Scientists ... have published new findings about a cause of a condition at the root of genetic disorders such as Down Syndrome, pregnancy loss and infertility.
Called aneuploidy, the condition is an abnormal number of chromosomes, and the research team found that if a mother's egg cell has a mutation in just one copy of a gene, called Bub1, then she is less likely to have offspring that survive to birth.
... the harmful effects of this mutation increased with a mother's age. As the female mice got older, there was eventually a complete loss of their ability to support a full-term pregnancy that lined up with an increase in aneuploidy. The same is true in humans: the chance of having an aneuploid pregnancy increases with the age of the mother.