An early approach to this question was Mary Anne Warren's 1973 article "On the Moral and Legal Status of Abortion." She imagines a man kidnapped by space aliens with advanced technology; they want to put a bunch of humans in a zoo on their planet, but only took the one. (We can presume that the cloned humans will be cared for lavishly and would lead happy lives.) So he's strapped down on an assembly line which will take him into their disassembly/cloning lab and make many of his cells into new humans; in one version this procedure kills him, in another it merely takes some replaceable skin cells. The process is already in motion and will work if not stopped. Does the man have the right to try to escape? She thinks most people will answer: Yes, and obviously so. If so, the right to life of a potential x is much less than the right to life, or even the right to free movement, of an actual x.
Nor does it seem to matter if there is merely a potential for there to be more humans at the end of the process, but for specific, identifiable cells to become fully-developed humans (this one, and that one, etc.) The potentiality of such cells, which are very literally on a path (say, a conveyor belt) towards this full development, is very much like that of a fertilized egg, so if the man has the right to stop the process, likewise a pregnant woman has a right to stop this process, because doing so does not interfere with any other being's very important rights, Warren concludes.
One might object that there are at four least significant differences between this scenario and (most) ordinary pregnancies: 1) the process is artificial, rather than natural, 2) the potential is due to external manipulations rather than internal cellular machinery, 3) the process has not yet begun for the man's cells, but has for the woman's, 4) the man gave no consent for the cloning. First, note that if any of these matter, then it's not potentiality as such that confers a right to life, but a certain kind thereof, and we would need an argument for why that kind of potentiality matters and not others. There are problems for developing any such distinctions. The following responses to these objections are mine, and are not taken directly from Warren's work.
We often keep ill people alive, temporarily or permanently, via artificial means; the fact that their potential to be living persons tomorrow requires artificial means would hardly take away their right to life.
It is possible that the cloning technology works merely by removing a barrier to a cell's natural propensity to create a cloned human being, one which all cells have. This may not reflect biological reality, even though most cells carry a complete genetic code for producing a full human being. But we can imagine a possible world where cells did work this way, and it would be odd to say that in such a world, which otherwise looked much like ours, the man had no right to escape the cloning lab.
Suppose that this cloning process has already been triggered, and the man knows it, but the cells will begin their cloning process while still attached to his body; after a while they will grow into buds and fall off, then further develop into full human beings. The man still wants to escape, and doesn't want to be a parent of clones; he either seeks to escape and scrape these proto-buds off so they die before they develop further, or a side-effect of his escaping will be that he has to squeeze through a narrow passage which will scrape them off. Again, most people will presumably agree that he has this right, but it is possible that some would disagree.
If non-consent alone justifies an escape, then abortion in cases of rape would also be justifiable; some do make this distinction, but it concedes that the right to life (or whether such a right may be overridden) has nothing to do with potentiality. In any case, we can imagine cases where the man first consented to the cloning, then changed his mind after thinking about its implications, or consented with only a limited understanding of what it involved--possibilities with obvious parallels to various cases of pregnancy. Maintaining the distinction would require defending the judgment that the man's right to escape depends upon the validity of his prior consent.
Perhaps some combination of these distinctions, or other ones, can be made, between the man in the cloning lab and a pregnant woman and her fertilized eggs. But it is far from obvious how it can be made successfully.
Warren appeals only to intuitions about various cases, and does not explore why only actual personhood (presumably close to what you mean by "intelligent life") matters as opposed to merely potential personhood. An answer commonly given, with great variations in detail, by many philosophers (Kant, Scanlon, Tooley, Boonin, McMahan, Singer, etc.) is that persons have a very strong desire to live, and hence strongly disapprove of others killing us, or even failing to help prevent our deaths. But desires are only morally justifiable if you could approve of anyone else with a similar desire, in a similar situation, satisfying that same desire, i.e., we must "universalize" this desire (conceptions of moral universalizability differ among philosophers, e.g., between Kantians and consequentialists; we can bracket that for now). So we must not only not kill other people with such desires, but must help prevent their being killed (all of this is ceteris paribus; in wartime, medical emergencies, criminal justice, etc., where lives are somehow mutually threatening, the relevant situation may not be the same between persons). Even sleeping people, or depressed people, had prior times in their lives when they wanted to live after they went to sleep or became depressed, and killing them would frustrate these desires. But fertilized eggs and fetuses do not have, and never had, such desires (nor do most animals, who cannot conceptualize and hence desire their future existence, though they can desire to eat food, avoid pain, etc.) Hence killing them does not frustrate a morally-permissible desire, because they have no desire for continued life. Versions of this argument have been critiqued, of course, but it seems to support the basic distinction between actual and merely potential persons.