Doctors now believe a fetus can become viable during the 23 rd week--a week earlier than was thought 24 years ago. Most hospitals will only perform abortions through the 22 nd week of pregnancy.ecause the point of viability varies, the court ruled, it could only be determined case by case and by the woman's own doctor. Even if the fetus is viable, the court said, states could not outlaw an abortion if the woman's life or health was at stake.