In my experience, virtually the only reason why people don’t want more kids is that they don’t feel like spending any more time on childcare.  The strictly financial cost of another child almost never comes up. 

Granted, I greatly oversample the well-educated and the top two quintiles of the income distribution.  But it’s not like these people never gripe about money.  They just don’t gripe about money in the context of family size.  When they think “bad stuff about another kid,” it’s all “sleepless nights, changing diapers, lactating, and crying,” not “no French vacation, no nice restaurants, and waiting three more years for a new car.”

When someone rattles off a list of unwanted childcare duties, it’s easy to understand the connection between their complaints and their unwillingness to have another child.  They don’t feel like doing the work, and the work is, in their eyes, the bulk of the cost of the next kid.

What I don’t understand, though, is why people are so resistant to reversing this argument.  If another kid means a lot of work, that’s a big reason against having another kid.  Doesn’t it necessarily follow, then, that if someone figures out how to sharply reduce the per-child workload, that is a big reason in favor of having another kid? 

I don’t see any way around this.  Do you?