The correlation between blastocyst morphological parameters and chromosomal euploidy, aneuploidy and other chromosomal abnormalities following pre-implantation genetic testing-a single center retrospective study

PURPOSE

To examine the association between blastocyst morphology and chromosomal status utilizing pre-implantation genetic testing for aneuploidy (PGT-A).

METHODS

A single-center retrospective cohort study including 169 in-vitro fertilization cycles that underwent PGT-A using Next Generation Sequencing (2017-2022). Blastocysts were morphologically scored based on Gardner and Schoolcraft's criteria. Chromosomal analysis results included: euploid; aneuploid (single or double); segmental; mosaic; and complex (≥ 3 chromosome abnormalities). We examined associations between morphological parameters and chromosomal statuses of biopsied embryos utilizing multivariate logistic regression.

RESULTS

Overall, 855 blastocysts underwent PGT-A (PGT-A alone: N = 804; unaffected PGT for monogenic disease (PGT-M) embryos along with PGT-A: N = 51). Of these, 826 were successfully analyzed, with 321 euploid embryos (38.86%). Various morphological parameters (embryo quality, inner cell mass (ICM), trophectoderm (TE), and expansion stage) were more frequent within the double (n = 72, 8.72%), complex (n = 97, 11.74%), mosaic (n = 139, 16.83%), and segmental aneuploidy (n = 28, 3.39%) groups, with similar associations between different morphological parameters and single aneuploidy (n = 169, 20.46%). Utilizing multivariate logistic regression, higher expansion, embryo quality, and TE and ICM grades, were associated with increased odds of euploidy (versus non-euploidy). Higher expansion was a positive predictor of single versus double aneuploidy (aOR 2.94, 95% CI 1.52-5.56, p = 0.001); and higher ICM grade was a positive predictor of single versus complex aneuploidy (aOR 2.86, 95% CI 1.15-7.12, p = 0.024). No morphological parameter was found to be associated with single versus mosaic aneuploidy.

CONCLUSION

Various morphological parameters are associated with euploidy and different aneuploidy statuses of pre-implantation blastocysts. These findings may aid in the selection of the assumed best chromosomally structured blastocyst for transfer when PGT-A is not performed.

The assessing of clinical relevance of chromosomal microarray analysis in the prenatal diagnosis of fetal growth restriction

OBJECTIVE

Chromosomal variations are known to play a role in the etiology of fetal growth restriction (FGR). Here, we intend to investigate the significance of Chromosomal Microarray Analysis (CMA) in the prenatal diagnosis of definite FGR.

METHOD

182 pregnant women with FGR participated in our study, undergoing CMA to identify chromosomal abnormalities. The cohort was categorized into isolated FGR, FGR with ultrasound soft marker abnormalities, and FGR associated with structural malformations.

RESULTS

The detection rates of PCNVs in FGR with structural anomalies are significantly higher than those in the isolated FGR group and the FGR group with abnormal ultrasound soft markers (19.0% vs. 2.1%, 19% vs. 1.5%; χ²=9.33, p = 0.005). Compared to FGR with a single system malformation, the diagnostic rate of chromosomal variations in FGR with multiple system malformations is markedly increased (60% vs. 6.3%; p = 0.028). Advanced maternal age, early-onset FGR, and severe FGR do not appear to influence the diagnostic rate of chromosomal variations (p > 0.05).

CONCLUSION

Chromosomal variations pose a significant risk in FGR with structural abnormalities, associated with the number of organ systems involved. Notably, advanced maternal age, early-onset FGR, and severe FGR do not affect the diagnostic rate of chromosomal variations in FGR.

Current quantitative methodologies for preimplantation genetic testing frequently misclassify meiotic aneuploidies as mosaic

OBJECTIVE

To study the biological origin of chromosomal abnormalities in embryos reported as mosaic after next-generation sequencing (NGS)-based preimplantation genetic testing for aneuploidy (PGT-A) and to assess the accuracy of current NGS-based methods in distinguishing meiotic from mitotic errors.

DESIGN

Retrospective cohort study utilizing single-nucleotide polymorphism genotyping and karyomapping to identify meiotic aneuploidy in clinically reported mosaic embryos.

SUBJECTS

A total of 146 embryos from 87 patients who underwent in vitro fertilization cycles with NGS-based PGT-A between 2018 and 2020 at The Evewell, London, United Kingdom.

EXPOSURE

Embryos underwent clinical NGS-based PGT-A to identify chromosomal abnormalities. Haplotype-based methods such as single-nucleotide polymorphism-based genotyping and karyomapping were performed on the same amplified material used for NGS-based PGT-A to determine the origin of the chromosomal errors.

MAIN OUTCOME MEASURES

The proportion of embryos reported as mosaic by NGS that contained meiotic errors, and the distribution of meiotic vs. mitotic origin among chromosomal abnormalities identified in the mosaic range.

RESULTS

Of the 141 embryos identified as mosaic after NGS-based PGT-A, 32.6% (n = 46/141) contained an error of meiotic origin, challenging their classification as "mosaic embryos." In total, 191 individual chromosomal errors were reported in the mosaic range by NGS-based PGT-A. Of those, 29.3% (56/191) errors (both below and above the 50% copy number threshold) were found to be of meiotic origin. The majority (94.6%) of meiotic errors were maternal in origin. Embryos with multiple chromosomal abnormalities were significantly more likely to have at least one meiotic error. Higher intermediate copy number values correlated with an increased probability of an error being of meiotic origin.

CONCLUSION

This study presents the first direct evidence that a third of embryos reported as mosaic (both low- and high-level mosaic) by NGS-based PGT-A contain meiotic errors, highlighting the potential misclassification of aneuploid embryos as mosaic by current NGS-based PGT-A methods that cannot accurately distinguishing between meiotic and mitotic errors. Single-nucleotide polymorphism genotyping provides essential information for accurately determining the origin of chromosomal abnormalities and should be integrated with NGS-based copy number analysis to enhance diagnostic accuracy. Further studies are needed to refine mosaicism classification and to better understand its true implications in in vitro fertilization treatment.

Value of PGT-A when only one or two blastocysts are obtained: propensity-score matching and cost-effectiveness study

OBJECTIVE

To compare the effectiveness and cost of in-vitro fertilization (IVF) with or without preimplantation genetic testing for aneuploidy (PGT-A) when only one or two blastocysts are obtained.

METHODS

A dataset was gathered from 1829 patients including 368 non-PGT-A and 1461 PGT-A cycles with one or two blastocysts obtained, between April 2013 and July 2022. Patients were matched 1:1 by propensity-score matching for maternal age, number of metaphase-II oocytes inseminated and number of blastocysts obtained, achieving a database of 242 patients per group. The non-PGT-A and PGT-A groups were compared for differences in live birth rate (LBR) per embryo transfer (ET), cumulative LBR per patient, miscarriage rate (MR) per clinical pregnancy, number of days between oocyte retrieval and conclusion of the IVF cycle (primary outcome), mean expenses incurred at the clinic and incremental cost-effectiveness ratio (ICER).

RESULTS

More than twice as many ETs were conducted in the non-PGT-A group compared with the PGT-A group, yet the cumulative LBR per patient was similar between groups (23.6% (95% CI, 18.5-29.5%) vs 27.3% (95% CI, 21.9-33.4%)). This outcome was achieved with a higher LBR per ET (16.2% (95% CI, 12.6-20.5%) vs 41.5% (95% CI, 33.9-49.4%)) and lower MR per clinical pregnancy (30.1% (95% CI, 21.8-42.6%) vs 13.9% (95% CI, 7.5-24.0%)) in the PGT-A group. The MR per patient was also lower in the PGT-A group (9.5% (95% CI, 6.2-14.1%) vs 4.5% (95% CI, 2.4-8.2%)). The mean duration between oocyte retrieval and IVF cycle conclusion was 131 (95% CI, 113-150) days in the non-PGT-A group vs 74 (95% CI, 61-87) days in the PGT-A group (P < 0.001; power = 99.8%). The ICER of PGT-A for the months saved between oocyte retrieval and conclusion of the IVF cycle was €499 overall, ranging between €170 and €2065 according to the number of blastocysts obtained and/or maternal age. The ICER of PGT-A for prevented miscarriages was €18 968, decreasing to €3525 when calculated among patients aged ≥ 35 years with two blastocysts obtained.

CONCLUSIONS

When conducted in expert IVF clinics for patients indicated for the procedure, PGT-A is clinically valuable even when only one or two blastocysts are obtained. PGT-A reduces the number of ETs and miscarriages while the cumulative LBR per patient remains unaffected, and allows these outcomes to be achieved in a shorter timeframe. The ICER of PGT-A vs non PGT-A decreased as maternal age increased. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

From live birth to live birth: a strong correlation between the outcomes of first and second frozen-thawed euploid blastocyst transfers from sibling oocytes

PURPOSE

To investigate any correlation between the outcomes of the first euploid frozen-thawed blastocyst embryo transfer (FBT) and the subsequent euploid FBT derived from sibling oocytes.

METHODS

This retrospective study analyzed data from 1051 women who underwent preimplantation genetic testing for aneuploidy and had a euploid FBT. Of these patients, 159 underwent a second transfer. The primary outcome was the live birth rate.

RESULTS

Overall, 159 women who underwent a second euploid FBT were categorized into two subgroups depending on the implantation success of the first FBT. Of these patients, 94 (59.1%) belonged to the nonclinical group, signifying a negative result or a biochemical pregnancy. The remaining 65 (40.9%) patients belonged to the clinical group, indicating either a miscarriage or a live birth. In the binary logistic regression analysis, the live birth outcome during the first euploid FBT was a statistically significant and independent predictor of live birth in the subsequent FBT [odds ratio 4.14, 95% confidence interval (1.184-14.531), p < 0.026). Miscarriages, including those that occurred before intracytoplasmic sperm injection and in the first euploid FBT, reduced the live birth rate by approximately 34% (p < 0.027). No significant difference in the miscarriage rate was found between the two subgroups (19.2% (10/52) vs. 25.4% (14/55), p = 0.38).

CONCLUSION

The live birth outcome of the second euploid FBT is mainly determined by the live birth outcome of the first. Miscarriages that occurred before in vitro fertilization negatively affect the live birth outcome.

Preconception carrier screening in couples seeking IVF: exploring the patient perspective

RESEARCH QUESTION

What is the level of understanding, and what are the attitudes and considerations regarding preconception carrier screening (PCS) among couples seeking IVF or intracytoplasmic sperm injection (ICSI)?

DESIGN

A mixed-methods design was used. Nine interviews were conducted with couples or individual partners (n = 16) who had an initial consultation for IVF/ICSI in the 2 years preceding this study. A questionnaire was completed by 115 participants. No actual PCS was offered.

RESULTS

All interviewed couples expressed a positive attitude towards PCS, and over half of the respondents stated that they would pursue or seriously consider pursuing PCS if possible. Some couples falsely believed that PCS could identify a cause for their fertility problems and increase their chance of conceiving. The desire to make an informed reproductive decision was the most important argument in favour of PCS. The primary argument against PCS was the apprehension of being confronted with reproductive dilemmas. The longer the delay to IVF/ICSI treatment required to perform PCS, the more couples would be inclined to decline screening. Participants indicated that they would prefer to receive information about PCS from a medical specialist at an early stage in their IVF/ICSI treatment.

CONCLUSION

Although attitudes towards PCS were generally positive, some concerns were raised about treatment delays and potential reproductive dilemmas, and some couples had misconceptions about the purpose of screening within the context of their IVF/ICSI treatment. These findings highlight the importance of tailoring information and counselling to the specific needs of couples seeking IVF/ICSI.

