Impact of Group vs Individual Embryo Culture Strategies on Blastocyst and Clinical Outcomes.

Embryo culture is one of the most important steps in an assisted reproduction laboratory. Embryos can be cultured individually, one embryo per media drop, or in groups, culturing several embryos in the same media drop. Due to the controversy generated on this subject, we wondered which embryo culture method would have the best results in terms of quality and blastocyst formation rate. We designed a prospective randomized study comparing two different embryo culture strategies: group and individual embryo culture. The data were obtained from 830 embryos from 103 egg donation treatments. The zygotes were randomized into two groups: individual culture (group 1) or group culture (group 2). The embryos were cultured in 35-µl drops until day 5 when they were classified morphologically. We observed a significant increase in the blastocyst formation rate and in the usable embryo rate in individual culture on day 5 compared to group culture. However, good embryo quality (A/B blastocysts), implantation, and pregnancy rates were similar regardless of the type of embryo-culture. As a conclusion, individual culture may increase blastocyst formation rate and may benefit embryo quality on day 5. Our results support previous reports suggesting that individual culture could improve embryo development.

Random-start ovarian stimulation in an oocyte donation programme: a large, single-centre, experience.

RESEARCH QUESTION: Do live birth rates differ between recipients matched with donors using conventional ovarian stimulation compared with those using random-start protocols? DESIGN: Retrospective analysis of 891 ovarian stimulations in egg donors (January-December 2018) and clinical outcomes in matched recipients (n = 935). Donors commenced ovarian stimulation on day 1-3 of the menstrual cycle (n = 223) or in the mid/late-follicular (n = 388) or luteal phase (n = 280) under a conventional antagonist protocol. Live birth rate of matched recipients was the main outcome. RESULTS: Duration of stimulation and total gonadotrophin dose were comparable between conventional versus random-start groups. The number of collected eggs were similar (17.6 ± 8.8 versus 17.2 ± 8.5, P = 0.6, respectively). Sub-group analysis showed that stimulation length (10.2 ± 1.8 versus 9.8 ± 1.7 versus 10.4 ± 1.7, P < 0.001) and gonadotrophin consumption (2041.5 ± 645.3 versus 2003.2 ± 647.3 versus 2158.2 ± 685.7 IU, P = 0.01) differed significantly between the conventional, mid/late follicular and luteal phase groups, respectively. In matched recipients receiving fresh oocytes and undergoing fresh embryo transfer, the biochemical pregnancy (63.8% and 63.3%; P = 0.9), clinical pregnancy (54.6% and 56.1%; P = 0.8) and live birth rates (47.7% and 46.6%; P = 0.7) per embryo-transfer were similar between conventional versus random groups. Similar results were obtained in recipients receiving vitrified eggs. Euploidy rate was also comparable. CONCLUSIONS: No notable variations were found in clinical outcomes using oocytes obtained from random-start protocols and those proceeding from conventional ovarian stimulation in oocyte donation treatments. Luteal-phase stimulation seems to require longer stimulation and higher FSH consumption. Random-start stimulation strategy does not impair the potential of the oocyte yield or clinical outcomes in oocyte donation cycles.

Does mRNA COVID-19 vaccination in oocyte donors impact ovarian stimulation parameters or IVF outcomes for recipients?

