Child with Disabilities

I am a parent of a child diagnosed with a disability. They don't know what caused his disabilities but they wonder if it was the stress while I was pregnant with him (the stress of somebody trying to start a fight with me while pregnant leaving me in contractions at 4-1/2 months pregnant, the stress of being punched in the lower back while 8-1/2 months pregnant from this same person). Nobody can give me a clear answer on what caused it and it's a bit maddening.

I'm lucky in that his disabilities have been manageable and are not life threatening.