China has a highly mobile population of 140 million rural-to-urban migrants (10% of the total population) a number that is expected to increase in the coming decade. Migrants tend to follow a temporary and circular pattern moving between cities and provinces in search of improved opportunities. Overall the migrant population tends to be younger and is more likely to be male and single than the general population although more women and families have also started to migrate in recent years and more people are settling in cities. Indicators of socioeconomic status place the migrants below that of the urban population but above their rural counterparts. Migrants are largely excluded from urban services including access to public health. The health-care community in China has focused on three main concerns about migrant health. The first is infectious diseases: this highly mobile group can be both victims and vectors of such diseases which was particularly highlighted during the epidemic of severe acute respiratory syndrome. The second issue is maternal health. On every indicator of maternal and infant health the migrant population fares worse than the urban population. The third concern has been occupational disease and injuries in migrant workers including silicosis chemical poisoning and accidents caused by machinery. Those three main concerns however are only part of a broader picture that is poorly indicated in research about health issues for migrants. At the root of the issue is the self-selection of migrants that affects health in two ways. First young and healthy people are more likely to migrate than elderly people leaving the weak and sick at home. Second more serious and incapacitating diseases and intensive-care conditions (including old age pregnancy and delivery of the newborn child) result in a migrants return to the home in the village to seek family support and to avoid the high medical and living costs in cities. In essence the countryside is exporting good health and reimporting ill-health. (excerpt)