A pilot clinical trial led by researchers at King’s College London, King’s College Hospital, and King’s Fertility suggests that genetic testing of embryos could improve IVF outcomes for women aged 35 and older.
The study, published in the Journal of Clinical Medicine, examined the use of preimplantation genetic testing for aneuploidy (PGT-A)—a screening method that identifies embryos with chromosomal abnormalities. Women in this age group face a higher risk of producing such embryos, which can result in failed implantation or miscarriage.
“The number of women starting families after 35 is increasing, and these women are more likely to create embryos with the wrong number of chromosomes,” said first author Yusuf Beebeejaun, PhD, a consultant in reproductive medicine at King’s Fertility. “Our findings suggest that targeted use of PGT-A in this age group could help women have a baby sooner, while reducing the emotional toll of repeated unsuccessful cycles.”
The randomized pilot trial, conducted between June 2021 and June 2023 at King’s Fertility, enrolled 100 women aged 35–42 undergoing IVF. Participants were randomly assigned to one of two groups: embryo selection by morphology alone with fresh transfer, or PGT-A with frozen transfer of a chromosomally normal embryo.
Of the 247 eligible patients, 138 agreed to participate—a recruitment rate of nearly 56%. The primary aim was to evaluate the feasibility of a larger multicenter trial, while also exploring pregnancy and live birth outcomes.
Results showed that 72% of women in the PGT-A group achieved a live birth after up to three embryo transfers, compared with 52% in the control group. Although the difference was not statistically significant due to the small sample size, researchers noted the trend suggested potential benefits. Clinical pregnancy after the first transfer was also higher in the PGT-A group (82% vs. 70%).
Lead author Sesh Sunkara, MD, highlighted the study’s unique focus. “By focusing exclusively on women aged 35–42 and including mosaic embryos, we addressed questions that previous trials did not fully explore,” she said. Mosaic embryos, which contain both normal and abnormal cells, are common in IVF but are often excluded from clinical research.
The study also underscored the feasibility of conducting larger randomized controlled trials (RCTs) of PGT-A in older women. The researchers recommend that future trials measure live birth and miscarriage rates, recruit more diverse populations, and adopt multicenter designs to strengthen findings.
Despite its limited size, the trial had several strengths, including its focus on women with high risk of chromosomal abnormalities and its use of intention-to-treat analysis, which reflects real-world outcomes.
The researchers concluded that while larger studies are needed, this pilot trial offers valuable insights into tailoring IVF strategies for women over 35.
