Natural proliferative phase frozen embryo transfer-a new approach which may facilitate scheduling without hindering pregnancy outcomes.

STUDY QUESTION: How does a natural proliferative phase (NPP) strategy for frozen embryo transfer (FET) compare with the conventional artificial (AC) and natural (NC) endometrial preparation protocols in terms of live birth rates (LBR)? SUMMARY ANSWER: This study supports the hypothesis that, just as for NC, NPP-FET may be a superior alternative to AC in terms of LBR. WHAT IS KNOWN ALREADY: Although FETs are increasing worldwide, the optimal FET protocol is still largely controversial. Despite recent evidence supporting a possibly higher efficacy and safety of NC FETs, their widespread use is limited by the difficulties encountered during cycle monitoring and scheduling. STUDY DESIGN, SIZE, DURATION: In this single center retrospective cohort study, we describe the NPP-FET protocol, in which vaginal progesterone is initiated during the proliferative phase as soon as an endometrium with a thickness of at least 7 mm is identified and ovulation is ruled out, regardless of mean diameter of the dominant follicle. PARTICIPANTS/MATERIALS, SETTING, METHODS: For comparison, we considered all blastocyst stage FET cycles preformed at a private infertility center between January 2010 and June 2022, subdivided according to the following subgroups of endometrial preparation: AC, NPP, and NC. We performed multivariable generalized estimating equations regression analysis to account for the following potential confounding variables: oocyte age at retrieval, oocyte source (autologous without preimplantation genetic testing for aneuploidies (PGT-A) versus autologous with PGT-A versus donated), number of oocytes retrieved/donated, embryo developmental stage (Day 5 versus Day 6), number of embryos transferred, quality of the best embryo transferred, and year of treatment. The main outcome measure was LBR. The secondary outcomes included hCG positive, clinical pregnancy and miscarriage rates, and the following perinatal outcomes: first trimester bleeding, second/third trimester bleeding, preterm rupture of membranes, gestational diabetes, gestational hypertensive disorders (GHD), and gestational age at delivery. MAIN RESULTS AND THE ROLE OF CHANCE: A total of 5791 FET cycles were included in this analysis (2226 AC, 349 NPP, and 3216 NC). The LBR for FET was lower in the AC subgroup when compared to the NPP and NC (38.4%, 49.1%, and 45.2%, respectively; P < 0.01 AC versus NPP and AC versus NC). The rates of miscarriage were also lower in the NPP and NC subgroups when compared to AC (19.7%, 25.0%, and 34.9%, respectively; P < 0.01 NPP versus AC and NC versus AC). Considering perinatal outcomes, NPP-FET and NC were associated with a significantly lower first trimester bleeding compared to AC (17.3%, 14.7%, and 37.6%, respectively; P < 0.01 NPP versus AC and NC versus AC). Additionally, NC was associated with a lower rate of GHD when compared with AC (8.6% versus 14.5%, P < 0.01), while the rate following NPP-FET was 9.4%. LIMITATIONS, REASONS FOR CAUTION: This study is limited by its retrospective design. Moreover, there was also a low number of patients in the NPP subgroup, which may have led the study to be underpowered to detect clinically relevant differences between the subgroups. WIDER IMPLICATIONS OF THE FINDINGS: Our study posits that the NPP-FET protocol may be an effective and safe alternative to both NC and AC, while still allowing for enhanced practicality in patient follow-up and FET scheduling. Further investigation on NPP-FET is warranted, with prospective studies including a larger and more homogeneous subsets of patients. STUDY FUNDING/COMPETING INTEREST(S): This research was supported by the IVI-RMA-Lisbon (2008-LIS-053-CG). The authors did not receive any funding for this study. The authors have no competing interests. TRIAL REGISTRATION NUMBER: Not applicable.

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

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).

Modified natural cycle allows a window of 7 days for frozen embryo transfer planning.

RESEARCH QUESTION: Should ovulation be triggered in a modified natural cycle (mNC) with recombinant human chorionic gonadotrophin (rHCG) as soon as a mean follicle diameter of 17 mm is visible, or is more flexible planning possible? DESIGN: This multicentre, retrospective, observational study of 3087 single frozen blastocyst transfers in mNC was carried out between January 2020 and September 2022. The inclusion criteria included endometrial thickness ≥7 mm and serum progesterone <1.5 ng/ml. The main outcome was ongoing pregnancy rate. Secondary end-points were pregnancy rate, implantation rate, clinical pregnancy rate and miscarriage rate. The mean follicle size at triggering was stratified into three groups (13.0-15.9, 16.0-18.9 and 19.0-22 mm). RESULTS: The baseline characteristics between the groups did not vary significantly for age, body mass index and the donor's age for egg donation. No differences were found in pregnancy rate (64.5%, 60.2% and 57.4%; P = 0.19), clinical pregnancy rate (60.5%, 52.8% and 50.6%; P = 0.10), implantation rate (62.10%, 52.9% and 51.0%; P = 0.05) or miscarriage rate (15.0%, 22.2%; and 25.0%; P = 0.11). Although ongoing pregnancy rate (54.9%, 46.8% and 43.1%; P = 0.02) varied significantly in the univariable analysis, it was no longer significant after adjustment for the use of preimplantation genetic testing for aneuploidies and egg donation. CONCLUSIONS: The findings showed rHCG could be flexibly administered with a mean follicle size between 13 and 22 mm as long as adequate endometrial characteristics are met, and serum progesterone is <1.5 ng/ml. Considering the follicular growth rate of 1-1.5 mm/day, this approach could allow a flexibility for FET scheduling of 6-7 days, simplifying mNC FET planning in clinical practice.