Time will tell: time-lapse technology and artificial intelligence to set time cut-offs indicating embryo incompetence

STUDY QUESTION

Can more reliable time cut-offs of embryo developmental incompetence be generated by combining time-lapse technology (TLT), artificial intelligence, and preimplantation genetics screening for aneuploidy (PGT-A)?

SUMMARY ANSWER

Embryo developmental incompetence can be better predicted by time cut-offs at multiple developmental stages and for different ranges of maternal age.

WHAT IS KNOWN ALREADY

TLT is instrumental for the continual and undisturbed observation of embryo development. It has produced morphokinetic algorithms aimed at selecting embryos able to generate a viable pregnancy, however, such efforts have had limited success. Regardless, the potential of this technology for improving multiple aspects of the IVF process remains considerable. Specifically, TLT could be harnessed to discriminate developmentally incompetent embryos: i.e. those unable to develop to the blastocyst stage or affected by full-chromosome meiotic aneuploidies. If proven valuable, this application would prevent the non-productive use of such embryos, thereby improving laboratory and clinical efficiency and reducing patient stress and costs due to unnecessary embryo transfer and cryopreservation.

STUDY DESIGN, SIZE, DURATION

The training dataset involved embryos of PGT-A cycles cultured in Embryoscope with a single media (836 euploid and 1179 aneuploid blastocysts and 1874 arrested embryos; 2013-2020). Selection criteria were ejaculated sperm, own (not donated) fresh oocytes, trophectoderm biopsy and comprehensive-chromosome-testing to diagnose uniform aneuploidies. Out-of-sample (30% of training), internal (299 euploid and 490 aneuploid blastocysts and 680 arrested embryos; 2021-2022) and external (97 euploid, 110 aneuploid and 603 untested blastocysts and 514 arrested embryos, 2018 to early 2022) validations were conducted.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A training dataset (70%) was used to define thresholds. Several models were generated by fitting outcomes to each timing (tPNa-t8) and maternal age. ROC curves pinpointed in-sample classification values associated with 95%, 99% and 99.99% true-positive rate for predicting incompetence. These values were integrated with upper limits of maternal age ranges (<35, 35-37, 38-40, 41-42, and >42 years) in logit functions to identify time cut-offs, whose accuracy was tested on the validation datasets through confusion matrices.

MAIN RESULTS AND THE ROLE OF CHANCE

For developmental (in)competence, the best performing (i) tPNa cut-offs were 27.8 hpi (error-rate: 0/743), 32.6 hpi (error rate: 0/934), 26.8 hpi (error rate: 0/1178), 22.9 hpi (error-rate: 1/654, 0.1%) and 17.2 hpi (error rate: 4/423, 0.9%) in the <35, 35-37, 38-40, 41-42, and >42 years groups, respectively; (ii) tPNf cut-offs were 36.7 hpi (error rate: 0/738), 47.9 hpi (error rate: 0/921), 45.6 hpi (error rate: 1/1156, 0.1%), 44.1 hpi (error rate: 0/647) and 41.8 hpi (error rate: 0/417); (iii) t2 cut-offs were 50.9 hpi (error rate: 0/724), 49 hpi (error rate: 0/915), 47.1 hpi (error rate: 0/1146), 45.8 hpi (error rate: 0/636) and 43.9 hpi (error rate: 0/416); (iv) t4 cut-offs were 66.9 hpi (error rate: 0/683), 80.7 hpi (error rate: 0/836), 77.1 hpi (error rate: 0/1063), 74.7 hpi (error rate: 0/590) and 71.2 hpi (error rate: 0/389); and (v) t8 cut-offs were 118.1 hpi (error rate: 0/619), 110.6 hpi (error rate: 0/772), 140 hpi (error rate: 0/969), 135 hpi (error rate: 0/533) and 127.5 hpi (error rate: 0/355). tPNf and t2 showed a significant association with chromosomal (in)competence, also when adjusted for maternal age. Nevertheless, the relevant cut-offs were found to perform less well and were redundant compared with the blastocyst development cut-offs.

LIMITATIONS, REASONS FOR CAUTION

Study limits are its retrospective design and the datasets being unbalanced towards advanced maternal age cases. The potential effects of abnormal cleavage patterns were not assessed. Larger sample sizes and external validations in other clinical settings are warranted.

WIDER IMPLICATIONS OF THE FINDINGS

If confirmed by independent studies, this approach could significantly improve the efficiency of ART, by reducing the workload and patient impacts (extended culture and cleavage stage cryopreservation or transfer) associated with embryos that ultimately are developmentally incompetent and should not be considered for treatment. Pending validation, these data might be applied also in static embryo observation settings.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the participating institutions. The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

ICSI and PGT-A in PCOS phenotype-D patients: a matched case-control study versus idiopathic infertile women

PURPOSE

To assess oocyte competence and embryo chromosomal constitution in phenotype-D PCOS women undergoing ICSI for PGT-A at the blastocyst stage.

METHODS

Retrospective study at a private IVF center. In the period 2013-2021, 58 naïve phenotype-D PCOS women (i.e., oligomenorrhea, ovarian PCO-morphology, and absence of hyperandrogenism) underwent ICSI with ejaculated sperm for PGT-A. These cases were matched to 58 controls selected from 2211 naïve women with idiopathic infertility planned for the same treatment in the same period. The matching variables were age (≈ 36 years), BMI (≈ 22), cumulus oocyte complexes (COCs) retrieved (≈ 21-23), and sperm quality (≈ 43-45% men with all sperm parameters > 5th percentile). The primary outcome was euploid blastocyst rate (EBR) per cohort of inseminated oocytes.

RESULTS

Maturation rates per COCs and euploidy per biopsied blastocysts were similar. PCOS patients with phenotype-D showed higher fertilization per inseminated oocytes and higher blastulation per zygotes. This resulted into a higher EBR per inseminated oocytes and more euploid blastocysts available for transfer, although these differences adjusted for confounders were not significant. The live birth rate per first euploid transfers was comparable, so were all other outcomes considered.

CONCLUSIONS

Oocyte competence was not compromised in phenotype-D PCOS women, while good prognosis idiopathic infertile women might have unknown oocyte issues. In case of repeated failures after intrauterine insemination, a timely referral to IVF might represent an efficient strategy, in line with the "one-and-done" approach fulfilling a family planning perspective. Indeed, 22% of the phenotype-D PCOS women had 2 singleton LBs and 76% had surplus oocytes/euploid blastocysts after achieving ≥ 1 live birth.

A multi-cycle approach via DuoStim is beneficial to treat couples indicated to PGT-M plus PGT-A. A propensity score matching-based case series

OBJECTIVE

To compare DuoStim versus a conventional approach in patients indicated to Preimplantation-Genetic-Testing for both monogenic conditions and aneuploidies (PGT-M + PGT-A).

STUDY DESIGN

Retrospective case-control study. In 5 years, 132 couples indicated to PGT-M + PGT-A who obtained ≤5 blastocysts after a first retrieval were suggested to undergo a second stimulation in the same ovarian cycle. Of them, 55 accepted, while 77 preferred the standard approach. Propensity-Score-Matching method was adopted to produce two matched groups of 41 patients per arm. The primary outcome was the cumulative-live-birth-rate (cLBR) per couple within 1 year from the first oocyte retrieval.

RESULTS

In the DuoStim arm, 100 % of the patients underwent two ovarian stimulations. In the conventional approach group, 85 % discontinued the treatment after a failed first cycle (N = 28/33, 95 %CI:69.1-93.4 %). After DuoStim, 16 couples had ≥ 1 healthy LB (1-year cLBR: 39 %, 95 %CI:25.7-54.3 %),19 % of them delivered 2 healthy babies after singleton pregnancies (N = 3/16, 95 %CI:6.6-43 %) and 68 % have surplus transferable blastocysts (N = 11/16, 95 %CI:44.4-85.8 %). In the control, 9 couples obtained a healthy LB (1-year cLBR: 22 %, 95 %CI:12.0-36.7 %), and only 1 havesurplus transferable blastocysts. Overall, couples opting for DuoStim obtained 3.9 ± 2.5 blastocysts of which 1.2 ± 1.3 transferable, while couples opting for the conventional approach obtained 2.3 ± 2.1 blastocysts of which 0.8 ± 1.0 transferable.

CONCLUSIONS

DuoStim may minimize treatment discontinuation and increase the probability to obtain transferable blastocysts in the studied population. Nevertheless, larger prospective studies are required. Also, the suitability of a threshold set at 5 blastocysts should be further validated.

A WHO 2021-based comprehensive scheme outlining sperm parameters' associations with IVF outcomes in PGT-A cycles

OBJECTIVE

To examine the association between semen parameters, assessed according to World Health Organization (WHO)-2021 criteria, and paternal body mass index (BMI) and age, with embryological and clinical outcomes in ICSI cycles involving preimplantation genetic testing for aneuploidy (PGT-A).

DESIGN

Retrospective study at a private in vitro fertilization (IVF) clinic.

SUBJECTS

3101 couples undergoing 4013 intracytoplasmic sperm injection (ICSI) + PGT-A cycles with own-oocytes (years 2013-2021).

INTERVENTION

We performed trophectoderm biopsy, and comprehensive chromosome testing to report uniform aneuploidies and vitrified-warmed euploid single-blastocyst-transfers. Regression analyses adjusted for relevant confounders were conducted to outline putative associations of semen analysis and characteristics and paternal BMI and age with all embryological/clinical outcomes.

RESULTS

Maternal age was the only significant confounding variable affecting euploidy blastocyst rate (EBR) (primary embryological outcome). When categorized, motility < 5th-percentile (-2.5%, 95%CI -4.9 to -0.2%, p = 0.03), concentration plus morphology < 5th-percentile (-2.7%,95%CI -4.8 to -0.6%, p = 0.01), concentration plus morphology plus motility < 5th-percentile (-4.0%,95%CI -5.5 to -2.6%, p < 0.01), obstructive-azoospermia [OA] (-5.5%,95%CI -9 to -2%, p = 0.02) and non-obstructive azoospermia (NOA) (-5.8%,95%CI -10.9 to -0.6%, p = 0.03) showed significantly lower results compared to all parameters > 5th-percentile. Furthermore, after adjusting for maternal age and the number of metaphase-II-oocytes inseminated, the only significant confounding variable affecting the chance of obtaining ≥ 1 live birth among completed cycles (primary clinical outcome) was basal and post sperm processing motility. When categorized, concentration plus morphology plus motility < 5th-percentile (multivariable-OR: 0.73, 95%CI 0.58-0.93, p = 0.01) and OA (multivariable-OR: 0.47, 95%CI 0.24-0.92, p = 0.03) showed significantly lower chances compared to all parameters > 5th-percentile. Advanced paternal age (defined as > 44 years) was associated only with lower day 5-blastocyst and Gardner's AA-grade (i.e., top quality) blastocyst rates.

CONCLUSIONS

This comprehensive analysis provides IVF professionals with useful figures to counsel infertile couples about their chances of success, taking into account the impact of semen characteristics and paternal BMI and age. These estimates are valuable for personalized decision-making about the most effective reproductive strategies to adopt, especially not underestimating male factor, by improving sperm concentration and motility whenever possible before assisted reproductive technologies.

Exploring the anti-ovarian aging mechanism of He's Yangchao formula: Insights from multi-omics analysis in naturally aged mice

BACKGROUND

The rapid acceleration of female reproductive aging has become a major public health concern. He's Yangchao formula (HSYC), a compound comprising eight herbs, has demonstrated efficacy in enhancing ovarian function. Thus, an in-depth study of its anti-ovarian aging mechanism is required.

