The chances of your child getting ms, if you have it, are something like 8 times higher than for the general population -- but that is still not a huge chance. Not to put a negative spin on it, but there is just as much chance of any baby having some other kind of birth defect.
If you want to improve your child's odds, you should move as close to the equator as you can -- the effect of latitude (probably sunlight) seems to be able to overcome a good proportion of predisposition. Studies show ms is lower in places closer to the equator, and people who move to those places have lower ms rates than in the places they moved from.