RESEARCH QUESTION: What is the effect of mRNA severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination in young oocyte donors in terms of ovarian response to stimulation, fertilization rate, embryo development and clinical outcomes in recipients? DESIGN: This retrospective, multicentre cohort study evaluated 115 oocyte donors who had undergone at least two ovarian stimulation protocols (before and after complete SARS-CoV-2 vaccination) between November 2021 and February 2022. Comparisons were made of the primary outcomes of days of stimulation, total dose of gonadotrophins and laboratory performance in ovarian stimulation in oocyte donors before and after vaccination. A total of 136 cycles in matched recipients were analysed as secondary outcomes and, from those, 110 women received a fresh single-embryo transfer, with analysis of biochemical ß-human chorionic gonadotrophin concentrations and rates of clinical pregnancy with heartbeat. RESULTS: Longer stimulation was required in the post-vaccination than pre-vaccination group (10.31 ± 1.5 versus 9.51 ± 1.5 days; P < 0.001) along with higher gonadotrophin consumption (2453.5 ± 740 versus 2235.5 ± 615 IU; P < 0.001) with a similar starting dose of gonadotrophins in both groups. More oocytes were retrieved in the post-vaccination group (16.62 ± 7.1 versus 15.38 ± 7.0; P = 0.02). However, the number of metaphase II (MII) oocytes was similar between groups (pre-vaccination 12.61 ± 5.9 versus post-vaccination 13.01 ± 6.6; P = 0.39) and the ratio of MII/retrieved oocytes favoured the pre-vaccination group (0.83 ± 0.1 versus 0.77 ± 0.2 post-vaccination; P = 0.019). In recipients with a similar number of provided oocytes, the fertilization rate, total number of obtained blastocysts, number of top-quality blastocysts, and rates of biochemical pregnancy and clinical pregnancy with heartbeat were not significantly different between groups. CONCLUSIONS: This study shows no adverse influence of mRNA SARS-CoV-2 vaccination on ovarian response in a young population.

Conventional follicular-phase ovarian stimulation vs. luteal-phase stimulation in suboptimal responders: a randomized controlled trial.

Objective: To compare the oocyte yield between follicular-phase stimulation (FPS) and luteal-phase stimulation (LPS) in suboptimal responders. Design: Prospective, randomized, crossover clinical trial. Patients: Forty-one patients with infertility according to the POSEIDON (Patient-Oriented Strategies Encompassing IndividualizeD Oocyte Number) criteria (1b/2b). Interventions: Crossover study on 2 assigned ovarian stimulations that started randomly in the follicular or luteal phase. The in vitro fertilization cycles were not consecutive but separated in time (45 days to 6 months). The random crossover design ensured that all subjects received the first treatment by chance. Main Outcome Measures: The primary objective was the number of cumulus-oocyte complexes retrieved in each cycle. Secondary objectives were number of metaphase II and fertilized oocytes, additional doses of recombinant follicle-stimulating hormone, and the duration of ovarian stimulation (days). Results: The mean number of cumulus-oocyte complexes retrieved was similar between the FPS and LPS groups (7.5 ± 4.6 vs. 7.0 ± 4.1; 95% confidence interval [CI] for the mean, 5.8-8.7 vs. 5.6-8.3, respectively; the difference between means, -0.5; 95% CI, -1.8 to +1.5). Similarly, the mean number of metaphase II oocytes retrieved was not different between the FPS and LPS groups (5.4 ± 3.6 vs. 5.2 ± 2.8; 95% CI for the mean, 4.2-6.5 vs. 4.3-6.1, respectively; the difference between means, -0.2; 95% CI, -1.2 to +1.1). Moreover, the secondary objectives were similar between FPS and LPS groups. Conclusions: In this study, the oocyte yield in LPS did not increase in suboptimal responders compared with that in FPS when the onset of LPS was separated in time from FPS. Clinical Trial Registration Number: NCT039393990 https://beta.clinicaltrials.gov/study/NCT03939390.

Application of machine learning to predict aneuploidy and mosaicism in embryos from in vitro fertilization cycles.

