Paradox, if I remember pregnancy and early motherhood (my oldest is nearing 18 so it has been a while), I found that even while pregnant I became very protective of my child and changed in many ways to reflect that. For example, I became obsessive about wearing a seat belt in the car (years before it became law to). I also called the IRS to tell them I wanted to settle and old debt (big mistake..don't ever do this).
I am not, nor have ever been a JW, but from what I am learning from my partner and these boards, is that the JWs believe that you must be a member in good standing in order to be resurrected after Armageddon, and that if you don't believe and act accordingly, you are doomed to Hell. As a mother, it makes sense to protect your children, and for a JW mom, that includes protecting their soul and their eternity. Hence her need to get back into the fold, even if it means excluding you, makes sense if you consider this belief.
She may well still love you, but her overriding need to protect her baby is winning. Also, depending upon her relationship with her family, she may feel the need to be closer to them, and to do that, she may have to be in the church.
At least that is what I suspect may be going on. Perhaps you can ask her. Getting her to assess her feelings honestly is a good start. IF this is the case, then you can figure out what your next path is. As to getting her to see the light and not go back, I can't offer any advice there as I haven't a clue. As an outsider it seems so illogical to me, but you're in a good place to ask those questions for many here have been through it.
However none of it looks optimistic. I will say though, if her goal in going back is to protect her child, it may prove to be the foundation by which the two of you can reach some agreements to keep you in YOUR child's life as that is in the baby's best interest, even if the church doesn't see it that way. Kids need both parents and many couples on these boards where one partner is in and one is out, have reached a compromise so they can coparent effectively.