The social science of population health was a product of Enlightenment rationalism created in an effort to calculate the strength of the state in terms of the health of its subjects. Policy-makers also began to understand welfare provision in terms of family economy in the modern period, and by the late nineteenth and twentieth century maternalism and child welfare became the central platform of social policy. The concept of social hygiene which emerged in Sweden after 1900 aimed to improve population quality as part of a broad social project to address the ‘people’s health’ in order to achieve national efficiency, strength and modernization. The public health profession was able to use imperialist concerns about national efficiency and eugenic anxieties about human reproduction to mobilize support for an expansion of their demands for health services. The pronatalist campaign followed a period of rapid expansion in public health and social welfare legislation.