Defining Personhood
What is a person?
A person is... "a philosophical concept designed to determine which individuals have human rights and responsibilities. Personhood may be distinguished by possession of defining characteristics, such as consciousness and rationality, or in terms of relationships with others."
Also, a person is a functioning member of society. Even if they are too young or too old to contribute much, if they have a mind, physical independence (they can live and breathe without the needed use of another person's body), they have hopes, dreams, intelligence, and other attributes that define a person that can function in a society, then they deserve human rights.
By nature, every person owns their own body and doesn't need another person to survive a few minutes or a few hours. You control your body and mind. Your body is all that you truly own in life, making it extremely valuable. Thus a person should never cause intentional harm to another person. If someone chooses to harm another person, then they forfeit their natural freedom, and are a danger to a free society, and must face punishment for their offenses. Most of all, no person has the right to use another person's body to survive, or to use another person's body to selfishly benefit themselves. That is slavery, and slavery devalues humanity. It should never be tolerated.
Not to sound cruel, but by nature, the unborn do not have personhood until they can inhale breath and exist on their own. By definition, a person is a human being regarded as an individual. It literally means a person will be able exist on their own. By nature, a parasitic organism inside another person's body is not a person or an individual. That doesn't mean the organism lacks value, but it is not a person, and it cannot be used to devalue the person that carries it. The host alone owns the unborn like they own their body since their body sustains the organism. The unborn is never more important than the fully functioning person that carries it. To declare otherwise is an attempt to steal someone's freedom and make them a slave to something they own. A parasitic organism that does not breathe, feel pain, or love is not a person. The host gives it value by choosing to protect it, and by nature, the host has full rights to their own body and the organism inside it. Once the organism is viable (can take air into its lungs) and can exist on its own outside of the womb, it can be considered a person and protected by law. Until then, the person carrying it should be protected and free to do what they need to do to take care of their body without interference.