Shim-pua marriage occurred over a range of socioeconomic classes, but was particularly common among poor and rural families. Among the well to do, marrying a son in a major marriage was prestigious and a display of status, but also costly. In poorer and more rural communities, shim-pua minor marriage was inexpensive and helped to ensure that no matter how poor a family was, their sons would have wives when they reached marrying age, and thus a greater likelihood of producing descendants. In contrast, the high bride price to acquire a bride for a son to wed in a major marriage could be prohibitive, sometimes as much as a year's income for the family. If the family could not afford such a bride for major marriage, this could result in a failure to produce descendants and the end of the family lineage. In contrast, the costs of adopting an infant daughter were low and the costs of raising her as a shim-pua often included only food and clothing. In poor communities, limited wealth or status motivated both the adoption of a shim-pua daughter into the family and the giving up of biological daughters as shim-pua to other families. For a family of limited means or social status, a biological daughter offered little surety; traditionally she would be married off into another family and would neither care for her parents in old age nor extend the family lineage. In contrast, a shim-pua daughter would remain in the household, caring for the parents through their old age, and would bear their descendants. For these reasons, adoption of an infant shim-pua daughter frequently coincided with giving up a biological infant daughter for adoption and then raising the shim-pua daughter in her place.