Genetic testing of IVF-created embryos could help more women over 35 have a baby sooner

Genetic testing of IVF-created embryos could help more women over 35 have a baby in less time, a clinical trial by researchers from King's College London, King's College Hospital, and King's Fertility has found.

Published today in the Journal of Clinical Medicine, this is the first randomised controlled trial worldwide to focus exclusively on women aged 35–42, a group at higher risk of producing embryos with chromosomal abnormalities. The trial looked at the use of Preimplantation genetic testing for aneuploidy (PGT-A) to check embryos for chromosomal abnormalities before transfer.

Older women are more likely to produce embryos with the wrong number of chromosomes, which can lead to difficulties conceiving, and increases the risk of miscarriage. Current NICE guidance does not currently recommend routine use of PGT-A, driving women to pursue this test privately or skip it altogether. This guidance is based on previous evidence from studies which had a young average age of participants where the rate of aneuploidy, abnormal number of chromosomes in a cell, is lower. The study also broke new ground by including mosaic embryos, those containing both normal and abnormal cells, which are frequently encountered in IVF but rarely included in research.

The pilot study of 100 women undergoing fertility treatment at King's Fertility was aimed to fill the evidence gap by focusing on older patients, and assessing the feasibility of conducting a multi-centre randomised controlled trial that explores the test's impact on pregnancy and live birth rates in women aged 35-42. Both the clinical treatment and embryology procedures for the study were carried out at King's Fertility.

The unblinded trial was conducted from June 2021 to June 2023. There were 50 patients in the PGT-A group and 50 patients in the control group.

The study showed that the PGT-A test showed a higher cumulative live birth rate after up to three embryo transfers with 72% in the PGT-A group versus 52% in the control group.

Women in the PGT-A group achieved pregnancy in fewer transfers, reducing the time to conception, an important factor for women of advanced reproductive age.

Whilst this is a pilot study and the difference did not reach statistical significance due to the small sample size, the trend suggests a potential benefit that warrants investigation in a larger, multi-centre trial.

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. This increases the risk of unsuccessful implantation and miscarriages. 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."

Dr. Yusuf Beebeejaun, first author of the paper at King's College London and King's Fertility

Lead author Dr Sesh Sunkara from King's College London and King's Fertility added: "By focusing exclusively on women aged 35–42 and including mosaic embryos, we have addressed questions that previous studies have not adequately explored. While larger multi-centre trials are needed to confirm these findings, 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."

Dr. Ippokratis Sarris, Director of King's Fertility and co-author of the study, said: "This research is a testament to the dedication and expertise of the team at King's Fertility. Not only were all patients recruited and treated here, but the embryology work was also carried out by our laboratory staff. We are proud to have led this pioneering trial, which addresses one of the most important questions in IVF treatment for women over 35, and we look forward to building on these findings in larger, multi-centre studies."