PURPOSE

To evaluate the anti-ovarian aging effect of HSYC in naturally aged mice and investigate the underlying mechanism by analyzing the gut microbiota (GM), metabolome, and transcriptome.

METHODS

Young and advanced maternal age (AMA) mice were selected for this study. Hematoxylin and eosin staining, fluorescence staining, western blotting, and qPCR analyses were used to detect the phenotypes associated with ovarian aging. Subsequently, analyses of the GM, transcriptome, and metabolome analyses were performed to explore the potential mechanisms of action of HSYC. Finally, in vivo and in vitro experiments were performed to verify potential therapeutic mechanisms.

RESULTS

HSYC promoted follicular development in AMA mice and ameliorated age-related mitochondrial dysfunction, apoptosis, and defects in DNA damage repair. GM analysis revealed that HSYC treatment significantly increased the abundance of Akkermansia and Turicibacter. Transcriptome and metabolome analyses showed that HSYC might mitigate ovarian aging by regulating metabolic pathways, amino acid metabolism, glutathione metabolism, and the synthesis of pantothenic acid and coenzyme A. Combined transcriptomic and metabolomic analyses identified the glutathione metabolic pathway as the key pathway through which HSYC counteracts ovarian aging. Additional experimental verification confirmed that HSYC upregulated the glutathione metabolic genes GPX8, GSTA1, and GSTA4, increased glutathione-related products (GSH), and reduced ROS levels.

CONCLUSIONS

HSYC exerts beneficial therapeutic effects on ovarian aging by regulating multiple endogenous metabolites, targets, and metabolic pathways, with an emphasis on its anti-ovarian aging effects through the glutathione metabolic pathway. These findings underscore the innovative potential of HSYC in addressing ovarian aging and offer a novel therapeutic approach that targets multiple biological pathways to improve the reproductive health of women with AMA..

The updated understanding of advanced maternal age

The rising rates of pregnancies associated with advanced maternal age (AMA) have created unique challenges for healthcare systems worldwide. The elevated risk of poor maternal outcomes among AMA pregnancies is only partially understood and hotly debated. Specifically, AMA is associated with reduced fertility and an increased incidence of pregnancy complications. Finding a balance between global fertility policy, socioeconomic development and health care optimization ultimately depends on female fertility. Therefore, there is an urgent need to develop technologies and identify effective interventions. Support strategies should include prepregnancy screening, intervention and postpartum maintenance. Although some reviews have considered the relationship between AMA and adverse pregnancy outcomes, no previous work has comprehensively considered the long-term health effects of AMA on mothers. In this review, we will begin by presenting the current knowledge of global health issues associated with AMA and the effects of advanced age on the female reproductive system, endocrine metabolism, and placental function. We will then discuss physiological alterations, pregnancy complications, and long-term health problems caused by AMA.

Mutation of the SUMOylation site of Aurora-B disrupts spindle formation and chromosome alignment in oocytes

Aurora-B is a kinase that regulates spindle assembly and kinetochore-microtubule (KT-MT) attachment during mitosis and meiosis. SUMOylation is involved in the oocyte meiosis regulation through promoting spindle assembly and chromosome segregation, but its substrates to support this function is still unknown. It is reported that Aurora-B is SUMOylated in somatic cells, and SUMOylated Aurora-B contributes the process of mitosis. However, whether Aurora-B is SUMOylated in oocytes and how SUMOylation of Aurora-B impacts its function in oocyte meiosis remain poorly understood. In this study, we report that Aurora-B is modified by SUMOylation in mouse oocytes. The results show that Aurora-B colocalized and interacted with SUMO-2/3 in mouse oocytes, confirming that Aurora-B is modified by SUMO-2/3 in this system. Compared with that in young mice, the protein expression of SUMO-2/3 decreased in the oocytes of aged mice, indicating that SUMOylation might be related to mouse aging. Overexpression of Aurora-B SUMOylation site mutants, Aurora-BK207R and Aurora-BK292R, inhibited Aurora-B recruitment and first polar body extrusion, disrupting localization of gamma tubulin, spindle formation and chromosome alignment in oocytes. The results show that it was related to decreased recruitment of p-HDAC6 which induces the high stability of whole spindle microtubules including the microtubules of both correct and wrong KT-MT attachments though increased acetylation of microtubules. Therefore, our results corroborate the notion that Aurora-B activity is regulated by SUMO-2/3 in oocytes, and that SUMOylated Aurora B plays an important role in spindle formation and chromosome alignment.

Preserving Fertility in People With Rheumatic Diseases

ABSTRACT

Rheumatology patients historically were told they "can't" or "shouldn't" become pregnant. Improved rheumatic diagnostics and treatments have led to decreased morbidity and mortality and increased quality of life resulting in an opportunity to focus on fertility and its preservation. In the same vein as rheumatic disease care, assisted reproductive technology (ART), which includes freezing of egg and sperm as well as in vitro fertilization, has made considerable strides in the recent past. ART is safe for those with rheumatic diseases and has comparable outcomes to the general public, but may take additional effort due to optimal timing, rheumatic medications, and other nuances. In a specialty that treats chronic inflammatory diagnoses using teratogens and gonadotoxins, it is important to address family building desires with patients so their goals can be met.Rheumatologists have little knowledge of ART and how it impacts or applies to their patients; however, patients want their rheumatologist to be the source of knowledge for this information (Arthritis Rheumatol. 2022;74:suppl 9). Many barriers to ART exist and will be explored, with the financial burden being paramount (Glob J Health Sci. 6;1:181-191). Future efforts to examine the future fertility of rheumatology patients in an era of biologics and "treat-to-target" are needed to better understand who would most benefit from this costly and not without risk medical treatment. Given the changing landscape of financial support for ART due to insurance mandates, rheumatologists should not modify counseling based on the anticipated ability of patients to afford care. Preservation should also be broached with patients without partners and those from the LGBTQAI+ community. In addition to expanding the education of rheumatologists regarding this topic and its incorporation into clinical care, advocacy for ART access and insurance coverage is a much-needed future direction.

Basal FSH values are positively associated with aneuploidy incidence in pre-advanced maternal age (AMA) but not in AMA patients

PURPOSE

To assess the impact of maternal age on the association between maternal basal FSH and aneuploidy.

METHODS

A retrospective study including data from 1749 blastocysts diagnosed as euploid or aneuploid by PGT-A (preimplantation genetic testing for aneuploidy). Aneuploidy incidence was compared between embryos from mothers with high vs. low basal FSH levels (above and below the group median, respectively) in total, pre-AMA (advanced maternal age; < 35 years, 198 embryos) and AMA (≥ 35 years, 1551 embryos) patient groups, separately. To control for the interference of potentially confounding variables, the association between aneuploidy and high basal FSH levels was assessed by multivariate logistic analysis in overall, pre-AMA and AMA patient groups.

RESULTS

Overall, aneuploidy rate was 9% higher (p = 0.02) in embryos from patients with high basal FSH (63.7%) compared to those with low basal FSH (58.4%). In the pre-AMA subgroup, aneuploidy incidence was 35% higher (p = 0.04) in embryos from patients with high basal FSH (53.5%) compared to those with low basal FSH (39.4%). Differently, aneuploidy occurrence did not vary between embryos from AMA patients with low (61.0%) and high (64.8%) basal FSH (p = 0.12). The multivariate analysis revealed that, in pre-AMA embryos, the association between aneuploidy occurrence and high basal FSH is independent of potential confounding variables (p = 0.04).

CONCLUSION

Maternal basal FSH values are associated with embryo aneuploidy in pre-AMA but not in AMA patients. The present findings suggest that basal FSH is a useful parameter to assess aneuploidy risk in pre-AMA patients and reinforce the hypothesis that excessive FSH signalling can predispose to oocyte meiotic errors.

Preconception carrier screening and preimplantation genetic testing in the infertility management

BACKGROUND

Genetic testing serves as a valuable element of reproductive care, applicable at various stages of the reproductive journey: (i) before pregnancy, when a couple's genetic reproductive risk can be evaluated; (ii) before embryo implantation, as part of in vitro fertilization (IVF) treatment, to ascertain several inherited or de novo genetic/chromosomal diseases of the embryo before transfer; (iii) during the prenatal period, to assess the genetic costitution of the fetus. Preconception carrier screening (CS) is a genetic test typically performed on couples planning a pregnancy. The primary purpose of CS is to identify couples at-risk of conceiving a child affected by a severe genetic disorder with autosomal recessive or X-linked inheritance. Detection of high reproductive risk through CS allows prospective parents to be informed of their predisposition and improve reproductive decision-making. These include undergoing IVF with preimplantation genetic testing (PGT) or donor gametes, prenatal diagnosis, adoption, remaining childless, taking no actions. Both the presence of the affected gene (PGT-M) and chromosomal status (PGT-A) of the embryo can be comprehensively assessed through modern approaches.

OBJECTIVES

We provide a review of CS and PGT applications to equip healthcare providers with up-to-date information regarding their opportunities and complexities.

RESULTS AND DISCUSSION

The use of CS and PGT is currently considered the most effective intervention for avoiding both an affected pregnancy whilst using autologous gametes in couples with known increased risk, and chromosomal abnormalities. As our understanding in the genetic component in pathological conditions increases, the number of tested disorders will expand, offering a more thorough assessment of one's genetic inheritance. Nevertheless, implementation and development in this field must be accompanied by scientific and ethical considerations to ensure this approach serves the best long-term interests of individuals and society, promoting justice and autonomy and preserving parenthood and the healthcare system.

CONCLUSION

The combination of CS and PGT aligns with principles of personalized medicine by offering reproductive care tailored to the individual's genetic makeup.

Ongoing pregnancy rates in single euploid frozen embryo transfers remain unaffected by female age: a retrospective study

RESEARCH QUESTION

Is female age a significant factor in the likelihood of an ongoing pregnancy in single euploid frozen embryo transfers (FET)?

DESIGN

Retrospective study of 1923 single euploid FET cycles in 1464 women, either in a natural cycle or a hormone replacement therapy cycle. The primary outcome was the ongoing pregnancy rate (OPR).

RESULTS

There were 990 (51.48%) ongoing pregnancies among 1923 included transfers. The OPR were 51.4%, 49.1%, 53.3% and 52.3% for women aged ≤35, >35-≤37, >37-≤40 and >40 years at oocyte retrieval (OCR), without a significant trend for decreasing OPR (P = 0.679). No significant differences in female age at embryo transfer (P = 0.609) and female age at OCR (P = 0.816) were found between the groups (ongoing pregnancy versus no pregnancy or miscarriage). Women who received good-quality embryos (P < 0.001), had a lower body mass index (BMI) (P < 0.001), had achieved at least one pregnancy previously (P < 0.001), and underwent natural cycle endometrial preparation (P < 0.001) were more likely to achieve an ongoing pregnancy. Multivariable regression analysis (adjusted for BMI, embryo quality and endometrial preparation) did not show a significant effect of female age at OCR on achieving an ongoing pregnancy. Compared with women aged ≤35 years, none of the age groups had significantly higher or lower OPR. A multinomial regression analysis showed that BMI, embryo quality and endometrial preparation were associated with miscarriage/no pregnancy versus ongoing pregnancy (P = 0.001, 0.001 and 0.001, respectively). Female age had no significant association with either outcome.

CONCLUSIONS

Female age in itself does not have a substantial impact on the OPR in single euploid FET cycles, but the OPR is impacted significantly by embryo quality, BMI, previous parity, and a natural cycle endometrial preparation protocol.

