Successful ART outcome in a woman with McCune-Albright syndrome: a case report and literature review.

McCune-Albright syndrome (MAS) is a rare genetic disease affecting multiple organs, including endocrine tissues. This endocrinopathy is sometimes responsible for infertility, as it may induce an independent functioning of the ovaries leading to anovulatory cycles. This case report describes the infertility journey of a 22-year-old female who had early puberty and irregular periods with high estrogen and progesterone levels, low FSH and LH (on day 3 of her menstrual cycle), and a multi-cystic right ovary. She received several infertility treatments: initially in vitro oocyte maturation (IVM) followed by cyst transvaginal ultrasound-guided aspiration, all unsuccessful. A right hemi-ovariectomy was performed that eventually restored regular cycles and made it possible to perform ovarian stimulation (OS) and in vitro fertilization (IVF). Live birth was obtained after the first embryo transfer.

The importance of on-site genetic counseling for prospective assisted reproductive technology patients.

PURPOSE: To assess the value of having an onsite genetic counseling service integrated into an assisted reproductive technology (ART) center. METHODS: Since January 2021, we have offered genetic counseling at our ART center for couples whose medical history suggests risk of transmission of a genetic disorder. The percentage of couples referred for genetic counseling, the distribution of couples according to reasons for consultation, the mode of transmission in cases of Mendelian disorders, and the frequency of mutations for those with identified genetic disorders were determined. RESULTS: In an 18-month period, 150 of 1340 couples (11.2%) enrolled for ART treatment were referred to the genetic counseling unit. Two-thirds (99/150, 66.0%) were referred for a known genetic risk, a family history of a genetic disorder or chromosomal abnormality, a serious condition of unknown cause, or consanguinity. The remaining couples had a putative genetic risk (diminished ovarian reserve, high incidence of oocyte immaturity, recurrent abortion, or severe male infertility). Of the 99 with known genetic risk, 62 (62.7%), were approved for ART treatment, 23 (23.2%) were recommended prenatal or preimplantation testing, and 14 (14.1%) were referred for further testing before undergoing ART. CONCLUSIONS: Our findings reveal great value in having an on-site genetic counseling unit for referral of ART patients. Such a unit makes the ART process smoother and safer for couples, and it lightens the burden of ART staff by removing responsibilities for which they are neither trained, nor should they have to assume.

Cryptic splice site poisoning and meiotic arrest caused by a homozygous frameshift mutation in RBMXL2: A case report.

Gene expression in meiotic cells in the testis is characterized by intense transcriptional activity and alternative splicing. These processes are mainly controlled by RNA-binding proteins expressed strongly in germ cells. Functional impairments in any of these proteins' functions can lead to defects in meiosis and thus severe male infertility. Here, we have identified a homozygous frameshift mutation (NM_014469.4:c.301dup; p.Ser101LysfsTer29) in the RNA-binding motif protein, X-linked like 2 (RBMXL2) gene in a man with an azoospermia due to meiotic arrest. As RBMXL2 is known to be crucial for safeguarding the meiotic transcriptome in mice testes, we hypothesized that this variant leads to cryptic splice site poisoning. To determine the variant's impact on spermatogenesis, we confirmed the absence of RBMXL2 protein in the patient's testis tissue and then evidenced abnormal expression of several spermatogenesis proteins (e.g. meiosis-specific with coiled-coil domain) known to be altered in rbmxl2 knock-out mice with meiotic arrest. Our results indicate that RBMXL2's function in spermatogenesis is conserved in mammals. We hypothesize that deleterious variant in the RBMXL2 gene can result in male infertility and complete meiotic arrest, due to the disruption of gene expression by cryptic splice site poisoning.

Case Report: Post-Partum SARS-CoV-2 Infection After the First French Uterus Transplantation.