BACKGROUND: The factors associated with embryo aneuploidy have been extensively studied. Mostly maternal age and to a lesser extent male factor and ovarian stimulation have been related to the occurrence of chromosomal alterations in the embryo. On the other hand, the main factors that may increase the incidence of embryo mosaicism have not yet been established. OBJECTIVE: This study aimed to establish a machine learning model that would allow prediction of aneuploidies and mosaicism in embryos conceived via in vitro fertilization, and thus help to determine which variables are associated with these chromosomal alterations. STUDY DESIGN: The study design was observational and retrospective. A total of 6989 embryos from 2476 cycles of preimplantation genetic testing for aneuploidies were included (January 2013 to December 2020). The trophoectoderm biopsies on day-5, -6, or -7 blastocysts were analyzed by preimplantation genetic testing for aneuploidies (PGT-A). The different maternal, paternal, couple, embryo, and in vitro fertilization cycle characteristics were recorded in a database (22 predictor variables) from which predictive models of embryo aneuploidy and mosaicism were developed; 16 different unsupervised classification machine learning algorithms were used to establish the predictive models. RESULTS: Two different predictive models were performed: one for aneuploidy and the other for mosaicism. The predictor variable was of multiclass type because it included the segmental- and whole-chromosome alteration categories. The best predicting models for both aneuploidies and mosaicism were those obtained from the Random Forest algorithm. The area under ROC curve (AUC) value was 0.792 for the aneuploidy explanatory model and 0.776 for mosaicism. The most important variable in the final aneuploidy model was maternal age, followed by paternal and maternal karyotype and embryo quality. In the predictive model of mosaicism, the most important variable was the technique used in preimplantation genetic testing for aneuploidies and embryo quality, followed by maternal age and day of biopsy. CONCLUSION: It is possible to predict embryo aneuploidy and mosaicism from certain characteristics of the patients and their embryos.

Vitrification does not affect birth weight: lessons from the oocyte donation model.

RESEARCH QUESTION: Is embryo cryopreservation a cause of high birth weight and large for gestational age (LGA) in singletons resulting from vitrified-warmed embryo transfer? DESIGN: Retrospective cohort study evaluating 670 oocyte recipients who underwent fresh (367 cycles) or vitrified-warmed embryo transfer (303 cycles) at Instituto Bernabeu between July 2017 and March 2019. All single blastocyst transfers carried out in an artificial cycle that resulted in a singleton live birth were included. RESULTS: Maternal age (42.21 ± 4.45; 42.79 ± 3.83; P = 0.519), body mass index (23.34 ± 3.69; 23.80 ± 3.78; P = 0.075), gestational age (38.96 ± 1.97; 38.77 ± 2.15; P = 0.207), maternal smoking (10.8%; 13.0%; P = 0.475), gestational diabetes (4.9%; 4.3% P = 0.854), preeclampsia (2.7%; 5.6%; P = 0.074), hypertensive disorders (3.3%; 2.3%; P = 0.494), maternal parity (multiparous 18.5%; 14.5%; P = 0.177) and liveborn gender (female 44.5%; 48.8%; P = 0.276) were not significantly different between fresh or vitrified-warmed groups. Endometrial thickness was significantly higher in the fresh versus vitrified-warmed group (8.83 ± 1.73 versus 8.57 ± 1.59; P = 0.035, respectively). Oocyte donor height was similar between the fresh versus vitrified-warmed group (163.22 ± 5.88 versus 164.27 ± 6.66 cm; P = 0.057, respectively). Mean birth weight was not significantly different (3239.21 ± 550.43; 3224.56 ± 570.83; adjusted P = 0.058). No differences were observed in macrosomia (7.1%; 6.3%; adjusted OR 0.857, 95% CI 0.314 to 2.340, P = 0.764), LGA (6.0%; 6.7%; adjusted OR 0.450, 95% CI 0.176 to 1.149, P = 0.095), pre-term birth (10.9%; 9.0% adjusted P = 0.997), very pre-term birth (0.8%; 1.3%; adjusted P = 1.000), extremely pre-term birth (0%; 1.0%; adjusted P = 0.998); underweight (10.0%; 7.0%; adjusted P = 0.050); very low weight (0.6; 1.1%; adjusted P = 1.000) and small for gestational age (1.9%; 0.7%; adjusted P = 0.974) between fresh or vitrified-warmed groups. CONCLUSION: This study eliminates potential confounders that might influence fetal growth and demonstrates that embryo vitrification and warming procedures do not affect birth weight.

Comparison of the assisted reproductive technology outcomes between conventional IVF and ICSI with donor oocytes in normozoospermic patients.

