A recent study published in the Nature Medicine Journal developed a Global Maternal Health microsimulation model to measure global maternal death incidence between 1990 and 2050.

Study: Simulation-based estimates and projections of global, regional and country-level maternal mortality by cause, 1990–2050. Image Credit: TanyaAntusenok/Shutterstock.com

Background

Maternal mortality is a major healthcare crisis worldwide, especially in low-and middle-income countries (LMICs). Despite many cost-effective interventions to manage pregnancy-related complications, maternal mortality significantly varies globally, primarily due to improper adaptation and implementation of these interventions due to global health disparities.

Compared to the frequency of pregnancy, maternal death is considered a rare event. Thus, a large sample size is required to estimate the pregnancy-related mortality rate accurately.

However, many countries lack proper infrastructures to report maternal mortality. Misclassification is another major problem because many distinct conditions with diverse pathophysiology are associated with maternal mortality.

The United Nations (UN) Sustainable Development Goals (SDGs) set a target to restrict the global maternal mortality ratio to fewer than 70 deaths per 100,000 live births by 2030.

It has also been targeted that no country worldwide should exceed a maternal mortality ratio of 140 deaths per 100,000 live births.

In the current study, scientists have developed and calibrated the Global Maternal Health microsimulation model to estimate and predict cause-specific maternal mortality rates for 200 countries and territories from 1990 to 2050.

Study model

The Global Maternal Health microsimulation model simulated the reproductive histories of individual women belonging to 200 countries and territories, accounting for the educational background, geographical locations, family planning preferences, and previous maternal complications of individual women.

The model accounted for demographic characteristics and secular trends at the population level to simulate different maternal health-related processes, including biological processes, family planning behaviors, and clinical practice and health system factors, at the individual level.

The model was calibrated using empirical data from 1990 to 2015. The model’s prediction accuracy was assessed using maternal mortality indicators from 2016 to 2020.

Current estimation of maternal mortality

The model estimated that the number of global maternal deaths reduced from 587,500 in 1990 to 337,600 in 2020. During the same period, the global maternal mortality ratio reduced from 416 deaths per 100,000 live births to 194 deaths per 100,000 live births.

Although similar to the UN’s, these estimates are significantly higher than the Global Burden of Disease (GBD). Unlike the individual-level structural simulation used in this study, UN and GBD estimates are based on aggregate-level regression models.

According to the model estimations, about 99% of maternal deaths occurred in low- and middle-income countries in 2020.

Moreover, the model revealed about 25 times the variation in the estimated maternal mortality ratio and 75 times the variation in lifetime risk of maternal mortality between low- and high-income countries.

Prediction of maternal mortality

Considering the current estimates, the model predicted that global maternal mortality is expected to decrease from 339,000 in 2022 to 327,400 in 2030 and to 320,200 in 2050. A significant reduction in maternal deaths in Asia could be responsible for this overall global decline. However, most future maternal deaths were predicted to occur in Africa.

Regarding the global maternal mortality ratio, the model predicted a reduction from 190 in 2022 to 167 in 2030 and 146 in 2050. According to the predictions, 105 and 142 countries are expected to have a maternal mortality ratio of less than 70 and 140, respectively, in 2030.

A future maternal mortality ratio of more than the SDG target (>140) was predicted for 58 countries, including sub-Saharan Africa.

Causes of maternal mortality

A gradual change in the main causes of maternal deaths over time was observed in the study. In Africa, indirect causes, such as human immunodeficiency virus (HIV) infection and malaria, were identified as the leading causes of maternal deaths, which showed a gradual decline over time.

In contrast, maternal mortality due to direct causes (anesthesia complications and obstetric embolism) was predicted to increase slowly in African countries.

Later-stage pregnancy and abortion-related complications in Asia were identified as the leading direct causes of maternal mortality. However, other direct causes, such as sepsis and hemorrhage, were predicted to decline over time.

Study significance

The study provides global and country-specific estimates of maternal mortality and predictions of future mortality.

The study identifies 58 countries, including sub-Saharan Africa, where maternal mortality ratios are still higher than the target value set by the SDGs. Moving forward, future research must identify context-specific policy interventions that will drive reductions in maternal deaths.