The Molecular Mechanism of Aurora-B Regulating Kinetochore-Microtubule Attachment in Mitosis and Oocyte Meiosis

BACKGROUND

Aurora kinase B (Aurora-B), a member of the chromosomal passenger complex, is involved in correcting kinetochore-microtubule (KT-MT) attachment errors and regulating sister chromatid condensation and cytoplasmic division during mitosis.

SUMMARY

However, few reviews have discussed its mechanism in oocyte meiosis and the differences between its role in mitosis and meiosis. Therefore, in this review, we summarize the localization, recruitment, activation, and functions of Aurora-B in mitosis and oocyte meiosis. The accurate regulation of Aurora-B is essential for ensuring accurate chromosomal segregation and correct KT-MT attachments. Aurora-B regulates the stability of KT-MT attachments by competing with cyclin-dependent kinase 1 to control the phosphorylation of the SILK and RVSF motifs on kinetochore scaffold 1 and by competing with protein phosphatase 1 to influence the phosphorylation of NDC80 which is the substrate of Aurora-B. In addition, Aurora-B regulates the spindle assembly checkpoint by promoting the recruitment and activation of mitotic arrest deficient 2.

KEY MESSAGES

This review provides a theoretical foundation for elucidating the mechanism of cell division and understanding oocyte chromosomal aneuploidy.

Ex ovo omnia-why don't we know more about egg quality via imaging?

Determining egg quality is the foremost challenge in assisted reproductive technology (ART). Although extensive advances have been made in multiple areas of ART over the last 40 years, oocyte quality assessment tools have not much evolved beyond standard morphological observation. The oocyte not only delivers half of the nuclear genetic material and all of the mitochondrial DNA to an embryo but also provides complete developmental support during embryonic growth. Oocyte mitochondrial numbers far exceed those of any somatic cell, yet little work has been done to evaluate the mitochondrial bioenergetics of an oocyte. Current standard oocyte assessment in in vitro fertilization (IVF) centers include the observation of oocytes and their surrounding cell complex (cumulus cells) via stereomicroscope or inverted microscope, which is largely primitive. Additional oocyte assessments include polar body grading and polarized light meiotic spindle imaging. However, the evidence regarding the aforementioned methods of oocyte quality assessment and IVF outcomes is contradictory and non-reproducible. High-resolution microscopy techniques have also been implemented in animal and human models with promising outcomes. The current era of oocyte imaging continues to evolve with discoveries in artificial intelligence models of oocyte morphology selection albeit at a slow rate. In this review, the past, current, and future oocyte imaging techniques will be examined with the goal of drawing attention to the gap which limits our ability to assess oocytes in real time. The implications of improved oocyte imaging techniques on patients undergoing IVF will be discussed as well as the need to develop point of care oocyte assessment testing in IVF labs.

The impact of maternal age on aneuploidy in oocytes: Reproductive consequences, molecular mechanisms, and future directions

Age-related aneuploidy in human oocytes is a major factor contributing to decreased fertility and adverse reproductive outcomes. As females age, their oocytes are more prone to meiotic chromosome segregation errors, leading primarily to aneuploidy. Elevated aneuploidy rates have also been observed in oocytes from very young, prepubertal conceptions. A key barrier to developing effective treatments for age-related oocyte aneuploidy is our incomplete understanding of the molecular mechanisms involved. The challenge is becoming increasingly critical as more people choose to delay childbearing, a trend that has significant societal implications. In this review, we summarize current knowledge regarding the process of oocyte meiosis and folliculogenesis, highlighting the relationship between age and chromosomal aberrations in oocytes and embryos, and integrate proposed mechanisms of age-related meiotic disturbances across structural, protein, and genomic levels. Our goal is to spur new research directions and therapeutic avenues.

Etiologic evaluation and pregnancy outcomes of fetal growth restriction (FGR) associated with structural malformations

This study aimed to evaluate the etiology and pregnancy outcomes of fetuses underwent invasive prenatal diagnosis for fetal growth restriction (FGR) accompanied by structural malformations. Data from 130 pregnancies referred for prenatal diagnosis for FGR accompanied by structural malformations were obtained between July 2011 and July 2023. Traditional karyotyping was conducted for all the subjects. A total of 37 (28.5%) cases of chromosomal abnormalities were detected by karyotyping, including 30 cases of numerical anomalies and seven cases of unbalanced structural anomalies. Trisomy 18 was the most common abnormalities, accounting for 51.4%, significantly higher than any other chromosomal abnormality. The cohort was predominantly comprised of early-onset FGR (88.5%) compared to late-onset FGR (11.5%). The incidences of chromosomal abnormalities in this two groups were 29.6% (34/115) and 20.0% (3/15), respectively (p > 0.05). The majority (74.6%, 97/130) of the cohort were affected by a single system malformation, with chromosomal abnormalities found in 19.6% (19/97) of cases. In pregnancies of structural malformations involving two and multiple systems, the frequencies were 56.5% (13/23), and 50.0% (5/10), respectively. Single nucleotide polymorphism array (SNP array) was performed in parallel for 65 cases, revealing additional 7.7% cases of copy number variants (CNVs) compared to karyotyping. Polymerase chain reaction (PCR) was used for detection of cytomegalovirus (CMV) DNA in 92 cases. All fetuses with FGR associated with two or more system malformations were either terminated or stillborn, irrespective of chromosomal aberrations. Conversely, 71.8% of pregnancies with a single-system malformation and normal genetic testing results resulted in live births. Furthermore, two (2.2%) cases tested positive for CMV DNA, leading to one termination and one case of serious developmental disorder after birth. Our study suggests that structural malformations associated with FGR are more likely to affect a single organ system. When multiple systems are involved, the incidence of chromosomal abnormalities and termination rates are notably high. We advocate for the use of CMA and CMV DNA examinations in FGR cases undergo invasive prenatal diagnosis, as these tests can provide valuable insights for etiological exploration and pregnancy management guidance.

How should the best human embryo in vitro be? Current and future challenges for embryo selection

In-vitro fertilization (IVF) aims at overcoming the causes of infertility and lead to a healthy live birth. To maximize IVF efficiency, it is critical to identify and transfer the most competent embryo within a cohort produced by a couple during a cycle. Conventional static embryo morphological assessment involves sequential observations under a light microscope at specific timepoints. The introduction of time-lapse technology enhanced morphological evaluation via the continuous monitoring of embryo preimplantation in vitro development, thereby unveiling features otherwise undetectable via multiple static assessments. Although an association exists, blastocyst morphology poorly predicts chromosomal competence. In fact, the only reliable approach currently available to diagnose the embryonic karyotype is trophectoderm biopsy and comprehensive chromosome testing to assess non-mosaic aneuploidies, namely preimplantation genetic testing for aneuploidies (PGT-A). Lately, the focus is shifting towards the fine-tuning of non-invasive technologies, such as "omic" analyses of waste products of IVF (e.g., spent culture media) and/or artificial intelligence-powered morphologic/morphodynamic evaluations. This review summarizes the main tools currently available to assess (or predict) embryo developmental, chromosomal, and reproductive competence, their strengths, the limitations, and the most probable future challenges.

Preconception Non-criteria Antiphospholipid Antibodies and Risk of Subsequent Early Pregnancy Loss: a Retrospective Study

The aim of this study was to investigate the subsequent early pregnancy outcomes in women positive for non-criteria antiphospholipid antibodies (NC-aPLs) before pregnancy. A total of 273 patients who had experienced sporadic or recurrent pregnancy loss and had been screened for 13 NC-aPLs at preconception were recruited in this study from September 2019 to February 2022. Serum levels of NC-aPLs were measured by ELISA using specific kits. The primary outcome was early pregnancy loss, and the secondary outcomes were biochemical pregnancy, clinically confirmed pregnancy loss, and ongoing pregnancy. Among these subjects, 56 patients had one previous pregnancy loss, and 217 had recurrent pregnancy loss (RPL). The NC-aPLs (+) and NC-aPLs (-) groups had similar rates of early pregnancy loss (EPL) after adjustment, regardless of the number of positive NC-aPLs (aOR = 1.054, 95% CI 0.602-1.846). Other outcomes were comparable in both groups, including the rates of biochemical pregnancy (aOR = 1.344, 95% CI 0.427-4.236), clinically confirmed pregnancy loss (aOR = 0.744, 95% CI 0.236-2.344), and ongoing pregnancy (aOR = 0.949, 95% CI 0.542-1.660). Based on sensitivity analysis, the NC-aPLs (+) were not associated with adverse early pregnancy outcomes in women with RPL. Furthermore, the difference in gestational weeks of pregnancy loss between the two groups was also insignificant. This study found no evidence linking preconception NC-aPL positivity to early pregnancy outcomes but offers a reference for future research to clarify NC-aPLs' potential clinical impact.

Oocyte competence is comparable between progestin primed ovarian stimulation with Norethisterone acetate (NETA-PPOS) and GnRH-antagonist protocols: A matched case-control study in PGT-A cycles

OBJECTIVE

To outline oocyte competence after progestin primed ovarian stimulation with Norethisterone acetate (NETA-PPOS) compared to conventional GnRH-antagonist protocol.

STUDY DESIGN

Retrospective matched case-control study involving advanced-maternal-age women undergoing ICSI with PGT-A. 89 NETA-PPOS were matched with 178 control patients based on maternal age and ovarian reserve biomarkers. Both groups underwent recombinant-FSH OS with GnRH-agonist ovulation trigger and collected ≥1 MII. In the study group, NETA (10 mg/day) was administered orally starting from day2 of the menstrual cycle. Euploid blastocyst rate per cohort of metaphase-II oocytes (EBR per MII) was the primary outcome. All other embryological and clinical outcomes were reported. Gestational age, birthweight and length were also assessed.

RESULTS

The EBR per MII was comparable among PPOS and control (13.9 % ± 19.3 % versus 13.3 % ± 17.9 %; the sample size allowed to exclude up to a 10 % difference). Blastocysts morphology and developmental rate were similar. No difference was reported for all clinical outcomes among the 61 and 107 vitrified-warmed euploid single blastocyst transfers respectively conducted. The cumulative live birth delivery rate per concluded cycles was also comparable (24.7 % versus 21.9 %). Neonatal outcomes were analogous.

CONCLUSIONS

Oocyte competence after NETA-PPOS and standard OS is comparable. This evidence is reassuring and, because of its lower cost and possibly higher patients' compliance, supports PPOS administration whenever the patients are indicated to freeze-all (e.g., fertility preservation, PGT-A, oocyte donation). More data are required about follicle recruitment, oocyte yield, gestational and perinatal outcomes. Randomized-controlled-trials are advisable to confirm our evidence.

Genetic evaluation for twin pregnancies using karyotyping and single nucleotide polymorphism array analysis

The study aimed to assess chromosomal abnormalities in twin pregnancies using karyotyping and SNP array analysis. The research involved 530 twin pregnancies from two prenatal diagnosis centers between October 2012 and October 2022. Two types of twin pregnancies were considered: monochorionic diamniotic (MCDA) and dichorionic diamniotic (DCDA), with a total of 177 MCDA and 353 DCDA cases. Chromosomal abnormalities were examined based on chorionic and amniotic sac properties and clinical indications. Among 42 twin pregnancies, 50 fetuses showed chromosomal abnormalities by karyotyping, with 35 cases of aneuploidy in DCDA and 10 in MCDA. Trisomy 21 was the most common aberration, affecting 15 fetuses in DCDA and 4 in MCDA. The rate of discordant karyotypes in MCDA and DCDA groups was 1.1% and 8.8%, respectively. Ultrasound abnormalities and advanced maternal age were frequent indications (55.3% and 39.2%, respectively). Aneuploidy frequencies in DCDA and MCDA pregnancies with advanced maternal age were 10.6% and 4.5%. Cardiac defects and increased nuchal translucency were common anomalies, with higher incidences of chromosomal abnormalities in DCDA (12.5% and 6.9%) and MCDA groups (23.5% and 3.7%). SNP array identified 1.6% clinically significant copy number variants in DCDA fetuses with ultrasound abnormalities, while no significant CNVs were found in MCDA pregnancies. Chromosomal aneuploidies were the primary abnormalities in twin pregnancies, with detectable abnormalities and clinically significant CNVs more likely in DCDA pregnancies, especially those with ultrasound abnormalities.

