An aneuploid embryo, egg or sperm has an abnormal number of chromosomes — either an extra chromosome (trisomy) or a missing chromosome (monosomy) — rather than the expected number. Aneuploidy is common in human eggs and embryos, particularly with increasing maternal age, and is a frequent cause of failed implantation and early miscarriage. On a PGT-A report, an embryo classified as aneuploid is generally not recommended for transfer because of a substantially lower chance of a successful, ongoing pregnancy, though the clinical significance can vary with the specific chromosome involved. Being told an embryo is aneuploid does not mean a couple or individual has 'bad' eggs or sperm — aneuploidy is a common biological event, not a reflection of a person's health or worth.
Also known as: aneuploidy, chromosomally abnormal embryo, trisomy embryo, monosomy embryo
Sources
- ICMR Standard Treatment Workflows (icmr.gov.in/standard-treatment-workflows-stws)
- European Society of Human Reproduction and Embryology (eshre.eu)
Last reviewed: 9 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.