There is no evidence for the superiority of conventional in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) using donor oocytes. This retrospective descriptive study aimed to compare the outcomes of conventional IVF (n = 506) and ICSI (n = 613) with donor oocytes in (n = 968) normozoospermic patients. Although the fertilization rate was statistically higher in the ICSI group (p < 0.001), conventional IVF provided better results than ICSI with respect to embryo quality (number of grade A embryos, p < 0.001). In addition, we observed more blastocysts in the conventional IVF group (p < 0.001) and more good quality embryos were obtained for cryopreservation compared to ICSI (p < 0.001). Regarding clinical results, there were no statistical significant differences in the positive pregnancy test, clinical pregnancy and clinical miscarriage rates between IVF and ICSI. However, the implantation rate was statistically higher when IVF was performed (50.4% vs. 43.0%, p = 0.031, OR (95% CI): 1.185 (1.050-2.530)). In conclusion, with the use of normozoospermic samples in our oocyte donation programme, IVF offers more embryo efficiency and increased implantation rates than ICSI.

Sperm DNA fragmentation on the day of fertilisation is not associated with assisted reproductive technique outcome independently of gamete quality.

The evaluation of sperm DNA fragmentation has been postulated as a predictive molecular parameter of the semen fertilising potential, as well as the ability to give rise to a healthy embryo and an ongoing pregnancy. However, there are controversial results due to oocyte quality, the use of different measurement techniques and interpretation criteria. Our objective is to investigate if sperm DNA fragmentation on the day of fertilisation influences in vitro fertilisation (IVF) outcome in a prospective double-blind study. Three groups of patients were defined: (i) 68 couples undergoing intracytoplasmic sperm injection (ICSI) due to severe male factor with normal ovarian response (NOR); (ii) 113 couples undergoing conventional in vitro fertilisation (IVF) in our oocyte donation programme due to ovarian failure; and (iii) 150 low ovarian response (LOR) patients undergoing ICSI or IVF. TUNEL assay was performed from an aliquot of each capacitated semen sample to detect DNA fragmentation. There was no relationship between blood serum ß-hCG positive test, clinical pregnancy and first trimester miscarriage with DFI levels in NOR (p = 0.41, p = 0.36, p = 0.40), recipient (p = 0.49, p = 0.99 and p = 0.38) and LOR (p = 0.52, p = 0.20, p = 0.64) groups of patients, respectively. Therefore, ART outcomes are not affected by sperm DNA fragmentation independently of gamete quality.

Impact of the Vaginal and Endometrial Microbiome Pattern on Assisted Reproduction Outcomes.

Uterine microbiota may be involved in reproductive health and disease. This study aims to describe and compare the vaginal and endometrial microbiome patterns between women who became pregnant and women who did not after in vitro fertilization. We also compared the vaginal and endometrial microbiome patterns between women with and without a history of repeated implantation failures (RIF). This pilot prospective cohort study included 48 women presenting to the fertility clinic for IVF from May 2017 to May 2019. Women who achieved clinical pregnancy presented a greater relative abundance of Lactobacillus spp. in their vaginal samples than those who did not (97.69% versus 94.63%; p = 0.027. The alpha and beta diversity of vaginal and endometrial samples were not statistically different between pregnant and non-pregnant women. The Faith alpha diversity index in vaginal samples was lower in women with RIF than those without RIF (p = 0.027). The alpha diversity of the endometrial microbiome was significantly higher in women without RIF (p = 0.021). There were no significant differences in the vaginal and endometrial microbiomes between pregnant and non-pregnant women. The relative abundance of the genera in women with RIF was different from those without RIF. Statistically significant differences in the endometrial microbiome were found between women with and without RIF.

Effect of ovarian stimulation on embryo aneuploidy and mosaicism rate.

