Racial and ethnic disparities in severe maternal morbidity prevalence and trends.

PURPOSE: Racial/ethnic disparities in severe maternal morbidity (SMM) are substantial, but little is known about whether these disparities are changing over time or the role of maternal and obstetric factors.

METHODS: We examined disparities in SMM prevalence and trends using linked birth certificate and delivery discharge records from Californian births during 1997-2014 (n = 8,252,025).

RESULTS: The prevalence of SMM was highest in non-Hispanic (NH) Black women (1.63%), lowest in NH White women (0.84%), and increased from 1997 to 2014 by approximately 170% in each racial/ethnic group. The magnitude of SMM disparities remained consistent over time. Compared with NH White women, the adjusted risk of SMM was higher in women who identified as Hispanic (RR 1.14; 95% CI 1.12, 1.16), Asian/Pacific Islander (RR 1.23; 95% CI 1.20, 1.26), NH Black (RR 1.27; 95% CI 1.23, 1.31), and American Indian/Alaska Native (RR 1.29; 95% CI 1.15, 1.44), accounting for comorbidities, anemia, cesarean birth, and other maternal characteristics.

CONCLUSIONS: The prevalence of SMM varied considerably by race/ethnicity but increased at similarly high rates among all racial/ethnic groups. Comorbidities, cesarean birth, and other factors did not fully explain the disparities in SMM, which remained persistent over time.