So you disagree - you have not demonstrate any LOGICAL or FACTUAL basis for that disagreement - which was what your original claim was.

the facts are that you cannot distinguish chromosomally the cell in your bed or the cell coming down the fallopian tubes.

the facts are that both cells require hormonal baths and the proper environment to potentiate.

the facts are that eventually both have the potential to be either sloughed or to create some sort of organism.

And the distinguishing difference is your perception of the two cells, the meaning you ASSIGN to them, nothing inherent in their existance.

As for womb-proximity - that is all the difference in the world. The Government has a right to act on separate persons. The Government has been ceded no rights to reach into a person and control their organs. So if something is contained within an organ of a person, it is offlimits to The Government. In this case the organ is the uterus, but it could just as easily be a kidney or part of a liver or intenstine or skin.

Since The Government is neither ceded the right to intrude and is explicitly prohibited from compelling involuntary service, the barrier of the skin and the uterus is the differentiating factor in The Government's right to act.