Factors associated with maternal morbidity among Black women in the United States.

OBJECTIVE: Non-Hispanic Black people (NHBP) have a 3-fold higher rate of maternal mortality compared to other racial groups. Racial disparities in maternal morbidity are well described however there are substantial differences in cultural, economic, and social determinants of health among racial groups. We sought to study the, at-risk, non-Hispanic Black population as its own cohort to identify factors most associated with severe maternal morbidity (SMM).

METHODS: This is a population-based retrospective case control study of all livebirths in the U.S. between 2017 and 2019 using birth records obtained from the National Center for Health Statistics. The primary outcome for this study was to determine demographic, social, medical, and obstetric factors associated with maternal morbidity among NHBP who did and did not experience a SMM event. Multivariable logistic regression was used to estimate the adjusted OR between each individual factor and the outcome of SMM among NHBP.

RESULTS: Of the 1,624,744 NHBP who delivered between 2017 and 2019, 1.1% experienced a SMM event defined as a composite of blood product transfusion, eclamptic seizure, ICU admission, unplanned hysterectomy, and uterine rupture. The rates of these individual SMM events per 10,000 deliveries were 50, 40, 20, 5, and 4 among NHBP, respectively. Among NHBP, factors associated in multivariable regression analysis with SMM in order of strength of association included cesarean delivery, earlier gestational age at delivery, preeclampsia, induction of labor, chronic HTN, prior preterm birth, multifetal gestation, advanced maternal age, and pregestational diabetes. The population attributable fraction for cesarean delivery, preterm birth, and pregnancy induced hypertensive disease for the outcome of SMM were 0.23, 0.46, and 0.07 respectively.

CONCLUSION: The 3 factors most associated with SMM among NHBP are potentially avoidable or modifiable by aggressive screening, prevention, and treatment of preeclampsia and preterm birth as well as reducing cesarean rates in this population.