Impact of dydrogesterone use in cycles with low progesterone levels on the day of frozen embryo transfer.

PURPOSE: This study aims to evaluate whether the clinical outcomes of cycles with frozen embryo transfer (FET) in hormonal replacement treatment supplemented with dydrogesterone (DYD) following detection of low circulating levels of progesterone (P4) were comparable to the results of cycles with otherwise normal serum P4 values. METHODS: Extended analyses of a retrospective cohort that included FET cycles performed between July 2019 and March 2022 after a cycle of artificial endometrial preparation using valerate-estradiol and micronized vaginal P4 (400 mg twice daily). Whenever the serum P4 value was considered low on the morning of the planned transfer, 10 mg of DYD three times a day was added as a supplement. Only single-embryo transfers of a blastocyst were considered. The primary endpoint was live birth rate. RESULTS: Five-hundred thirty-five FET cycles were analyzed, of which 136 (25.4%) underwent treatment with DYD. There were 337 pregnancies (63%), 207 live births (38.6%), and 130 miscarriages (38.5%). The P4 values could be modeled by a gamma distribution, with a mean of 14.5 ng/ml and a standard deviation of 1.95 ng/ml. The variables female age on the day of FET, ethnicity, and weight were associated with a variation in the serum P4 values. There were no differences in the results between cycles with or without the indication for DYD supplementation. CONCLUSIONS: Live birth rate did not vary significantly in females with low and normal serum P4 levels on the day of FET when DYD was used as rescue therapy.

The combined effect of BMI and age on ART outcomes.

STUDY QUESTION: For a woman with infertility and overweight/obesity, can infertility treatment be postponed to first promote weight loss? SUMMARY ANSWER: Advice regarding a delay in IVF treatment to optimize female weight should consider female age, particularly in women over 38 years for whom only substantial weight loss in a short period of time (3 months) seems to provide any benefit. WHAT IS KNOWN ALREADY: Body weight excess and advanced age are both common findings in infertile patients, creating the dilemma of whether to promote weight loss first or proceed to fertility treatment immediately. Despite their known impact on fertility, studies assessing the combined effect of female age and BMI on cumulative live birth rates (CLBRs) are still scarce and conflicting. STUDY DESIGN, SIZE, DURATION: We performed a multicentre retrospective cohort study including 14 213 patients undergoing their first IVF/ICSI cycle with autologous oocytes and subsequent embryo transfers, between January 2013 and February 2018 in 18 centres of a multinational private fertility clinic. BMI was subdivided into the following subgroups: underweight (<18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25.0-29.9 kg/m2), and obesity (≥30.0 kg/m2). PARTICIPANTS/MATERIALS, SETTING, METHODS: The primary outcome was CLBR. The secondary outcome was time to pregnancy. To assess the influence of female age and BMI on CLBR, two multivariable regression models were developed with BMI being added in the models as either an ordinal categorical variable (Model 1) or a continuous variable (Model 2) using the best-fitting fractional polynomials. CLBR was estimated over 1-year periods (Model 1) and shorter timeframes of 3 months (Model 2). We then compared the predicted CLBRs according to BMI and age. MAIN RESULTS AND THE ROLE OF CHANCE: When compared to normal weight, CLBRs were lower in women who were overweight (adjusted odds ratio (aOR) 0.86, 95% CI 0.77-0.96) and obese (aOR 0.74, 95% CI 0.62-0.87). A reduction of BMI within 1 year, from obesity to overweight or overweight to normal weight would be potentially beneficial up to 35 years old, while only a substantial reduction (i.e. from obesity to normal BMI) would be potentially beneficial in women aged 36-38 years. Above 38 years of age, even considerable weight loss did not compensate for the effect of age over a 1-year span but may be beneficial in shorter time frames. In a timeframe of 3 months, there is a potential benefit in CLBR if there is a loss of 1 kg/m2 in BMI for women up to 33.25 years and 2 kg/m2 in women aged 33.50-35.50 years. Older women would require more challenging weight loss to achieve clinical benefit, specifically 3 kg/m2 in women aged 35.75-37.25 years old, 4 kg/m2 in women aged 37.50-39.00 years old, and 5 kg/m2 or more in women over 39.25 years old. LIMITATIONS, REASONS FOR CAUTION: This study is limited by its retrospective design and lower number of women in the extreme BMI categories. The actual effect of individual weight loss on patient outcomes was also not evaluated, as this was a retrospective interpatient comparison to estimate the combined effect of weight loss and ageing in a fixed period on CLBR. WIDER IMPLICATIONS OF THE FINDINGS: Our findings suggest that there is potential benefit in weight loss strategies within 1 year prior to ART, particularly in women under 35 years with BMI ≥25 kg/m2. For those over 35 years of age, weight loss should be considerable or occur in a shorter timeframe to avoid the negative effect of advancing female age on CLBR. A tailored approach for weight loss, according to age, might be the best course of action. STUDY FUNDING/COMPETING INTEREST(S): No specific funding was obtained for this study. All authors have no conflicts to declare. TRIAL REGISTRATION NUMBER: N/A.

