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Holod M, Reyes S, McCormick A. Association of race and ethnicity in cesarean rates in a diverse low-risk population. HPHR. 2024. 85. https://doi.org/10.54111/0001/GGGG4
To evaluate racial disparities in cesarean delivery rates in an ethnically diverse nulliparous, term, singleton, vertex (NTSV) population at an inner-city tertiary care center.
This is a retrospective cohort study evaluating cesarean delivery rates by race and ethnicity in an ethnically diverse NTSV population with approximately equal numbers of Hispanic, non-Hispanic Black and non-Hispanic White participants from January 1st through December 31st, 2020. The primary outcome was cesarean delivery rate. The secondary outcome was urgency of cesarean delivery categorized as emergent, unscheduled or elective. Univariable analysis was utilized to evaluate the association of maternal clinical characteristics and the primary and secondary outcomes. Multivariable analysis was performed for variables significant in univariable analysis (p <0.05).
A total of 872 patients were included in the study. 290 were non-Hispanic White (33.3%), 258 were non-Hispanic Black (29.6%), 245 were Hispanic (28.1%), and 79 were Asian (9.1%). The overall cesarean rate was 32.5%. The cesarean delivery rates for non-Hispanic White, non-Hispanic Black, Hispanic, and Asian patients were 26.6%, 40.7%, 31.4%, and 30.4%, respectively. Non-Hispanic Black patients had significantly higher odds of cesarean delivery when compared to non-Hispanic White patients (OR 1.96, 95% CI: 1.37-2.81). This increased risk persisted in the multivariable analysis (aOR 1.83, 95% CI: 1.13-2.97). The risk of emergent cesarean delivery for non-Hispanic Black patients was also significantly increased (OR 3.69, 95% CI: 2.28-5.75), (aOR 3.39, 95% CI: 1.90-6.05).
Non-Hispanic Black patients had significantly higher risk of cesarean delivery and emergent cesarean delivery when compared to non-Hispanic White patients in an NTSV population at an inner-city tertiary care center.
The United States has one of the highest maternal mortality rates amongst developed countries.1 Recent data reflects a nearly 60% increase in national maternal mortality rates from 2019 to 2021.2 Additionally, racial health inequities exist with non-Hispanic Black patients three times more likely to die from pregnancy-related causes than non-Hispanic White patients in the United States.2
Nulliparous Term Singleton Vertex (NTSV) patients are defined as patients with first pregnancy resulting in live birth at or beyond 37 weeks of a singleton (one fetus) gestation in the vertex (cephalic or head down) presentation. Cesarean delivery rates in NTSV populations are commonly used as a quality metric for safe obstetric care initiatives to decrease the cesarean birth rates.3 NTSV populations are considered low-risk for cesarean delivery given known risk factors such as multiple gestation and malpresentation are eliminated.3,4 Given the increasing cesarean delivery rates in the United States, the NTSV cesarean rate has been a target for the quality initiatives to lower the cesarean delivery rate.5 The Joint Commission now requires all hospitals with greater than 300 deliveries per year to report this metric and it is also utilized by the Centers for Medicare and Medicaid Services. While cesarean delivereis can be necessary procedures, they are major abdominal surgeries associated with increased morbidity. Postpartum complications include increased risk of infection, uterine rupture, bladder injury, hemorrhage, subsequent pregnancy complications, and death when compared to vaginal deliveries. History of prior cesarean delivery implies increased risk in subqequent pregnancies for cesarean delivery as well as implying risk for placenta accreta spectrum or invasive placentation.6,7
Non-Hispanic Black patients have higher primary cesarean delivery rates and are more likely to die from pregnancy-related causes than non-Hispanic White women in the United States.8 In Illinois, non-Hispanic Black women are nearly six times more likely to die during or within one year of pregnancy than non-Hispanic White women despite having similar birth rates.9 It is known that non-Hispanic Black patients are disproportionately affected by co-morbid conditions placing them at increased risk for cesarean birth such as obesity, hypertensive disorders of pregnancy and diabetes.9–12
Racial disparities in NTSV populations and cesarean birth rates have been studied previously, however prior studies use populations with heavily weighted non-Hispanic White referent groups making up much of the population studied.8,11,13,14 These studies are limited given that they attempt to address racial disparities in sample populations which are not equally representative of respective racial groups.13 Additionally, prior studies are not representative of most academic centers serving a racially diverse population.14 Using a non-racially diverse sample population could skew the data and dampen the disparity found in cesarean rates.
