Clustering of deaths in families: infant and child mortality in historical perspective.

This introduction surveys the field of family clustering of deaths and discusses the contributions in this special issue. The main focus is on mortality in historical contexts. Clustering of deaths in families has been found both in historical and contemporary populations, and we argue that the 'family approach' to infant and child mortality yields important and interesting insights for our understanding of different mortality patterns and the mortality transition. The articles in this issue, representing different but complementary approaches to the problem of death clustering, demonstrate that we should be aware of the strong family effects on child health, but also that we need to develop adequate methods for the analysis of this complex phenomenon. Here we discuss several explanations for death clustering, such as different biodemographic factors and those focusing on socioeconomic and cultural variables. We also discuss some of the methodological challenges in studying family clustering, and emphasize the need for comparison and the adoption of common measures.