Clinical pregnancy rate for frozen embryo transfer with HRT: a randomized controlled pilot study comparing 1 week versus 2 weeks of oestradiol priming.

RESEARCH QUESTION: Does a frozen-embryo transfer in an artificially-prepared endometrium (FET-HRT) cycle yield similar clinical pregnancy rate with 7 days of oestrogen priming compared to 14 days? DESIGN: This is a single-centre, randomized, controlled, open-label pilot study. All FET-HRT cycles were performed in a tertiary centre between October 2018 and January 2021. Overall, 160 patients were randomized, with a 1:1 allocation, into two groups of 80 patients each: group A (7 days of E2 prior to P4 supplementation) and group B (14 days of E2 prior to P4 supplementation). Both groups received single blastocyst stage embryos on the 6th day of vaginal P4 administration. The primary outcome was the feasibility of such strategy assessed as clinical pregnancy rate, secondary outcomes were biochemical pregnancy rate, miscarriage rate, live birth rate and serum hormone levels on the day of FET. Chemical pregnancy was assessed by an hCG blood test 12 days after FET and clinical pregnancy was confirmed by transvaginal ultrasound at 7 weeks. RESULTS: The analysis included 160 patients who were randomly assigned to either group A or group B on the seventh day of their FET-HRT cycle if the measured endometrial thickness was above 6.5 mm. Following screening failures and of drop-outs, 144 patients were finally included both in group A (75 patients) or group B (69 patients). Demographic characteristics for both groups were comparable. The biochemical pregnancy rate was 42.5% and 48.8% for group A and group B, respectively (p 0.526). Regarding the clinical pregnancy rate at 7 weeks, no statistical difference was observed (36.3% vs 46.3% for group A and group B, respectively, p = 0.261). The secondary outcomes of the study (biochemical pregnancy, miscarriage, and live birth rate) were comparable between the two groups for IIT analysis, as well as the P4 values on the day of FET. CONCLUSIONS: In a frozen embryo transfer cycle, performed with artificial preparation of the endometrium, 7 versus 14 days of oestrogen priming are comparable, in terms of clinical pregnancy rate; the advantages of a seven-day protocol include the shorter time to pregnancy, reduced exposure to oestrogens, and more flexibility of scheduling and programming, and less probability to recruit a follicle and have a spontaneous LH surge. It is important to keep in mind that this study was designed as a pilot trial with a limited study population as such it was underpowered to determine the superiority of an intervention over another; larger-scale RCTs are warranted to confirm our preliminary results. TRIAL REGISTRATION: Clinical trial number: NCT03930706.

Nature (almost) always prevails - challenging the status quo of artificial cycle frozen embryo transfers.

Frozen embryo transfers (FET) have become increasingly popular in assisted reproductive technology (ART) due to advancements in cryopreservation techniques and the implementation of the 'freeze-all' strategy. The choice between artificial or natural cycles for FET preparation has been a subject of debate, considering factors such as endometrial receptivity, flexibility of scheduling and pregnancy outcomes. While artificial cycle protocols offer convenience and flexibility, studies have suggested potential drawbacks, including higher miscarriage rates and a greater risk of hypertensive disorders during pregnancy. In contrast, natural cycle protocols involve a frequently demanding monitoring of both endometrial proliferation and follicular growth, which may lead to increased clinic visits and scheduling issues. Multiple strategies have been proposed to enhance the usage of natural cycle FET, including addressing anovulation through minimal stimulation, reducing cycle monitoring and exploring novel FET approaches. These novel approaches, such as widening the window for human chorionic gonadotrophin administration and the natural proliferative phase protocol, offer promising outcomes and increased convenience for patients. However, further research is needed to establish the optimal timing and effectiveness of these strategies. Overall, enhancing the practicality of natural cycle FETs is crucial for expanding their utilization during ART.

Perinatal outcomes in children born after fresh or frozen embryo transfer using donated oocytes.

