Maternal mortality in the USA before and during COVID-19 pandemic

By Neha MathurReviewed by Danielle Ellis, B.Sc.Jun 30 2022

In the latest issue of the JAMA Network Open, researchers assessed the impact of the coronavirus disease 2019 (COVID-19) pandemic on maternal death rates in the United States (US).

Research letter: All-Cause Maternal Mortality in the US Before vs During the COVID-19 Pandemic. Image Credit: Tomas Ragina / Shutterstock

Background

The National Center for Health Statistics (NCHS) reported maternal mortality during or within 42 days of pregnancy increased by 18.4% in the US between 2019 and 2020. A large proportion of maternal deaths in 2020 (16.8%) were directly or indirectly associated with the onset of the COVID-19 pandemic.

About the study

In the present study, researchers from the University of Maryland and Boston University obtained deidentified maternal mortality and natality data from NCHS for 2018 to 2020. They stratified maternal deaths by month, and year of death into two broad periods, i.e., before and during the COVID-19 pandemic. The time before the COVID-19 pandemic covered the years 2018, 2019, the first quarter of 2020, and during the pandemic spanned April to December 2020.

International Statistical Classification of Diseases and Related Health Problems, Tenth Revision [ICD-10] codes do not exclusively identify COVID-19 as the cause of maternal death even when it is a contributing factor. Therefore, the authors limited their study analyses to ICD-10 codes A34, O00-O95, and O98-O99 per NCHS guidelines. They ascertained that COVID-19 was a secondary cause of maternal mortality from the multiple causes of death, similar to other reports documenting excess COVID-19 mortality.

They compared the rate of maternal mortality with a secondary COVID-19 code by the time and cause of death and race/ethnicity. The team used a z-test of proportions to evaluate the differences during different study time periods, where a two-sided p=0.05 was statistically significant.

Study findings

There were 1588 maternal deaths before the onset of the COVID-19 pandemic. The relative increase in deaths during the pandemic was 33.3%; subsequently, there were 684 deaths. In addition, the late maternal death rates increased by 41%.

US Maternal Mortality Rates (95% CI) Before and During the COVID-19 Pandemic by Race and Ethnicity

The relative increase among Hispanic, non-Hispanic Black, and White women was 44.4%, 25.7%, and 6.1%, respectively. Both the relative and absolute changes in maternal deaths were also highest for Hispanics at 74.2%, while it was lowest for non-Hispanic White women at 17.2%. During the pandemic, 14.9% of maternal deaths listed COVID-19 as a secondary code. Yet again, the percentage of such maternal deaths was highest for Hispanic females at 32.1%. The non-Hispanic Black and White mothers shared only 12.9% and 7.3%  of this percentage, respectively.

Indirect causes accounted for 56.9% of the overall increase in the underlying cause-of-death codes. The share of other viral diseases, respiratory diseases, and diseases of the circulatory system was 2374.7%, 111.7%, and 72.1%, respectively. Direct causes of death, such as diabetes in pregnancy, hypertensive disorders, and other pregnancy-related health conditions, increased by 95.9%, 39%, and 48%, respectively. Overall, there was a 27.7% increase in direct causes. COVID-19 was commonly associated with other viral diseases (16 out of 16 deaths [100%]) and diseases of the respiratory system (11 out of 19 deaths [57.9%]). However, half of them (49/102) had a non-specific ICD-10 code as the cause of death.

Conclusions

The study analyses showed an increase of 33.3% in maternal deaths in the US after March 2020. Clearly, COVID-19 onset increased maternal deaths in the US by more than the 22% overall excess death estimate. The increase in maternal deaths was higher for the Hispanic and non-Hispanic Black mothers and was either directly related to COVID-19 or conditions worsened by COVID-19.

Although there is not enough data to discern the indirect effects of COVID-19, it certainly worsened pre-existing health conditions, such as gestational diabetes and cardiovascular diseases. According to the authors, more studies should examine how racial and ethnic inequities during the COVID-19 pandemic contributed to higher maternal deaths in the US.