Absolute uterus factor infertility, whether congenital or acquired, renders the woman unable to carry a child. Although uterus transplantation (UTx) is being increasingly performed as a non-vital procedure to address this unfortunate condition, the immunosuppression required presents risks that are further compounded by pregnancy and during the puerperium period. These vulnerabilities require avoidance of SARS-CoV-2 infection in pregnant UTx recipients especially during the third trimester, as accumulating evidence reveals increased risks of morbidity and mortality. Here we describe a successful UTx case with delivery of a healthy child, but in which both mother and neonate developed asymptomatic SARS-CoV-2 infection seven days after RNA vaccination, on day 35 post-partum. Although the patient was successfully treated with a combination therapy comprised of two monoclonal antibodies, this case highlights the challenges associated with performing UTx in the era of Covid-19. More broadly, the risks of performing non-vital organ transplantation during a pandemic should be discussed among team members and prospective patients, weighing the risks against the benefits in improving the quality of life, which were considerable for our patient who achieved motherhood with the birth of a healthy child.

Investigation of the reliability of semi-automatic annotation by the Geri time-lapse system.

RESEARCH QUESTION: What is the reliability of Geri® Assess 2.0 software time-lapse technology for annotating kinetic events and identifying abnormal phenotypes in preimplantation human embryos? DESIGN: Embryos were annotated using Assess 2.0 for the appearance and fading of pronuclei, and for progression to the 2-, 3-, 4-, 5- and 6-cell stages and to three blastocyst stages. Identification of reverse cleavage and direct cleavage phenotypes was also recorded. Manual annotation was undertaken after these events in a blinded fashion. Embryo scores were compared between Assess 2.0 and manual annotation. RESULTS: A total of 513 oocytes from 34 women were included. Detection rates for Assess 2.0 versus manual annotation among the 10 kinetic events and including direct cleavage and reverse cleavage ranged between 0% and 94.4%. The percentage of discordant pairs was significantly different for all 12 events analysed (P-value range 0.036 to <0.0001). The sensitivity of Assess 2.0 ranged from 68.2% to 94.4% and specificity ranged from 63.8% to 97.3%. Assess 2.0 called for verification by the embryologist for at least one event in 55.2% of oocytes assessed. Of the 297 embryos scored by manual annotation, Assess 2.0 assigned the same score for only 125 (42.1%), although after manual corrections, concordance with manual annotation scores was raised to 66.0%. CONCLUSIONS: The results reveal striking differences between Assess 2.0 and manual annotation for kinetic annotations. Failure of Assess 2.0 to detect direct cleavage events and the low detection rate of reverse cleavage are further limitations. These collective findings highlight the importance of validating time-lapse annotation software before clinical implementation. Manual verification of Assess 2.0 outputs remains essential for accurate data interpretation.

Are There Ovarian Responsive Indexes That Predict Cumulative Live Birth Rates in Women over 39 Years?

