Why when a women gets older does it become more likely for her child to be born with down syndrome? And how come – Search I'm a Scientist. Get me Out of Here!

Question: Why when a women gets older does it become more likely for her child to be born with down syndrome? And how come chromosome 21 can not be altered or checked in the case of that?

Asked by on 19 Mar 2020.

Question: Why when a women gets older does it become more likely for her child to be born with down syndrome? And how come chromosome 21 can not be altered or checked in the case of that?