Differences in pregnancy outcomes in donor egg frozen embryo transfer (FET) cycles following preimplantation genetic screening (PGS): a single center retrospective study

Assessing the impact of both preimplantation genetic testing for aneuploidy with blastocyst morphologic grade on live birth rates in frozen embryo transfers from fresh and frozen donor oocytes

PURPOSE

To evaluate the live birth rate (LBR) following donor frozen embryo transfer (dFET) of preimplantation genetic testing for aneuploidy (PGT-A) versus untested donor embryos, stratified by blastocyst morphologic grade (MG).

METHODS

This was a retrospective cohort study of 146 patients undergoing dFET of a single euploid blastocyst from fresh or frozen oocytes using PGT-A compared to age-matched controls (1:1 ratio) who did not use PGT-A. Primary outcome was LBR. LBR was compared among cohorts, with further stratification by (1) high/low MG and (2) fresh/frozen oocyte status. Secondary outcomes included perinatal outcomes.

RESULT(S)

Median age in both groups was 44.5 years (p = 0.98). LBR was similar among the two cohorts (PGT-A: 57.5% vs. untested: 50.0%, p = 0.20). There was similar LBR in fresh (PGT-A: 59.2% vs. untested: 50.0%, p = 0.20) and frozen (PGT-A: 47.6% vs. untested: 50.0%, p = 0.85) oocyte subgroups. When stratified by MG, we appreciated similar LBR among high-quality blastocysts (PGT-A-high: 56.5% vs. untested-high: 52.3%, p = 0.49) among the whole cohort, as well as in fresh (fresh-PGT-A-high: 58.3% vs. fresh-untested-high: 52.9%, p = 0.46) and frozen (frozen-PGT-A-high: 44.4% vs. frozen-untested-high: 51.7%, p = 0.59) subgroups. Similarly, we appreciated no difference in LBR among low-quality blastocysts (PGT-A-low: 75.0% vs. untested-low: 31.2%, p = 0.08) among the whole cohort, as well as in the fresh (fresh-PGT-A-low: 80.0% vs. fresh-untested-low: 16.1%, p = 0.08) or frozen (frozen-PGT-A-low: 66.7% vs. frozen-untested-low: 40.0%, p = 0.56) subgroups. Gestational age (37.8 weeks, p = 1.0) and infant birth weight (PGT-A: 3128.0 g vs. untested: 3150.2 g, p = 0.60) were similar.

CONCLUSION(S)

Though limited by the small number of MG blastocysts, overall PGT-A did not improve LBR regardless of blastocyst quality from fresh and previously frozen donor oocytes.

CAPSULE

Use of PGT-A did not improve live birth rate regardless of blastocyst quality from both fresh and previously frozen donor oocytes.

Gestational carrier cycles: embryology trends, national guideline compliance, and resultant perinatal outcomes in the United States, 2014-2020

BACKGROUND

The increased use of gestational carriers has expanded family-building opportunities for people and couples unable to carry pregnancies on their own. National American Society of Reproductive Medicine guidelines for gestational carriers have changed over time to reflect advances in reproductive technology and mounting evidence supporting the medical benefits associated with singleton gestations.

OBJECTIVE

Assess changes in gestational carrier cycle practice patterns and resultant pregnancy outcomes in the United States in relation to changing national American Society of Reproductive Medicine guidelines, which changed in 2013 and 2017.

STUDY DESIGN

This retrospective study used data from the Society for Assisted Reproductive Technology Clinic Outcomes Reporting System and included all cycles that were reported from 2014-2020 involving an embryo transfer to a gestational carrier. Binomial regression models evaluated trends in preimplantation genetic testing for aneuploidy, American Society of Reproductive Medicine guideline adherence, number of embryos transferred, and pregnancy outcomes over time.