Objective: Ovarian response indexes have been proposed in assisted reproductive technology (ART) in order to optimize live birth rates (LBR), adjusting ovarian stimulation (OS), and minimizing risks. Gonadotropin doses are commonly adjusted according to ovarian reserve parameters, including antral follicle count (AFC), anti-Mullerian hormone (AMH), and basal follicle stimulating hormone (FSH) levels. The retrospective assessment of ovarian responses allows one to identify three primary indexes: (i) follicular output rate (FORT), the ratio of the number of pre-ovulatory follicles obtained at OS completion over AFC; (ii) follicle oocyte index (FOI), the ratio of oocytes retrieved over AFC; (iii) ovarian sensitivity index (OSI), the ratio of oocytes retrieved over the total gonadotropin dose administered. In recent publications, these indexes were reported to predict ART outcome. In the present study, we assessed the ability of these indexes to predict cumulative ART outcome in women ≥39 years. Materials and Methods: Retrospective cohort study. All patients ≥39 years who performed their first ART cycle with an antagonist protocol in our center between 01/2018 and 04/2020 were included. Patients with basal FSH > 20 IU/l, AMH < 0.1 ng/mL and severe male factors (azoospermia with testicular biopsy) were excluded. All patients received both recombinant FSH and human menopausal gonadotropin (hMG). Cumulative live birth rate (cLBR) was the primary outcome. Secondary outcomes included: the number of MII oocytes, cumulative implantation (cIR), and usable blastulation rates. Logistic regressions were performed to assess the predictive values of FORT, FOI, and OSI in cLBR and embryo culture success. For each parameter, the ability of the logistic regression models to predict embryo culture success was quantified by the area under the ROC curve (AUC). Only the significant findings related to FORT, FOI, and OSI were included in the multiple logistic regression model. Linear regression models were performed between cIR, cLB, FORT, FOI, and OSI. Each statistic model was adjusted for age. Concerning OR for OSI, values were multiplied *100 due to the very low value. Results: 429 patients met the inclusion criteria. There were 298 obtained usable blastocysts after ART treatment. Age-adjusted OSI was significantly associated with cLBR [OR = 17.58 95% CI (5.48−56.40), AUC = 0.707 95% CI (0.651−0.758)) and cIR (beta = 30.22 (SE: 7.88), p < 0.001, R2= 0.060). Both FOI (OR = 6.33 95% CI (3.27−12.25), AUC = 0.725 95% CI (0.675−0.771), R2 = 0.090, p < 0.001) and OSI (OSI*100; OR = 1808.93 95% CI (159.24−19,335.13), AUC = 0.790 95% CI (0.747−0.833), R2 = 0.156, p < 0.001) were independently, when age adjusted, associated with embryo culture success. OSI showed a main performance to explain successful embryo culture than FOI (R2 = 0.156 vs. R2 = 0.090, p < 0.001). In the age-adjusted linear regression model, FOI (R2 = 0.159, p < 0.001), OSI (R2 = 0.606, p < 0.001), and FORT (r2 = 0.030, p < 0.001) were predictive of the number of MII oocytes collected. Furthermore, for OSI (r2 = 0.759, p < 0.001) and FOI (r2 = 0.297, p < 0.001), the correlation with the number of metaphase II oocytes collected was significantly higher in the non-linear regression model. Conclusions: Our findings suggest that the best index, among those analyzed, to predict cIR and cLBR, is OSI. Both OSI and FOI predict embryo culture with success, but OSI is more accurate. OSI, FOI, and FORT are significantly related to the number of MII oocytes obtained.

Serous Borderline Ovarian Tumor Diagnosis, Management and Fertility Preservation in Young Women.

Borderline ovarian tumors (BOT) represent about 10 to 20 percent of all epithelial tumors of the ovary. They constitute intermediate lesions between benign ovarian cysts and invasive carcinomas. They often occur in young women of reproductive age, and, albeit with a favorable prognosis, it may recur on the ipsilateral or contralateral ovary. Controversies surround the diagnostic criteria used for their assessment, and the optimal management to minimize their risk of recurrence and/or transformation into malignant carcinoma. Fertility preservation (FP) is considered a priority in the management of these patients, and studies aim at finding the safest and most effective way to help women with BOT history conceive with minimal risk. We present the experience of a single institution in managing three cases of serous BOT in young nulliparous women, followed by a thorough review of the existing literature, highlighting controversies and exploring the possible FP techniques for these women.

Impact of Ovarian Yield-Number of Total and Mature Oocytes Per Antral Follicular Count-On Live Birth Occurrence After IVF Treatment.

To assess the relation between oocytes yield including total retrieved oocytes (O)c and total mature oocytes (MII) relative to the antral follicular count (AFC) (3-9 mm in diameter) and relative to anti-müllerian hormone (AMH) ng/mL level: Oc/AFC, MII/AFC, Oc/AMH, and MII/AMH, respectively, and ART outcomes. We included retrospectively 264 IVF cycles after the first embryo transfer (ET) and after the cumulative ET (CET). The implantation rate (IR) and the live birth rate (LBR) after first ET were 31 ± 39% and 32.6%, respectively, and after CET 35 ± 38% and 45.1%, respectively. There was a significantly higher average of Oc/AFC and MII/AFC when live birth (LB) occurred after the first ET (0.82 ± 0.4 vs. 0.71 ± 0.35 and 0.57 ± 0.4 vs. 0.68 ± 0.3, respectively, P < 0.05). We reported a significantly higher average of MII/AFC when LB occurred after CET (0.66 ± 0.3 vs. 0.56 ± 0.30, P = 0.02) in comparison to the group where no LB was obtained. Increased Oc/AFC and MII/AFC ratios were associated with the occurrence of LB and increased IR after first ET (P < 0.05). Increased MII/AFC ratio was associated with the occurrence of LB and IR after CET (P = 0.02 and P = 0.04, respectively). After age-adjusted multivariate analyses, all these trends were confirmed (P < 0.05) except for the effect of MII/AFC ratio on IR after CET. In conclusion, Oc/AMH and MII/AMH ratios have no effect on the occurrence of LBR or on IR after first ET or CET at either age grouping. Ratios Oc/AFC and MII/AFC seem promising indicators to assess ovarian response.