The current study aims to evaluate the association of race and ethnicity and primary cesarean rates using an equally distributed race representation in the sample population while adjusting for known risk factors for cesarean delivery.
The United States has one of the highest maternal mortality rates amongst developed countries.1 Recent data reflects a nearly 60% increase in national maternal mortality rates from 2019 to 2021.2 Additionally, racial health inequities exist with non-Hispanic Black patients three times more likely to die from pregnancy-related causes than non-Hispanic White patients in the United States.2
Nulliparous Term Singleton Vertex (NTSV) patients are defined as patients with first pregnancy resulting in live birth at or beyond 37 weeks of a singleton (one fetus) gestation in the vertex (cephalic or head down) presentation. Cesarean delivery rates in NTSV populations are commonly used as a quality metric for safe obstetric care initiatives to decrease the cesarean birth rates.3 NTSV populations are considered low-risk for cesarean delivery given known risk factors such as multiple gestation and malpresentation are eliminated.3,4 Given the increasing cesarean delivery rates in the United States, the NTSV cesarean rate has been a target for the quality initiatives to lower the cesarean delivery rate.5 The Joint Commission now requires all hospitals with greater than 300 deliveries per year to report this metric and it is also utilized by the Centers for Medicare and Medicaid Services. While cesarean delivereis can be necessary procedures, they are major abdominal surgeries associated with increased morbidity. Postpartum complications include increased risk of infection, uterine rupture, bladder injury, hemorrhage, subsequent pregnancy complications, and death when compared to vaginal deliveries. History of prior cesarean delivery implies increased risk in subqequent pregnancies for cesarean delivery as well as implying risk for placenta accreta spectrum or invasive placentation.6,7
Non-Hispanic Black patients have higher primary cesarean delivery rates and are more likely to die from pregnancy-related causes than non-Hispanic White women in the United States.8 In Illinois, non-Hispanic Black women are nearly six times more likely to die during or within one year of pregnancy than non-Hispanic White women despite having similar birth rates.9 It is known that non-Hispanic Black patients are disproportionately affected by co-morbid conditions placing them at increased risk for cesarean birth such as obesity, hypertensive disorders of pregnancy and diabetes.9–12
Racial disparities in NTSV populations and cesarean birth rates have been studied previously, however prior studies use populations with heavily weighted non-Hispanic White referent groups making up much of the population studied.8,11,13,14 These studies are limited given that they attempt to address racial disparities in sample populations which are not equally representative of respective racial groups.13 Additionally, prior studies are not representative of most academic centers serving a racially diverse population.14 Using a non-racially diverse sample population could skew the data and dampen the disparity found in cesarean rates.
The current study aims to evaluate the association of race and ethnicity and primary cesarean rates using an equally distributed race representation in the sample population while adjusting for known risk factors for cesarean delivery.
This was a retrospective cohort study of patient data collected from a single inner-city tertiary care center located in Chicago, Illinois from January 1st through December 31st, 2020. Patients were included if they met criteria for NTSV deliveries.3 The primary outcome was cesarean delivery rate. The secondary outcome was urgency of cesarean delivery defined as emergent (delivery within one hour of determination of recommendation for cesarean delivery), unscheduled (delivery timed according to clinical scenario), or elective (scheduled procedures at appropriate gestational age).
Demographic and clinical data including maternal age, self-reported race and ethnicity, body mass index (kg/m2), at the time of delivery, insurance status (private versus public), the presence of hypertensive disease, quantitative blood loss during delivery (mL), documented intrapartum maternal infection, and admission of the neonate to the Neonatal Intensive Care Unit (NICU) were obtained through individual chart review in the electronic medical records system.
