The PGS/PGT-A controversy in IVF addressed as a formal conflict resolution analysis

Current Applications and Controversies in Preimplantation Genetic Testing for Aneuploidies (PGT-A) in In Vitro Fertilization

Preimplantation genetic testing for aneuploidy (PGT-A) has evolved over recent years, including improvements in embryo culture, biopsy, transfer, and genetic testing. The application of new comprehensive chromosome screening analysis has improved the accuracy in determining the chromosomal status of the analyzed sample, but it has brought new challenges such as the management of partial aneuploidies and mosaicisms. For the past two decades, PGT-A has been involved in a controversy regarding its efficiency in improving IVF outcomes, despite its widespread worldwide implementation. Understanding the impact of embryo aneuploidy in IVF (in vitro fertilization) should theoretically allow improving reproductive outcomes. This review of the literature aims to describe the impact of aneuploidy in human reproduction and how PGT-A was introduced to overcome this obstacle in IVF (in vitro fertilization). The article will try to analyze and summarize the evolution of the PGT-A in the recent years, and its current applications and limitations, as well as the controversy it generates. Conflicting published data could indicate the lacking value of a single biopsied sample to determine embryo chromosomal status and/or the lack of standardized methods for embryo culture and management and genetic analysis among other factors. It has to be considered that PGT-A may not be a universal test to improve the reproductive potential in IVF patients, rather each clinic should evaluate the efficacy of PGT-A in their IVF program based on their population, skills, and limitations.

Preimplantation genetic testing for aneuploidy helps to achieve a live birth with fewer transfer cycles for the blastocyst FET patients with unexplained recurrent implantation failure

PURPOSE

This retrospective cohort study aimed to investigate the value of preimplantation genetic testing for aneuploidy (PGT-A) as a screening test for patients suffering from unexplained recurrent implantation failure (RIF).

METHODS

After screening patients in one reproductive medicine center, twenty-nine, forty-nine and thirty-eight women (< 40 years old) who had suffered unexplained RIF with PGT-A, or RIF without PGT-A, or no RIF with PGT-A were included. The clinical pregnancy rate and live birth rate per transfer, the conservative and optimal cumulative clinical pregnancy rates (CCPR) and live birth rates (CLBR) after three blastocyst FETs were analyzed.

RESULTS

The live birth rate per transfer was significantly higher in the RIF + PGT-A group than that in the RIF + NO PGT-A group (47.6% vs. 24.6%, p = 0.014). After 3 cycles of FET, RIF + PGT-A group had significantly higher conservative CLBR and optimal CLBR compared to the RIF + NO PGT-A group (69.0% vs. 32.7%, p = 0.002 and 73.7% vs. 57.5%, p = 0.016), but had similar conservative and optimal CLBRs compared to the NO RIF + PGT-A group. The number of FET cycles required when half women achieved a live birth was 1 in the PGT-A group and 3 in RIF + NO PGT-A group. The miscarriage rates were not different between the RIF + PGT-A and RIF + NO PGT-A, RIF + PGT-A and NO RIF + PGT-A groups.

CONCLUSION

PGT-A did be superior in reducing the number of transfer cycles required to achieve a similar live birth rate. Further studies to identify the RIF patients who would benefit most from PGT-A are necessary.

Comment on the recent PGDIS Position Statement on the Transfer of Mosaic Embryos 2021

The worldwide demand of preimplantation genetic testing for aneuploidy (PGT-A) is still growing. However, chromosomal mosaic results greatly challenge the clinical practice. The recently published PGDIS Position Statement on the Transfer of Mosaic Embryos is the third PGDIS position statement on how to deal with embryos diagnosed as chromosomal mosaics (CM) and, one of many attempts of different societies and working groups to provide a guideline for clinicians, laboratories, clinics, and genetic counselors. But still, as in previous statements, many issues remained unresolved. Moreover, from our point of view, the question how to deal with embryos diagnosed as CM, consisting of two or more karyological cell lines cannot be separated from all the other aspects of PGT-A including its accuracy. The paucity of clearcut indications for PGT-A and evidence of benefit as well as an overall cost-benefit assessment is given below.

