[Reliability of birth certificate data in Rio de Janeiro, Brazil, 1999-2001].

The objective of this article is to assess coverage and reliability of data from the Information System on Live Births in the City of Rio de Janeiro, based on an analysis of live birth certificates issued by the various hospitals and compared to information from the "Study on Neonatal and Perinatal Morbidity and Mortality and Care in the City of Rio de Janeiro". A total of 9,608 interviews with post-partum women were paired case-by-case with the respective birth certificates. The statistical analysis consisted of calculating the Kappa index adjusted to the prevalence of categorical variables and the intra-class correlation coefficient for continuous variables, with a 95% significance level. The study showed excellent coverage (96.5%) for hospital births in the City of Rio de Janeiro during the period studied. The variables presenting the highest concordance levels (over 0.90) were the infant's sex, birth weight, mother's age, type of delivery, and type of pregnancy. The variables marital status, mother's schooling, and number of prenatal visits showed lower reliability indices (Kappa < 0.70). The article discusses the importance of data quality in the Information System on Live Births (SINASC) and the system's use as a tool to help define maternal and child health policies.