Estimation of live birth underreporting with a capture-recapture method, Sergipe, Northeastern Brazil

Estimate the number of live births and, therefore, underreporting of live births.

The databases of the Live Birth Information System and the Civil Registry of the Brazilian Institute of Geography and Statistics, from the second and third trimesters of 2006 in Sergipe state (Northeastern Brazil) were paired by deterministic linkage based on the number of the Live Birth Declaration. The geographic disaggregation utilized was mother's microregion of residence. Huggins closed population models were used to estimate the capture probabilities for each database and the total live births during the period, within each geographic subdivision. MARK® software was used for the estimates.

Underregistration during the period studied was 19.3%. Application of the capture-recapture method to estimate underregistration of live births is possible, including for geographic disaggregations smaller than a state. The deterministic linkage was impaired in four microregions, due to non-inclusion of the Live Birth Declaration number in the database of the Brazilian Institute of Geography and Statistics. Maternal age, a heterogeneity characteristic in the population of live births, affected the probability of capture by the civil registry.

Capture-recapture was a viable method to estimate the underregistration of live births.