Reproduction can be said to be incentivized in low-income groups as children can often participate in the tasks (typically manual labor) performed by the family

Reproduction can be said to be incentivized in low-income groups as children can often participate in the tasks (typically manual labor) performed by the family. Meanwhile, in high-income groups, children take away resources that could be invested into the parents' career progression and wealth management. Of course low-income groups also suffer from lack of access to contraception, so it's not as straightforward, but that is the birds' eye overview of how it typically works.