The test should go like this: Once the child can perform its biological functions independently without a biological link to the mother, abortion should no longer be allowed. That's viability, and that's something that we would then call murder. I'm all about pro choice for women, but there has to be a line drawn somewhere.
Any time that an embryo that would otherwise develop normally is aborted, it is murdered, for it's life is cut short. Many claim this is not a human life, however it is undeniable that it would become a human life, regardless of how one defines human. If one is still in the womb and is destroyed, then it is murdered. Therefore viability is a good cut-off point for abortion.
When a child can live independently of its mother, we can
consider it a separate person. This also avoids the slippery slope of parents
deciding when they can kill the child at any point, as ethicists like John
Harris and Peter Singer said that even newborns could be killed because they
lack rational thought. Viability is a dividing line that permits abortion in the first and into the second trimester, giving women months to choose to end a pregnancy. It also recognizes the
child’s right to exist once it can live outside of the mother.
A good cut off point for abortion is the viability for such an operation that could have dire emotional consequences to the mother of the child. Abortion is a controversial topic and any viability that causes a mother to think twice about the procedure is causation to support women's choice.
Viability depends on the technology available to support the baby's life. The cutoff for viability will continue to be pushed back as we learn new ways to support the life of a premature infant, even in cases where the child suffer lifelong disabilities as a result of premature delivery. By about 20 weeks gestation, the fetus has developed structures in place that allow for consciousness. This makes more sense as a cutoff, after which point the rights of the child must be carefully weighed against the woman's right to bodily autonomy.