I've seen a lot of people in the comments saying people needing to pass a test to have kids is a good idea, but I don't think they understand what that means. The US government used to take Indigenous children from their parents for reasons as asinine as grandparents living in the home (called "overcrowded environment") or using only their native language at home instead of English (because it "failed to prepare" children for a world where English is the dominant langauge).
Children placed in residental schools were abused, murdered, and sold into arranged marriages with white men. More recently, children "adopted" out into white households are often also subjected to the same, as well as forcibly converted to Christianity.
The most effective way to protect children in the country is to give them rights to ensure their safety, autonomy and dignity. Eugenics and laws to control reproduction will not do that. Crafting legislation with the help of child wellness experts is a better choice.