Few studies have analyzed the SINASC (Live Birth Information System) and MIS (Mortality Information System) applying qualitative methodology seeking to understand data production processes and contexts. This article aims to study the social representation of health professionals about Live Birth Certificates (LBC) and perinatal Death Certificates (DC). A total of 24 interviews were conducted with nurses and other professionals of 16 Unified Health System (SUS) and non-SUS hospitals of the city of São Paulo in 2009. Qualitative methodology was adopted along with the Collective Subject Discourse technique. Professionals acknowledged that they are an integral part of the information production process of SINASC and their reports indicate that they incorporate it in their work routine. They also perceive that training activities are a tool to understand the information produced by them and are aware of the utility of LBC information. Although physicians are legally responsible for the DC, other professionals frequently provide some of the information to complete it. The professionals see themselves as participants of the SINASC. Despite providing information to complete the DC, they do not see themselves as participants of the MIS operation.