Bayesian mediation modeling of racial disparity for maternal birth outcomes in United States

In the United States, racial disparities for adverse maternal health outcomes persist, and the causes remain unknown. The disparities for women of Black ethnicity include increased risk of gestational hypertension, hypertension eclampsia, cesarean section, and admission to an Intensive Care Unit, and reduced risk of parturition induction. Without evaluating racial disparity, studies identify one cause of these conditions as the interaction between pre-gestational body mass index and gestational weight gain. What has not been determined is how body mass index and gestational weight gain contribute to racial disparity. The study's objective was to determine if the interaction between body mass index and gestational weight gain can explain the racial disparity in five maternal outcomes.

The approach involved mediation analysis by performing Bayesian estimation of potential outcomes for each combination of causes. Causes included risk of Black ethnicity, body mass index, and gestational weight gain.

Improving both body mass index and gestational weight gain to what is considered optimal would increase the racial disparity for gestational hypertension by 19.2%, have a non-significant effect on racial disparity for hypertension eclampsia, reduce the racial advantage for Black women receiving induction by 16.9%, and reduce the racial disadvantage for delivery by cesarean and admission to an Intensive Care Unit by 49.9% and 36.9%, respectively.

Preventive programs can have a wide range of effects on racial disparity, from decreasing to increasing the disparity. Implementing the mediation evaluation approach illustrated here would optimize clinical decisions, guide public health policy, and eventually mitigate racial mistrust.