See how fast your right to life disappears if you don't exercise moral restraint and refrain from taking the lives of others. Contrary to popular sentiment, all rights are earned by constantly exercising your moral competence, which fetuses have none of.
One thing I like to do is explore the consequences of a proposed system of ethics using real-life situations. This concept of earning one's rights, or earning one's citizenship which entitles you to rights (presumably including the right not to be killed by another) is an approach that I have not encountered before. It would be interesting to see where this concept leads us in various situations.
First, let me say that the examples I will present are based on personal experience. I share information of this kind not to gain sympathy or approbation, but to short-circuit any accusations of setting up and knocking down strawmen. With that in mind, lets begin with:
Case 1: Infancy
I, like many others here, have had the experience of fathering and raising a child. There is a period of time, for average children, ranging between birth and somewhere between a year or two old, wherein the child's interactions are essentially needs-driven. While the child is capable of appropriate responses and interaction, it is clear that the development of the individual is insufficient to formulate and exercise moral judgements. IOW, by the standards you discuss, this individual has not earned any rights. But, the child is undeniably human, fully formed for its normal stage of development, individuated, and present before your eyes. Now, because this person is not a citizen, that is, hasn't shown the capacity to exercsie moral judgements, does it have a right to not be killed by another?
Lets put all the rights on the table and weigh them. The child is innocent of any serious moral wrongdoing. Sure, it has needs and wants, but this is nothing extraordinary given the state of its natural development. However, to its parents, it may be a burden. Perhaps the mother (who seems to have absolute power in the pre-birth stage, so why not afterwards?) has changed her mind. She doesn't like waking up at 2 a.m. for feedings, perhaps is sick of dirty diapers, and just wants to get out more. The child is impeding her pursuit of happiness. Now, can she call in an abortionist and burn the skin off that kid until it dies? Why or why not? Remember, this is not a full citizen because it hasn't earned it by exercising any moral competance.
I should point out that, in some ways, we have already seen this kind of behavior as a consequence of the pro-abortion, morally relativistic society we seem to be drifting into. You hear horror stories all the time of mothers giving birth to children and stuffing them in a dumpster, or flushing them down a toilet and heading back out to the dance, or maybe drowning them one by one in a bathtub. Most of us with any shred of decency and civilized thought find such acts damnable and repugnant in the extreme.
Case 2: The Handicapped Child
One of the children of one of my cousins was born with a profound mental developmental delay. She is blind, and has the mind of a child of about one year of age, although she is now just over 20 years old, and is otherwise healthy. She will likely live a normal lifespan. As in the case of the infant, this individual is able to express needs-based responses, and limited interactions with others, but shows no clear sign, after all this time, of any ability to exercise moral competancy. IOW, this person has not earned any rights, by your standrds, and evidently is not a "citizen". Now, as such, may this person be proactively killed by another? She has done nothing to "earn" anything, and one might argue is certainly a burden on her parents and perhaps society at large. Putting those rights out on the table, there is clearly a conflict. Can we resolve it on the basis of the non-citizen argument, and simply do away with the inconvenient person? If we did so, would we be exempt from any legal or moral consequences?
Case 3: The Aged Parent
I was my mother's legal guardian and caregiver in her later years when she was stricken with Alzheimer's Disease. As anyone who has dealt with this illness in a loved one will attest, as the illness progresses, the victim is less able to process or recall information, make sense of their situation and surroundings, and certainly reaches a point of not being able to excercise any modicum of moral competance. Has this person then lost some or all of their rights? Have they lost their "citizenship"? If so, are they fair game for a late-life abortion? Again, put the rights on the table and weigh them. By the standards you seem to espouse, they have no rights, perhaps not even a right to live? Can I take out a .38 pistol and end their misery (or is it my misery I'm ending by killing them)? What gives me the moral authority to do so? Certainly the individual is a burden and perhaps impeding my pursuit of happiness. Does that trump whatever the other individual might have to counter my right to take action (kill them) to restore my pursuit of happiness? After all, I'm paying $4000 a month for her care, and visit her every day on my lunch hour and over the weekends. Surely the authorities will not charge me with murder if I quietly, in secret where no one will see or hear any screams, in the most private of all places I can find in my home, place a pillow over her nose and mouth and proactively end her life?
No, I don't think so. While you can argue that maybe I willingly undertook the burden of care (which I did, out of love and loyalty to my parent), that is insufficent to deny that the individual is viewed, in the eyes of the law and any kind of enlightened ethical system, as an entity that is permitted to exist, as its natural development and circumstance allows, in peace, without threat of being murdered by another based on whatever motives or perceived rights they may assert they have. IOW, the operable factor is something inherent in the individual, not granted by government or any other human agency, that allows them to exist with the life they are endowed with.
And these examples illustrate well the danger inherent in vesting the right to live, one's personhood, or humanity, or whatever you choose to call it, in an agency other than the individual him/herself, encompassing the broadest sweep of the continuum that is human life. For, if we insist on imposing narrow definitions of one sort or another, the result can only be measureless destruction.