Far from having too many children, many women in developing countries, like their peers in the rich world, are actually having too few: that is, fewer children than they’d like to have. This claim may seem strange: we’re used to hearing about the problem of excessively high fertility in Africa, or the unmet need for contraception. But while unintended or undesired pregnancies are indeed concerningly high in many developing countries, where contraceptive access could be improved, that...