Economic migration and growth in informal employment in many of the major cities of developing countries, combined with health sector reforms that are increasingly relying on insurance and out-of-pocket payment, are raising concerns about equity and sustainability of economic and social development. In China, the number of internal migrants has dramatically grown since economic transition started in 1980, and maternal health care for these is a pressing issue to be addressed. To provide information for policy-makers and health administrators, a medical records review, a questionnaire survey and qualitative interviews were carried out in Minhang District, Shanghai. This paper describes important inequities in main maternal health outcomes and utilization indicators relating to economic and social transformation of the Chinese society. Analysis of the data collected clarifies that insufficient antenatal care is one of the main determinants for poor maternal health outcomes and that migrants are using antenatal care services significantly less than permanent residents. The data suggest that there is no single explanatory factor, but that migrants are faced with a package of obstacles to accessing health care services, and that health systems may need to rethink and redesign their delivery approaches to specifically target those groups that are faced with such multi-faceted packages of obstacles to service-access. Although the study addresses a specific Chinese phenomenon related to internal migration and registration of residency, parallels can be drawn to other settings where a combination of economic and social transitions of the society and a reform of health care financing are potentially creating the same conditions of significant inequalities.