There is a high incidence of chromosome abnormalities in human embryos that leads to a failed IVF cycle. Different studies have shown that maternal age is the determining factor in the appearance of chromosomal alterations in the embryo. However, the possible influence of ovarian stimulation on oocyte and embryo aneuploidies and mosaicism is controversial. A retrospective study was carried out in which 835 embryos from 280 couples undergoing reproductive treatment using their oocytes were chromosomally analyzed. A binary logistic regression analysis was performed to evaluate the relationship between different parameters characterizing controlled ovarian stimulation (COS) and the rate of aneuploidy and embryonic mosaicism. The embryo aneuploidy rate showed no association with the use of oral contraceptives, type, total and daily doses of gonadotropins, stimulation protocol type, and drugs used for ovulation trigger (p > 0.05). In contrast, the duration of the ovarian stimulation treatment was correlated with the aneuploidy rate: patients requiring more days of stimulation presented a lower rate of aneuploid embryos (p = 0.015). None of the variables studied showed any association with the rate of embryo mosaicism. However, the duration of COS showed association with the appearance of aneuploidy, suggesting that faster recruitment could be deleterious for those reassuming meiosis, yielding more abnormal karyotype.Abbreviations: IVF: in vitro fertilization; COS: controlled ovarian stimulation; PGT-A: preimplantation genetic test for aneuploidy; hCG: human chorionic gonadotropin; GnRH: gonadotropin-releasing hormone; LH: luteinizing hormone; FSH: follicle-stimulating hormone; NGS: next-generation sequencing; a-CGH: comparative genomic hybridization; TUNEL: Terminal transferase dUTP Nick End Labeling; FISH: fluorescent in situ hybridization.

Consistent results of non-invasive PGT-A of human embryos using two different techniques for chromosomal analysis.

RESEARCH QUESTION: Are discordances in non-invasive preimplantation genetic testing for aneuploidies (niPGT-A) results attributable to the technique used for chromosomal analysis? DESIGN: A prospective blinded study was performed (September 2018 to December 2019). In total 302 chromosomal analyses were performed: 92 trophectoderm PGT-A biopsies and their corresponding spent embryo culture medium (SCM) evaluated by two methods (n = 184), negative controls (n = 8), and trophectoderm and inner cell mass biopsies from trophectoderm-aneuploid embryos (n = 18). Trophectoderm analyses were carried out using Veriseq (Illumina), and SCM was analysed using Veriseq and NICS (Yikon). RESULTS: Genetic results were obtained for 96.8% of trophectoderm samples versus 92.4% for both SCM techniques. The mosaicism rate was higher for SCM regardless of the technique used: 30.4% for SCM-NICS and 28.3% for SCM-Veriseq versus 14.1% for trophectoderm biopsies (P = 0.013, P = 0.031, respectively). No significant differences in diagnostic concordance were seen between the two SCM techniques (74.6% for SCM-NICS versus 72.3% for SCM-Veriseq; P = 0.861). For embryos biopsied on day 6, these rates reached 92.0% and 86.5%, respectively. On reanalysing trophectoderm-aneuploid embryos, the discrepancies were shown to be due to maternal DNA contamination (55.6%; 5/9), embryo mosaicism (22.2%; 2/9) and low resolution in SCM-NICS (11.1%; 1/9) and in both SCM techniques (11.1%; 1/9). CONCLUSIONS: This is the first study evaluating the consistency of different chromosomal analysis techniques for niPGT-A. In conclusion, the diagnostic concordance between PGT-A and niPGT-A seems independent of the technique used. Optimization of culture conditions and medium retrieval provides a potential target to improve the reliability of niPGT-A.

Monozygotic twinning following embryo biopsy at the blastocyst stage.

