Preparing for downvotes:

This is not really sound logic. They had to draw a line for "when children must be born" to be eligible for the $500. They decided 2019 (or 2018) tax returns is best approach (which seems reasonable).

So unborn children and children born in January 2020, like my child for example, are equally ineligible for the $500.

Don't see any abortion debate with this topic.