: Migration background is known to be an important risk factor for a number of medical outcomes. Still, relatively little is known about the epidemiologic relevance of different definitions of migration status. : Data from 5250 school entry examinations spanning three consecutive years (2015-2017) were gathered from the Public Health Department in Halle, Germany. Data were stratified according to six different migration statuses and evaluated for differences in health service utilization and developmental outcomes. : Compared to non-migrant children, migrant children have a lower utilization of preventative services, and higher frequencies of developmental delays. Children with first-generation migration background consistently show results worse than all others, while children with one-sided second-generation migration background show results similar to those of their non-migrant peers. These findings are not substantially altered by adjustment for social status. : Children with first-generation migration background should receive special attention in school entry examinations, since they constitute a group with consistently higher health risks compared to other groups of preschoolers.