Let’s consider three ideas.
First, breastfeeding reduces infant sickness and death in poor and tropical places, largely because it insulates the child from water-borne illness.
Second, breastfeeding naturally reduces a mother’s fertility, and so mothers that want to have another child may stop breastfeeding early.
Third, in places where a sons are preferred over daughters newborn girls may be weaned sooner than boys.
If all three propositions are true, then [read the rest]