OBJECTIVE: Monozygotic twinning incidence following preimplantation genetic testing in embryos at cleavage-stage does not appear to increase; however, data regarding the possible impact of the blastocyst-stage preimplantation genetic testing is lacking. We compared the incidence of monozygotic twinning in preimplantation genetic testing cycles performed at the blastocyst-stage, versus cycles without PGT, following single embryo transfer. METHODS: In this retrospective cohort study, we analyzed the incidence of twin pregnancies in patients undergoing intracytoplasmic sperm injection and blastocyst-preimplantation genetic testing (253 cycles), versus a period-matched control population of patients undergoing intracytoplasmic sperm injection and single embryo transfer without preimplantation genetic testing (606 cycles). RESULTS: The overall monozygotic twinning rate was 14/859 (1.6%) per clinical pregnancy. The incidence of zygotic splitting following intracytoplasmic sperm injection and preimplantation genetic testing was 3.5% (95% Confidence interval 1.8%-6.6%) versus 0.8% (95% Confidence interval 0.3%-1.9%) following intracytoplasmic sperm injection without preimplantation sperm injection. After adjusting for potential confounders, preimplantation genetic testing cycles were associated with an increase in the incidence of monozygotic twinning when compared to cycles without embryo biopsy (Odd ratio 3.44, 95% Confidence interval 1.05-11.27, p=0.041). CONCLUSIONS: Our findings indicate that embryo biopsy for preimplantation genetic testing performed at the blastocyst stage is associated to an increase in the incidence of monozygotic twinning. Further validation in larger sample size studies is warranted. Patients undergoing preimplantation genetic testing must receive proper counselling about the potential risks of the technique.

Luteal phase stimulation versus follicular phase stimulation in poor ovarian responders: results of a randomized controlled trial.

BACKGROUND: In young women with poor ovarian response, luteal-phase ovarian stimulation (LPOS) is a potential method for collecting competent oocytes. The aim of this study was to assess the efficacy of LPOS compared with follicular phase ovarian stimulation (FPOS) in young women with poor ovarian response (POR). METHODS: This single-center, prospective, randomized pilot study compared LPOS and FPOS in women with POR fulfilling Bologna criteria who underwent in vitro fertilization at the Instituto Bernabeu. The primary outcome was the number of metaphase II (MII) oocytes obtained by follicular puncture. RESULTS: Sixty women were included in the study, with 27 women completing LPOS and 30 undergoing FPOS. There was no statistically significant difference in the number of MII oocytes obtained between the LPOS group and the FPOS group (2.1 ± 2.0 vs. 2.6 ± 2.2, p = 0.31). Length of stimulation was also similar in both groups (8.35 ± 2.8 vs. 8.15 ± 4.1 days, p = 0.69). Similarly, there was no significant difference in the follicle-stimulating hormone total dose, number of cumulus-oocyte complexes, survival rate, fertilization rate, or cancellation rate between groups. A significantly higher Ovarian Sensitivity Index was observed in the LPOS group versus the FPOS group (0.96 vs. 0.57, p = 0.037). CONCLUSION: LPOS was comparable with FPOS in terms of efficacy and may improve ovarian responsiveness in young women with POR. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02625532; EudraCT identifier: 2015-003856-31.

The use of fluorescence in situ hybridization analysis on sperm: indications to perform and assisted reproduction technology outcomes.

PURPOSE: To determine the consequences of an altered sperm fluorescence in situ hybridization (FISH) result for ART outcomes and the indications for a sperm FISH analysis. METHODS: Data from 439 infertile men were collected. Bivariate analyses were performed to determine the association of men's age, seminal alterations, and sperm FISH indication, with the incidence of X, Y, 13, 18, and 21 sperm chromosomal abnormalities. A multivariate logistic regression analysis was performed to establish the most predictive variables for altered sperm FISH. Results from the IVF/ICSI cycles were collected for 248 out of 439 patients. Two distinct groups were established: 151 couples that used their own oocytes and 97 couples involved in egg donation programs. In both groups, ART outcomes were compared between normal and altered sperm FISH. RESULTS: Teratozoospermia and oligozoospermia were associated with sperm chromosome anomalies (p < 0.05). Indications for sperm FISH analysis with the highest predictability were teratozoospermia, male age, oligozoospermia, and implantation failure (AUC = 0.702). Embryo quality (p = 0.096), pregnancy rate (p = 0.054), and implantation rate (p = 0.089) were higher in own-oocytes couples with normal sperm FISH than in altered sperm FISH couples, although differences were not statistically significant. In donor-oocytes couples, in which high-quality embryos were transferred later than in own-oocytes couples (3.8 vs. 3.0 days), we did not identify differences in the ART outcome between normal and altered sperm FISH couples. In both groups, the possible interference of woman age was negligible. CONCLUSIONS: Sperm FISH is indicated in middle-aged oligoteratozoospermic patients with implantation failures in previous IVF/ICSI cycles. Sperm chromosome anomalies have a moderate detrimental impact on embryo quality, implantation, and pregnancy rates.

