She'll be hitting menopause soon, and at 45 she is probably already in peri-menopause. That will be the natural end of childbearing for her. In the meantime, I think her baby-making behind is writing checks her worn out uterus can't cash. Mother Nature gets the final say. And, since that's the way creation works, I guess you could call that God's will.
after her last two pregnancies, it's hard to believe that her husband (much less her doctor!) would encourage her to keep trying for yet another high risk pregnancy. I do understand her conviction to obey what she thinks is the will of God. But I also question her judgement, if not her sanity. It seems to me that she sees procreation as her main purpose in life, and that motherhood is much further down on her list of priorities.
That may seem judgmental and harsh. But, I ask you: did you have to make an appointment 2 weeks in advance to talk to your parents?