Does PGT-A improve assisted reproduction treatment success rates: what can the UK Register data tell us?

PURPOSE

To show how naïve analyses of aggregated UK ART Register data held by the Human Fertilisation and Embryology Authority to estimate the effects of PGT-A can be severely misleading and to indicate how it may be possible to do a more credible analysis. Given the limitations of the Register, we consider the extent to which such an analysis has the potential to answer questions about the real-world effectiveness of PGT-A.

METHODS

We utilise the publicly available Register datasets and construct logistic regression models for live birth events (LBE) which adjust for confounding. We compare all PGT-A cycles to control groups of cycles that could have had PGT-A, excluding cycles that did not progress to having embryos for biopsy.

RESULTS

The primary model gives an odds ratio for LBE of 0.82 (95% CI 0.68-1.00) suggesting PGT-A may be detrimental rather than beneficial. However, due to limitations in the availability of important variables in the public dataset, this cannot be considered a definitive estimate. We outline the steps required to enable a credible analysis of the Register data.

CONCLUSION

If we compare like with like groups, we obtain estimates of the effect of PGT-A that suggest an overall modest reduction in treatment success rates. These are in direct contrast to an invalid comparison of crude success rates. A detailed analysis of a fuller dataset is warranted, but it remains to be demonstrated whether the UK Register data can provide useful estimates of the impact of PGT-A when used as a treatment add-on.

State-Mandated Insurance Coverage and Preimplantation Genetic Testing in the United States

OBJECTIVE

To examine the association between state-mandated insurance coverage for infertility treatment in the United States and the utilization of and indication for preimplantation genetic testing.

METHODS

This was a retrospective cohort study of 301,465 in vitro fertilization (IVF) cycles reported to the Society for Assisted Reproductive Technology between 2014 and 2016. Binomial logistic regression was performed to examine associations between state-mandated insurance coverage and preimplantation genetic testing use. The neonate's sex from each patient's first successful cycle was used to calculate sex ratios. Sex ratios then were compared by state mandates and preimplantation genetic testing indication for elective sex selection.

RESULTS

The proportion of IVF cycles using preimplantation genetic testing increased from 17% in 2014 to 34% in 2016. This increase was driven largely by preimplantation genetic testing for aneuploidy testing. Preimplantation genetic testing was less likely to be performed in states with mandates for insurance coverage than in those without mandates (risk ratio [RR] 0.69, 95% CI 0.67-0.71, P<.001). Preimplantation genetic testing use for elective sex selection was also less likely to be performed in states with mandates (RR 0.44, 95% CI 0.36-0.53, P<.001). Among liveborn neonates, the male/female sex ratio was higher for IVF cycles with preimplantation genetic testing for any indication (115) than for those without preimplantation genetic testing (105) (P<.001), and the use of preimplantation genetic testing specifically for elective sex selection had a substantially higher (164) male/female sex ratio than preimplantation genetic testing for other indications (112) (P<.001).

CONCLUSION

The proportion of IVF cycles using preimplantation genetic testing in the United States is increasing and is highest in states where IVF is largely self-funded. Preimplantation genetic testing for nonmedical sex selection is also more common in states where IVF is self-funded and is more likely to result in male offspring. Continued surveillance of these trends is important, because these practices are controversial and could have implications for future population demographics.

Disrupting the biological clock: Fertility benefits, egg freezing and proactive fertility management

In the last decade, the in-vitro fertilization (IVF) sector has witnessed a shift from so-called 'reactive IVF' to a new model of proactive fertility care. Whereas IVF was traditionally developed to treat people who found they were unable to conceive, the indication for IVF has broadened significantly to include a much wider group of potential patients through a new focus on proactive treatment of future (in)fertilities. This shift combines a number of new trends pertaining to preservation, prediction, private equity and platformization, all of which have gained influence in contemporary assisted reproduction. This article focuses on the emergence of company-sponsored fertility benefits, which combines each of these trends. Whereas fertility benefits - especially egg freezing insurance - have primarily been discussed in terms of women's empowerment or disenfranchisement, this article instead calls attention to the discursive, clinical and infrastructural shifts in contemporary assisted reproduction that have emerged with the rising popularity of these benefits. The analysis addresses these underdiscussed aspects of fertility benefits by focusing on the dynamics of demand; the shifts in the rationalization of intensified treatment pathways in the face of new reimbursement practices; and the online, platform-based infrastructures that are built to provide these treatments. In doing so, it analyses how this remaking of fertility towards an ethos of proactive fertility management reflects broader capitalist tailwinds.