STUDY QUESTION: Do children born after vitrified-thawed embryo transfers (ETs) using donated oocytes have worse perinatal outcomes when compared with fresh ET? SUMMARY ANSWER: No significant difference in birthweight and prematurity rates between fresh or frozen embryo transfers (FETs) in newborns after oocyte donation was found. WHAT IS KNOWN ALREADY: Autologous singletons born after fresh ET have been previously associated with higher rates of preterm birth and low birthweight, while FETs seem to confer a higher risk of hypertensive disorders during pregnancy and macrosomia. However, studies comparing these outcomes using autologous oocytes are unable to adequately disentangle the putative detrimental consequences of embryo vitrification from the possible effects that ovarian stimulation and endometrial preparation may have on endometrial receptivity prior to ET. The oocyte donation model is, for this reason, a more appropriate setting to study these hypotheses; however so far, the information available regarding neonatal outcomes in this patient population is limited to either small and/or heterogeneous studies. STUDY DESIGN, SIZE, DURATION: We performed a multicentre retrospective cohort study including 5848 singletons born between 2009 and February 2020 following oocyte donation and single blastocyst transfer, subdivided according to whether a fresh ET or FET was performed. We also performed two additional sensitivity analyses, subgrouping the sample according to the type of endometrial preparation (natural versus artificial) and whether the donated oocytes had previously been vitrified or not. PARTICIPANTS/MATERIALS, SETTING, METHODS: Patients with a first singleton livebirth after single blastocyst transfer were compared using multivariable regression analysis to account for potential confounding factors. The primary outcome was birthweight. Secondary outcomes were birthweight z-scores and percentiles, small/large for gestational age, gestational age at delivery, gender, prematurity (<37 weeks and <32 weeks), neonatal morbidity (Apgar scores and need for neonatal intensive care) and maternal morbidity (gestational hypertensive disorders, gestational diabetes and caesarean delivery). MAIN RESULTS AND THE ROLE OF CHANCE: There was no significant difference between the fresh ET and FET groups in terms of mean birthweight (3215 g versus 3200 g) and birthweight z-scores (0.03 versus 0.1), in both the unadjusted and confounder-adjusted models. However, artificial endometrial preparation was associated with a higher birthweight (3220 g versus 3105 g) and birthweight z-scores (0.06 versus -0.13) when compared with a transfer in a natural cycle. Although a 1-day statistically significant difference in gestational age at birth (275 versus 274 days) was detected, premature birth rates (<37 weeks) did not vary significantly between groups (9.9% and 11.2% for fresh ET and FET, respectively). No other statistically significant differences were found in the remaining neonatal and maternal outcomes studies between the fresh ET and FET groups. LIMITATIONS, REASONS FOR CAUTION: This study is limited by its retrospective design and lack of information regarding congenital malformations. Moreover, the sample selection criteria that were used may limit the generalizability of our results. WIDER IMPLICATIONS OF THE FINDINGS: Perinatal outcomes did not seem to be affected significantly by the embryo vitrification process in an oocyte donation model. Hence, other factors may contribute to the hindered perinatal outcomes described in ART, particularly the potential effect that ovarian stimulation and endometrial preparation may have on endometrial receptivity. STUDY FUNDING/COMPETING INTEREST(S): No specific funding was obtained for this study. All authors have no conflicts to declare. TRIAL REGISTRATION NUMBER: N/A.

Effect of A23187 ionophore treatment on human blastocyst development-a sibling oocyte study.

PURPOSE: To investigate whether treatment with commercially available ready-to-use A23187 ionophore (GM508-CultActive) improves embryo development outcome in patients with a history of embryo developmental problems. METHODS: This is a uni-center prospective study in which sibling oocytes of patients with embryos of poor quality on day 5 in the previous cycle were treated or not with CultActive. RESULTS: Two hundred forty-seven metaphase II (MII) oocytes from 19 cycles performed between 2016 and 2019 were included in the study. After ICSI, the sibling oocytes were assigned to the treatment group or to the control group, following an electronically generated randomization list. A number of 122 MII were treated with CultActive and 125 MII had no treatment and were assigned to the control group. No difference in fertilization rate (p = 0.255) or in the capacity of embryos to reach good quality on day 5 (p = 0.197) was observed between the two groups. The utilization rates defined as the number of embryos transferred or cryopreserved per mature oocyte (p = 0.438) or per fertilized oocytes (p = 0.299) were not significantly different between the treated group and the control group. CONCLUSION: The results of the current study do not support the use of CultActive in cases with embryo developmental problems.

The effect of late-follicular phase progesterone elevation on embryo ploidy and cumulative live birth rates.

RESEARCH QUESTION: Does late-follicular phase progesterone elevation have a deleterious effect on embryo euploidy, blastocyst formation rate and cumulative live birth rates (CLBR)? DESIGN: A multicentre retrospective cross-sectional study including infertile patients aged 18-40 years who underwent ovarian stimulation in a gonadotrophin-releasing hormone antagonist protocol and preimplantation genetic testing for aneuploidies (PGT-A) followed by a freeze-all strategy and euploid embryo transfer between August 2017 and December 2019. The sample was stratified according to the progesterone concentrations on the day of trigger: normal (≤1.50 ng/ml) and high (>1.50 ng/ml). Moreover, sensitivity analyses were performed to determine whether different conclusions would have been drawn if different cut-offs had been adopted. The primary outcome was the embryo euploidy rate. Secondary outcomes were the blastocyst formation rate, the number of euploid blastocysts and CLBR. RESULTS: Overall 1495 intracytoplasmic sperm injection PGT-A cycles were analysed. Late-follicular phase progesterone elevation was associated with significantly higher late-follicular oestradiol concentrations (2847.56 ± 1091.10 versus 2240.94 ± 996.37 pg/ml, P < 0.001) and significantly more oocytes retrieved (17.67 ± 8.86 versus 12.70 ± 7.00, P < 0.001). The number of euploid embryos was significantly higher in the progesterone elevation group (2.32 ± 1.74 versus 1.86 ± 1.42, P = 0.001), whereas the blastocyst formation rate (47.1% [43.7-50.5%] versus 51.0% [49.7-52.4%]), the embryo euploidy rate (48.3% [44.9-51.7%] versus 49.1% [47.7-50.6%], the live birth rate in the first frozen embryo transfer (34.1% versus 31.1%, P = 0.427) and CLBR (38.9% versus 37.0%, P = 0.637) were not significantly different between the two groups. CONCLUSIONS: Euploidy rate and CLBR do not significantly differ among PGT-A cycles with and without late-follicular progesterone elevation in a freeze-all approach.

The freeze-all strategy versus agonist triggering with low-dose hCG for luteal phase support in IVF/ICSI for high responders: a randomized controlled trial.