The Mare: A Pertinent Model for Human Assisted Reproductive Technologies?

Although there are large differences between horses and humans for reproductive anatomy, follicular dynamics, mono-ovulation, and embryo development kinetics until the blastocyst stage are similar. In contrast to humans, however, horses are seasonal animals and do not have a menstrual cycle. Moreover, horse implantation takes place 30 days later than in humans. In terms of artificial reproduction techniques (ART), oocytes are generally matured in vitro in horses because ovarian stimulation remains inefficient. This allows the collection of oocytes without hormonal treatments. In humans, in vivo matured oocytes are collected after ovarian stimulation. Subsequently, only intra-cytoplasmic sperm injection (ICSI) is performed in horses to produce embryos, whereas both in vitro fertilization and ICSI are applied in humans. Embryos are transferred only as blastocysts in horses. In contrast, four cells to blastocyst stage embryos are transferred in humans. Embryo and oocyte cryopreservation has been mastered in humans, but not completely in horses. Finally, both species share infertility concerns due to ageing and obesity. Thus, reciprocal knowledge could be gained through the comparative study of ART and infertility treatments both in woman and mare, even though the horse could not be used as a single model for human ART.

Validation of the French IVF guidelines during the COVID-19 pandemic.

RESEARCH QUESTION: Is a symptom questionnaire as per the French IVF guidelines adequate for screening patients during the COVID-19 pandemic? DESIGN: Patients planning IVF from June 2020 to February 2021 were included in the study. In compliance with French IVF guidelines, all patients fever-free on the day of oocyte retrieval were screened for risk of COVID-19 by completing a symptom questionnaire after being counselled regarding the importance of a COVID-19-free medical practice. Patients with IVF planned between June and September 2020 only completed the questionnaire (group 1), while those planning IVF after September 2020 also underwent the RT-PCR test for SARS-CoV-2 RNA (group 2). Cycle cancellation rates between groups were compared. Group 1 patients consented for follicular fluid testing for SARS-CoV-2 and an interview after cycle completion to determine COVID-19 exposure during the 6 months before and after retrieval. RESULTS: Cycle cancellation rates for groups 1 and 2 were 0% (0/214) versus 1.4% (8/577), respectively, (P = 0.116). All 183 follicular fluid samples from group 1 were negative for SARS-CoV-2 RNA. Of 171 patients interviewed post-IVF, 16 (93.4%) developed COVID-19 symptoms or a positive real-time PCR (RT-PCR) RT-PCR test, but none within 2 months pre- or post-retrieval. CONCLUSIONS: These results provide reassurance that, consistent with the COVID-19 French IVF guidelines, use of a symptom questionnaire is effective in screening patients planning to undergo IVF. Failure to detect viral RNA in any follicular fluid sample does not negate the possibility that follicular fluid is a viral reservoir. However, the findings provide reassurance that the follicular environment in this study's carefully screened population was COVID-free.

Utilization of in vitro maturation in cases with a FSH receptor mutation.

