Abstract
OBJECTIVE: To evaluate race and ethnicity differences in cesarean birth and maternal morbidity in low-risk nulliparous people at term. METHODS: We conducted a secondary analysis of a randomized trial of expectant management compared with induction of labor in low-risk nulliparous people at term. The primary outcome was cesarean birth. Secondary outcome was maternal morbidity, defined as: transfusion of 4 or more units of red blood cells, any transfusion of other products, postpartum infection, intensive care unit admission, hysterectomy, venous thromboembolism, or maternal death. Multivariable modified Poisson regression was used to evaluate associations between race and ethnicity, cesarean birth, and maternal morbidity. Indication for cesarean birth was assessed using multivariable multinomial logistic regression. A mediation model was used to estimate the portion of maternal morbidity attributable to cesarean birth by race and ethnicity. RESULTS: Of 5,759 included participants, 1,158 (20.1%) underwent cesarean birth; 1,404 (24.3%) identified as non-Hispanic Black, 1,670 (29.0%) as Hispanic, and 2,685 (46.6%) as non-Hispanic White. Adjusted models showed increased relative risk of cesarean birth among non-Hispanic Black (adjusted relative risk [aRR] 1.21, 95% CI 1.03-1.42) and Hispanic (aRR 1.26, 95% CI 1.08-1.46) people compared with non-Hispanic White people. Maternal morbidity affected 132 (2.3%) individuals, and was increased among non-Hispanic Black (aRR 2.05, 95% CI 1.21-3.47) and Hispanic (aRR 1.92, 95% CI 1.17-3.14) people compared with non-Hispanic White people. Cesarean birth accounted for an estimated 15.8% (95% CI 2.1-48.7%) and 16.5% (95% CI 4.0-44.0%) of excess maternal morbidity among non-Hispanic Black and Hispanic people, respectively. CONCLUSION: Non-Hispanic Black and Hispanic nulliparous people who are low-risk at term undergo cesarean birth more frequently than low-risk non-Hispanic White nulliparous people. This difference accounts for a modest portion of excess maternal morbidity.