Stillbirths constitute over half the global perinatal mortality, but only a minority will be registered in any health information system.(1) According to the World Health Organization (WHO) estimates, 3 million stillbirths occurred in 2004 (2), apparently down from 3.3 million in 2000 (1) and 4.3 million in 1995.(3) There is little reason to believe that this trend reflects a decade of success in stillbirth prevention, and the authors of the WHO estimates acknowledge that the latest figures by all accounts are a significant underestimation--due to definitions used, methods of counting and estimation for missing data, and underreporting; issues we address in this chapter.Considering the prevalence and enormity of the emotional burden to families, stillbirths are a major public health problem. Understanding the epidemiology of stillbirths is essential for any maternity and infant health care policy development, surveillance and international comparisons, clinical services, and research. For this, we need not only to understand the basic numbers, but accessible data is needed on core indicators of quality and availability of care, as well as on the most prevalent causes of death and associated conditions. This need for information is a pressing issue in stillbirth prevention, as the knowledge gap is wide.(4-9)Despite the scale of the problem, stillbirths have largely been ill-prioritized and understudied by most standards. Stillbirths are not included in the WHO reports on the Global Burden of Disease (10) and, in contrast to infant and maternal deaths, they are not included in the Millennium Development Goals and Targets of the United Nations. For every 50 publications on unexplained infant death (SIDS) in PubMed, there is only one on the far more prevalent entity of unexplained stillbirths, and as we will show in this chapter, the proportion of medical research that directly addresses stillbirth has fallen continuously for over 40 years. The "10/90 gap" indicating that less than 10% of research resources address conditions affecting more than 90% of the world's population (11) is used to highlight important gaps in the global research agenda. However, the research gap for stillbirths goes beyond this "10/90 gap"; of all publications on stillbirth in PubMed, about 3% relates to developing countries where 99% of third trimester stillbirths occur.The ultimate goal in studying stillbirth epidemiology is prevention. The vast majority of stillbirths are not only preventable, but simple inexpensive interventions could lead to an increase in births of healthy infants with greater life expectancy.(9, 12) Mothers and families could be spared the chagrin accompanying pregnancy loss, and societies spared loss of healthy lives.This chapter aims to introduce some of the concepts in stillbirth epidemiology; some core numbers on the global epidemiology; and how definitions, data collections, and statistics affect our understanding and guide our preventive efforts for some of the main categories of stillbirths. The actual interven...