As I have said before, I'm an old man. reading posts such as this makes me sad as I remember "the good old days".
We did't know we were poor, nobody had any more than we did and we darn near starved to death.
I do remember going into the neighbors fields and eating fresh green corn and beans. Going into the "woods" and hunting some rabbits and squirrels for supper. Fishing in some streams and creeks so cold during the summer, you didn't want to fall in.
All this reminds me of what a friend told me not long ago.

Grand dad had a farm.
Dad had a garden.
Today I bought a new can opener.

With all the junk they put in our food today, I am suprised we have lasted this long.

If you look into all of the factors that come in to makeing a child, you will find that it is accually quite hard to do. Also, population growth rates seem to be dropping because developed nations cost more to raise children in, then take into account the general attitude by people of breeding age and you'll find that people are leaving that part of life later and later. This puts stress on the body and tends to take longer for conception. Where as in poorer, more ag-centered economy nations they have kids early and often. You should also look at infant and child mortality. Alot of people will have 6 kids expecting three of them to die before adulthood. This is not a plot or anything, This is an amalgimation of economic, health, bological processes, and cultural norms creating a preception of a population drop.

NOTE: I am no doctor or reproductive health expert, but because I've managed to have three kids in four years I've done alot of reading on the subject. More to find a way to stop having kids, seriously, I look at my wife and she gets prego! ;D Sorry about the spelling to sleepy to fix.