Aneuploidy
The presence of an abnormal number of chromosomes in a cell, such as an embryo having too many or too few.
In plain English
It means an embryo's chromosomes aren't in the usual complete set, which usually stops it developing or implanting.
Why it matters
Aneuploidy becomes more common in eggs as women get older, and it's the main thing PGT-A testing looks for.
Related terms
Guides that cover this
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