The mosaic embryo: what it means for the doctor and the patient

INTRODUCTION

Mosaic embryos are embryos that on preimplantation genetic analysis are found to be composed of euploid and aneuploid cells. Although most of these embryos do not implant when transferred into the uterus following IVF treatment, some may implant and are capable of giving rise to babies.

EVIDENCE ACQUISITION

There is currently an increasing number of reports of live births following the transfer of mosaic embryos. Compared to euploid, mosaic embryos have lower implantation rates and higher rates of miscarriage, and occasionally aneuploid component persists. However, their outcome is better than that obtained after the transfer of embryos consisting entirely of aneuploid cells. After implantation, the ability to develop into a full-term pregnancy is influenced by the amount and type of chromosomal mosaicism present in a mosaic embryo. Nowadays many experts in the reproductive field consider mosaic transfers as an option when no euploid embryos are available. Genetic counseling is an important part of educating patients about the likelihood of having a pregnancy with healthy baby but also on the risk that mosaicism could persist and result in liveborn with chromosomal abnormality. Each situation needs to be assessed on a case-by-case basis and counseled accordingly.

EVIDENCE SYNTHESIS

So far, the transfers of 2155 mosaic embryos have been documented and 440 live births resulting in healthy babies have been reported. In addition, in the literature to date, there are 6 cases in which embryonic mosaicism persisted.

CONCLUSIONS

In conclusion, the available data indicate that mosaic embryos have the potential to implant and develop into healthy babies, albeit with lower success rates than euploids. Further clinical outcomes should be collected to better establish a refined ranking of embryos to transfer.

A homozygous stop codon in HORMAD2 in a patient with recurrent digynic triploid miscarriage

BACKGROUND

Recurrent miscarriage (RM) affects 1% to 5% of couples trying to conceive. Despite extensive clinical and laboratory testing, half of the RM cases remain unexplained. We report the genetic analysis of a couple with eight miscarriages and the search for their potential genetic etiology.

METHODS

Short tandem repeat (STR) markers, single nucleotide polymorphic (SNP) microarray, and human DNA methylation microarray were used to analyze the genotypes of two miscarriages. Exomes sequencing was performed on DNA from the two partners and identified variants were validated by Sanger sequencing.

RESULTS

STR marker genotyping demonstrated that the two available miscarriages are triploid digynic and resulted from the failure of Meiosis II. SNP microarray analysis revealed an additional Meiosis I abnormality that is the segregation of the two maternal homologous chromosomes in one triploid miscarriage. Whole-exome sequencing on DNA from the two partners identified candidate variants only in the female partner in two genes with roles in female reproduction, a missense in EIF4ENIF1 (OMIM 607445) and a stop gain in HORMAD2 (OMIM 618842). EIF4ENIF1 is a eukaryotic translation initiation factor 4E nuclear import factor required for the oocyte germinal vesicle breakdown, and HORMAD2 is part of the synaptonemal complex that was hypothesized to act as a checkpoint mechanism to eliminate oocytes with asynapsis during meiotic prophase I in mice.

CONCLUSION

While both genes may contribute to the phenotype, the Meiosis I abnormalities in the conceptions favor the causal role of HORMAD2 in the etiology of RM in this couple. This report illustrates the importance of comprehensively analyzing the products of conception to guide the search for the genetic causation of RM.

Implicit bias in diagnosing mosaicism amongst preimplantation genetic testing providers: results from a multicenter study of 36 395 blastocysts

STUDY QUESTION

Does the diagnosis of mosaicism affect ploidy rates across different providers offering preimplantation genetic testing for aneuploidies (PGT-A)?

SUMMARY ANSWER

Our analysis of 36 395 blastocyst biopsies across eight genetic testing laboratories revealed that euploidy rates were significantly higher in providers reporting low rates of mosaicism.

WHAT IS KNOWN ALREADY

Diagnoses consistent with chromosomal mosaicism have emerged as a third category of possible embryo ploidy outcomes following PGT-A. However, in the era of mosaicism, embryo selection has become increasingly complex. Biological, technical, analytical, and clinical complexities in interpreting such results have led to substantial variability in mosaicism rates across PGT-A providers and clinics. Critically, it remains unknown whether these differences impact the number of euploid embryos available for transfer. Ultimately, this may significantly affect clinical outcomes, with important implications for PGT-A patients.

STUDY DESIGN, SIZE, DURATION

In this international, multicenter cohort study, we reviewed 36 395 consecutive PGT-A results, obtained from 10 035 patients across 11 867 treatment cycles, conducted between October 2015 and October 2021. A total of 17 IVF centers, across eight PGT-A providers, five countries and three continents participated in the study. All blastocysts were tested using trophectoderm biopsy and next-generation sequencing. Both autologous and donation cycles were assessed. Cycles using preimplantation genetic testing for structural rearrangements were excluded from the analysis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The PGT-A providers were randomly categorized (A to H). Providers B, C, D, E, F, G, and H all reported mosaicism, whereas Provider A reported embryos as either euploid or aneuploid. Ploidy rates were analyzed using multilevel mixed linear regression. Analyses were adjusted for maternal age, paternal age, oocyte source, number of embryos biopsied, day of biopsy, and PGT-A provider, as appropriate. We compared associations between genetic testing providers and PGT-A outcomes, including the number of chromosomally normal (euploid) embryos determined to be suitable for transfer.

MAIN RESULTS AND THE ROLE OF CHANCE

The mean maternal age (±SD) across all providers was 36.2 (±5.2). Our findings reveal a strong association between PGT-A provider and the diagnosis of euploidy and mosaicism. Amongst the seven providers that reported mosaicism, the rates varied from 3.1% to 25.0%. After adjusting for confounders, we observed a significant difference in the likelihood of diagnosing mosaicism across providers (P < 0.001), ranging from 6.5% (95% CI: 5.2-7.4%) for Provider B to 35.6% (95% CI: 32.6-38.7%) for Provider E. Notably, adjusted euploidy rates were highest for providers that reported the lowest rates of mosaicism (Provider B: euploidy, 55.7% (95% CI: 54.1-57.4%), mosaicism, 6.5% (95% CI: 5.2-7.4%); Provider H: euploidy, 44.5% (95% CI: 43.6-45.4%), mosaicism, 9.9% (95% CI: 9.2-10.6%)); and Provider D: euploidy, 43.8% (95% CI: 39.2-48.4%), mosaicism, 11.0% (95% CI: 7.5-14.5%)). Moreover, the overall chance of having at least one euploid blastocyst available for transfer was significantly higher when mosaicism was not reported, when we compared Provider A to all other providers (OR = 1.30, 95% CI: 1.13-1.50). Differences in diagnosing and interpreting mosaic results across PGT-A laboratories raise further concerns regarding the accuracy and relevance of mosaicism predictions. While we confirmed equivalent clinical outcomes following the transfer of mosaic and euploid blastocysts, we found that a significant proportion of mosaic embryos are not used for IVF treatment.

LIMITATIONS, REASONS FOR CAUTION

Due to the retrospective nature of the study, associations can be ascertained, however, causality cannot be established. Certain parameters such as blastocyst grade were not available in the dataset. Furthermore, certain platform-related and clinic-specific factors may not be readily quantifiable or explicitly captured in our dataset. As such, a full elucidation of all potential confounders accounting for variability may not be possible.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings highlight the strong need for standardization and quality assurance in the industry. The decision not to transfer mosaic embryos may ultimately reduce the chance of success of a PGT-A cycle by limiting the pool of available embryos. Until we can be certain that mosaic diagnoses accurately reflect biological variability, reporting mosaicism warrants utmost caution. A prudent approach is imperative, as it may determine the difference between success or failure for some patients.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Torres Quevedo Grant, awarded to M.P. (PTQ2019-010494) by the Spanish State Research Agency, Ministry of Science and Innovation, Spain. M.P., L.B., A.R.L., A.L.R.d.C.L., N.P.P., M.P., D.S., F.A., A.P., B.M., L.D., F.V.M., D.S., M.R., E.P.d.l.B., A.R., and R.V. have no competing interests to declare. B.L., R.M., and J.A.O. are full time employees of IB Biotech, the genetics company of the Instituto Bernabeu group, which performs preimplantation genetic testing. M.G. is a full time employee of Novagen, the genetics company of Cegyr, which performs preimplantation genetic testing.

TRIAL REGISTRATION NUMBER

N/A.

Aneuploidy in oocytes from women of advanced maternal age: analysis of the causal meiotic errors and impact on embryo development

STUDY QUESTION

In oocytes of advanced maternal age (AMA) women, what are the mechanisms leading to aneuploidy and what is the association of aneuploidy with embryo development?

SUMMARY ANSWER

Known chromosome segregation errors such as precocious separation of sister chromatids explained 90.4% of abnormal chromosome copy numbers in polar bodies (PBs), underlying impaired embryo development.

WHAT IS KNOWN ALREADY

Meiotic chromosomal aneuploidies in oocytes correlate with AMA (>35 years) and can affect over half of oocytes in this age group. This underlies the rationale for PB biopsy as a form of early preimplantation genetic testing for aneuploidy (PGT-A), as performed in the 'ESHRE STudy into the Evaluation of oocyte Euploidy by Microarray analysis' (ESTEEM) randomized controlled trial (RCT). So far, chromosome analysis of oocytes and PBs has shown that precocious separation of sister chromatids (PSSC), Meiosis II (MII) non-disjunction (ND), and reverse segregation (RS) are the main mechanisms leading to aneuploidy in oocytes.

STUDY DESIGN, SIZE, DURATION

Data were sourced from the ESTEEM study, a multicentre RCT from seven European centres to assess the clinical utility of PGT-A on PBs using array comparative genomic hybridization (aCGH) in patients of AMA (36-40 years). This included data on the chromosome complement in PB pairs (PGT-A group), and on embryo morphology in a subset of embryos, up to Day 6 post-insemination, from both the intervention (PB biopsy and PGT-A) and control groups.

PARTICIPANTS/MATERIALS, SETTING, METHODS

ESTEEM recruited 396 AMA patients: 205 in the intervention group and 191 in the control group. Complete genetic data from 693 PB pairs were analysed. Additionally, the morphology from 1034 embryos generated from fertilized oocytes (two pronuclei) in the PB biopsy group and 1082 in the control group were used for statistical analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Overall, 461/693 PB pairs showed abnormal segregation in 1162/10 810 chromosomes. The main observed abnormal segregations were compatible with PSSC in Meiosis I (MI) (n = 568/1162; 48.9%), ND of chromatids in MII or RS (n = 417/1162; 35.9%), and less frequently ND in MI (n = 65/1162; 5.6%). For 112 chromosomes (112/1162; 9.6%), we observed a chromosome copy number in the first PB (PB1) and second PB (PB2) that is not explained by any of the known mechanisms causing aneuploidy in oocytes. We observed that embryos in the PGT-A arm of the RCT did not have a significantly different morphology between 2 and 6 days post-insemination compared to the control group, indicating that PB biopsy did not affect embryo quality. Following age-adjusted multilevel mixed-effect ordinal logistic regression models performed for each embryo evaluation day, aneuploidy was associated with a decrease in embryo quality on Day 3 (adjusted odds ratio (aOR) 0.62, 95% CI 0.43-0.90), Day 4 (aOR 0.15, 95% CI 0.06-0.39), and Day 5 (aOR 0.28, 95% CI 0.14-0.58).