STUDY QUESTION: Does the freeze-all strategy in high-responders increase pregnancy rates and improve safety outcomes when compared with GnRH agonist triggering followed by low-dose hCG intensified luteal support with a fresh embryo transfer? SUMMARY ANSWER: Pregnancy rates after either fresh embryo transfer with intensified luteal phase support using low-dose hCG or the freeze-all strategy did not vary significantly; however, moderate-to-severe ovarian hyperstimulation syndrome (OHSS) occurred more frequently in the women who attempted a fresh embryo transfer. WHAT IS KNOWN ALREADY: Two strategies following GnRH agonist triggering (the freeze-all approach and a fresh embryo transfer attempt using a low-dose of hCG for intensified luteal phase support) are safer alternatives when compared with conventional hCG triggering with similar pregnancy outcomes. However, these two strategies have never been compared head-to-head in an unrestricted predicted hyper-responder population. STUDY DESIGN, SIZE, DURATION: This study included women with an excessive response to ovarian stimulation (≥18 follicles measuring ≥11 mm) undergoing IVF/ICSI in a GnRH antagonist suppressed cycle between 2014 and 2017. Our primary outcome was clinical pregnancy at 7 weeks after the first embryo transfer. Secondary outcomes included live birth and the development of moderate-to-severe OHSS. PARTICIPANTS/MATERIALS, SETTING, METHODS: Following GnRH agonist triggering, women were randomized either to cryopreserve all good-quality embryos followed by a frozen embryo transfer in an subsequent artificial cycle or to perform a fresh embryo transfer with intensified luteal phase support (1500 IU hCG on the day of oocyte retrieval, plus oral estradiol 2 mg two times a day, plus 200 mg of micronized vaginal progesterone three times a day). MAIN RESULTS AND THE ROLE OF CHANCE: A total of 212 patients (106 in each arm) were recruited in the study, with three patients (one in the fresh embryo transfer group and two in the freeze-all group) later withdrawing their consent to participate in the study. One patient in the freeze-all group became pregnant naturally (clinical pregnancy diagnosed 38 days after randomization) prior to the first frozen embryo transfer. The study arms did not vary significantly in terms of the number of oocytes retrieved and embryos produced/transferred. The intention to treat clinical pregnancy and live birth rates (with the latter excluding four cases lost to follow-up: one in the fresh transfer and three in the freeze-all arms, respectively) after the first embryo transfer did not vary significantly among the fresh embryo transfer and freeze-all study arms: 51/105 (48.6%) versus 57/104 (54.8%) and 41/104 (39.4%) versus 42/101 (41.6%), respectively (relative risk for clinical pregnancy 1.13, 95% CI 0.87-1.47; P = 0.41). However, moderate-to-severe OHSS occurred solely in the group that received low-dose hCG (9/105, 8.6%, 95% CI 3.2% to 13.9% vs 0/104, 95% CI 0 to 3.7, P < 0.01). LIMITATIONS, REASONS FOR CAUTION: The sample size calculation was based on a 19% absolute difference in terms of clinical pregnancy rates, therefore smaller differences, as observed in the trial, cannot be reliably excluded as non-significant. WIDER IMPLICATIONS OF THE FINDINGS: This study offers the first comparative analysis of two common strategies applied to women performing IVF/ICSI with a high risk to develop OHSS. While pregnancy rates did not vary significantly, a fresh embryo transfer with intensified luteal phase support may still not avoid the risk of moderate-to-severe OHSS and serious consideration should be made before recommending it as a routine first-line treatment. Future trials may allow us to confirm these findings. STUDY FUNDING/COMPETING INTEREST(S): The authors have no conflicts of interest to disclose. No external funding was obtained for this study. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov identifier NCT02148393. TRIAL REGISTRATION DATE: 28 May 2014. DATE OF FIRST PATIENT'S ENROLMENT: 30 May 2014.

Outcome of in-vitro oocyte maturation in patients with PCOS: does phenotype have an impact?

