OK. So in the US specifically, the number of kids awaiting adoption is over 110,000, and rising significantly every year. 20,000 age out of foster care annually because (as Mysteriousgx says) people are much more likely to adopt infants. If there are theoretically over a million families looking to adopt, then clearly 1) geographic, 2) suitability, or 3) practical/ procedural/ financial factors are big enough to prevent them neatly matching up with kids needing families and solving the issue.No, there aren't. There is at all times an order of magnitude more families wanting to adopt than there are children to adopt (in the US*). There are older children stuck in the foster system, mostly either because their parents have only temporarily lost custody or because they have unique issues that any random family isn't equipped to manage, but there are dozens of hopeful would-be parents for every infant adopted. The average wait time is in years, without counting that the majority of people who consider adopting a baby give up on it.
*The UK is different, because for some reason your government has decided to make both giving away and adopting a child into miserable, arduous processes.
So the fact remains: you raise the likelihood of kids being born to people who cannot raise them, and you increase the number of kids without homes and families.
(On a side note, not aimed at tstorm, it should also be remembered that the US party most deeply preoccupied with restricting abortion is also the one most happy to gut funding for social programs like foster care, and the one which pursues preventing gay couples from adopting. The Republicans have very little interest in actually making these lives liveable. They're pro-life... until the point of birth, at which point they cease to give a shit).