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

PGT-A: what's it for, what's wrong?

PGT-A, what's it for? Considering the increase in fetal aneuploidies with a woman's age and the high number of miscarriages associated with fetal karyotype anomalies, the concept of selecting IVF embryos based on their karyotype in order to transfer only euploid embryos and eliminate aneuploid ones was proposed. Preimplantation genetic testing for aneuploidy (PGT-A) was then established, nearly 30 years ago, with the expectation that the transfer of euploid embryos would lead to a significant improvement in medically assisted reproduction (MAR) outcomes. PGT-A, what's wrong? Despite the practice and widespread use, PGT-A has not consistently proven its effectiveness. The clinical value of PGT-A remains controversial. The initial studies reported an increase in MAR outcomes. However, these studies used embryo transfer as the reference point. More recent studies, which use intention-to-treat as the reference point, show, at best, slight improvements and, at worst, a reduction in the considered IVF outcomes. In this article, we attempt to answer two key questions: "What is it for?" and "What's wrong with PGT-A?". We also explore some of the ethical issues raised by these conclusions. Ultimately, we suggest that PGT-A should no longer be offered to infertile couples.

Effects of preimplantation genetic testing for aneuploidy on embryo transfer outcomes in women of advanced reproductive age with no more than three retrieved oocytes

OBJECTIVE

To evaluate whether preimplantation genetic testing for aneuploidy (PGT-A) benefits women of advanced reproductive age (≥38 years old) with a diminished ovarian reserve (not more than three retrieved oocytes).

DESIGN

A retrospective analysis comparing two groups: (a) PGT-A group: women who chose PGT-A and subsequent single re-warmed embryo transfers and (b) non-PGT-A group: women who chose not to genetically test their embryos and underwent subsequent fresh or re-warmed embryo transfers of one to two embryos on days 3 or 5.

SUBJECTS

Two hundred thirty patients underwent PGT-A therapy, with 49 of these individuals undergoing more than one PGT-A cycle. Meanwhile, 309 patients received non-PGT-A treatment, among whom 89 underwent more than one cycle of this type. Collectively, this study encompassed a total of 298 PGT-A cycles and 429 non-PGT-A cycles from a single center (April 2019-June 2023). All women had a diminished ovarian reserve and advanced reproductive age.

EXPOSURE

The exposure variable was the use of PGT-A.

MAIN OUTCOME MEASURES

The primary outcome was live birth rates (per cycle and retrieval). Secondary outcomes were clinical pregnancy rates (per cycle and retrieval) and miscarriage rates (per pregnancy and retrieval).

RESULTS

Although PGT-A cycles had lower transfer rates (14.1% vs. 73.2%), they achieved significantly higher pregnancy (66.7% vs. 12.4%) (adjusted odds ratio [aOR] = 11.474; 95% confidence interval [CI], 5.462, 24.102) and live birth rates (57.1% vs. 7.5%) per transfer (aOR = 13.065; 95% CI, 5.987, 28.510). In addition, the PGT-A group had lower miscarriage rates (14.3% vs. 40.0%) (aOR = 0.142; 95% CI, 0.030, 0.661). However, overall pregnancy and live birth rates were similar, and the PGT-A group required fewer cycles for live birth.

CONCLUSION

Although PGT-A improved clinical pregnancy and live birth rates per transfer cycle in women of advanced reproductive age with a low oocyte yield, it did not impact these rates per retrieval.

Preimplantation genetic testing for aneuploidy in patients of different age: a systematic review and meta-analysis

This study aimed to summarize the current knowledge on the benefits of in vitro fertilization/intracytoplasmic sperm injection with preimplantation genetic testing for aneuploidy (PGT-A) and to discuss the role of PGT-A in patients of different ages undergoing assisted reproduction. A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 checklist. Registration number: CRD42022354697. Studies were identified by searching the PubMed, Cochrane Library, Google Scholar, Scopus, Embase, and ClinicalTrials databases. Seven meta-analyses were performed with additional stratification of age and prognosis of the women studied. Clinical pregnancy rate per embryo transfer in patients aged >35 years was higher in the PGT-A group (P=0.0002) than in controls. Live birth rate (LBR) per embryo transfer in women 35 years old or younger (P=0.002) was higher in the PGT-A group. The LBR per patient in women aged >35 years was higher in the PGT-A group (P=0.004). The effects of PGT-A on LBR in patients with poor prognosis showed a statistically significant increase (P=0.003). There was no significant difference in the rate between the two groups. PGT-A is effective and can be recommended for patients aged >35 years undergoing assisted reproduction to improve their reproductive outcomes. Moreover, our study showed the possible benefits of PGT-A in patients with a poor prognosis. Overall, our findings suggest that PGT-A is a valuable tool for improving the reproductive outcomes of assisted reproductive procedures in older women and those with a history of pregnancy complications.

Live birth rates in in vitro fertilization cycles with five or fewer follicles

PURPOSE

To evaluate live birth rates (LBRs) for in vitro fertilization (IVF) cycles with ≤5 follicles at trigger, with the goal of helping patients with low follicle counts decide whether to proceed to retrieval.

