Many migrants cluster in certain neighborhoods of large cities, primarily in squatter settlements at the edges of the cities (40). People who live in urban slums and squatter settlements often have little access to health care and other services (83). Clustering, however, offers an opportunity for reproductive health care providers to focus information and services on migrant communities (178). Other migrants live together at their places of work—for example, in factory dormitories, where service providers may be able to reach them (137, 232) (See Reaching Out with Services in Chapter 5.3.).

New migrants from rural areas often settle among earlier migrants. They are drawn together by common ethnicity, the presence of family or friends, or by the fact that they are joining others from the same village or region. How this pattern affects migrants' adaptation is not clear. On one hand, the tendency for recent migrants to live among earlier migrants might slow adaptation to urban attitudes and reproductive behavior by sheltering new arrivals from urban influences. On the other hand, it could speed their adaptation, because earlier migrants have already "learned the ropes" and can help new arrivals adapt (252).

Surveys such as the DHS can provide some information about characteristics of rural-to-urban migrants. Almost all information about characteristics of refugees and displaced persons are based on assessments by relief agencies. Because refugee situations change quickly, even accurate information can soon become inaccurate (258). Reproductive health programs need to collect and analyze data themselves to learn more about the people who have recently arrived in their service areas (see sidebar, Research Needs for Planning Services).