RESULTS

Of the 40,177 gestational carrier transfer cycles from 2014-2020, there was a significant increase in frozen-thawed cycles (41.3% increase), use of assisted hatching (53.4% increase), intracytoplasmic sperm injection (50.0% increase), and preimplantation genetic testing for aneuploidy (155.7% increase). The likelihood of preimplantation genetic testing for aneuploidy was higher in 2020 than in 2014 for autologous oocyte transfers to gestational carriers, both for those aged ≥38 years (adjusted relative risk, 2.38 [95% confidence interval, 2.11-2.70]) and than those aged <38 years (adjusted relative risk, 2.85 [95% confidence interval, 2.58-3.15]). As preimplantation genetic testing for aneuploidy usage increased, single embryo transfer rose for both autologous (adjusted relative risk, 2.22 [95% confidence interval, 1.94-2.50]) and donor cycles (relative risk, 1.91 [95% confidence interval, 1.81-2.02]). This shift toward single embryo transfer corresponded with a decrease in multiple embryo transfer by 79.2% and subsequent decreases in multiple gestations by 68.8% in donor and 73.6% in autologous oocyte cycles from 2014-2020. Gestational carrier cycles remained highly adherent to changing American Society of Reproductive Medicine guidelines throughout the study period. Among live births, there was a 19.4% and 7.9% increase in term deliveries among donor and autologous oocyte cycles, respectively, from 2014 to 2020.

CONCLUSION

Practice patterns have drastically changed throughout the study period, with major increases in the use of preimplantation genetic testing for aneuploidy, intracytoplasmic sperm injection, assisted hatching, and frozen transfers. In response to changing American Society of Reproductive Medicine guidelines, the use of multiple embryo transfers has decreased for gestational carrier cycles with subsequent decreases in multiple gestations and miscarriages and slight increases in live birth rates.

The use of preimplantation genetic testing for aneuploidy: a committee opinion

The use of preimplantation genetic testing for aneuploidy (PGT-A) in the United States has been increasing steadily. Moreover, the underlying technology used for 24-chromosome analysis continues to evolve rapidly. The value of PGT-A as a routine screening test for all patients undergoing in vitro fertilization has not been demonstrated. Although some earlier single-center studies reported higher live-birth rates after PGT-A in favorable-prognosis patients, recent multicenter, randomized control trials in women with available blastocysts concluded that the overall pregnancy outcomes via frozen embryo transfer were similar between PGT-A and conventional in vitro fertilization. The value of PGT-A to lower the risk of clinical miscarriage is also unclear, although these studies have important limitations. This document replaces the document of the same name, last published in 2018.

Systematic review and meta-analysis: does pre-implantation genetic testing for aneuploidy at the blastocyst stage improve live birth rate?

PURPOSE

To establish if preimplantation genetic testing for aneuploidy (PGT-A) at the blastocyst stage improves the composite outcome of live birth rate and ongoing pregnancy rate per embryo transfer compared to conventional morphological assessment.

METHODS

A systematic literature search was conducted using PubMed, EMBASE and Cochrane database from 1st March 2000 until 1st March 2022. Studies comparing reproductive outcomes following in vitro fertilisation using comprehensive chromosome screening (CCS) at the blastocyst stage with traditional morphological methods were evaluated.

RESULTS

Of the 1307 citations identified, six randomised control trials (RCTs) and ten cohort studies fulfilled the inclusion criteria. The pooled data identified a benefit between PGT-A and control groups in the composite outcome of live birth rate and ongoing pregnancy per embryo transfer in both the RCT (RR 1.09, 95% CI 1.02-1.16) and cohort studies (RR 1.50, 95% CI 1.28-1.76). Euploid embryos identified by CCS were more likely to be successfully implanted amongst the RCT (RR 1.20, 95% CI 1.10-1.31) and cohort (RR 1.69, 95% CI 1.29-2.21) studies. The rate of miscarriage per clinical pregnancy is also significantly lower when CCS is implemented (RCT: RR 0.73, 95% CI 0.56-0.96 and cohort: RR 0.48, 95% CI 0.32-0.72).

CONCLUSIONS

CCS-based PGT-A at the blastocyst biopsy stage increases the composite outcome of live births and ongoing pregnancies per embryo transfer and reduces the rate of miscarriage compared to morphological assessment alone. In view of the limited number of studies included and the variation in methodology between studies, future reviews and analyses are required to confirm these findings.

