I don’t know about your country, but here in Europe, most historical statisticians point to two facts, that remained unchanged at least since medieval times and were proven times and times again:

• people in the cities have fewer children that people in the villages
• people in villages have fewer children the less they need hands to do the work

So yeah, everything you wrote is true, up to and including “people can’t afford children because of the new vampires”, but it’s not THE reason why they don’t have children.

(IIRC its best explained here: en.wikipedia.org/wiki/Demographic_transition)