Look I support women's right to choose their own reproductive activity, but that argument is nonsense. It's logically, and technically, invalid.
The fetus is an entity, or being if you prefer, that is unquestionably a human organism. "Personhood" is an imaginary quality that people sometimes apply to animals, or even inanimate objects in many cases.. Neither the words entity or being connote "personhood" in any way so that is flat out nonsense. People anthropomorphize their cars all the time, for example. They even name them. Are they people? No. That is a meaningless distinction.
If you want a decent argument argue that a person has a right to control their own health as they see fit, privately. It's really no ones business what happens when you go to the doctor. That's the only argument you need.