Preimplantation genetic testing for aneuploidies does not increase success rates in fresh oocyte donation cycles: a paired cohort study

PURPOSE

To determine whether in vitro fertilization cycles using fresh oocyte donations benefit from preimplantation genetic testing for aneuploidies.

METHODS

A paired cohort study compared 44 fresh oocyte donation cycles with or without preimplantation genetic testing for aneuploidy (PGT-A). The sibling oocyte study analyzed fertilized oocytes, blastocyst development, and euploidy rate. Only frozen embryo transfers were performed. Pregnancy, implantation, biochemical pregnancy, miscarriage, stillbirth, live birth, and twin pregnancy rates were analyzed between groups.

RESULTS

Fresh oocyte donation cycles between PGT-A and non-PGT-A groups were similar in all laboratory and clinical outcomes. A euploidy rate of 74.2% was observed in the PGT-A group. Although a slight trend was observed for implantation rate in the PGT-A group, it was not statistically significant. No difference was observed for live birth between groups.

CONCLUSION

PGT-A associated with fresh oocyte donation cycles does not improve clinical outcomes and can be seen as over-treatment for patients.

The evolving landscape of donor egg treatment: success, women's choice, and anonymity

PURPOSE

To analyze donor oocyte (DE) data across 6 years for oocyte usage efficiency, trends, and whether changes impacted outcomes.

METHODS

From 2014 to 2019, 323 DE embryo transfers were completed in 200 recipients using oocytes derived of 163 donors. We assessed data for oocytes being freshly retrieved (FRESH-EGG) vs. purchased frozen (FROZEN-EGG); embryos transferred fresh (FRESH-ET) vs. frozen (FROZEN-ET); cycles SHARED (two recipients) vs. SOLE (one recipient); single (SET) vs. double (DET) embryo transfers and usage of PGT-A. Primary outcome was ongoing pregnancy plus live birth (OP/LB) rate.

RESULTS

A total of 229 FRESH-EGG (70%) and 94 FROZEN-EGG (30%) cycles were completed. Overall, the use of FRESH-EGG yielded a higher OP/LB compared to FROZEN-EGG (49% vs. 30%, p = 0.001); within the FRESH-EGG group, OP/LB was similar when comparing FRESH-ET vs. FROZEN-ET (58% vs. 45%, p = 0.07). Within the FRESH-ET group, those using FRESH-EGG had a higher OP/LB than those using FROZEN-EGG (58% vs. 27%, p < 0.001). SHARED vs. SOLE cycles (p = 0.6), donor age (21-32 years; p = 0.4), and age of intended parents (maternal p = 0.3, paternal p = 0.2) did not significantly impact OP/LB. Notably, the use of PGT-A did not improve odds for an OP/LB (p = 0.7).

CONCLUSION

The use of FRESH-EGG with FRESH-ET without PGT-A remains superior to newer DE treatment combinations. Specifically, the use of FROZEN-EGG and PGT-A did not improve outcomes. Although changing DE practices may enhance experience and affordability, patients and providers must appreciate that choices do not always favorably impact success. Additionally, newly available genetic-ancestry testing may pose longer-term ramifications mandating change in treatment and/or counseling.

Preimplantation genetic testing for aneuploidy in uterus transplant patients

Uterus transplantation is an emerging treatment for uterine factor infertility. In vitro fertilization with cryopreservation of embryos prior is required before a patient can be listed for transplant. Whether or not to perform universal preimplantation genetic testing for aneuploidy should be addressed by centers considering a uterus transplant program. The advantages and disadvantages of preimplantation genetic testing for aneuploidy in this unique population are presented. The available literature is reviewed to determine the utility of preimplantation genetic testing for aneuploidy in uterus transplantation protocols. Theoretical benefits of preimplantation genetic testing for aneuploidy include decreased time to pregnancy in a population that benefits from minimization of exposure to immunosuppressive agents and decreased chance of spontaneous abortion requiring a dilation and curettage. Drawbacks include increased cost per in vitro fertilization cycle, increased number of required in vitro fertilization cycles to achieve a suitable number of embryos prior to listing for transplant, and a questionable benefit to live birth rate in younger patients. Thoughtful consideration of whether or not to use preimplantation genetic testing for aneuploidy is necessary in uterus transplant trials. Age is likely a primary factor that can be useful in determining which uterus transplant recipients benefit from preimplantation genetic testing for aneuploidy.

