Maternal age drives embryo arrest independently of chromosomal errors

A new research paper was published in Volume 17, Issue 10 of Aging-US on October 10, 2025, titled "Developmental arrest rate of an embryo cohort correlates with advancing reproductive age, but not with the aneuploidy rate of the resulting blastocysts in good prognosis patients: a study of 25,974 embryos."

In this large-scale study, Andres Reig of the IVIRMA Global Research Alliance and Robert Wood Johnson Medical School, along with Emre Seli of the IVIRMA Global Research Alliance and Yale School of Medicine, investigated how female age and chromosomal abnormalities affect embryo development in patients undergoing in vitro fertilization (IVF). They found that embryo developmental arrest (EDA) becomes more common as women age. However, this arrest is not directly associated with the presence of chromosomal errors in the embryos that continue to develop. These findings could help improve fertility counseling and treatment strategies.

The researchers analyzed 25,974 embryos from 1,928 IVF cycles, all from patients with a good chance of success. The study showed that the percentage of embryos that stopped developing before reaching the blastocyst stage increased with age: from 33% in women under 35 to 44% in those over 42. Despite this rise, the rate of chromosomal abnormalities, known as aneuploidy, in the embryos that did reach the blastocyst stage did not show a strong connection with the rate of arrest after adjusting for age.

This distinction is important because both developmental arrest and aneuploidy reduce the number of embryos suitable for transfer. But this study suggests they are caused by different biological processes. In other words, an embryo may stop developing even if it has the correct number of chromosomes, and some embryos with chromosomal abnormalities may still grow to the blastocyst stage.

Importantly, the study focused on embryos that developed far enough to be tested, which helped avoid technical problems that come with analyzing arrested embryos directly. This approach allowed for more reliable comparisons across age groups and embryo quality.

Overall, the study highlights the importance of maternal age as a key factor in embryo development, independent of chromosomal results. It also opens new directions for research, aiming to better understand why embryos fail to develop and how this knowledge might lead to improved fertility treatments in the future.