When you live in a society dominated by agriculture children are an asset. When you live in an industrial/service based society like our own children are a cos

When you live in a society dominated by agriculture children are an asset. When you live in an industrial/service based society like our own children are a cost. So generally speaking, most people have fewer children. As the world develops the trend continues. China is probably a data anomaly because of it's one child policy... however if it had not had it, i'd be willing to bet you could watch the trend. I'll just throw this out there, I pay $1600 a month for daycare. It's the reason I have 1 kid, and waiting before having a second. Throw into the mix better birth control tech/education/use, and this kind of restraint is possible.