PURPOSE: To identify the FSH receptor (FSHR) variant and efficacy of in vitro maturation (IVM) in a 28-year-old woman with secondary amenorrhea, primary infertility, and ovarian resistance to FSH, and to analyze the genotype-to-phenotype relationship in cases of FSHR mutation for the development of an IVM algorithm for use in patients with gonadotropin resistance syndrome (GRS). METHODS: Oocytes retrieved after menstruation induction with norethisterone, followed by daily estrogen and an ovulatory trigger, underwent IVM, ICSI, and culture in a time-lapse (TL) incubator. Embryo transfers were performed on day 2, and after thawing on day 5. Genes associated with disorders of sex development were sequenced for both the patient and her parents. All reported cases of FSHR mutation were analyzed to investigate genotype/phenotypic relationships. RESULTS: After ovum pickup, seven of 16 oocytes matured and all fertilized. After unsuccessful day 2 transfer, our patient delivered with a thawed day 5 blastocyst, the sole embryo without abnormal TL phenotypes. Genetic analysis revealed a new composite heterozygous FSHR variant. Analysis of our patient case with published cases of GRS revealed associations among FSHR variant genotype, location on the FSHR, functionality of tested variants, and type of amenorrhea. An algorithm for application of IVM for GRS patients was developed. CONCLUSIONS: We report two novel variants of the FSHR. Although IVM successfully matured some oocytes, only one resulted in an embryo with normal TL phenotypes. We recommend FSHR genetic testing in GRS patients, which will help guide their suitability for IVM.

Is there a link between plasma progesterone 1-2 days before frozen embryo transfers (FET) and ART outcomes in frozen blastocyst transfers?

OBJECTIVE: To study the efficacy of combined administration of subcutaneous and vaginal progesterone for priming frozen blastocysts transfers, looking at progesterone levels and ART outcome. DESIGN: Retrospective study. SETTING PATIENTS: Three hundred and twenty frozen blastocyst transfer cycles conducted in 213 women aged up to 42 years, BMI between 18 and 30 kg/m2, with anatomically normal uterus who underwent frozen embryo transfers (FETs) from February 2019 to December 2019 with a combined luteal-phase support (LPS) associating subcutaneous and vaginal progesterone. Patients with recurrent pregnancy loss (RPL) were excluded. RESULTS: When using combined vaginal and subcutaneous LPS, SPL >10.50 ng/mL in 95% of cases, with a minimum value of 7.02 ng/mL. CPR, OPR, and global miscarriage rates were 38.4%, 30.9%, and 19.5%, respectively. Analyzing results per quartiles, revealed that miscarriage rates were significantly inferior, and IR were higher in the upper two quartiles of serum progesterone (>21.95 ng/mL) on the day before FET, while there was no difference in CPR and OPR. CONCLUSIONS: We report ART outcome of frozen blastocyst transfers performed using a combination of vaginal and subcutaneous progesterone for LPS. ART results were honorable and SPL favorable 1-2 days before FET in 99% of cases.

Genetic analyses of a large cohort of infertile patients with globozoospermia, DPY19L2 still the main actor, GGN confirmed as a guest player.

Globozoospermia is a rare phenotype of primary male infertility inducing the production of round-headed spermatozoa without acrosome. Anomalies of DPY19L2 account for 50-70% of all cases and the entire deletion of the gene is by far the most frequent defect identified. Here, we present a large cohort of 69 patients with 20-100% of globozoospermia. Genetic analyses including multiplex ligation-dependent probe amplification, Sanger sequencing and whole-exome sequencing identified 25 subjects with a homozygous DPY19L2 deletion (36%) and 14 carrying other DPY19L2 defects (20%). Overall, 11 deleterious single-nucleotide variants were identified including eight novel and three already published mutations. Patients with a higher rate of round-headed spermatozoa were more often diagnosed and had a higher proportion of loss of function anomalies, highlighting a good genotype phenotype correlation. No gene defects were identified in patients carrying < 50% of globozoospermia while diagnosis efficiency rose to 77% for patients with > 50% of globozoospermia. In addition, results from whole-exome sequencing were scrutinized for 23 patients with a DPY19L2 negative diagnosis, searching for deleterious variants in the nine other genes described to be associated with globozoospermia in human (C2CD6, C7orf61, CCDC62, CCIN, DNAH17, GGN, PICK1, SPATA16, and ZPBP1). Only one homozygous novel truncating variant was identified in the GGN gene in one patient, confirming the association of GGN with globozoospermia. In view of these results, we propose a novel diagnostic strategy focusing on patients with at least 50% of globozoospermia and based on a classical qualitative PCR to detect DPY19L2 homozygous deletions. In the absence of the latter, we recommend to perform whole-exome sequencing to search for defects in DPY19L2 as well as in the other previously described candidate genes.