Gestational carrier pregnancy outcomes from frozen embryo transfer depending on the number of embryos transferred and preimplantation genetic testing: a retrospective analysis

OBJECTIVE

To compare gestational age, birth weight (BW), and live birth rates in gestational carriers (GC) after the transfer of 1 or 2 frozen embryo(s) with or without preimplantation genetic testing for aneuploidy (PGT-A), with the understanding that several social and economic factors may motivate intended parents to request the transfer of 2 embryos and/or PGT-A when using a GC.

DESIGN

Retrospective cohort study SETTING: An assisted reproductive technology practice.

PATIENT(S)

All frozen blastocyst transfers with GCs from 2009-2018.

INTERVENTION(S)

One or 2 embryo frozen embryo transfers with and without PGT-A.

MAIN OUTCOME MEASURE(S)

Live birth, preterm birth, and low BW.

RESULTS

A total of 583 frozen embryo transfer cycles with vitrified high-grade blastocysts (grade BB or higher) to GCs were analyzed. Although the live birth rate was significantly greater in frozen embryo transfers with 2 embryos, after single embryo transfer (SET), the mean gestational age and BW of live births were statistically significantly greater than those of double embryo transfer (DET). The rate of multiple births was 1.9% for SET compared to 20.0% for DET per transfer. Only 3.8% of live births from SET experienced low BW and 0.6% had very low or extremely low BW. By comparison, 12.5% of DET live births were low BW and 5% were very low BW. After SET, 13.4% of live births were preterm, compared with 40% in DET. The analysis also included a total of 194 transfers with PGT-A compared to 389 cycles without. Overall, live births per transfer were not significantly different between these latter 2 subgroups.

CONCLUSION

Frozen embryo transfer cycles in GCs with DET were associated with more preterm births and lower birth weights compared with those of SET. Intended parents and GCs should be counseled that DET is associated with greater risks of adverse pregnancy and perinatal outcomes, which mitigates higher live birth rates. The use of PGT-A did not appear to improve the live birth rate.

Cost-effectiveness of preimplantation genetic testing for aneuploidy for fresh donor oocyte cycles

OBJECTIVE

To determine whether in vitro fertilization (IVF) with preimplantation genetic testing for aneuploidy (PGT-A) is cost effective to achieve a live birth compared with IVF alone in fresh donor oocyte cycles.

DESIGN

Theoretical cost-effectiveness study.

SETTING

Not applicable.

PATIENTS

None.

INTERVENTIONS

Comparison between the cost of IVF with PGT-A vs. IVF alone to achieve a live birth. The model analyzed a hypothetical single fresh oocyte donor IVF cycle with PGT-A vs. IVF alone and followed the progression of a single embryo through the different decision nodes. Cost estimates assigned to each clinical event were based on data obtained from the literature and institutional costs.

MAIN OUTCOME MEASURES

Cost per live birth.

RESULTS

In the base-case analysis, IVF with PGT-A was not cost effective in fresh donor oocyte cycles when compared with IVF alone to achieve a live birth. The cycles using PGT-A cost an additional $6,018.66. The incremental cost-effectiveness ratio was found to be $119,606.59 per additional live birth achieved with IVF with PGT-A. Monte Carlo simulations demonstrated that IVF with PGT-A was not cost effective in nearly all iterations.

CONCLUSIONS

PGT-A in fresh donor oocyte IVF cycles is not cost effective compared with IVF alone over a wide range of probabilities and costs.

