“The child has its own rights to life and liberty.”
Actually, under current law, a child has few if any rights until the age of majority which is 16,18 or 21 depending on the state. That is why it is a child and not an adult.
Furthermore, until about month 6 after conception, the unborn will fail to be able to biologically function on its own without extraordinary medical intervention. It is totally dependent on the mother’s biological processes to continue to live.
Something that is that dependent and interwoven with the mother could be considered an extension of the mom’s body and she has ownership until the time when that appendage can be removed and function on its own biologically.
The most fundamental liberty is life itself, and a child doesn’t give up that right simply because it is dependent on its parent. Although some might consider an unborn child an extension of the mom’s body, it’s not. It’s medically and scientifically a separate entity.