Historical Perspective of US Maternal Mortality
Historically and internationally maternal mortality was measured using the maternal mortality ratio defined as any maternal death during pregnancy or up to 6 weeks postpartum per 100,000 live births and this remains the World Health Organization metric. However, in an attempt to capture and analyze more pregnancy-related deaths, in 1987 the Centers for Disease Control and Prevention with the American College of Obstetricians and Gynecologists created the Pregnancy-Related Mortality Surveillance System.[6,7] For this system, the pregnancy-related maternal mortality ratio was developed and defined as maternal death within 1 year of pregnancy from pregnancy-related complications per 100,000 live births. Deaths were considered pregnancy related if they were deemed due to complications of pregnancy, a chain of events initiated by pregnancy, or pregnancy aggravation of an already existing disease or event.[7] The purpose of this change in focus was to collect data on more pregnancy-related deaths and better understand and ultimately reduce such deaths in the USA. In 1990s the pregnancy-related maternal mortality ratio was 10/100,000 live births and in 2012 it is 17/100,000. This translates into approximately 600 deaths per year in the USA. Fortunately, the actual number of deaths is a small number, however this low number makes it difficult to meaningfully study the etiology and preventability of the deaths and hence develop interventions to reduce maternal mortality. However, we do know some basic facts. The top three causes of maternal death have been consistently hemorrhage, hypertensive disease and thrombosis until recently when cardiovascular disease has become a leading cause of maternal death[1,8] (Figure 1; modified from[1]). We know that there is a persistent and disturbing disparity in maternal morbidity and mortality with African American women having a fourfold higher mortality compared with Caucasian or Asian or Hispanic women.[1,9] And, we know that a large proportion of maternal deaths are likely preventable.[10–13] Further, we know that preventability is related to causes of death. For example, 93% deaths due to hemorrhage, 60% deaths due to hypertension and 40% deaths from cardiovascular disease were deemed preventable.[10] Although interesting and important, these descriptive characteristics are neither new information nor have they led to a reduction in maternal deaths.
Figure 1.
Change in causes of maternal death.
Adapted with permission from [1] © Wolters Kluwer Health (2011).
Women's Health. 2015;11(2):193-199. © 2015 Future Medicine Ltd.
