That falls under the heading of "if my grandmother had wheels, she would be a wagon."
I know lots of people who go that route, and it is just plain stupid. Could we double our income if my wife worked? Well, yes, but we could also double our income if I took a sales job and spent 80 percent of my time traveling.
But that isn't the same as money spent on the child.
And the $450/month/child isn't money spent on the kids, it is money spent on yourself to maintain a certain lifestyle.
Ah, so to raise a child properly, one parent must sacrifice their career while the other is never around ... how enriching. I guess the other option is to not have children at all. I'll take the "stupid" route thank you.