Effect of the vaginal microbiome on the pregnancy rate in women receiving assisted reproductive treatment.

PURPOSE: To investigate if the vaginal microbiome influences the IVF outcome. METHODS: Thirty-one patients undergoing assisted reproductive treatment (ART) with own or donated gametes and with cryotransfer of a single euploid blastocyst were recruited for this cohort study. Two vaginal samples were taken during the embryo transfer procedure, just before transferring the embryo. The V3 V4 region of 16S rRNA was used to analyze the vaginal microbiome, and the bioinformatic analysis was performed using QIIME2, Bioconductor Phyloseq, and MicrobiomeAnalyst packages. Alpha diversity was compared between groups according to the result of the pregnancy test. RESULTS: Fourteen (45.2%) patients did not and seventeen (54.8 %) did achieve pregnancy under ART. A greater index of alpha diversity was found in patients who did not achieve pregnancy comparing to those who did, although this difference was not significant (p = 0.088). In the analysis of beta diversity, no statistically significant differences were observed between groups established as per the pregnancy status. Samples from women who achieved pregnancy showed a greater presence of Lactobacillus spp. The cluster analysis identified two main clusters: the first encompassed the genera Lactobacillus, Gardnerella, Clostridium, Staphylococcus, and Dialister, and the second included all other genera. Women who achieved pregnancy were mainly detected microorganisms from the first cluster. CONCLUSIONS: The vaginal microbiome can influence the results of ART. The profiles dominated by Lactobacillus were associated with the achievement of pregnancy, and there was a relationship between the stability of the vaginal microbiome and the achievement of pregnancy.

Implantation potential of mosaic embryos.

Chromosomal mosaicism is a relatively common finding in human IVF embryos. However, the association between mosaicism in trophoectoderm and inner mass cells, the mechanisms involved, and its effects on implantation are far from established. We retrospectively reanalyzed array-CGH results from 1,362 trophoectoderm biopsies. We detected chromosomal mosaicism in 183 blastocysts (13.4%). A decrease in the clinical pregnancy rate when we compared the cycles where only mosaic embryos were transferred (26.9%) vs. euploid embryos were transferred (40.2%) was not statistically different (p = 0.127). Also a tendency to increase the biochemical miscarriage was reported (21.2% mosaic group vs. 12.3% euploid group; p=0.102). Our data suggests that the transfer of some mosaic embryos achieve full term pregnancies. Additional studies are needed to clarify how embryo mosaicism affects the outcomes of the IVF cycles.

Chromosomal polymorphic variants increase aneuploidies in male gametes and embryos.

UNLABELLED: Chromosomal polymorphisms involve heterochromatic regions and occur in the general population. However, previous studies have reported a higher incidence of these variants in infertile patients. The aim of this study was to examine the relationship between polymorphic variants and infertility and their association with aneuploidies in male gametes and embryos. We retrospectively considered 1,551 cytogenetic studies involving infertile patients (study group; n=866) and oocyte/sperm donors as the control group (n=685). We had detected 168 polymorphisms in the study group and 92 in the control group. An increase in the frequency of polymorphic variants was observed among infertile patients (19.4% study group vs. 13.4% control group; P < 0.01). Sperm aneuploidies among 145 infertile men were evaluated by fluorescent in situ hybridization (FISH). The frequency of infertile men with increased rates of sperm aneuploidy was higher among polymorphism carriers. Twenty men showed an abnormal rate of sperm aneuploidy in the carrier group (n=53) vs. 15 in the non-carrier group (n=92) (37.7% vs. 16.3%, respectively; P < 0.01). Finally, aneuploidies in blastocysts (n=301) resulting from donated oocytes were also examined by array comparative genomic hybridization (array-CGH). Significant differences were reported in the embryo aneuploidy rate between female carriers and non-carriers in oocyte donation cycles (50.0% vs. 27.6%; P < 0.001). This study suggests that polymorphic variants have an impact on fertility. Moreover, our results show a relationship between polymorphisms and aneuploidy in spermatozoa and embryos. ABBREVIATIONS: FISH: fluorescent in situ hybridization; CGH: comparative genomic hybridization; ESHRE: European Society of Human Reproduction and Embryology; ASRM: American Society for Reproductive Medicine; RPL: recurrent pregnancy loss; WHO: World Health Organization; ISCN: International System for Human Cytogenetic Nomenclature guidelines; WGA: whole genome amplification; SPSS: Statistical Package for Social Sciences.