STUDY QUESTION: Does the phenotype of patients with polycystic ovary syndrome (PCOS) affect clinical outcomes of ART following in-vitro oocyte maturation? SUMMARY ANSWER: Cumulative live birth rates (CLBRs) after IVM were significantly different between distinct PCOS phenotypes, with the highest CLBR observed in patients with phenotype A/HOP (= hyperandrogenism + ovulatory disorder + polycystic ovaries), while IVM in patients with phenotype C/HP (hyperandrogenism + polycystic ovaries) or D/OP (ovulatory disorder + polycystic ovaries) resulted in lower CLBRs (OR 0.26 (CI 0.06-1.05) and OR 0.47 (CI 0.25-0.88), respectively, P = 0.03). WHAT IS KNOWN ALREADY: CLBRs in women with hyperandrogenic PCOS phenotypes (A/HOP and C/HP) have been reported to be lower after ovarian stimulation (OS) and ART when compared to CLBR in women with a normo-androgenic PCOS phenotype (D/OP) and non-PCOS patients with a PCO-like ovarian morphology (PCOM). Whether there is an influence of the different PCOS phenotypes on success rates of IVM has been unknown. STUDY DESIGN, SIZE, DURATION: This was a single-centre, retrospective cohort study including 320 unique PCOS patients performing their first IVM cycle between April 2014 and January 2018 in a tertiary referral hospital. PARTICIPANTS/MATERIALS, SETTING, METHODS: Baseline patient characteristics and IVM treatment cycle data were collected. The clinical outcomes following the first IVM embryo transfer were retrieved, including the CLBR defined as the number of deliveries with at least one live birth resulting from one IVM cycle and all appended cycles in which fresh or frozen embryos were transferred until a live birth occurred or until all embryos were used. The latter was considered as the primary outcome. A multivariate regression model was developed to identify prognostic factors for CLBR and test the impact of the patient's PCOS phenotype. MAIN RESULTS AND THE ROLE OF CHANCE: Half of the patients presented with a hyperandrogenic PCOS phenotype (n = 140 A/HOP and n = 20 C/HP vs. n = 160 D/OP). BMI was significantly different between phenotype groups (27.4 ± 5.4 kg/m2 for A/HOP, 27.1 ± 5.4 kg/m2 for C/HP and 23.3 ± 4.4 kg/m2 for D/OP, P < 0.001). Metformin was used in 33.6% of patients with PCOS phenotype A/HOP, in 15.0% of C/HP patients and in 11.2% of D/OP patients (P < 0.001). Anti-müllerian hormone levels differed significantly between groups: 12.4 ± 8.3 µg/l in A/HOP, 7.7 ± 3.1 µg/l in C/HP and 10.4 ± 5.9 µg/l in D/OP patients (P = 0.01). The number of cumulus-oocyte complexes (COC) was significantly different between phenotype groups: 25.9 ± 19.1 COC in patients with phenotype A/HOP, 18.3 ± 9.0 COC in C/HP and 19.8 ± 13.5 COC in D/OP (P = 0.004). After IVM, patients with different phenotypes also had a significantly different number of mature oocytes (12.4 ± 9.3 for A/HOP vs. 6.5 ± 4.2 for C/HP vs. 9.1 ± 6.9 for D/OP, P < 0.001). The fertilisation rate, the number of usable embryos and the number of cycles with no embryo available for transfer were comparable between the three groups. Following the first embryo transfer, the positive hCG rate and LBR were comparable between the patient groups (44.7% (55/123) for A/HOP, 40.0% (6/15) for C/HP, 36.7% (47/128) for D/OP, P = 0.56 and 25.2% (31/123) for A/HOP, 6.2% (1/15) for C/HP, 26.6% (34/128) for D/OP, respectively, P = 0.22). However, the incidence of early pregnancy loss was significantly different across phenotype groups (19.5% (24/123) for A/HOP, 26.7% (4/15) for C/HP and 10.2% (13/128) for D/OP, P = 0.04). The CLBR was not significantly different following univariate analysis (40.0% (56/140) for A/HOP, 15% (3/20) for C/HP and 33.1% (53/160) for D/OP (P = 0.07)). When a multivariable logistic regression model was developed to account for confounding factors, the PCOS phenotype appeared to be significantly correlated with CLBR, with a more favourable CLBR in the A/HOP subgroup (OR 0.26 for phenotype C/HP (CI 0.06-1.05) and OR 0.47 for phenotype D/OP (CI 0.25-0.88), P = 0.03)). LIMITATIONS, REASONS FOR CAUTION: These data should be interpreted with caution as the retrospective nature of the study holds the possibility of unmeasured confounding factors and misassignment of the PCOS phenotype. Moreover, the sample size for phenotype C/HP was too small to draw conclusions for this subgroup of patients. WIDER IMPLICATIONS OF THE FINDINGS: Caucasian infertile patients with a PCOS phenotype A/HOP who undergo IVM achieved a higher CLBR than their counterparts with C/HP and D/OP. This is in strong contrast with previously reported outcomes following OS where women with PCOS and hyperandrogenism (A/HOP and C/HP) performed significantly worse. For PCOS patients who require ART, the strategy of OS followed by an elective freeze-all strategy remains to be compared with IVM in a prospective fashion; however, the current data provide support for IVM as a valid treatment option, especially in the most severe PCOS phenotypes (A/HOP). Our data suggest that proper patient selection is of utmost importance in an IVM programme. STUDY FUNDING/COMPETING INTEREST(S): The clinical IVM research has been supported by research grants from Cook Medical and Besins Healthcare. All authors declared no conflict of interest. TRIAL REGISTRATION NUMBER: N/A.

Impact of endometrial polyps detected during the follicular phase of intrauterine insemination treatments.

RESEARCH QUESTION: Endometrial polyps are a frequent finding during fertility treatment. Although up to 27% of small polyps (<10 mm) regress spontaneously, there is clinical benefit to removing a polyp detected before intrauterine insemination (IUI), regardless of size. However, the clinical outcome of IUI following a new suspicion of a polyp during follicle tracking is unknown. DESIGN: This retrospective cohort study included all patients with a normal baseline uterine ultrasound and/or hysteroscopy result who started an IUI cycle between May 2009 and March 2017. In 139 of 6606 patients (2.1%), encompassing 340 out of 15,147 cycles (2.3% of cycles), a polyp was diagnosed during the follicular phase. The 6467 controls had ultrasound results with no suspicion of a polyp. Each patient was included only once in the analysis during a maximum of three consecutive cycles of IUI. RESULTS: Female age was significantly higher in the polyp group than the controls (35.4 ± 4.8 versus 33.0 ± 5.0, P < 0.01). The unadjusted cumulative live birth rate (CLBR) after three IUI cycles in women with and without a polyp was 24.1% versus 33.0% (P = 0.03), indicating a deleterious effect of polyp(s). However, after multivariate Cox regression analysis for body mass index, female age, number of follicles and sperm concentration, the presence of a polyp appeared not to influence the CLBR (adjusted hazard ratio 0.742, 95% confidence interval 0.477-1.156, P = 0.19). CONCLUSIONS: These results may be reassuring, as ultrasound diagnosis of a polyp during the follicular phase of an IUI cycle does not seem to compromise clinical outcome when previous baseline examinations have been normal.

