Most third-world countries see their population growth as a problem. And their governments desperately try to reach their people with information on birth control. And sterilization and abortion, too, yes, sometimes supported by outside forces, sometimes from internal pressures. I'm wandering, here, so let me try to get more concise:
1) Affluence and education are negatively correlated with population growth. The richer and better educated people are, the fewer children they have. This is not just a first-world vs third-world phenomenon--even within individual countries you can see this pattern repeated. The poor and uneducated breed the most.
2) Following from 1), educating and raising the living standard of the poor and uneducated will cause them to have less kids. You don't need to sterilize them or force them to abort. It's a natural consequence. You can see it happening throughout the world. There is a brief (fifty year or so) growth spike in countries as they move from "the dark ages" into "the modern world". It's the time frame where the country catches on to things like hygiene and health practices, but hasn't yet become well-off enough to have figured out the benefits of birth control. Or maybe they just haven't figured out that they don't need to have quite so many kids if more than 60% of children make it past the age of 5. I could postulate cause vs effect all day, but however you slice it, that's the way things have worked--so far, anyway.
3) Personally, I am more interested in the propogation of my ideas than I am of my genes. You referenced an article earlier this week showing that Christian populations are growing faster (and arguably more orthodox) in African, South American, and Middle Eastern countries than they are in European or North American ones. As long as the ideals of Christianity are being instilled into more people, I shouldn't think it would matter where or to whom they were born.
4) I wouldn't dream of telling you how many, or how few, children YOU PERSONALLY should have. If you and your wife want to raise ten children, more power to you. I do not believe that the world as a whole is going to suffer because you, as an individual, want to have lots of children. Why? Because there are plenty of people like, say, me, who do not want to have lots -- or even any -- children. My brother and his wife, who are about the most intelligent, successful, and loving people I know, have four children. If they wanted to, and did have, eight or ten more, I would be thrilled. I would love to see more people like them in the world. :)
5) I have the luxury of this stance because the current population trend world-wide is for a modest growth in population. Real-world statistics (not the hypothesized "no population control" ones I invented in the previous entry) estimate 9.3 billion people by 2050. That's a lot of additional people, granted, but I think technological advancements can handle that without significantly impacting quality of life for most people. We will lose some things, and we will gain others, and life will go on. It's nothing like the impact that a 400% increase would have. I don't think that the world currently has a significant population growth problem. As with economics and inflation, a little growth is OK. :)
6) My concern is with a hypothetical situation I consider highly unlikely--one where the world, as a whole, accepts the ideology of Biblical days: have as many children as you can possibly manage, and doing anything less is immoral. The world isn't moving in this direction and I doubt anything you or I say will cause the to happen. But if it did, I think it would cause a population explosion which would be bad for the ecology of the planet, and bad for the quality of life, including sanity and happiness, of the human race as a whole.
7) 6) above is why I do not believe that contraception is necessarily immoral.
8) Of course, it's still possible to debate whether the human race as a whole, or Americans or Christians as groups, have truly reached a point where maximum population growth is a mistake. But...for myself, I'm inclined to think we have. We've reached the point where overcrowding is an issue in many places, where the reserves of the earth are being significantly taxed, etc. Moreover, we have reached the point where children are not an economic asset to the parents. (And this is a good thing!) "Be fruitful and multiply" is an instruction, like eating and sleeping, to do something which was good for the people to do anyway, quite outside of spiritual matters. It isn't any more. I think that should mean that people should choose for themselves whether or not they want to raise children, rather than doing it "because G-d says it's right."
9) I'm less convinced by 8) than I was by the points immediately preceding it.
10) I think that's all I have to say.