Univariable analyses were performed using χ2 and ANOVA tests as appropriate to compare maternal demographic and clinical characteristics across race and ethnicity categories. Univariable and multivariable logistic regression analysis were used to evaluate the association between race and ethnicity and rate of cesarean delivery. Variables found to be significant in univariable analysis were included in the multivariable logistic regression. Statistical significance was defined as p <0.05 and all tests were two-tailed. No imputation for missing data was performed. All statistical analyses were performed with Stata 15.1. Approval for this study was obtained from the Institutional Review Board (IRB#21050404) and additional ethics review was deemed unncessary.
Table 1: Baseline maternal characteristics stratified by race and ethnicity
Total n=872 (%) | Non-Hispanic White n=290 (33.3) | Non-Hispanic Black n=258 (29.6) | Hispanic n=245 (28.1) | Asian n=79 (9.1) | p-value | |
Maternal age (years) | 29 +/- 8 | 32 +/- 4 | 25 +/- 7 | 26 +/- 9 | 31 +/- 6 | <0.001 |
BMI (kg/m2) | 30.5 +/- 7.7 | 29.2 +/- 5.4 | 32.7 +/- 9.8 | 31.5 +/- 8.6 | 28.2 +/- 6.5 | <0.001 |
Public insurance | 306 (35.1) | 21 (7.2) | 152 (58.9) | 120 (49.0) | 13 (16.5) | <0.001 |
Hypertensive disorders cHTN cHTN with siPreE gHTN PreE without SF PreE with SF Eclampsia | 24 (2.7) 21 (2.4) 144 (16.9) 46 (4.2) 29 (3.3) 2 (0.2) | 7 (2.4) 5 (1.7) 44 (15.2) 9 (3.1) 8 (2.8) 0 (0) | 10 (3.9) 11 (4.3) 65 (24.2) 20 (7.8) 14 (5.7) 1 (0.4) | 7 (2.9) 5 (2.0) 32 (13.1) 5 (2.0) 7 (2.9) 1 (0.4) | 0 (0) 0 (0) 6 (8) 6 (7.6) 0 (0) 0 (0) | <0.001 |
Infection | 96 (11.1) | 21 (7.2) | 26 (10.1) | 36 (114.7) | 13 (16.5) | 0.017 |
Readmission within 6 weeks postpartum | 77 (8.8) | 19 (6.6) | 26 (10.1) | 27 (11.0) | 5 (6.3) | 0.217 |
Gestational age at delivery (week) | 39 +/- 2 | 39 +/- 1 | 39 +/- 1 | 39 +/- 2 | 39 +/- 1 | 0.296 |
Cesarean delivery | 283 (32.5) | 77 (26.6) | 105 (40.7) | 77 (31.4) | 24 (30.4) | 0.005 |
NICU admission | 195 (22.5) | 45 (15.5) | 72 (27.9) | 66 (26.9) | 13 (16.5) | 0.001 |
QBL (mL) (n=870) | 424 (561) | 400 (501) | 400 (637) | 459 (515) | 520 (556) | 0.020 |
Blood transfusion required | 20 (2.3) | 2 (0.7) | 6 (2.3) | 9 (3.7) | 3 (3.8) | 0.102 |
Number of units of blood received | 1.4 (1) | 2 (2) | 2 (1) | 1 (1) | 1 (0.5) | 0.815 |
Data presented as median interquartile range (IQR) or n(%)
Abbreviations: BMI, body mass index; cHTN, chronic hypertension; siPreE, superimposed preeclampsia; gHTN, gestational hypertension; PreE, preeclampsia; SF, severe features; NICU, neonatal intensive care unit; QBL, quantitative blood loss
*of those patients undergoing cesarean
Data presented as median interquartile range (IQR) or n(%)
Abbreviations: BMI, body mass index; cHTN, chronic hypertension; siPreE, superimposed preeclampsia; gHTN, gestational hypertension; PreE, preeclampsia; SF, severe features; NICU, neonatal intensive care unit; QBL, quantitative blood loss
*of those patients undergoing cesarean
Table 2: Univariable analysis of race/ethnicity and outcomes
| Non-Hispani c White OR (95% CI) | Non-Hispanic Black OR (95% CI) | Hispanic OR (95% CI) | Asian OR (95% CI) |
Primary outcome |
|
|
|
|