Is ovarian response associated with adverse perinatal outcomes in GnRH antagonist IVF/ICSI cycles?

RESEARCH QUESTION: Is there an association between ovarian response and perinatal outcomes? DESIGN: A retrospective, single-centre cohort study including all women undergoing their first ovarian stimulation cycle in a gonadotrophin releasing hormone antagonist protocol, with a fresh embryo transfer that resulted in a singleton live birth from January 2009 to December 2015. Patients were categorized into four groups according to the number of oocytes retrieved: one to three (category 1), four to nine (category 2), 10-15 (category 3), or over 15 oocytes (category 4). RESULTS: The overall number of patients analysed was 964. No relevant statistical difference was found among neonatal outcomes across the four ovarian response categories. Neonatal weight (in grams) was comparable between all groups (3222 ± 607 versus 3254 ± 537 versus 3235 ± 575 versus 3200 ± 622; P = 0.85, in categories 1, 2, 3 and 4, respectively). No statistically significant differences were found among the ovarian response categories for birth weight z-scores (taking into account neonatal sex and delivery term). The incidence of pre-term birth and low birth weight was comparable across the different ovarian response groups (P = 0.127 and P = 0.19, respectively). Finally, the occurrence of adverse obstetric outcomes did not differ among the ovarian response categories. Multivariate regression analysis revealed that the number of oocytes was not associated with neonatal birth weight. CONCLUSIONS: No association was found between ovarian response and adverse perinatal outcomes in antagonist IVF and intracytoplasmic sperm injection cycles. Future, larger scale and prospectively designed investigations are needed to validate these results.

The effect of cigarette smoking on the semen parameters of infertile men.

INTRODUCTION: 36.9% of men worldwide use tobacco. Previous studies suggest a negative effect of cigarette smoking on semen quality, but the results are contradictory. We have studied the effects of smoking on the semen characteristics such as sperm concentration, semen volume, sperm motility, sperm vitality and sperm morphology in a large group of infertile men. METHODS: This retrospective study was conducted on a total of 5146 infertile men with at least one year of idiopathic infertility, who admitted to the Centre for Reproductive medicine (CRG) at the Brussels University Hospital, Belgium between 2010 and 2017. The smokers were classified as mild (1-10 cigarettes/d), moderate (11-20 cigarettes/d) or heavy smokers (> 20 cigarettes/d). Semen analysis was performed for all patients. Statistical analysis was performed using the R software package and t-test or Mann-Whitney U tests were used, group comparisons were performed using ANOVA, ANCOVA or Kruskal-Wallis tests as appropriate. A p-value <0.05 was considered as statistically significant. RESULTS: Comparing the semen parameters in the two global groups showed that smoking had a significant decrease in semen volume (p=0.04074) and sperm concentration (p=0.029). ANOVA testing on the different smoking groups versus non-smoking group showed a significant decrease in sperm concentration (p=0.0364). After adjusting for the confounders, age and testosterone, ANCOVA testing showed significant effect on the sperm concentration (p=0.03871) in smokers versus non-smokers. No significant correlation was detected between the other semen characteristics. CONCLUSION: We concluded that smoking had a significant and independent effect on the sperm concentration in a semen analysis. Other parameters, like semen volume, sperm motility, sperm vitality and sperm morphology were not influenced by smoking.

Birthweight of singletons born after blastocyst-stage or cleavage-stage transfer: analysis of a data set from three randomized controlled trials.

PURPOSE: The present post hoc analysis aims to study the neonatal data of singletons born from three randomized controlled trials (RCTs) which compared the outcome of day 3 and day 5 transfers. METHODS: Our analysis included 208 liveborn singletons from three existing RCTs (publication dates 2004, 2005, and 2006), 93 children from cleavage-stage transfers and 115 from blastocyst-stage transfers. Vanishing twins were excluded from the analysis. Singleton birthweight was the primary outcome measure. Gestational age and gender of the newborn were accounted for in the multiple regression analysis, along with other confounding factors, such as maternal age, BMI, parity, and smoking behavior. RESULTS: There was no significant difference in gestational age (median, interquartile range) between cleavage-stage transfer (275 days; 267-281) and blastocyst-stage transfer (277 days; 270-281; p = 0.22). Singleton birthweight (median, interquartile range) was not significantly different between cleavage-stage transfer (3330 g; 3020-3610) and blastocyst-stage transfer (3236 g; 2930-3630; p = 0.40), even following multivariable regression analysis to control for potential maternal and newborn confounders. CONCLUSION: The gestational age and birthweight were not significantly different after cleavage-stage and blastocyst-stage transfers. One limitation to be recognized is the age of the data, with original data collection dates from 2001 to 2004. Additionally, the RCTs used for the present analysis have a fairly young age restriction.

Modified natural cycle IVF versus conventional stimulation in advanced-age Bologna poor responders.

