This is a subject a friend and I have tossed around for a while now. And I see it come up a lot in homeschool circles. And, frankly, it really bugs me..
Let me say that I think every marriage should be open to having children. It's one of the primary designs for marriage. I think married people should be fruitful and multiply, to pass on a Christian heritage to their children.
But the "quiver-full" movement says that you MUST, you are COMMANDED, to have as many children as possible (sounds like my Mormon neighbors...) to be an obedient Christian. There is a status, a pride involved here. That's not to say that all large families are arrogant about it, but when parents of very large families look down on or criticize a smaller family as though they are living in sin for not having ten kids, then I think there's a problem.