That's a tough one. Depending on whether she wants to keep the baby or not.
She needs to leave the abusive husband, but that's not always that easy. Sometimes the abusers will follow a person to the ends of the earth.
And the Legal System helping? Why do the above posters think that this is a slam-dunk???
If she carries the child to term there is a chance of the abuser taking the woman to court and getting legal custody of the child. Yes, surprise! It happens! Courts typically give children to the parent with the most money.
Also, with the Battered-Woman's Syndrom, sometimes if the Court does not believe what the woman is saying about the abuse, they will view her as "having psychological problems", which is exactly what the Syndrom can do. It can turn a person into a wreck!
So then if the abuser gets custody there is a chance that he would abuse or kill the child.
This is NOT an easy scenario. Again, it depends on whether she wants to have the baby or not, however, it just may be safer for her to get an abortion. This might spare her and the child from a life of hell! (If the abuser even allows either of them to live)