RESEARCH QUESTION: Do ongoing pregnancy rates (OPR) differ between modified natural cycle IVF (MNC-IVF) and conventional high-dose ovarian stimulation (HDOS) in advanced-age Bologna poor responders? DESIGN: This was a retrospective cohort study including patients with poor ovarian response (POR) attending a tertiary referral university hospital from 1 January 2011 to 1 March 2017. All women who fulfilled the Bologna criteria for POR and aged ≥40 years who underwent their first intracytoplasmic sperm injection (ICSI) cycle in the study centre were included. RESULTS: In total, 476 advanced-age Bologna poor responder patients were included in the study: 189 in the MNC-IVF group and 287 in the HDOS group. OPR per patient were significantly lower in the MNC-IVF group (5/189, 2.6%) compared with the HDOS group (29/287, 10.1%) (P = 0.002). However, after adjustment for relevant confounders (number of oocytes and presence of at least one top-quality embryo), the multivariate logistic regression analysis showed that the type of treatment strategy (HDOS versus MNC-IVF) was not significantly associated with OPR (odds ratio 2.56, 95% confidence interval 0.9-7.6). CONCLUSIONS: In advanced-age Bologna poor responders, MNC-IVF, which is a more patient-friendly approach, could be a reasonable alternative in this difficult-to-treat group of women.

Evaluating the benefit of measuring serum progesterone prior to the administration of HCG: effect of the duration of late-follicular elevated progesterone following ovarian stimulation on fresh embryo transfer live birth rates.

RESEARCH QUESTION: Progesterone overproduction during ovarian stimulation is associated with lower live birth rates (LBR) after fresh embryo transfer. Therefore, circulating P concentrations on the day of HCG administration are frequently measured in clinical practice and followed by an elective cryopreservation strategy whenever late-follicular elevated P (LFEP) occurs. A recent study concluded that the duration of LFEP >1.00 ng/mL prior to HCG administration may also affect clinical pregnancy rates. The objective of this current study was to assess whether this hypothesis was reproducible using LBR as the primary outcome. DESIGN: Retrospective analysis including women undergoing IVF/ICSI between 2010-2015. LBR were compared among different P elevation duration subgroups (0, 1 or >1 day) using two LFEP thresholds (>1.00 ng/mL and >1.50 ng/mL). RESULTS: The duration of LFEP >1.00 ng/mL was not associated with a significant decrease in LBR according to whether the patient had LFEP lasting for 0, 1 or >1 days (29.9%, 30.3% and 26.3%, respectively). Conversely, when using >1.50 ng/mL as the LFEP threshold, LBR decreased significantly (30.3% 20.4% and 20.5%, respectively). However, the relative frequency of having LFEP >1.50 ng/mL for >1 day was exceedingly rare (1.9%) and the additional benefit of evaluating LFEP beyond the day of HCG triggering no longer remained statistically significant after confounder-adjustment with multivariable regression analysis. CONCLUSION: These results suggest a lack of benefit in measuring serum P in the days preceding HCG administration, since LBR in women with LFEP >1 day do not vary significantly from those with LFEP detected only on the day of HCG administration.

Oocyte donation in donors with levonorgestrel intrauterine device: a good match?

RESEARCH QUESTION: Does the levonorgestrel-releasing intrauterine device (LNG-IUD) influence cumulative live birth rate (CLBR) in oocyte donor cycles? DESIGN: Retrospective cohort study based on prospectively collected data from 1 May 2009 to 31 December 2017, without attrition, consisting of 491 consecutive cycles of vitrified oocyte donation, none lost to follow-up (unique donor-recipient pairs). All donors underwent ovarian stimulation using gonadotrophin releasing hormone (GnRH) antagonist co-treatment and GnRH agonist trigger. CLBR was chosen as primary outcome measure. RESULTS: In total, 103 (21.0%) cycles were carried out in donors carrying a LNG-IUD. In 388 (79.0%) cycles, no LNG-IUD was present. After confounder-adjustment, the use of an LNG-IUD did not have a statistically significant influence on CLBR. CONCLUSIONS: The LNG-IUD does not negatively affect CLBR.

Rare genetic variants potentially involved in ovarian hyperstimulation syndrome.

PURPOSE: We aim to investigate whether there is a genetic predisposition in women who developed ovarian hyperstimulation syndrome (OHSS) after GnRH antagonist protocol with GnRH agonist trigger and freeze-all approach. METHODS: Four patients with OHSS after GnRH agonist trigger and freeze-all approach were gathered from the worldwide patient population. These patients were analyzed through Whole Exome Sequencing. In this study known causes of OHSS were investigated and new causes present in at least two individuals were searched for. RESULTS: In the first part of the study, we evaluated the presence of mutations in genes already known to be involved in OHSS. In PGR and TP53, heterozygous alterations were detected. PGR is predicted to be involved in progesterone resistance with a recessive inheritance pattern and is, therefore, not considered as being causal. The consequences of the variant detected in TP53 currently remain unknown. In part 2 of the study, we assessed the clinical significance of variants in genes previously not linked to OHSS. We especially focused on genes with variants present in ≥ 2 patients. Two patients have variants in the FLT4 gene. Mutations in this gene are linked to hereditary lymphedema, but no link to OHSS has been described. CONCLUSIONS: Defining a genetic predisposition for OHSS is essential in view of prevention. In this study, a potential link between the FLT4 gene and OHSS has been suggested. Future functional studies are essential to define a more precise involvement of the detected variants in the development of OHSS.