I can't really help re pregnancy, my father has been diagnosed since I was 2.
I would get onto the MS Society and get in contact with PWMS, they will be able to give you some info re pregnancy and should be able to get you into contact with other women with experience.
The other thing I would do is find out exactly what it is they are concerned about wrt your pregnancy and birth, then chat to your neurologist and discuss the likelihood of those things presenting as complications, and how you can manage them.

What form of MS do you have?