system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does waiting until you're older to have a baby increase the chances of it having autism?
gpt
Women are born with all the eggs they will ever have, they aren't created month to month.  Those eggs age and can break down like all the other cells in the body.  Autism and other disorders happen because of problems of brain development, most often between parts of the brain that create links between the part of the brain that processes information in a conceptual manner.  
TL;DR old eggs are more prone to developing abnormalities.