Several state legislatures are taking it upon themselves to define "personhood" as something that begins at one's first heartbeat, i.e. which is defined by the presence of a natural heartbeat. Okay well what about children, or any other people, with artificial hearts? I guess they're...not people then...right?
You see, people, personhood is so much more than just having a heartbeat, human DNA, or "potential". (Any egg cell or sperm has the "potential" to become a person, but that obviously doesn't mean it deserves legal rights, and we can all recognize that much.) Everything of value to human beings -- from our ability to perceive the world around us to our ability to form relationships -- is made possible by birth. Without these sorts of capacities, our's is but a shell of a life in comparison; a life only in a technical sense, not in a recognizable one.