: A decision-tree cost-effectiveness model was developed based on the total costs and CLBR per ovarian stimulation (OS) for a follitropin alfa biosimilar (Bemfola®, Gedeon Richter Plc, Budapest, Hungary) and the originator (Gonal-f®, Merck KGaA, Darmstadt, Germany). A time horizon of one year from oocyte retrieval to embryo transfer was used but costs from resulting transfers were also included. Clinical inputs were taken from the REOLA real-world study or clinician insights, while acquisition costs were taken from French public databases. The output was cost per CLB following one OS. One-way sensitivity analysis was performed to determine the largest model drivers. Results: Cost per CLB was €18,147 with follitropin alfa biosimilar and €18,834 with the originator, saving €687 per CLB following OS with the biosimilar. When wastage estimates were considered the biosimilar cost saving is estimated to be between €796 and €1155 per CLB further increasing cost savings. Irrespective of wastage, if used ubiquitously throughout France for ART, the biosimilar could save the French health system €13,994,190 or lead to 771 more births when compared to its higher-cost originator. Sensitivity analysis showed that the originator's relative CLBR had the greatest impact on the model. Conclusion: This analysis demonstrates that the follitropin alfa biosimilar, Bemfola®, is a more cost-effective option for OS compared with the originator from a French healthcare payer perspective, in terms of cost per CLB.

Prospective multicenter observational real-world study to assess the use, efficacy and safety profile of follitropin delta during IVF/ICSI procedures (DELTA Study).

OBJECTIVE: To describe the use, efficacy and safety profile of follitropin delta in women undergoing IVF/ICSI in routine clinical practice after one treatment cycle. STUDY DESIGN: This was a French multicenter, prospective, observational study conducted in 14 fertility centers between June 2020 and June 2021. During this period, 248 women undergoing IVF or ICSI were treated with follitropin delta for the first time. Women were followed up to 10-11 weeks after the first fresh or frozen embryo transfer. The main outcomes were use of dosing algorithm, follitropin delta dosing patterns, ovarian response, pregnancy, and adverse drug reactions in routine clinical practice. RESULTS: The analyzable population consisted of 223 patients with mean ± SD age of 33.0 ± 4.4 years, body weight of 65.7 ± 11.8 kg, and the median (IQR) AMH level was 2.6 (1.5-4.0) ng/mL. For 193 patients (86.5 %) it was the first IVF/ICSI cycle and for 30 (13.5 %) the second. The algorithm was used for the calculation of the starting dose for 88.3 % of the patients. The mean daily starting dose of follitropin delta was 11.4 ± 4.1mcg for the whole analyzable population and 14.4 ± 5.2 mcg for the sub-group of 26 patients dosed without the algorithm. The mean duration of stimulation with follitropin delta was 10.8 ± 5.2 days. The mean total dose of follitropin delta administered was 122.2 ± 80.0 mcg. An antagonist protocol was used in 90.3 % of patients. The mean ± SD number of oocytes retrieved among patients that started stimulation was 11.3 ± 6.8 and 46.1 % of patients achieved the targeted response of the algorithm of 8-14 oocytes retrieved. A fresh transfer was performed for 77.6 % of patients; the mean ± SD number of embryos transferred was 1.3 ± 0.5. The implantation rate was 36.0 %. Per started cycle, clinical pregnancy was reported in 35.0 % of the patients and ongoing pregnancy in 29.6 %. In total, 5 patients (2.2 %) reported an event of OHSS. CONCLUSION: Clinical results as collected in routine clinical practice are promising, showing a favorable effectiveness-safety profile of follitropin delta for a very varied patient population (including anovulatory PCOS, very poor responders, or non-IVF naïve patients). These real-world data complement results from clinical trials and provide useful information for usual clinical practice within a heterogeneous population group.

A real-world study of ART in France (REOLA) comparing a biosimilar rFSH against the originator according to rFSH starting dose.

