PGT-A might reduce unsuccessful embryo transfers in over 35s

Genetic testing of IVF embryos could help some women over 35 have a baby in less time, according to a small study focused exclusively on women aged 35-42.

Women above 35 are more likely to produce embryos with aneuploidy, an abnormal number of chromosomes, which can cause difficulties conceiving and increase the risk of miscarriage. While preimplantation genetic testing for aneuploidy (PGT-A) can screen IVF embryos for such abnormalities before transfer, UK guidelines from the National Institute for Health and Care Excellence currently do not recommend its routine use. This new trial, however, suggests that PGT-A could help women over 35 conceive faster.

'The number of women starting their family above the age of 35 is increasing and women in this age group are more likely to create embryos with the wrong number of chromosomes,' said Dr Yusuf Beebeejaun of King's College London and first author of the study. 'Our findings suggest that targeted use of PGT-A in this age group could help more women have a baby sooner, while also reducing the emotional toll of repeated unsuccessful cycles.'

PGT-A cannot improve the quality or number of embryos a patient has available, and can only help decide which ones to transfer. Researchers from King's College London, King's College Hospital and King's Fertility conducted this study from June 2021 to June 2023, enrolling 100 women aged 35 to 42 undergoing IVF with at least three good-quality embryos. Half were assigned to embryo selection using PGT-A, while the other half had selection based on appearance (morphology).

The results, published in the Journal of Clinical Medicine, showed that 72 percent of women in the PGT-A group had a baby after up to three embryo transfers, compared to 52 percent in the group using morphology alone. Women who received PGT-A also became pregnant in fewer transfer attempts, shortening the time to conception, a key concern for older patients.

Although the study was too small for the difference to be statistically significant, the researchers say the trend is encouraging and supports the feasibility for larger, multicentre trials. The trial also included mosaic embryos, those with both normal and abnormal cells, which are common in IVF but rarely studied.

'By focusing exclusively on women aged 35 to 42 and including mosaic embryos, we have addressed questions that previous studies have not adequately explored,' said Dr Sesh Sunkara from King's Fertility and lead author. 'Improving treatment efficiency with a shorter time to achieving pregnancy and live birth could reduce the physical and emotional burden of IVF for women of advanced reproductive age'.

PGT-A is not currently offered on the NHS and is usually accessed privately. It involves removing a few cells from an embryo, which the UK fertility regulator, the Human Fertilisation and Embryology Authority, warns can occasionally cause damage or misdiagnosis.

Some embryos that are identified as aneuploid can go on to become healthy babies (see BioNews 1097), and there are concerns that viable embryos like these have been discarded following PGT-A in the past.

The researchers noted that they were unable to draw conclusions regarding the effectiveness of the two intervention methods – due to the small sample size – and that further investigation is warranted to confirm the trial's findings. They suggest future studies should include women over 39 and lower the embryo quality threshold to increase eligibility and participation.