Hi, thanks for using healtcare magic
If he has already had surgical repair of the gastroschisis
(the bowel outside of the abdomen) then the baby has a good chance of full recovery with regard to this issue.
In terms of the prosthesis- he will adapt to it and it would require changing the length as he grows older. This would be done by his doctor, children with prosthesis can do well with adequate love and support. It would be important to focus on his strengths and nor any difficulties he may have at the moment. I know this may be easier said than done.
You may want to discuss any potential issues you are unsure about with your family and your doctor.
I hope everything works out for the best, for you and the baby