Maternal mortality: protocol of a study integrated to the Birth in Brazil II survey

The Maternal Mortality Study conducts a hospital investigation of maternal deaths that occurred in 2020/2021 in the maternity hospitals sampled by the Birth in Brazil II survey, with the following objectives: estimate the maternal mortality underreporting; calculate a correction factor and the corrected (MMR); validate the causes of maternal mortality reported in the death certificate (DC); and analyze the factors associated with maternal mortality. The Birth in Brazil II includes approximately 24,250 puerperal women distributed in 465 public, private, and mixed hospitals with ≥ 100 live births/year in the five macroregions of Brazil. The Maternal Mortality Study data will be completed using the same Birth in Brazil II questionnaire, from the consultation of hospital records. Trained obstetricians will fill out a new DC (redone DC) from independent analysis of this questionnaire, comparing it to official data. The database of the investigated deaths will be related to the deaths listed in the Mortality Information System of the Brazilian Ministry of Health, allowing the estimation of underreporting and calculation of the corrected MMR. To calculate the reliability of the causes of death, the kappa test and prevalence-adjusted kappa with 95% confidence interval will be used. A case-control study to estimate the risk factors for maternal mortality will be developed with the investigated deaths (cases) and the controls obtained in the Birth in Brazil II survey, using conditional multiple logistic regression models. We expect this research to contribute to the correction of the underreporting of maternal mortality and to a better understanding of the determinants of the persistence of a high MMR in Brazil.