23w pregnant. petrified baby will be born with a severe disability such as cerebral palsy. are the odds high?

Not high: Unless you have strong risk factors for preterm labor, the odd are not high that you will deliver early. Stressing over this possibility won't help either. Try and relax.

Realistic risks: Every pregnancy at any age has a background of potential risks. Add them all up and they reach 4% including all types of defects, prematurity, newborn illnesses, etc. That means 96% will have a good outcome.If you have a specific risk brought about by an illness or genetic factor that adds a slight amount. You may want to talk it over with a genetic counselor who can be more specific for your case.