I would love to loan you money at 20% interest. Send me a private message if you're interested.

but they're not yet;

When playing chess, how many moves ahead do you look?

you're not doing harm to a person by infanticide any more than you are by using contraception.

A man produces about 47 billion sperm a year; a woman releases 13 eggs a year; a couple that tries to become pregnant over the course of a year will have a 75% chance of live birth pregnancy if the female is 30. So each feasible sperm-egg combination over the course of a year has about a trillionth chance of making it to a live birth. *

As soon as conception happens, then you've got a zygote which is very likely to make it to live birth. And once it makes it to live birth, it's very likely to make it to adulthood. So there seems to be a very bright line at conception. (Contraceptives prevent conception; condoms by preventing sperm from entering, the pill by preventing ovulation, and so on.)

(I should note that I think there are sound reasons to treat a risk that will end one out of a trillion people chosen at random as less of a concern than a risk that is certain to end a certain person, and that this line of reasoning depends heavily on this premise, but it would take too long to go into those reasons here. I can in another comment if you're interested.)

*Noting that 'potential resulting individual DNAs' are individually much less likely than just sperm-egg combinations.