One of the greatest incentives behind the reason why people who live in the least industrialized nations have more children is

There are three reasons why people living in low industrialized nations have more children:(1)  the status that parenthood provides(2) the community supports the "parenthood status" viewThe first two reasons stress that in the least industrialized nations, there is the abundance of the patriarchal status, including that of reproduction. There is an importance placed on the male virility and dominance that includes being able to father multiple children. (3) children are considered as economic assetsThe third reason is that parents rely on the children to care for them once they are older.

The answer would be political systems .

Accumulating more land so that your country can continue expanding without running into problems such as overpopulation