We provide an analysis of the main sources of data used to estimate fertility schedules in developing countries, giving special attention to Brazil. In addition to the brief history of various data sources, we present several indirect demographic methods, commonly used to estimate fertility and assess the quality of data. From the methods used, the Synthetic Relational Gompertz model gives the most robust estimates of fertility, independent of the data source considered. We conclude that different demographic data sources and methods generate differing estimates of fertility and that the country should invest in quality of birth statistics.