Preimplantation genetic testing for aneuploidy in patients with low embryo numbers: benefit or harm?

Evaluating PGT-A in patients with limited good-quality embryos: A retrospective cohort study

BACKGROUND

Preimplantation genetic testing for aneuploidy (PGT-A) is widely used to screen for aneuploidy with the aim of improving the live birth rate. Remarkably, previous studies have focused on the effect of PGT-A on cumulative clinical outcomes in women with a good pregnancy prognosis. However, it is still unclear whether PGT-A is superior for cumulative pregnancy outcomes in patients with limited good-quality embryos.

METHODS

In total, 1553 patients who intended to pursue PGT-A for the first time but only obtained two or fewer good-quality embryos on day 3 after oocyte retrieval were divided into two groups: 997 in the PGT-A group and 556 in the drop-out group (i.e., decided not to undergo PGT-A due to poor embryological outcome). The main outcome measures were cumulative live birth rate per oocyte retrieval cycle and live birth rate per embryo transfer (ET) cycle.

RESULTS

After adjustment for potential confounders, the PGT-A group exhibited significantly lower cumulative rates of biochemical pregnancy [19.96 % vs. 30.22 %, p-adjusted (p-adj) < 0.001], clinical pregnancy (17.55 % vs. 23.38 %, p-adj < 0.001) and live birth (14.14 % vs. 16.19 %, p-adj = 0.005) per oocyte retrieval compared with the drop-out group. In contrast, when analysed per ET procedure, the PGT-A group showed marked improvements in rates of biochemical pregnancy (72.16 % vs. 35.50 %, p-adj < 0.001), clinical pregnancy (61.86 % vs. 26.98 %, p-adj < 0.001) and live birth (48.45 % vs. 18.26 %, p-adj < 0.001) compared with the drop-out group. No significant differences were observed in cumulative miscarriage and ectopic pregnancy rates, number of ETs per live birth, and neonatal outcomes between the groups.

CONCLUSIONS

This retrospective study of patients with limited good-quality embryos found that the PGT-A group had a lower cumulative live birth rate per oocyte retrieval, but superior pregnancy outcomes per ET compared with the drop-out group.

Frozen versus fresh embryo transfer in women with low prognosis for in vitro fertilisation treatment: pragmatic, multicentre, randomised controlled trial

OBJECTIVE

To test the hypothesis that a freeze-all strategy would increase the chance of live birth compared with fresh embryo transfer in women with low prognosis for in vitro fertilisation (IVF) treatment.

DESIGN

Pragmatic, multicentre, randomised controlled trial.

SETTING

Nine academic fertility centres in China.

PARTICIPANTS

838 women with a low prognosis for IVF treatment defined by ≤9 oocytes retrieved or poor ovarian reserve (antral follicle count <5 or serum anti-Müllerian hormone level <8.6 pmol/L).

INTERVENTIONS

Eligible participants were randomised (1:1) to undergo either frozen embryo transfer or fresh embryo transfer on the day of oocyte retrieval. Participants in the frozen embryo transfer group had all of their embryos cryopreserved and underwent frozen embryo transfer later. Participants in the fresh embryo transfer group underwent fresh embryo transfer after oocyte retrieval.

MAIN OUTCOME MEASURES

The primary outcome was live birth, defined as the delivery of neonates with a heartbeat and respiration at ≥28 weeks' gestation. Secondary outcomes were clinical pregnancy, singleton or twin pregnancy, pregnancy loss, ectopic pregnancy, birth weight, maternal and neonatal complications, and cumulative live birth after embryo transfers within one year after randomisation.

RESULTS

In an intention-to-treat analysis, the rate of live birth was lower in the frozen embryo transfer group than in the fresh embryo transfer group (32% (132 of 419) v 40% (168 of 419); relative ratio 0.79 (95% confidence interval 0.65 to 0.94); P=0.009). The frozen embryo group had a lower rate of clinical pregnancy than the fresh embryo group (39% (164 of 419) v 47% (197 of 419); 0.83 (0.71 to 0.97)). The cumulative live birth rate was lower in the frozen embryo transfer group compared with the fresh embryo transfer group (44% (185 of 419) v 51% (215 of 419), 0.86 (0.75 to 0.99)). No difference was observed in birth weight, incidence of obstetric complications, or risk of neonatal morbidities.

CONCLUSIONS

Fresh embryo transfer may be a better choice for women with low prognosis in terms of live birth rate compared with a freeze-all strategy. The treatment strategies that prevent fresh embryo transfers, such as accumulating embryos with back-to-back cycles or performing routine preimplantation genetic testing for aneuploidy, warrant further studies in women with a low prognosis.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2100050168.

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.

Preimplantation genetic testing: A narrative review

Preimplantation genetic testing (PGT) is a diagnostic procedure that has become a powerful complement to assisted reproduction techniques. PGT has numerous indications, and there is a wide range of techniques that can be used, each with advantages and limitations that should be considered before choosing the more adequate one. In this article, it is reviewed the indications for PGT, biopsy and diagnostic technologies, along with their evolution, while also broaching new emerging methods.

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.

PGT-A: Houston, we have a problem

Preimplantation genetic testing for aneuploidy (PGT-A) is a common add-on to IVF cycles. As it is presently performed, PGT-A relies on whole genome amplification of small amounts of DNA from cells removed from the trophectoderm (TE) of a blastocyst for determination of gain or loss of chromosomal material by next-generation sequencing. Whole genome amplification may introduce artifacts such as allele dropout and loss of heterozygosity in up to 25% of cases. In addition, the high prevalence of mosaicism in human embryos is a complicating factor in interpreting the results of PGT-A screening. In the presence of mosaicism, biopsy of TE cells cannot provide accurate results regarding the chromosomal make-up of the inner cell mass. The available clinical data suggest that PGT-A is probably harmful when IVF outcomes are analyzed by intention to treat or by live birth rate per cycle started rather than per embryo transfer, especially in women with three or fewer blastocysts. In addition, hypothesized advantages of reduced spontaneous abortion rate and reduced time to conception may be modest at best.