Demographic Winter. If you haven't seen it, you should. It addresses some of the reasons for and potential problems of population decline. It actually reminded me a lot of the Feminine Minority, which I liked parts of, but not others. Demographic Winter actually made me think, sounds like we ought to have another baby! It was eye-opening and nice to see so many other people interested in the survival of the family. I wish I could write a better summary, but I'm pooped!
Warning: I have to add that it does have a bit of a doom & gloom and propaganda feel to it. Doom and gloom because of the stats (which can say anything, I know); and propaganda because of the constant dramatic music. There's also a bit of repeat in part 2 that was in part 1. I guess if you had to choose one to watch, I'd watch the 2nd, so you can get the conclusions.
If you watch it, let me know what you think.