METHODS

This is a retrospective cohort study from an urban, university-affiliated fertility center. All IVF cycles that yielded <10 oocytes between 2016 and 2020 were reviewed. Cycles were included if <5 follicles measuring >14 mm were verified on trigger day. The primary outcome was LBR per retrieval after fresh or frozen transfer. Secondary outcomes were number of oocytes, mature oocytes, 2-pronuclear zygotes (2-PNs), blastocysts for transfer/biopsy, and euploid blastocysts (if preimplantation genetic testing for aneuploidy (PGT-A) was used).

RESULTS

1502 cycles (900 with PGT-A) from 972 patients were included. Mean number of oocytes, mature oocytes, 2-PNs, blastocysts for transfer/biopsy, and euploid blastocysts differed by follicle number (p < 0.001). Across all age groups, there were differences in LBR associated with follicle number (p < 0.001). However, within age groups, not all results were significant. For example, for patients <35 years, LBR did not differ by follicle number and among patients 35-37 years; LBR with two or three follicles was lower than with five (p < 0.02). LBR for patients 35-40 years was <20% with 1-3 follicles and 25-40% with 4-5 follicles. LBR for patients >41 years was <5% with 1-3 follicles and <15% with 4-5 follicles.

CONCLUSION

As expected, LBR is higher with more follicles. Providing patients with <5 follicles with specific data can help them weigh the emotional, physical, and financial costs of retrieval.

Novel embryo selection strategies-finding the right balance

The use of novel technologies in the selection of embryos during in vitro fertilisation (IVF) has the potential to improve the chances of pregnancy and birth of a healthy child. However, it is important to be aware of the potential risks and unintended consequences that may arise from the premature implementation of these technologies. This article discusses the ethical considerations surrounding the use of novel embryo selection technologies in IVF, including the growing uptake of genetic testing and others, and argues that prioritising embryos for transfer using these technologies is acceptable, but discarding embryos based on unproven advances is not. Several historical examples are provided, which demonstrate possible harms, where the overall chance of pregnancy may have been reduced, and some patients may have missed out on biological parenthood altogether. We emphasise the need for caution and a balanced approach to ensure that the benefits of these technologies outweigh any potential harm. We also highlight the primacy of patients' autonomy in reproductive decision-making, especially when information gained by utilising novel technologies is imprecise.

Exploring the efficacy and beneficial population of preimplantation genetic testing for aneuploidy start from the oocyte retrieval cycle: a real-world study

BACKGROUND

Preimplantation genetic testing for aneuploidy (PGT-A) is widely used as an embryo selection technique in in vitro fertilization (IVF), but its effectiveness and potential beneficiary populations are unclear.

METHODS

This retrospective cohort study included patients who underwent their first oocyte retrieval cycles at CITIC-Xiangya between January 2016 and November 2019, and the associated fresh and thawed embryo transfer cycles up to November 30, 2020. PGT-A (PGT-A group) and intracytoplasmic sperm injection (ICSI)/IVF (non-PGT-A group) cycles were included. The numbers of oocytes and embryos obtained were unrestricted. In total, 60,580 patients were enrolled, and baseline data were matched between groups using 1:3 propensity score matching. Sensitivity analyses, including propensity score stratification and traditional multivariate logistic regression, were performed on the original unmatched cohort to check the robustness of the overall results. Analyses were stratified by age, body mass index, ovarian reserve/responsiveness, and potential indications to explore benefits in subgroups. The primary outcome was cumulative live birth rate (CLBR). The other outcomes included live birth rate (LBR), pregnancy loss rate, clinical pregnancy rate, pregnancy complications, low birth weight rate, and neonatal malformation rate.

RESULTS

In total, 4195 PGT-A users were matched with 10,140 non-PGT-A users. A significant reduction in CLBR was observed in women using PGT-A (27.5% vs. 31.1%; odds ratio (OR) = 0.84, 95% confidence interval (CI) 0.78-0.91; P < 0.001). However, women using PGT-A had higher first-transfer pregnancy (63.9% vs. 46.9%; OR = 2.01, 95% CI 1.81-2.23; P < 0.001) and LBR (52.6% vs. 34.2%, OR = 2.13, 95% CI 1.92-2.36; P < 0.001) rates and lower rates of early miscarriage (12.8% vs. 20.2%; OR = 0.58, 95% CI 0.48-0.70; P < 0.001), preterm birth (8.6% vs 17.3%; P < 0.001), and low birth weight (4.9% vs. 19.3%; P < 0.001). Moreover, subgroup analyses revealed that women aged ≥ 38 years, diagnosed with recurrent pregnancy loss or intrauterine adhesions benefited from PGT-A, with a significant increase in first-transfer LBR without a decrease in CLBR.

CONCLUSION

PGT-A does not increase and decrease CLBR per oocyte retrieval cycle; nonetheless, it is effective in infertile populations with specific indications. PGT-A reduces complications associated with multiple gestations.

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.

How to deal with confounders in an infertility study?

Confounding variables represent one of the most important considerations for researchers and readers of scientific clinical papers.