The constitution allows rights upon birth or naturalization - not upon conception, or any point between conception and birth. That would cause a legal nightmare. "Little Johnny was conceived on my trip to Miami judge, so he should be allowed US citizenship and rights. Of course that was 45 years ago - but see here is the airline ticket and hotel receipt that proves I was in Miami 8-1/2 months before he was born (he was 2 weeks early)."
Locke certainly includes 'born' as a precondition to life liberty and property... not conceived.
A state also of equality, wherein all the power and jurisdiction is reciprocal, no one having more than another; there being nothing more evident, than that creatures of the same species and rank, promiscuously born to all the same advantages of nature, and the use of the same faculties, should also be equal one amongst another without subordination or subjection, unless the lord and master of them all should, by any manifest declaration of his will, set one above another, and confer on him, by an evident and clear appointment, an undoubted right to dominion and sovereignty.
and
Man being born, as has been proved, with a title to perfect freedom, and an uncontrouled enjoyment of all the rights and privileges of the law of nature, equally with any other man, or number of men in the world, hath by nature a power, not only to preserve his property, that is, his life, liberty and estate, against the injuries and attempts of other men; but to judge of, and punish the breaches of that law in others, as he is persuaded the offence deserves, even with death itself, in crimes where the heinousness of the fact, in his opinion, requires it.
Locke knew of the biological progression from conception to birth - and yet, birth was the point where rights and privileges of the law of nature began.
Adams included it in the Declaration of Rights of the Inhabitants of the Commonwealth of Massachusetts
All men are born free and equal, and have certain natural, essential, and unalienable rights; among which may be reckoned the right of enjoying and defending their lives and liberties; that of acquiring, possessing, and protecting property; in fine, that of seeking and obtaining their safety and happiness.
Jefferson also used 'born' as a qualifier..
Under the law of nature, all men are born free, every one comes into the world with a right to his own person, which includes the liberty of moving and using it at his own will. This is what is called personal liberty, and is given him by the Author of nature, because necessary for his own sustenance.
George Mason included it in the Virginia Declaration of Rights
That all men are born equally free and independent, and have certain inherent natural Rights, of which they cannot, by any Compact, deprive, or divest their Posterity; among which are the Enjoyment of Life and Liberty, with the Means of acquiring and possessing Property, and pursuing and Obtaining Happiness and Safety.
Ben Franklin went with 'born' for Pennsylvania's Declaration of Rights
That all men are born equally free and independent, and have certain natural, inherent and inalienable rights, amongst which are, the enjoying and defending life and liberty, acquiring, possessing and protecting property, and pursuing and obtaining happiness and safety.
Abortions have been around for centuries - and certainly were available at the time of the founding fathers and Locke, and were not punished as a criminal act. Rights, unalienable ones, started at birth, not at conception. None of them used 'all men are conceived with certain rights'.
Shag, judges decide on cases all the time where they are 'unqualified'. Do they really understand the hazardous properties of radioactive waste? Are they doctors and do they really comprehend the nuances of the health effects of formaldehyde? Yet they routinely decide cases where those issues are in play.
Who should decide Shag when life begins? You asked the question - no doubt you have an answer.