Cesarean delivery | (ref) | 1.96 (1.37-2.81) | 1.24 (0.85-1.81) | 1.23 (0.71-2.12) |
Secondary outcome |
|
|
| |
Indication for cesarean delivery Emergent Non-emergent Elective | (ref) | 3.69 (2.28-5.75) 0.94 (0.55-1.62) 0.17 (0.04-0.74) | 1.69 (1.01-2.81) 1.21 (0.72-2.04) 0.26 (0.07-0.94) | 1.89 (0.94-2.72) 0.91 (0.40-2.06) 0.55 (0.12-2.51) |
Boldface data indicates statistically significant findings
Table 3: Multivariable analysis of race/ethnicity and cesarean delivery rate*
| Non-Hispani c White aOR (95% CI) | Non-Hispanic Black aOR (95% CI) | Hispanic aOR (95% CI) | Asian aOR (95% CI) |
Primary outcome |
|
|
|
|
Cesarean delivery | (ref) | 1.83 (1.13-2.97) | 1.24 (0.79-1.96) | 1.27 (0.70-2.31) |
Secondary outcome |
|
|
|
|
Indication for cesarean delivery* Emergent Non-emergent Elective | (ref) | 3.39 (1.90-6.05) 0.94 (0.46-1.91) 0.55 (0.01-0.60) | 1.65 (0.92-2.93) 1.31 (0.70-2.45) 0.19 (0.04-0.94) | 1.40 (0.64-3.01) 1.28 (0.55-2.99) 0.83 (0.17-4.12) |
Boldface data indicates statistically significant findings
*adjusted for maternal age, BMI, insurance status, HTN disorder, infection during or after delivery
Data from a total of 872 patients meeting inclusion criteria was available for analysis. There were 79 Asian patients (9.1%), 245 Hispanic patients (28.1%), 258 non-Hispanic Black patients (29.6%), and 290 non-Hispanic White patients (33.3%) included in the analysis.
Non-Hispanic Black patients had significantly higher rates of hypertensive disorders of pregnancy (HDP). Asian, Hispanic, and Non-Hispanic Black patients had higher rates of intrapartum infection, Neonatal Intensive Care Unit (NICU) admissions, and quantitative blood loss than non-Hispanic White patients (Table 1).
The overall cesarean delivery rate in this cohort was 32.5%. Non-Hispanic Black patients had the highest rate of cesarean delivery at 40.7% as compared to non-Hispanic White patients (26.6%). Asian and Hispanic patients also had higher rates of cesarean delivery when compared to non-Hispanic White patients (30.4%, 31.4%, and 26.6%, respectively) (Table 1).
In univariable analysis, non-Hispanic Black patients had significantly higher odds of undergoing cesarean delivery than non-Hispanic White patients (OR 1.96, 95% CI 1.37, 2.81) (Table 2) and this risk persisted when adjusted for confounding factors (aOR 1.83, 95% CI 1.13, 2.97) (Table 3).
For urgency of cesarean delivery, non-Hispanic Black patients had higher odds of emergent cesarean delivery (OR 3.69, 95% CI 2.28, 5.75) (Table 2), which persisted in multivariable analysis (aOR 3.39, 95% CI 1.90, 6.05) (Table 3). Hispanic patients also had higher risk of emergent cesarean delivery when compared to non-Hispanic White patients (OR 1.69, 95% CI 1.01, 2.81) (Table 2) however this did not persist when adjusted for confounding factors (aOR 1.65, 95% CI 0.92, 2.93) (Table 3). In unadjusted analysis, both Hispanic and non-Hispanic Black groups had lower odds of elective cesarean delivery (OR 0.26, 95% CI 0.07, 0.94) and (0.17, 95% CI 0.04, 0.74), respectively (Table 2). This persisted for Hispanic and non-Hispanic Black patients in adjusted analysis (aOR 0.19, 95% CI 0.04, 0.94) and (0.55, 95% CI 0.01, 0.60), respectively (Table 3).
