What did Europe do to solve under population?

(1) A one-time bonus: the government provides parents with a fixed sum of money, as in Russia, where each family receives a bonus of $9,600 following the birth of a second child and any subsequent children.

(2) A parental leave program, allowing parents to stop work after a child is born, as in Sweden where either the mother (or the father) can take 480 days of parental leave with guaranteed reemployment.

(3) A government subsidy for a set period of time, often pegged to the parental leave program, as in Sweden, where the mother can receive 80% of her salary during the period of leave.

(4) Government-run daycare centers that take babies to preschool-aged children, as in France and Sweden.

(5) Small monthly subsidies for dependent children, called, in German-speaking countries, "Kindergeld."