LIMITATIONS, REASON FOR CAUTION

RS cannot be distinguished from normal segregation or MII ND using aCGH. The observed segregations were based on the detected copy number of PB1 and PB2 only and were not confirmed by the analysis of embryos. The embryo morphology assessment was static and single observer.

WIDER IMPLICATIONS OF THE FINDINGS

Our finding of frequent unexplained chromosome copy numbers in PBs indicates that our knowledge of the mechanisms causing aneuploidy in oocytes is incomplete. It challenges the dogma that aneuploidy in oocytes is exclusively caused by mis-segregation of chromosomes during MI and MII.

STUDY FUNDING/COMPETING INTEREST(S)

Data were mined from a study funded by ESHRE. Illumina provided microarrays and other consumables necessary for aCGH testing of PBs. None of the authors have competing interests.

TRIAL REGISTRATION NUMBER

Data were mined from the ESTEEM study (ClinicalTrials.gov Identifier NCT01532284).

Epigenetic aging of mammalian gametes

The process of aging refers to physiological changes that occur to an organism as time progresses and involves changes to DNA, proteins, metabolism, cells, and organs. Like the rest of the cells in the body, gametes age, and it is well established that there is a decline in reproductive capabilities in females and males with aging. One of the major pathways known to be involved in aging is epigenetic changes. The epigenome is the multitude of chemical modifications performed on DNA and chromatin that affect the ability of chromatin to be transcribed. In this review, we explore the effects of aging on female and male gametes with a focus on the epigenetic changes that occur in gametes throughout aging. Quality decline in oocytes occurs at a relatively early age. Epigenetic changes constitute an important part of oocyte aging. DNA methylation is reduced with age, along with reduced expression of DNA methyltransferases (DNMTs). Histone deacetylases (HDAC) expression is also reduced, and a loss of heterochromatin marks occurs with age. As a consequence of heterochromatin loss, retrotransposon expression is elevated, and aged oocytes suffer from DNA damage. In sperm, aging affects sperm number, motility and fecundity, and epigenetic changes may constitute a part of this process. 5 methyl-cytosine (5mC) methylation is elevated in sperm from aged men, but methylation on Long interspersed nuclear elements (LINE) elements is reduced. Di and trimethylation of histone 3 lysine 9 (H3K9me2/3) is reduced in sperm from aged men and trimethylation of histone 3 lysine 27 (H3K27me3) is elevated. The protamine makeup of sperm from aged men is also changed, with reduced protamine expression and a misbalanced ratio between protamine proteins protamine P1 and protamine P2. The study of epigenetic reproductive aging is recently gaining interest. The current status of the field suggests that many aspects of gamete epigenetic aging are still open for investigation. The clinical applications of these investigations have far-reaching consequences for fertility and sociological human behavior.

From oocytes to a live birth: Are we improving the biological efficiency?

OBJECTIVE(S)

The objectives of our study were to investigate the live birth rate (LBR) per oocyte retrieved during in vitro fertilization, in patients who had used all their embryos and to extrapolate the LBR in patients with remaining frozen embryos by calculating the expected LBR from these embryos.

DESIGN

A retrospective cohort study.

SETTING

A single academically affiliated fertility clinic.

PATIENT(S)

Autologous in vitro fertilization cycles from January 2014 to December 2020. Data on the number of oocytes retrieved, number of embryos obtained and transferred (at cleavage or blastocyst-stage), use of preimplantation genetic testing for aneuploidy (PGT-A), and number of live births were obtained. The expected LBR was estimated in patients with remaining frozen embryos according to nationally reported Society for Assisted Reproductive Technology LBR data.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Live birth rate per oocyte retrieved.

RESULT(S)

A total of 12,717 patients met the inclusion criteria and underwent a total of 20,677 oocyte retrievals which yielded a total of 248,004 oocytes and 57,268 embryos (fresh and frozen). In patients who had fully utilized all their embryos the LBR per oocyte was 2.82% (ranging from 11.3% aged <35 years to 1.2% aged >42 years). Stratification of the population based on PGT-A utilization yielded similar results (with PGT-A: 2.88% and without PGT-A: 2.79%). When stratified by the Society for Assisted Reproductive Technology age groups, the addition of PGT-A in patients aged 35-37 and 38-40 years yielded higher LBR per oocyte compared with patients who did not add PGT-A (P<.05). In patients with remaining frozen embryos who had added PGT-A, the projected LBR per oocyte was 8.34%. Use of PGT-A in patients aged <35 and 35-37 years decreased LBR per oocyte (P<.001 and P=.03, respectively) but improved LBR per oocyte in patients aged 38-40 and 41-42 years (P=.006 and P=.005, respectively). Poisson regression analysis demonstrated an age threshold of 38.5, below which PGT-A lowers LBR per oocyte compared with no PGT-A.

CONCLUSION(S)

Despite clinical and scientific advances in Assisted Reproductive Technology, with the current protocols of ovarian stimulation, the LBR per oocyte remains low reflecting a biological barrier that has yet to be overcome. Overall, the addition of PGT-A did not demonstrate improved outcomes.

Impact of having surplus blastocysts cryopreserved on the ongoing pregnancy rate following a fresh transfer

PURPOSE

This study aimed to investigate whether a surplus of vitrified blastocysts correlated with ongoing pregnancy by analyzing the clinical outcomes of fresh transfer cycles with/without a surplus of vitrified blastocysts.

METHODS

This was a retrospective analysis carried out in the Reproductive Medicine Center of Guizhou Medical University Affiliated Hospital between January 2020 and December 2021. Overall, 2482 fresh embryo transfer cycles were included in this study, including 1731 cycles with a surplus of vitrified blastocysts (group A) and 751 cycles with no surplus of vitrified blastocysts (group B). The clinical outcomes of fresh embryo transfer cycles were analyzed and compared between the two groups.

RESULTS

In total, the clinical pregnancy rate (CPR) and ongoing pregnancy rate (OPR) after fresh transfer in group A were significantly higher than those in group B (59% vs. 34.1%, p < .001; 51.9% vs. 27.8%, p < .001, respectively). Moreover, the miscarriage rate was significantly lower in group A when compared to that in group B (10.8% vs. 16.8%, p = .008). When grouped by either female age or the number of good-quality embryos transferred, the same trends for CPR and OPR were seen in all subgroups. After adjusting for potential confounding factors in multivariate analysis, a surplus of vitrified blastocysts remained significantly associated with a higher OPR (OR: 1.52; 95% CI:1.21-1.92).

CONCLUSION

Ongoing pregnancy outcome increases significantly in fresh transfer cycle with a surplus of vitrified blastocysts.

Advanced maternal age leads to changes within the insulin/IGF system and lipid metabolism in the reproductive tract and preimplantation embryo: insights from the rabbit model

Reproductive potential in women declines with age. The impact of ageing on embryo-maternal interactions is still unclear. Rabbits were used as a reproductive model to investigate maternal age-related alterations in reproductive organs and embryos on Day 6 of pregnancy. Blood, ovaries, endometrium, and blastocysts from young (16-20 weeks) and advanced maternal age phase (>108 weeks, old) rabbits were analysed at the mRNA and protein levels to investigate the insulin-like growth factor (IGF) system, lipid metabolism, and stress defence system. Older rabbits had lower numbers of embryos at Day 6 of pregnancy. Plasma insulin and IGF levels were reduced, which was accompanied by paracrine regulation of IGFs and their receptors in ovaries and endometrium. Embryos adapted to hormonal changes as indicated by reduced embryonic IGF1 and 2 levels. Aged reproductive organs increased energy generation from the degradation of fatty acids, leading to higher oxidative stress. Stress markers, including catalase, superoxide dismutase 2, and receptor for advanced glycation end products were elevated in ovaries and endometrium from aged rabbits. Embryonic fatty acid uptake and β-oxidation were increased in both embryonic compartments (embryoblast and trophoblast) in old rabbits, associated with minor changes in the oxidative and glycative stress defence systems. In summary, the insulin/IGF system, lipid metabolism, and stress defence were dysregulated in reproductive tissues of older rabbits, which is consistent with changes in embryonic metabolism and stress defence. These data highlight the crucial influence of maternal age on uterine adaptability and embryo development.

Preimplantation Genetic Testing for Genetic Diseases: Limits and Review of Current Literature

Preimplantation genetic testing (PGT) has emerged as a revolutionary technique in the field of reproductive medicine, allowing for the selection and transfer of healthy embryos, thus reducing the risk of transmitting genetic diseases. However, despite remarkable advancements, the implementation of PGT faces a series of limitations and challenges that require careful consideration. This review aims to foster a comprehensive reflection on the constraints of preimplantation genetic diagnosis, encouraging a broader discussion about its utility and implications. The objective is to inform and guide medical professionals, patients, and society overall in the conscious and responsible adoption of this innovative technology, taking into account its potential benefits and the ethical and practical challenges that it presents.

Embryo Culture Medium Has No Impact on Mosaicism Rates: a Sibling Oocyte Study

Human embryos cultured in vitro can contain two or more cytogenetically distinct cell lineages known as "chromosomal mosaicism". Since mosaicism is produced by mitotic errors after fertilization occurs, culture conditions might contribute to mosaicism origins. Many studies demonstrated that euploidy rates are not affected by culture media; however, whether oocytes cultured under continuous culture media (CCM) or sequential culture media (SCM) has a higher risk of mosaicism occurring remains unsolved. Therefore, this study aims to determine whether mosaicism rates differ when sibling oocytes are cultured in CCM or SCM. A single center observational study was performed including 6072 sibling oocytes. Mature oocytes (MII) were inseminated and cultured in CCM (n = 3,194) or SCM (n = 2,359) until blastocyst stage for trophectoderm (TE) biopsy on day (D) 5, D6, or D7 for preimplantation genetic testing analysis with a semi-automated next-generation sequencing. Mosaicism was classified as low (30-50%) or high (50-80%) based on the percentage of abnormal cells constitution detected in TE samples. As a result, 426 women with a mean age of 34.7 ± 6.4 years were included in the study. Fertilization rates were comparable between CCM and SCM (74.0% vs 72.0%, p = 0.091). Although total blastulation rate and usable blastocyst rate (biopsied blastocysts) were significantly higher in CCM than SCM (75.3 % vs. 70.3%, p < 0.001 and 58.0% vs. 54.5%, p = 0.026), euploidy rates did not differ significantly (45.2% vs. 45.7%, p = 0.810, respectively). Mosaicism rate was not significantly different for blastocysts cultured in CCM or SCM (4.7% vs. 5.1%, p = 0.650), neither the proportion of low or high mosaic rates (3.7% vs. 4.4%, p = 0.353 and 1.0% vs. 0.7%, p = 0.355, respectively). Hence, it was concluded that CCM or SCM does not have an impact on mosaicism rate of embryos cultured until the blastocyst stage.