Preimplantation Genetic Testing for Aneuploidy - a Castle Built on Sand

Preimplantation genetic testing for aneuploidy (PGT-A) has become a routine add-on for in vitro fertilization (IVF) to determine whether human embryos are to be clinically utilized or disposed of. Studies claiming IVF outcome improvements following PGT-A, however, used highly selected patient populations or inappropriate statistical methodologies. PGT-A was never clinically validated in its ability to define a human embryo as chromosomal normal, mosaic, or aneuploid, nor certified by a regulatory body, or an authoritative professional organization. Because of a high false-positive rate, PGT-A, actually reduces live IVF birth chances for many patients. Furthermore, in recent studies the PGT-A hypothesis was demonstrated to be mistaken for biological, mathematical and technical reasons. PGT-A, therefore, should clinically only be offered within experimental study frameworks.

Donor oocyte recipients do not benefit from preimplantation genetic testing for aneuploidy to improve pregnancy outcomes

STUDY QUESTION

Do donor oocyte recipients benefit from preimplantation genetic testing for aneuploidy (PGT-A)?

SUMMARY ANSWER

PGT-A did not improve the likelihood of live birth for recipients of vitrified donor oocytes, but it did avoid embryo transfer in cycles with no euploid embryos.

WHAT IS KNOWN ALREADY

Relative to slow freeze, oocyte vitrification has led to increased live birth from cryopreserved oocytes and has led to widespread use of this technology in donor egg IVF programs. However, oocyte cryopreservation has the potential to disrupt the meiotic spindle leading to abnormal segregation of chromosome during meiosis II and ultimately increased aneuploidy in resultant embryos. Therefore, PGT-A might have benefits in vitrified donor egg cycles. In contrast, embryos derived from young donor oocytes are expected to be predominantly euploid, and trophectoderm biopsy may have a negative effect relative to transfer without biopsy.

STUDY DESIGN, SIZE, DURATION

This is a paired cohort study analyzing donor oocyte-recipient cycles with or without PGT-A performed from 2012 to 2018 at 47 US IVF centers.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Vitrified donor oocyte cycles were analyzed for live birth as the main outcome measure. Outcomes from donors whose oocytes were used by at least two separate recipient couples, one couple using PGT-A (study group) and one using embryos without PGT-A (control group), were compared. Generalized estimating equation models controlled for confounders and nested for individual donors contributing to both PGT-A and non-PGT-A cohorts, enabling a single donor to serve as her own control.

MAIN RESULTS AND THE ROLE OF CHANCE

In total, 1291 initiated recipient cycles from 223 donors were analyzed, including 262 cycles with and 1029 without PGT-A. The median aneuploidy rate per recipient was 25%. Forty-three percent of PGT-A cycles had only euploid embryos, whereas only 12.7% of cycles had no euploid embryos. On average 1.09 embryos were transferred in the PGT-A group compared to 1.38 in the group without PGT-A (P < 0.01). Live birth occurred in 53.8% of cycles with PGT-A versus 55.8% without PGT-A (P = 0.44). Similar findings persisted in cumulative live birth from per recipient cycle.

LIMITATIONS, REASONS FOR CAUTION

Pooled clinical data from 47 IVF clinics introduced PGT-A heterogeneity as genetic testing were performed using different embryology laboratories, PGT-A companies and testing platforms.

WIDER IMPLICATIONS OF THE FINDINGS

PGT-A testing in donor oocyte-recipient cycles does not improve the chance for live birth nor decrease the risk for miscarriage in the first transfer cycle but does increase cost and time for the patient. Further studies are required to test if our findings can be applied to the young infertility patient population using autologous oocytes.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used for this study. There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Abnormal placental pathological findings and adverse clinical outcomes of oocyte donation

We sought to assess chronic inflammatory responses in patients who achieved pregnancy by oocyte donation and non-oocyte donation-assisted reproductive technology and delivered at The Ottawa Hospital. Data describing maternal health, obstetrical outcomes, neonatal outcomes, and placental pathology were collected and analyzed from electronic medical records. An increased frequency of adverse obstetrical outcomes was observed. In the oocyte donation-assisted reproductive technology group, placental pathology data demonstrated increased frequency of fetal vascular malperfusion (p = 0.02) and placenta accreta (p < 0.001), representing a chronic inflammatory response. Placental pathology reflecting dysregulated immune processes and vasculopathy is associated with oocyte donation.

