Impact of COVID-19 pandemic on time series of maternal mortality ratio in Bahia, Brazil: analysis of period 2011-2020.

Background: Most studies on the effects of SARS-CoV-2 infection have been conducted with adults and non-pregnant women. Thus, its impacts on maternal health are not yet fully established. This study aimed to verify the relationship between the maternal mortality ratio and the incidence of COVID-19 in the State of Bahia, Brazil, 2020.
Methods: This time-series study used publicly available information in Brazil, to obtain data on maternal deaths and live births in Bahia, State, from January 1, 2011, to December 31, 2020. The time trend of Maternal Mortality Ratio (MMR) was analysed through polynomial regression, of order 6. Expected MMR, monthly (Jan-Dec) and annual values for 2020, were predicted by the additive Holt-Winters exponential smoothing algorithm, with 95% confidence interval, based on the time series of the MMR from 2011 to 2019, and the accuracy of the forecasts for 2020 was assessed by checking the smoothing coefficients and the mean errors. According to the statistical forecast, the MMR values ​​recorded in the year 2020 were compared to those expected.
Results: In 2020, the annual MMR in Bahia, Brazil, was 78.23/100,000 live births, 59.46% higher than the expected ratio (49.06 [95% CI 38.70-59.90]). The increase in maternal mortality ratio relative to expected values was observed throughout the 2020 months; however, only after May, when the COVID-19 epidemic rose sharply, it exceeded the upper limit of the 95% CI of the monthly prediction. Of the 144 registered maternal deaths in 2020, 19 (13.19%) had COVID-19 mentioned as the cause of death.
Conclusions: Our study revealed the increase in maternal mortality, and its temporal relationship with the incidence of COVID-19, in Bahia, Brazil, in 2020. The COVID-19 pandemic may be directly and indirectly related to this increase, which needs to be investigated. An urgent public health action is needed to prevent and reduce maternal deaths during this pandemic, in Brazil.