Meiotic Cell Cycle Progression in Mouse Oocytes: Role of Cyclins

All eukaryotic cells, including oocytes, utilize an engine called cyclin-dependent kinase (Cdk) to drive the cell cycle. Cdks are activated by a co-factor called cyclin, which regulates their activity. The key Cdk-cyclin complex that regulates the oocyte cell cycle is known as Cdk1-cyclin B1. Recent studies have elucidated the roles of other cyclins, such as B2, B3, A2, and O, in oocyte cell cycle regulation. This review aims to discuss the recently discovered roles of various cyclins in mouse oocyte cell cycle regulation in accordance with the sequential progression of the cell cycle. In addition, this review addresses the translation and degradation of cyclins to modulate the activity of Cdks. Overall, the literature indicates that each cyclin performs unique and redundant functions at various stages of the cell cycle, while their expression and degradation are tightly regulated. Taken together, this review provides new insights into the regulatory role and function of cyclins in oocyte cell cycle progression.

The association between the number of oocytes retrieved and cumulative live birth rate in different female age strata

To evaluate the association between the number of oocytes retrieved and cumulative live birth rate (CLBR) in different female age strata. 17,931 women undergoing their first IVF/ICSI-ET cycle in the Sir Run Run Shaw Hospital of Zhejiang University were grouped by age (A: ≤ 35 years; B: ≥ 36 years) as well as the number of oocytes retrieved (a: ≤ 5; b:6-9; c:10-14; d: ≥ 15). Multivariate regression analysis was performed to assess the OR of CLBR for the variable 'age' and 'number of oocytes retrieved'. The group ≥ 36 years exhibited lower cumulative pregnancy rates (CPRs) and cumulative live birth rates (CLBRs), which are proportional to the number of oocytes retrieved but opposite to increasing age. Multivariate logistic regression analysis revealed that the age and number of oocytes retrieved remain significant independent predictive factors (P < 0.001). Age and number of oocytes retrieved are two independent factors affecting the CLBR. The discrepancy of the minimum number of oocytes retrieved for patients with different ages to achieve ideal CLBR is instructive for clinical practice. The practice of controlling the stimulation dose is feasible for patients ≤ 35 years who can achieve over 60% CLBR once the number of oocytes obtained is more than 6. However, additional stimulation cycles and accumulation of embryos are necessary for elderly group especially those ≥ 38 years old who need more than 14 oocytes to obtain higher live birth rate.

Association between duration of progesterone supplementation and clinical outcomes in artificial frozen-thawed embryo transfer cycles

Objective

The administration of progesterone before transfer in hormone replacement treatment (HRT) is crucial for the clinical outcomes of frozen-thawed embryo transfer (FET), but the optimal duration of progesterone remains controversial. This study aimed to investigate the effect of the duration of progesterone administration on the clinical outcomes of FET cycles.

Methods

This prospective cohort study included 353 artificial FET cycles conducted at a reproductive medicine center between April and October 2021. The FET cycles were stratified into four groups based on the duration of progesterone supplementation before the procedure and the embryonic development stage: group P3 (73 patients) received intramuscular progesterone for 3 days and group P4 (87 patients) for 4 days before Day 3 frozen embryo transfer, group P5 (70 patients) for 5 days and group P6 (123 patients) for 6 days before frozen blastocyst transfer. This trial was performed using one or two vitrified embryo(s) when the endometrial thickness reached 7 mm after estrogen supplementation in an artificial cycle. The primary outcome was clinical pregnancy, and secondary outcomes included biochemical pregnancy, implantation, early pregnancy loss, and live births.

Results

There were no significant differences in the demographic and clinical characteristics between the groups. No significant difference was observed in the clinical pregnancy rates between groups: 23/73 (31.5%) in group P3 vs 28/87 (32.2%) in group P4 (P = 0.927). Compared to group P5 (41/70, 58.6%), the clinical pregnancy rate was not significantly different in group P6 (77/123, 62.6%, P = 0.753). There was no significant difference in the implantation rates between groups: 33/136 (24.3%) in group P3 vs 34/166 (20.5%) in group P4 (P = 0.431), and 62/133 (46.6%) in group P5 vs 107/231 (46.3%) in group P6 (P = 0.956). The duration of progesterone supplementation (mean: 3.5 ± 0.5 days; range:3-4 days) before Day 3 frozen embryo transfer did not impact clinical pregnancy (odds ratio [OR] 1.048; 95% confidence interval [CI], 0.518-2.119). The duration of progesterone administration (mean: 5.6 ± 0.5 days; range:5-6 days) before frozen blastocyst transfer may not affect clinical pregnancy (OR 1.339; 95% CI, 0.717-2.497).

Conclusion

There may be no significant correlation between the duration of progesterone supplementation and pregnancy outcomes in artificial FET cycles, although the clinical pregnancy rate was higher when progesterone supplementation was extended for one day before FET.

Near-infrared fluorophore IR-61 improves the quality of oocytes in aged mice via mitochondrial protection

Maternal aging is associated with a decline in oocyte quality, which leads to the decreased fertility. Therefore, developing approaches to reduce aging-induced deterioration of oocyte quality in older women is important. Near-infrared cell protector-61 (IR-61), a novel heptamethine cyanine dye, has the potential for antioxidant effects. In this study, we found that IR-61 can accumulate in the ovaries and improved ovarian function of naturally aged mice; it also increased the oocyte maturation rate and quality by maintaining the integrity of the spindle/chromosomal structure and reducing the aneuploidy rate. In addition, the embryonic developmental competence of aged oocytes was improved. Finally, RNA-sequencing analysis indicated that IR-61 might perform the beneficial effects on aged oocytes by regulating mitochondrial function, this was confirmed by immunofluorescence analysis of mitochondrial distribution and reactive oxygen species. Taken together, our findings demonstrate that IR-61 supplementation in vivo can increase oocyte quality and protect oocytes from aging-induced mitochondrial dysfunction, and thus could improve the fertility of older women and efficiency of assisted reproductive technology.

Population monitoring of trisomy 21: problems and approaches

Trisomy 21 (Down syndrome) is the most common autosomal aneuploidy among newborns. About 90% result from meiotic nondisjunction during oogenesis, which occurs around conception, when also the most profound epigenetic modifications take place. Thus, maternal meiosis is an error prone process with an extreme sensitivity to endogenous factors, as exemplified by maternal age. This contrasts with the missing acceptance of causal exogenous factors. The proof of an environmental agent is a great challenge, both with respect to ascertainment bias, determination of time and dosage of exposure, as well as registration of the relevant individual health data affecting the birth prevalence. Based on a few exemplary epidemiological studies the feasibility of trisomy 21 monitoring is illustrated. In the nearer future the methodical premises will be clearly improved, both due to the establishment of electronic health registers and to the introduction of non-invasive prenatal tests. Down syndrome is a sentinel phenotype, presumably also with regard to other congenital anomalies. Thus, monitoring of trisomy 21 offers new chances for risk avoidance and preventive measures, but also for basic research concerning identification of relevant genomic variants involved in chromosomal nondisjunction.

Alpha-ketoglutarate supplementation ameliorates ovarian reserve and oocyte quality decline with aging in mice

Assisted reproductive technology is widely accepted as an effective treatment to improve female fertility, but the decline of aging oocyte quality remains an important factor in the decrease of female fecundity. However, the effective strategies for improving oocyte aging are still not well understood. In the study, we demonstrated that ROS content and abnormal spindle proportion were increased and mitochondrial membrane potential was decreased in aging oocytes. However, supplementation of α-ketoglutarate (α-KG), an immediate metabolite in the tricarboxylic acid cycle (TCA), for 4 months to aging mice, significantly increased the ovarian reserve showed by more follicle numbers observed. In addition, the oocyte quality was significantly improved, as demonstrated by reduced fragmentation rate and decreased reactive oxygen species (ROS) levels, in addition to a lower rate of abnormal spindle assembly, thereby improving the mitochondrial membrane potential. Consistent with the in vivo data, α-KG administration also improved the post-ovulated aging oocyte quality and early embryonic development by improving mitochondrial functions and reducing ROS accumulation and abnormal spindle assembly. Our data revealed that α-KG supplementation might be an effective strategy to improve the quality of aging oocytes in vivo or in vitro.

Maternal age affects pronuclear and chromatin dynamics, morula compaction and cell polarity, and blastulation of human embryos

STUDY QUESTION

Does maternal ageing impact early and late morphokinetic and cellular processes of human blastocyst formation?

SUMMARY ANSWER

Maternal ageing significantly affects pronuclear size and intra- and extra-nuclear dynamics during fertilization, dysregulates cell polarity during compaction, and reduces blastocoel expansion.

WHAT IS KNOWN ALREADY

In ART, advanced maternal age (AMA) affects oocyte yield, fertilization, and overall developmental competence. However, with the exception of chromosome segregation errors occurring during oocyte meiosis, the molecular and biochemical mechanisms responsible for AMA-related subfertility and reduced embryo developmental competence remain unclear. In particular, studies reporting morphokinetics and cellular alterations during the fertilization and pre-implantation period in women of AMA remain limited.

STUDY DESIGN, SIZE, DURATION

A total of 2058 fertilized oocytes were stratified by maternal age according to the Society for Assisted Reproductive Technology classification (<35, 35-37, 38-40, 41-42, and >42 years) and retrospectively analysed. AMA effects were assessed in relation to: embryo morphokinetics and morphological alterations; and the presence and distribution of cell polarity markers-Yes-associated protein (YAP) and protein kinase C-ζ (PKC-ζ)-involved in blastocyst morphogenesis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 1050 cycles from 1050 patients met the inclusion criteria and were analysed. Microinjected oocytes were assessed using a time-lapse culture system. Immature oocytes at oocyte retrieval and mature oocytes not suitable for time-lapse monitoring, owing to an excess of residual corona cells or inadequate orientation for correct observation, were not analysed. Phenomena relevant to meiotic resumption, pronuclear dynamics, cytoplasmic/cortical modifications, cleavage patterns and embryo quality were annotated and compared among groups. Furthermore, 20 human embryos donated for research by consenting couples were used for immunofluorescence.

MAIN RESULTS AND THE ROLE OF CHANCE

Static microscopic observation revealed that blastocyst formation and expansion were impaired in the 41-42 and >42-year groups (P < 0.0001). The morphological grades of the inner cell mass and trophectoderm were poorer in the >42-year group than those in the <35-year group (P = 0.0022 and P < 0.0001, respectively). Time-lapse microscopic observation revealed a reduction in nucleolus precursor body alignment in female pronuclei in the 41-42 and >42-year groups (P = 0.0010). Female pronuclear area decreased and asynchronous pronuclear breakdown increased in the >42-year group (P = 0.0027 and P < 0.0122, respectively). Developmental speed at cleavage stage, incidence of irregularity of first cleavage, type and duration of blastomere movement, and number of multinucleated cells were comparable among age groups. Delayed embryonic compaction and an increased number of extruded blastomeres were observed in the >42-year group (P = 0.0002 and P = 0.0047, respectively). Blastulation and blastocyst expansion were also delayed in the 41-42 and >42-year groups (P < 0.0001 for both). YAP positivity rate in the outer cells of morulae and embryo PKC-ζ immunoflourescence decreased in the >42-year group (P < 0.0001 for both).

LIMITATIONS, REASONS FOR CAUTION

At the cellular level, the investigation was limited to cell polarity markers. Cell components of other developmental pathways should be studied in relation to AMA.