Fertility preservation in borderline ovarian tumor patients and survivors.

Borderline ovarian tumors (BOTs) represent around 15% of all epithelial ovarian cancer. Around one third of those patients is under 40 and has not completed childbearing when the tumor is diagnosed. Cancer survivors are more and more concerned about their future fertility since a large proportion of those with BOTs are young. Whatever the tumor stage, information regarding future fertility after treatment and fertility preservation (FP) options must be delivered to all patients before treatment. A multidisciplinary team will discuss and propose personalized treatment and FP strategies. Nowadays, the FP options offered to patients with BOT are the followings: i) minimal invasive conservative surgery, ii) oocyte cryopreservation after controlled ovarian stimulation (COS) or in vitro maturation (IVM) and iii) ovarian tissue cryopreservation. Generally, the most common strategy to preserve future fertility is represented by minimal invasive conservative surgery. However, with the remarkable success and evolution of assisted reproductive technologies (ART) - notably progress and efficiency in COS and oocyte vitrification - have led to offer another potential approach for FP consisting in oocyte cryopreservation. Several COS protocols, such as random start or dual stimulation associating tamoxifen or aromatase inhibitors with gonadotropins provide similar results when compared to standard protocols while providing safety by minimizing the risk of high estrogen exposure. When COS is contraindicated, oocyte cryopreservation can still be possible throw IVM. Even though, oocyte competence after IVM is lower than that obtained after COS. A less used approach is cryopreservation of ovarian tissue, consisting in freezing ovarian cortex fragments for a future thawing and graft. Some concerns and limitations regard the ovarian cortex graft and the risk of reintroducing malignant cells once performed. Nonetheless, the latter it is the only option in prepubertal patients.

Which key performance indicators are optimal to assess clinical management of assisted reproduction cycles?

Like all industries, fertility clinics should identify and follow reference markers of its activity-key performance indicators (KPI)-to allow assisted reproductive technology outcomes to be monitored and compared. Clinical KPIs revolve around following set parameters of the patient population, procedures, and outcome data. Moreover, KPIs should also include identified protocols and standard operating procedures followed in daily practice and should keep track of multiple pregnancy rates, a ruthless confounder of assisted reproductive technology outcomes.

A high level of tetrasomy 9p mosaicism but no clinical manifestations other than moderate oligozoospermia with chromosomally balanced sperm: a case report.

Tetrasomy 9p (ORPHA: 3310) (i(9p)) is a rare chromosomal imbalance. It is characterized by the presence of a supernumerary chromosome incorporating two copies of the short arm of chromosome 9 and is usually present in a mosaic state postnatally. Depending on the level of mosaicism, the phenotype ranges from mild developmental delay to multiple congenital anomalies with severe intellectual disability. Here, we report on a patient diagnosed with i(9p) mosaicism after the recurrent failure of in vitro fertilization. Although the patient's clinical phenotype was normal, the level of mosaicism varied greatly from one tissue to another. A sperm analysis evidenced subnormal spermatogenesis with chromosomally balanced spermatozoa and no risk of transmission to the offspring. Although individuals with i(9p) and no clinical manifestations have rarely been described, the prenatal diagnosis of this abnormality in the absence of ultrasound findings raises a number of questions.

Day 5 versus Day 6 blastocyst transfers: a systematic review and meta-analysis of clinical outcomes.

