Moreover, the world's population has been heading toward stabilization for more than 30 years. Worldwide, women today have an average of 3 children compared to 3.2 in 1990, 3.7 in 1980, and 5 in 1950. The population controllers credit their efforts, while still complaining that not enough is being done. But the fall in those rates preceded their campaign. In preindustrial, agricultural economies, children produce wealth as farm workers, and later they provide retirement security for their parents.
Children are assets.
A large number of children correlates with wealth. In developed economies, children consume wealth, for education and the like. They are an expense. Thus people tend to have fewer kids. A low fertility rate is an effect, not a cause, of development.