WIDER IMPLICATIONS OF THE FINDINGS

The study indicates that maternal ageing affects the key functions of embryo morphogenesis, irrespective of the well-established influence on the fidelity of oocyte meiosis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the participating institutions. The authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Pre-meiotic deletion of PEX5 causes spermatogenesis failure and infertility in mice

Peroxisomes are involved in the regulation of various pathological processes. Peroxisomal biogenesis factor 5 (PEX5), which plays an essential role in peroxisomal biogenesis, is critical for reactive oxygen species (ROS) accumulation. However, its underlying functions in spermatogenesis have not yet been identified. Pex5 was deleted by crossing Stra8-Cre mice with Pex5^flox/flox mice before the onset of meiosis. The morphology of testes and epididymides, spermatogenesis function, and fertility in both wild type (WT) and Pex5^-/- mice were analysed by haematoxylin and eosin (HE) and immunofluorescent staining. Mechanism of PEX5 affecting peroxisomes and spermatogenesis were validated by Western blot and transmission electron microscopy (TEM). Transcriptome RNA sequencing (RNA-seq) was used to profile the dysregulated genes in testes from WT and Pex5^-/- mice on postnatal day (P) 35. The adult Pex5 knockout male mice were completely sterile with no mature sperm production. Loss of Pex5 in spermatocytes resulted in multinucleated giant cell formation, meiotic arrest, abnormal tubulin expression, and deformed acrosome formation. Furthermore, Pex5 deletion led to delayed DNA double-strand break repair and improper crossover at the pachytene stage. Impaired peroxisome function in Pex5 knockout mice induced ROS redundancy, which in turn led to an increase in germ cell apoptosis and a decline in autophagy. Pex5 regulates ROS during meiosis and is essential for spermatogenesis and male fertility in mice.

Variation of Female Pronucleus Reveals Oocyte or Embryo Chromosomal Copy Number Variations

The characteristics of the human pronuclei (PNs), which exist 16-22 h after fertilization, appear to serve as good indicators to evaluate the quality of human oocyte and embryo, and may reflect the status of female and male chromosome composition. Here, a quantitative PN measurement method that is generated by applying expert experience combined with deep learning from large annotated datasets is reported. After mathematic reconstruction of PNs, significant differences are obtained in chromosome-normal rate and chromosomal small errors such as copy number variants by comparing the size of the reconstructive female PN. After integrating the whole procedure of PN dynamics and adjusting for errors that occur during PN identification, the results are robust. Notably, all positive prediction results are obtained from the female propositus population. Thus, the size of female PNs may mirror the internal quality of the chromosomal integrity of the oocyte. Embryos that develop from zygotes with larger female PNs may have a reduced risk of copy number variations.

Prediction of risk factors for first trimester pregnancy loss in frozen-thawed good-quality embryo transfer cycles using machine learning algorithms

PURPOSE

Can the risk factors that cause first trimester pregnancy loss in good-quality frozen-thawed embryo transfer (FET) cycles be predicted using machine learning algorithms?

METHODS

This is a retrospective cohort study conducted at Sisli Memorial Hospital, ART and Reproductive Genetics Center, between January 2011 and May 2021. A total of 3805 good-quality FET cycles were included in the study. First trimester pregnancy loss rates were evaluated according to female age, paternal age, body mass index (BMI), diagnosis of infertility, endometrial preparation protocols (natural/artificial), embryo quality (top/good), presence of polycystic ovarian syndrome (PCOS), history of recurrent pregnancy loss (RPL), recurrent implantation failure (RIF), severe male infertility, adenomyosis and endometriosis.

RESULTS

The first trimester pregnancy loss rate was 18.2% (693/ 3805). The presence of RPL increased first trimester pregnancy loss (OR = 7.729, 95%CI = 5.908-10.142, P = 0.000). BMI, which is > 30, increased first trimester pregnancy loss compared to < 25 (OR = 1.418, 95%CI = 1.025-1.950, P = 0.033). Endometrial preparation with artificial cycle increased first trimester pregnancy loss compared to natural cycle (OR = 2.101, 95%CI = 1.630-2.723, P = 0.000). Female age, which is 35-37, increased first trimester pregnancy loss compared to < 30 (OR = 1.617, 95%CI = 1.120-2.316, P = 0.018), and female age, which is > 37, increased first trimester pregnancy loss compared to < 30 (OR = 2.286, 95%CI = 1.146-4,38, P = 0.016). The presence of PCOS increased first trimester pregnancy loss (OR = 1.693, 95%CI = 1.198-2.390, P = 0.002). The number of previous IVF cycles, which is > 3, increased first trimester pregnancy loss compared to < 3 (OR = 2.182, 95%CI = 1.708-2.790, P = 0.000).

CONCLUSIONS

History of RPL, RIF, advanced female age, presence of PCOS, and high BMI (> 30 kg/m2) were the factors that increased first trimester pregnancy loss.

The Progress of Research on Genetic Factors of Recurrent Pregnancy Loss

Recurrent pregnancy loss (RPL) is both mental and physical health problem affecting about 1-5% of women of childbearing age. The etiology of RPL is complex, involving chromosomal abnormalities, autoimmune diseases, metabolic disorders, and endometrial dysfunction. The causes of abortion are still unknown in more than 50% of these cases. With the development of science and technology, an increasing number of scholars focus on this field and find that genetic factors may play an essential role in unexplained RPL, such as embolism-related genes, immune factor-related genes, and chromosomal numeric, and structural variation. This review summarizes the genetic factors associated with RPL, including genetic mutations and genetic polymorphisms, chromosomal variants, and chromosomal polymorphisms. Many related genetic factors have been found to be demographically and geographically relevant, some of which can be used for risk prediction or screening for the etiology of RPL. However, it is difficult to predict and prevent RPL due to uncertain pathogenesis and highly variable clinical presentation. Therefore, the genetic factors of RPL still need plentiful research to obtain a more accurate understanding of its pathogenesis and to provide more detection means for the screening and prevention of RPL.

Impact of follicular size categories on oocyte quality at trigger day in young and advanced-age patients undergoing GnRH-ant therapy

Aim

To study the effect of follicle sizes of different proportions on oocyte and embryo quality in young and advanced-age patients, and provide evidence for personalized protocol adjustment.

Methods

This was a retrospective real-world data study including a total of 11,462 patients who had started their first in vitro fertilization cycle with a gonadotropin-releasing hormone antagonist (GnRH-ant) protocol during 2018-2021. We classified patients into groups according to the size of the dominant proportion of follicles on the human chorionic gonadotropin (hCG) trigger day: Large, Medium, Small, and Equal (containing equivalent proportions of all three size categories). The Cochran-Mantel-Haenszel test by different Anti-Mullerian Hormone (AMH) and antral follicle count (AFC) was used to compare factors such as the metaphase II (MII) oocyte rate, normal fertilization rate, and two pronuclei (2PN) cleavage rate between groups. General linear model (GLM) analysis was performed for inter-group comparison of the oocyte and embryo quality.

Results

In patients aged < 35 years and with AMH ≥ 1.2μg/L, the MII oocyte percentages in the Large and Medium groups were significantly higher than in the Small group (P < 0.001). The germinal vesicle (GV) oocyte and unavailable oocyte percentages in the Large and Medium groups were lower than in the Small group (P < 0.001). Among patients aged ≥ 35 years with AFC < 5 and AMH ≥ 1.2μg/L, the GV oocyte percentage in the Large group was significantly lower than in the Medium group (2.54% vs. 4.46%, P < 0.001). In patients < 35 years, the GLM demonstrated that the Large and Medium groups had positively impacted on the development of MII oocyte and live birth rate(LBR) of first embryo transfer(ET)(β>0, all P value < 0.05);and had less likely to develop into unavailable oocyte, degenerated oocyte, GV oocyte and MI oocyte rates relative to the Small group(β<0, all P value < 0.05). And among patients ≥ 35 years, the Medium group had positively impacted on the development of MII oocyte and 2PN rates relative to the Small group(β>0, all P value < 0.05); and had less likely to develop into MI oocytes relative to the Small group(β<0, all P value < 0.05). The GLM indicated that AMH, along with Gn total dose, start dose, and Gn days, had significant impact on oocyte and embryo quality. For young patients, age was not a significant influencing factor, but for advanced-age patients, age influenced the outcomes.

Conclusion

Our analysis suggests that for young patients (< 35 years), triggering when there is a high proportion of large or medium follicles results in better quality oocytes, while for older patients (≥ 35 years), it is better to trigger when the proportion of medium follicles is no less than that of small follicles. Further research is required to confirm these findings.

Metaphase-II oocyte competence is unlinked to the gonadotrophins used for ovarian stimulation: a matched case-control study in women of advanced maternal age

PURPOSE

An impact of different gonadotrophins selection for ovarian stimulation (OS) on oocyte competence has yet to be defined. In this study, we asked whether an association exists between OS protocol and euploid blastocyst rate (EBR) per metaphase-II (MII) oocytes.

METHODS

Cycles of first preimplantation genetic testing for aneuploidies conducted by women ≥ 35 years old with their own metaphase-II oocytes inseminated in the absence of severe male factor (years 2014-2018) were clustered based on whether recombinant FSH (rec-FSH) or human menopausal gonadotrophin (HMG) was used for OS, then matched for the number of fresh inseminated eggs. Four groups were outlined: rec-FSH (N = 57), rec-FSH plus rec-LH (N = 55), rec-FSH plus HMG (N = 112), and HMG-only (N = 127). Intracytoplasmic sperm injection, continuous blastocyst culture, comprehensive chromosome testing to assess full-chromosome non-mosaic aneuploidies and vitrified-warmed euploid single embryo transfers (SETs) were performed. The primary outcome was the EBR per cohort of MII oocytes. The secondary outcome was the live birth rate (LBR) per first SETs.

RESULTS

Rec-FSH protocol was shorter and characterized by lower total gonadotrophin (Gn) dose. The linear regression model adjusted for maternal age showed no association between the Gn adopted for OS and EBR per cohort of MII oocytes. Similarly, no association was reported with the LBR per first SETs, even when adjusting for blastocyst quality and day of full blastulation.

CONCLUSION

In view of enhanced personalization in OS, clinicians shall focus on different endpoints or quantitative effects related to Gn action towards follicle recruitment, development, and atresia. Here, LH and/or hCG was administered exclusively to women with expected sub/poor response; therefore, we cannot exclude that specific Gn formulations may impact patient prognosis in other populations.

Sex-specific meiosis responses to Gsdf in medaka (Oryzias latipes)

The meiotic entry of undifferentiated germ cells is sexually specific and strictly regulated by the testicular or ovarian environment. Germline stem cells with a set of abnormal sex chromosomes and associated autosomes undergo defective meiotic processes and are eventually eliminated by yet to be defined post-transcriptional modifications. Herein, we report the role of gsdf, a member of BMP/TGFβ family uniquely found in teleost, in the regulation of meiotic entry in medaka (Oryzias latipes) via analyses of gametogenesis in gsdf-deficient XX and XY gonads in comparison with their wild-type siblings. Several differentially expressed genes, including the FKB506-binding protein 7 (fkbp7), were significantly upregulated in pubertal gsdf-deficient gonads. The increase in alternative pre-mRNA isoforms of meiotic synaptonemal complex gene sycp3 was visualized using Integrative Genomics Viewer and confirmed by real-time qPCR. Nevertheless, immunofluorescence analysis showed that Sycp3 protein products reduced significantly in gsdf-deficient XY oocytes. Transmission electron microscope observations showed that normal synchronous cysts were replaced by asynchronous cysts in gsdf-deficient testis. Breeding experiments showed that the sex ratio deviation of gsdf^-/- XY gametes in a non-Mendelian manner might be due to the non-segregation of XY chromosomes. Taken together, our results suggest that gsdf plays a role in the proper execution of cytoplasmic and nuclear events through receptor Smad phosphorylation and Sycp3 dephosphorylation to coordinate medaka gametogenesis, including sex-specific mitotic divisions and meiotic recombination.