Vacuolization in embryos on days 3 and 4 of in vitro development: Association with stimulation protocols, embryo development, chromosomal status, pregnancy and neonatal outcomes

STUDY QUESTION

Is vacuolization in embryos on Days 3 and 4 associated with parent-related factors, stimulation protocols, embryo development, embryo ploidy, pregnancy and neonatal outcomes?

STUDY DESIGN SIZE DURATION

This is a retrospective cohort study that comprised 5,703 embryos from 611 patients who underwent preimplantation genetic testing and time-lapse monitoring of their embryos from August 2017 to September 2021.

MAIN RESULTS

Embryo vacuolization on Days 3 and 4 is associated with the LH level on the day of the hCG trigger and the number of retrieved oocytes. Compared to vacuole-negative embryos, the rates of blastocyst formation and good-blastocyst formation was significantly lower in vacuole-positive embryos. We observed no significant difference in the rates of euploidy, implantation, ongoing pregnancy, and live birth between vacuole-positive and vacuole-negative embryos. In vacuole-positive embryos, the embryos of which the vacuole-positive blastomeres were involved in embryo compaction exhibited significantly higher mosaicism rate compared with those of which the vacuole-positive blastomeres were not involved in embryo compaction.

CONCLUSION

Vacuolization in embryos on Days 3 and 4 is associated with reduced blastocyst formation rate and high-quality blastocyst rate. Blastocysts had a low mosaicism rate if the vacuole-containing cells were rejected in compaction process, which supports the hypothesis that exclusion of abnormal blastomeres from compaction is a self-correction mechanism.

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.

Preimplantation genetic testing for aneuploidies (abnormal number of chromosomes) in in vitro fertilisation

BACKGROUND

In in vitro fertilisation (IVF) with or without intracytoplasmic sperm injection (ICSI), selection of the most competent embryo(s) for transfer is based on morphological criteria. However, many women do not achieve a pregnancy even after 'good quality' embryo transfer. One of the presumed causes is that such morphologically normal embryos have an abnormal number of chromosomes (aneuploidies). Preimplantation genetic testing for aneuploidies (PGT-A), formerly known as preimplantation genetic screening (PGS), was therefore developed as an alternative method to select embryos for transfer in IVF. In PGT-A, the polar body or one or a few cells of the embryo are obtained by biopsy and tested. Only polar bodies and embryos that show a normal number of chromosomes are transferred. The first generation of PGT-A, using cleavage-stage biopsy and fluorescence in situ hybridisation (FISH) for the genetic analysis, was demonstrated to be ineffective in improving live birth rates. Since then, new PGT-A methodologies have been developed that perform the biopsy procedure at other stages of development and use different methods for genetic analysis. Whether or not PGT-A improves IVF outcomes and is beneficial to patients has remained controversial.

OBJECTIVES

To evaluate the effectiveness and safety of PGT-A in women undergoing an IVF treatment.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility (CGF) Group Trials Register, CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, and two trials registers in September 2019 and checked the references of appropriate papers.

SELECTION CRITERIA

All randomised controlled trials (RCTs) reporting data on clinical outcomes in participants undergoing IVF with PGT-A versus IVF without PGT-A were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, assessed risk of bias, and extracted study data. The primary outcome was the cumulative live birth rate (cLBR). Secondary outcomes were live birth rate (LBR) after the first embryo transfer, miscarriage rate, ongoing pregnancy rate, clinical pregnancy rate, multiple pregnancy rate, proportion of women reaching an embryo transfer, and mean number of embryos per transfer.

