[ponector]

It is as simply as that. Economic support you mentioned is never enough to cover basic needs. Better than nothing, but still require to sacrifice a lot to have an extra kid.

More kids means you need a bigger house, bigger car, extra furniture, a part time job for mother to manage kids.

[Tor3]

I specifically mentioned families where the economy is not a burden, and they still don't want many children. Very few will want more than two. Please note that in my country at least, as long as the economy is good enough that there aren't any real problems living, then it doesn't matter if it costs more with more children. That is not the reason.