STUDY QUESTION: Is there a difference in clinical pregnancy and live birth rates (LBRs) between blastocysts developing on Day 5 (D5) and blastocysts developing on Day 6 (D6) following fresh and frozen transfers? SUMMARY ANSWER: D5 blastocyst transfers (BTs) present higher clinical pregnancy and LBRs than D6 in both fresh and frozen transfers. WHAT IS KNOWN ALREADY: BT is increasingly popular in assisted reproductive technology (ART) centers today. To our knowledge, no meta-analysis has focused on clinical outcomes in both fresh and frozen BT. Concerning frozen blastocysts, one meta-analysis in 2010 found no significant difference in pregnancy outcomes between D5 and D6 BT. Since then, ART practices have evolved particularly with the wide use of vitrification, and more articles comparing D5 and D6 BT cycles have been published and described conflicting results. STUDY DESIGN, SIZE, DURATION: Systematic review and meta-analysis of published controlled studies. Searches were conducted from 2005 to February 2018 on MEDLINE and Cochrane Library and from 2005 to May 2017 on EMBASE, Eudract and clinicaltrials.gov, using the following search terms: blastocyst, Day 5, Day 6, pregnancy, implantation, live birth and embryo transfer (ET). PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 47 full-text articles were preselected from 808 references, based on title and abstract and assessed utilizing the Newcastle-Ottowa Quality Assessment Scales. Study selection and data extraction were carried out by two independent reviewers according to Cochrane methods. Random-effect meta-analysis was performed on all data (overall analysis) followed by subgroup analysis (fresh, vitrified/warmed, slow frozen/thawed). MAIN RESULTS AND THE ROLE OF CHANCE: Data from 29 relevant articles were extracted and integrated in the meta-analysis. Meta-analysis of the 23 studies that reported clinical pregnancy rate (CPR) as an outcome, including overall fresh and/or frozen ET cycles, showed a significantly higher CPR following D5 ET compared with D6 ET (risk ratio (RR) = 1.27, 95% CI: 1.15-1.39, P < 0.001). For CPR, calculated subgroup RRs were 2.38 (95% CI: 1.74-3.24, P < 0.001) for fresh BT; 1.27 (95% CI: 1.16-1.39, P < 0.001) for vitrified/warmed BT; and 1.15 (95% CI: 0.93-1.41, P = 0.20) for slow frozen/thawed BT. LBR was also significantly higher after D5 BT (overall RR = 1.50 (95% CI: 1.32-1.69), P < 0.001). The LBR calculated RRs for subgroups were 1.74 (95% CI: 1.37-2.20, P < 0.001) for fresh BT; 1.38 (95% CI: 1.23-1.56, P < 0.001) for vitrified/warmed BT; and 1.44 (95% CI: 0.70-2.96, P = 0.32) for slow frozen/thawed BT. Sensitivity analysis led to similar results and conclusions: CPR and LBR were significantly higher following D5 compared to D6 BT. LIMITATIONS, REASONS FOR CAUTION: The validity of meta-analysis results depends mainly on the quality and the number of the published studies available. Indeed, this meta-analysis included no randomized controlled trial (RCT). Slow frozen/thawed subgroups showed substantial heterogeneity. WIDER IMPLICATIONS OF THE FINDINGS: In regards to the results of this original meta-analysis, ART practitioners should preferably transfer D5 rather than D6 blastocysts in both fresh and frozen cycles. Further RCTs are needed to address the question of whether D6 embryos should be transferred in a fresh or a frozen cycle. STUDY FUNDING/COMPETING INTEREST(S): This work was sponsored by an unrestricted grant from GEDEON RICHTER France. The authors have no competing interests to declare. REGISTRATION NUMBER: CRD42018080151.

New Twists in Ovarian Stimulation and Their Practical Implications.

Ovarian stimulation (OS) has for objective to induce multiple ovulation in order to yield a multiple oocyte harvest and offer multiple embryos available for transfer thereby increasing the efficacy of ART. Originally, the primary risk associated with OS was the occurrence of frank ovarian hyperstimulation syndrome (OHSS), a possibly dreadful-sometime fatal-complication of ART. These fears limited the number of oocytes aimed for during OS in order to curb the risk of OHSS. On the contrary, the meager implantation rates of the early days of ART led to easily transfer multiple embryos in order to achieve acceptable pregnancy rates. Today the perspectives have changed. The advent of antagonist-based OS protocol and the possibility to trigger the ultimate phase of oocyte maturation with GnRH-a has allowed to reduce the risk of OHHS. Conversely, the markedly increased implantation rates of today's ART makes multiple pregnancy a worry that has come in the limelight worldwide, pushing the practice of single embryo transfer (SET).