BACKGROUND: Since the first launch of a biosimilar recombinant follicle stimulating hormone (rFSH), Bemfola®, in Europe in 2014, it has been possible to study in routine clinical care throughout France the effectiveness of a biosimilar rFSH including according to different rFSH starting doses. METHODS: REOLA was a non-interventional, retrospective, real world study using anonymized data from 17 Assisted Reproductive Technology (ART) centres' data management systems across France including 2,319 ART ovarian stimulation cycles with Bemfola® and 4,287 ART ovarian stimulation cycles with Gonal-f®. For both products, four populations were studied according to starting dose of rFSH: < 150 IU, 150 - 224 IU, 225 - 299 IU and ≥ 300 IU. The primary endpoint was the cumulative live birth rate (cLBR) per commenced ART ovarian stimulation cycle including all subsequent fresh and frozen-thawed embryo transfers starting during a follow up period of at least 1 year following oocyte retrieval. RESULTS: A direct relationship of increasing rFSH starting dose with increasing age, increasing basal FSH, decreasing AMH and increasing body mass index was noted. No clinically relevant differences were seen in all outcomes reported, including the cLBR, between Bemfola® and Gonal-f®, but for both drugs, an association was seen with increasing rFSH starting dose and decreasing cLBR. CONCLUSIONS: The REOLA study demonstrates that the cLBR with Bemfola® is very similar to Gonal-f® across all patient subpopulations. The cLBR is inversely related to the rFSH starting dose irrespective of the drug used, and the REOLA study provides reassurance of the clinical effectiveness of a biosimilar rFSH used in a real world setting.

Assisted reproductive techniques do not impact late neurodevelopmental outcomes of preterm children.

Objective: Assisted reproductive technology (ART) increases the rate of preterm births, though few studies have analyzed outcomes for these infants. No data are available on 4-year-old children born prematurely after ART. The objective was to investigate whether ART affect the neurodevelopmental outcomes at 4 years in preterm infants born before 34 weeks of gestational age (GA). Methods and results: A total of 166 ART and 679 naturally conceived preterm infants born before 34 weeks GA between 2013 and 2015 enrolled in the Loire Infant Follow-up Team were included. Neurodevelopment was assessed at 4 years using the age and stage questionnaire (ASQ) and the need for therapy services. The association between the socio-economic and perinatal characteristics and non-optimal neurodevelopment at 4 years was estimated. After adjustment, the ART preterm group remained significantly associated with a lower risk of having at least two domains in difficulty at ASQ: adjusted odds ratio (aOR) 0.34, 95% confidence interval (CI) (0.13-0.88), p = 0.027. The factors independently associated with non-optimal neurodevelopment at 4 years were male gender, low socio-economic level, and 25-30 weeks of GA at birth. The need for therapy services was similar between groups (p = 0.079). The long-term neurodevelopmental outcomes of preterm children born after ART are very similar, or even better than that of the spontaneously conceived children.

Impact of the duration of oestradiol treatment on live birth rate in Hormonal Replacement Therapy cycle before frozen blastocyst transfer.

Although the duration of progesterone administration in Hormonal Replacement Therapy (HRT) cycles before frozen embryo transfer is standardized, the optimal duration of oestrogen treatment remains controversial. In this monocentric retrospective study conducted in all single frozen blastocyst transfer (FBT) performed with HRT between January 2016 and July 2019, we evaluated the association between the duration of oestradiol treatment before FBT and live birth rate (LBR) in HRT cycles. Cycles were gathered in 3 groups according to quartiles of duration of oestrogen treatment. LBR was compared across the 3 groups and multivariate analysis was performed. We included 2235 single FBT cycles; 507, 1257 and 471 with E2 treatment below 23 days, 23-30 days (reference) and more than 30 days respectively. After multivariate analysis and adjustment, no significant difference in LBR was found between below 23 or more than 30 days and reference groups (OR = 0.93 [0.68-1.27] and OR = 1.29 [0.88-1.89] respectively). Complementary sensitivity analysis led to a non-significant adjusted OR = 1.66 [IC 0.9-3.1]. In conclusion, our study showed that the duration of E2 treatment in HRT cycles before FBT is not associated with LBR.