[Quality of data used to calculate reproductive and perinatal health indicators in native and migrant populations].

OBJECTIVE To assess the quality of data on births in the Natural Population Movement (NPM) and congenital metabolic disorders registers with regard to calculation of reproductive and perinatal health indicators. METHODS The following comparisons between registers were made: (1) the total number of births to mothers living in Catalonia and Valencia from 2005 to 2006, (2) the percentage of missing data on the mother's geographical origin, (3) the percentage of missing data on the mother's age and the infant's birthweight and gestational age according to maternal origin. RESULTS The congenital metabolic disorders registers exhaustively collected the total number of births gathered in the NPM. The percentages of missing data on material origin and age were higher in the congenital metabolic disorders registers, although the proportion of births by maternal origin and the mean maternal age in each ethnic group was fairly similar to that in the NPM. The percentages of missing data on birthweight and gestational age were much higher in the NPM data than in the congenital metabolic disorders registers, especially among births registered in Catalonia and births to foreign mothers. CONCLUSIONS Our results suggest some limitations in the quality of the data on gestational age and birthweight provided by NPM data, especially for comparisons of preterm and low birthweight indicators in the Spanish-born and immigrant populations. Moreover, the results point to the quality of the congenital metabolic disorders registers as a source to compare reproductive and perinatal health indicators.