Clinical application of embryo aneuploidy testing by next-generation sequencing

We review here the evolution in the field of embryo aneuploidy testing over the last 20 years, from the analysis of a subset of chromosomes by fluorescence in situ hybridisation to the transition toward a more comprehensive analysis of all 24 chromosomes. This current comprehensive aneuploidy testing most commonly employs next-generation sequencing (NGS). We present our experience in over 130 000 embryo biopsies using this technology. The incidence of aneuploidy was lower in trophectoderm biopsies compared to cleavage-stage biopsies. We also confirmed by NGS that embryo aneuploidy rates increased with increasing maternal age, mostly attributable to an increase in complex aneuploid embryos. In contrast, the number of MII oocytes retrieved or the use of oocyte vitrification did not affect aneuploidy rates. Similarly, neither maternal age, oocyte number, nor oocyte vitrification affected the incidence of mosaicism. Analysis of clinical outcomes, indications, and potential benefits of embryo aneuploidy testing revealed advanced maternal age as the most favored group, with some evidence of improved delivery rate per transfer as well as decreased miscarriage rates and time to pregnancy. Other indications are: recurrent miscarriage, repetitive implantation failure, severe male factor, previous trisomic pregnancy, and good prognosis patients mainly undergoing single embryo transfer, with the latter indication used to reduce the occurrence of multiple pregnancies without compromising cycle outcome. In conclusion, NGS has become the most appropriate technology for aneuploidy testing in trophectoderm biopsies, with accurate results, high throughput, and cost efficiency. This technology can be also applied to the analysis of the embryonic cell free DNA released to the culture media at blastocyst stage. This is a promising approach towards a non-invasive preimplantation genetic testing of aneuploidy.

Cumulative live birth rates among gestational surrogates in altruistic surrogacy arrangements

Understanding the likelihood of a live birth is important for fertility treatment planning, particularly when one cycle fails and further treatment may be contemplated. This study aims to estimate the chance of live birth among gestational surrogates undergoing altruistic surrogacy arrangements between 2009 and 2016 in Victoria, Australia. A total of 81 gestational surrogates with 170 embryo transfer cycles were included. Of the 170 embryo transfer cycles, the majority were single embryo transfers (SETs; 97.1%), using frozen/thawed embryos (97.6%) which had been fertilized by intracytoplasmic sperm injection (77.6%). The cumulative live birth rate was 23.5% (95% CI, 15.6-33.8%) after the first cycle and increased to 50.6% (95% CI, 40.0-61.2%) after the sixth cycle. Of the 41 deliveries, 40 were singletons and one was a twin delivery. Two of the 42 deliveries were preterm, two were low birthweight and one was small for gestational age. The findings imply that surrogacy treatment can be offered up to six consecutive embryo transfer cycles to gestational surrogates. SET is encouraged in surrogacy practice to improve perinatal outcomes. These estimates can be used in counselling and decision-making for intended parents and gestational surrogates to continue a surrogacy treatment and informing public policy on assisted reproductive technology treatment.

Pregnancy and birth outcomes of single versus multiple embryo transfer in gestational surrogacy arrangements: a systematic review and meta-analysis