Metabolites involved in cellular communication among human cumulus-oocyte-complex and sperm during in vitro fertilization.

BACKGROUND: Fertilization is a key physiological process for the preservation of the species. Consequently, different mechanisms affecting the sperm and the oocyte have been developed to ensure a successful fertilization. Thus, sperm acrosome reaction is necessary for the egg coat penetration and sperm-oolema fusion. Several molecules are able to induce the sperm acrosome reaction; however, this process should be produced coordinately in time and in the space to allow the success of fertilization between gametes. The goal of this study was to analyze the metabolites secreted by cumulus-oocyte-complex (COC) to find out new components that could contribute to the induction of the human sperm acrosome reaction and other physiological processes at the time of gamete interaction and fertilization. METHODS: For the metabolomic analysis, eighteen aliquots of medium were used in each group, containing: a) only COC before insemination and after 3 h of incubation; b) COC and capacitated spermatozoa after insemination and incubated for 16-20 hours; c) only capacitated sperm after 16-20 h in culture and d) only fertilization medium as control. Six patients undergoing assisted reproduction whose male partners provided normozoospermic samples were included in the study. Seventy-two COC were inseminated. RESULTS: The metabolites identified were monoacylglycerol (MAG), lysophosphatidylcholine (LPC) and phytosphingosine (PHS). Analysis by PCR and in silico of the gene expression strongly suggests that the cumulus cells contribute to the formation of the PHS and LPC. CONCLUSIONS: LPC and PHS are secreted by cumulus cells during in vitro fertilization and they could be involved in the induction of human acrosome reaction (AR). The identification of new molecules with a paracrine effect on oocytes, cumulus cells and spermatozoa will provide a better understanding of gamete interaction.

Efecto de la vitrificación de ovocitos humanos sobre la capacidad de unión y el estado acrosomal de espermatozoides humanos / Effect of the vitrification of human oocytes on the binding capacity and acrosome status of human sperm

Conocer los aspectos moleculares que acontecen en el proceso de unión de los espermatozoides humanos a la zona pelúcida (ZP) humana es uno de los grandes retos de la biología de la Reproducción. Por otra parte conocer si el proceso de fecundación puede verse afectado por la criopreservación de los gametos femeninos sigue siendo otra cuestión debatida en la literatura. En base a esto, el objetivo principal de este trabajo fue conocer si la vitrificación ovocitaria puede alterar la interacción de los espermatozoides con el glicocáliz de la ZP y demostrar si la ZP de estos ovocitos pierde la capacidad de inducir la reacción acrosómica en los espermatozoides. Según nuestros resultados el método de vitrificación ovocitaria cerrado (S3) no altera la capacidad de unión de los espermatozoides a la zona pelúcida, ni la capacidad de ésta para inducir la reacción acrosómica.

To know the molecular aspects that occur in the process of human sperm binding to the human zona pellucida (ZP) is one of the great challenges of reproduction biology. Moreover knowing if the fertilization process may be affected by cryopreservation of female gametes is still another issue discussed in the literature. Based on this, the main objective of this study was to determine whether the oocyte vitrification may alter the interaction of sperm with the glycocalyx of ZP and show whether these oocytes lost the ability to induce the acrosome reaction in sperm. According to our results the oocyte closed vitrification method (S3) does not alter the ability of the sperm binding to the zona pellucida, and their ability to induce the acrosome reaction.