MAIN RESULTS

We included 13 trials involving 2794 women. The quality of the evidence ranged from low to moderate. The main limitations were imprecision, inconsistency, and risk of publication bias. IVF with PGT-A versus IVF without PGT-A with the use of genome-wide analyses Polar body biopsy One trial used polar body biopsy with array comparative genomic hybridisation (aCGH). It is uncertain whether the addition of PGT-A by polar body biopsy increases the cLBR compared to IVF without PGT-A (odds ratio (OR) 1.05, 95% confidence interval (CI) 0.66 to 1.66, 1 RCT, N = 396, low-quality evidence). The evidence suggests that for the observed cLBR of 24% in the control group, the chance of live birth following the results of one IVF cycle with PGT-A is between 17% and 34%. It is uncertain whether the LBR after the first embryo transfer improves with PGT-A by polar body biopsy (OR 1.10, 95% CI 0.68 to 1.79, 1 RCT, N = 396, low-quality evidence). PGT-A with polar body biopsy may reduce miscarriage rate (OR 0.45, 95% CI 0.23 to 0.88, 1 RCT, N = 396, low-quality evidence). No data on ongoing pregnancy rate were available. The effect of PGT-A by polar body biopsy on improving clinical pregnancy rate is uncertain (OR 0.77, 95% CI 0.50 to 1.16, 1 RCT, N = 396, low-quality evidence). Blastocyst stage biopsy One trial used blastocyst stage biopsy with next-generation sequencing. It is uncertain whether IVF with the addition of PGT-A by blastocyst stage biopsy increases cLBR compared to IVF without PGT-A, since no data were available. It is uncertain if LBR after the first embryo transfer improves with PGT-A with blastocyst stage biopsy (OR 0.93, 95% CI 0.69 to 1.27, 1 RCT, N = 661, low-quality evidence). It is uncertain whether PGT-A with blastocyst stage biopsy reduces miscarriage rate (OR 0.89, 95% CI 0.52 to 1.54, 1 RCT, N = 661, low-quality evidence). No data on ongoing pregnancy rate or clinical pregnancy rate were available. IVF with PGT-A versus IVF without PGT-A with the use of FISH for the genetic analysis Eleven trials were included in this comparison. It is uncertain whether IVF with addition of PGT-A increases cLBR (OR 0.59, 95% CI 0.35 to 1.01, 1 RCT, N = 408, low-quality evidence). The evidence suggests that for the observed average cLBR of 29% in the control group, the chance of live birth following the results of one IVF cycle with PGT-A is between 12% and 29%. PGT-A performed with FISH probably reduces live births after the first transfer compared to the control group (OR 0.62, 95% CI 0.43 to 0.91, 10 RCTs, N = 1680, I² = 54%, moderate-quality evidence). The evidence suggests that for the observed average LBR per first transfer of 31% in the control group, the chance of live birth after the first embryo transfer with PGT-A is between 16% and 29%. There is probably little or no difference in miscarriage rate between PGT-A and the control group (OR 1.03, 95%, CI 0.75 to 1.41; 10 RCTs, N = 1680, I² = 16%; moderate-quality evidence). The addition of PGT-A may reduce ongoing pregnancy rate (OR 0.68, 95% CI 0.51 to 0.90, 5 RCTs, N = 1121, I² = 60%, low-quality evidence) and probably reduces clinical pregnancies (OR 0.60, 95% CI 0.45 to 0.81, 5 RCTs, N = 1131; I² = 0%, moderate-quality evidence).

AUTHORS' CONCLUSIONS

There is insufficient good-quality evidence of a difference in cumulative live birth rate, live birth rate after the first embryo transfer, or miscarriage rate between IVF with and IVF without PGT-A as currently performed. No data were available on ongoing pregnancy rates. The effect of PGT-A on clinical pregnancy rate is uncertain. Women need to be aware that it is uncertain whether PGT-A with the use of genome-wide analyses is an effective addition to IVF, especially in view of the invasiveness and costs involved in PGT-A. PGT-A using FISH for the genetic analysis is probably harmful. The currently available evidence is insufficient to support PGT-A in routine clinical practice.