Multiple embryo transfer (MET) is associated with both an increased risk of multiple pregnancy and of live birth. In recent years, MET has become standard practice for most surrogacy arrangements. There is limited review of the use of MET versus single embryo transfer (SET) in surrogacy practice. The present review systematically evaluated the pregnancy outcomes of surrogacy arrangements between MET versus SET among gestational carriers. A systematic search of five computerized databases without restriction to the English language or study type was conducted to evaluate the primary outcomes: (i) clinical pregnancy; (ii) live delivery; and (iii) multiple delivery rates. The search returned 97 articles, five of which met the inclusion criteria. The results showed that clinical pregnancy (RR = 1.21, 95% CI: 1.06-1.39, n  =  5, I² = 41%), live delivery (RR = 1.29, 95% CI: 1.10-1.51, n  =  4, I² = 35%) and multiple delivery rates (RR = 1.42, 95% CI: 6.58-69.73, n  =  4, I² = 54%) were statistically significantly different in MET compared to SET. Adverse events including miscarriage, preterm birth and low birthweight were found following MET. Our findings support the existing evidence that MET results in multiple pregnancy and subsequently more adverse outcomes compared to SET. From a public health perspective, SET should be advocated as the preferred treatment for gestational carriers.

Preimplantation Genetic Testing for Chromosomal Abnormalities: Aneuploidy, Mosaicism, and Structural Rearrangements

There is a high incidence of chromosomal abnormalities in early human embryos, whether they are generated by natural conception or by assisted reproductive technologies (ART). Cells with chromosomal copy number deviations or chromosome structural rearrangements can compromise the viability of embryos; much of the naturally low human fecundity as well as low success rates of ART can be ascribed to these cytogenetic defects. Chromosomal anomalies are also responsible for a large proportion of miscarriages and congenital disorders. There is therefore tremendous value in methods that identify embryos containing chromosomal abnormalities before intrauterine transfer to a patient being treated for infertility—the goal being the exclusion of affected embryos in order to improve clinical outcomes. This is the rationale behind preimplantation genetic testing for aneuploidy (PGT-A) and structural rearrangements (-SR). Contemporary methods are capable of much more than detecting whole chromosome abnormalities (e.g., monosomy/trisomy). Technical enhancements and increased resolution and sensitivity permit the identification of chromosomal mosaicism (embryos containing a mix of normal and abnormal cells), as well as the detection of sub-chromosomal abnormalities such as segmental deletions and duplications. Earlier approaches to screening for chromosomal abnormalities yielded a binary result of normal versus abnormal, but the new refinements in the system call for new categories, each with specific clinical outcomes and nuances for clinical management. This review intends to give an overview of PGT-A and -SR, emphasizing recent advances and areas of active development.

Innovations in assisted reproductive technologies: impact on contemporary donor egg practice and future advances

Innovations in assisted reproductive technologies (ART) have driven progress in the donor egg field since the birth of the first baby derived from a donor egg in 1983. Over time, donor oocytes have become an increasingly used option for patients unable to conceive with autologous oocytes. In donor egg, the unique separation of the oocyte source and recipient uterus has created a model that has propelled advances in ART. Progressive ART innovations that have optimized the oocyte donor and resulting embryo include the following: evaluation of ovarian reserve, controlled ovarian hyperstimulation regimens that reduce the risk of ovarian hyperstimulation syndrome, blastocyst culture, oocyte cryopreservation, and preimplantation genetic testing. For donor egg recipients, methods to optimize the endometrium to maximize implantation include endometrial receptivity testing, immunologic donor-recipient matching, and increased understanding of the uterine microbiome.

The role of chromosome segregation and nuclear organisation in human subfertility

Spermatogenesis is central to successful sexual reproduction, producing large numbers of haploid motile male gametes. Throughout this process, a series of equational and reductional chromosome segregation precedes radical repackaging of the haploid genome. Faithful chromosome segregation is thus crucial, as is an ordered spatio-temporal ‘dance’ of packing a large amount of chromatin into a very small space. Ergo, when the process goes wrong, this is associated with an improper chromosome number, nuclear position and/or chromatin damage in the sperm head. Generally, screening for overall DNA damage is relatively commonplace in clinics, but aneuploidy assessment is less so and nuclear organisation studies form the basis of academic research. Several studies have focussed on the role of chromosome segregation, nuclear organisation and analysis of sperm morphometry in human subfertility observing significant alterations in some cases, especially of the sex chromosomes. Importantly, sperm DNA damage has been associated with infertility and both extrinsic (e.g. lifestyle) and intrinsic (e.g. reactive oxygen species levels) factors, and while some DNA-strand breaks are repaired, unexpected breaks can cause differential chromatin packaging and further breakage. A ‘healthy’ sperm nucleus (with the right number of chromosomes, nuclear organisation and minimal DNA damage) is thus an essential part of reproduction. The purpose of this review is to summarise state of the art in the fields of sperm aneuploidy assessment, nuclear organisation and DNA damage studies.

A Comparison of Pregnancy Outcomes in Patients Undergoing Donor Egg Single Embryo Transfers With and Without Preimplantation Genetic Testing

Two of the many milestone developments in the field of assisted reproduction have been oocyte donation and preimplantation genetic testing for aneuploidy (PGT-A). Because it has been demonstrated that even young women produce a meaningful proportion of aneuploid embryos, screening out such abnormalities could potentially increase the efficacy of donor egg (DE) cycles. In this retrospective cohort study, we investigated the effect of PGT-A on DE cycle outcomes, including implantation rate (IR), spontaneous abortion rate (SABR), and ongoing pregnancy/live birth rate. We used fresh and frozen donor cycles not using PGT-A as comparison groups; all cases involved single embryo transfer. Data analysis revealed that PGT-A did not improve pregnancy outcome metrics in DE cycles, although there was a trend toward decreasing the SABR. There was a significant increase in IR with fresh cycles outperforming all frozen cycles. Overall, these results suggest that the benefits of performing PGT-A on embryos derived from young DEs may be limited and that there is an effect of the freezing process on pregnancy outcomes. These findings may provide useful insights into the science and practice of PGT-A across all of its applications.

How time to healthy singleton delivery could affect decision-making during infertility treatment: a Delphi consensus

RESEARCH QUESTION

How might time to healthy singleton delivery affect decision-making during infertility treatment?

DESIGN

This was a Delphi consensus investigating expert opinion that comprised three steps. In Step 1, 12 experts developed statements. In Step 2, 27 experts (including 12 from Step 1) voted (online survey) on their agreement/disagreement with each statement (providing reasons). Consensus was reached if ≥66% of participants agreed/disagreed. Statements not reaching consensus were revised and the process repeated until consensus was achieved. In Step 3 details of the final agreed statements were communicated.

RESULTS

Twelve statements were developed, and consensus (agreement) was reached on all after one round of voting.

CONCLUSIONS

Time to healthy singleton delivery should be taken into consideration when making decisions related to infertility treatment, and it is important that fertility treatment is provided in a timely manner, avoiding over- or under-treatment. In all subfertile women <40 years old, IVF outcomes could be optimized by performing up to six single-embryo transfers and certain procedures might reduce time to healthy singleton delivery. These procedures include preimplantation genetic testing for aneuploidies, frozen replacement cycles immediately after failed fresh cycles and use of gonadotrophin-releasing hormone antagonists. Finally, the number of oocytes retrieved should be maximized to increase cumulative live birth rate.

Effect of next-generation sequencing in preimplantation genetic testing on live birth ratio

The present study analysed live birth ratios in frozen embryo transfer (FET) cycles where embryo ploidy status was determined with preimplantation genetic testing (PGT) using next-generation sequencing (NGS). PGT was performed on trophectoderm cells biopsied at the blastocyst stage. The present prospective cohort study included 112 women undergoing frozen embryo transfer, with NGS PGT. The control group consisted of 85 patients who underwent the IVF procedure with FET planned for a subsequent cycle. The live birth rate per cycle was higher by ~18.5 percentage points in the investigated compared with control group (42.0% vs 23.5% respectively; P = 0.012). The differences between the study and control groups were also significant for clinical pregnancy (42.0% vs 23.5% respectively; P = 0.012), implantation (41.2% vs 22.2% respectively; P = 0.001) and pregnancy loss rates (9.6% vs 28.6% respectively; P = 0.027). The results show that PGT NGS is a useful method for embryo selection and it may be implemented in routine clinical practice with propitious results.