The results of this study demonstrate that in an equally distributed diverse NTSV population, non-Hispanic Black patients have higher risk of cesarean delivery compared to non-Hispanic White patients at this single institution. These findings are consistent with literature evaluating maternal health inequalities in the United States.14*
In this NTSV cohort, non-Hispanic Black patients had the highest odds of primary cesarean delivery and emergency cesarean delivery when compared to non-Hispanic White patients. This finding has been shown in non-NTSV studies previously. There is limited data evaluating cesarean rate inequities by race specifically in low risk NTSV populations.13. 15 One previous study performed in an NTSV population at Kaiser Permanente showed similar findings in odds of cesarean delivery although they did not evaluate urgency of cesarean delivery. The authors did however evaluate indication for cesarean delivery which can provide insight into trends leading to racial bias.13 For example, they found that non-Hispanic Black patients had highest rates of cesarean delivery secondary to fetal distress. In another study, Edmonds et al documented a significant racial and ethnic disparity in NTSV cesarean rates in a large data set available from the Centers for Disease Control and Prevention as well as linked it to a protective affect with higher level of education.15 Neither of these studies include informaiton on types of cesarean delivery. Historically it has been suggested that these trends in cesarean delivery rates are due to factors such as age, obesity, hypertensive disorders of pregnancy, intrapartum and postpartum infection, and insurance status.1617 However, this increased risk for cesarean delivery and specifically emergency cesarean delivery persisted even after adjusting for such confounding variables suggesting that factors such as implicit bias, provider-patient communication, delayed interventions, and cultural perceptions may contribute to these observed disparities.18 Of note, all providers caring for patients in the current study are required to complete yearly implicit bias and diversity training. Further studies are needed to evaluate the effectiveness of such training programs with the goal of improving known measurable health outcomes. Perhaps more in-depth integration of implicit bias training is needed in healthcare to be effective.
A strength of the current study is the utilization of a diverse NTSV population at an academic center as this is considered a low-risk population for cesarean delivery.4,14 In an exclusively NTSV patient population it may be assumed that the overall cesarean delivery rate be low and less susceptible to racial and ethnic disparities. However, the increased rates of cesarean delivery in Asian, Hispanic, and non-Hispanic Black patients were found despite utilizing a predefined, low-risk, relatively healthy cohort.
An additional strength of the current study is the relatively equal distribution of racial groups studied attempting to limit bias by studying a non-diverse sample population. The study cohort accurately reflects the diverse patient population that this tertiary care center serves and increases generalizability to other care centers serving equally diverse populations in the United States. In a similar recent published report, the referent race represented a much larger proportion of the total population studied, with non-Hispanic White patients accounting for nearly half of the study’s cohort.13,14
In contrast to previous studies which utlize birth certificate data, the present study utilized data collected from clinical chart reviews. Many previous studies on disparities in cesarean delivery rates have used administrative data and are thus limited in the availability and accuracy of detailed clinical variables in addition to differentiating between elective, non-emergent, and emergent cesarean deliveries.
There are several limitations to the current study. Being retrospective in nature, there remains the possibility of unintended confounders such as additional antenatal risk factors for cesarean delivery, provider type performing cesarean delivery and prenatal care obtained. The benefits of utilizing retrospective data are lower cost and resources necessary to perform the study and data analysis can be performed immediately after data collection. The study data collection was done in an academic institution with limited resources therefore there was a lapse in time between data collection and publicationThe findings of the study are likely irrespective of timing of data collection as there were no significant practice changes iniated over this period to current. Additionally, the indications for emergent cesarean delivery, which occurred at higher rates in Non-Hispanic Black patients as compared to non-Hispanic White patients, were not fully defined. This could have provided insight if non-Hispanic Black patients are at higher risk for cesarean delivery due to what most providers would consider objective emergencies or more subjective indications more vulnerable to introduction of implicit bias such as fetal intolerance to labor.
Future research is needed to guide change in policy to decrease the disparity in cesarean delivery rates. Given most studies of this nature to date are compiled from data from state or federal databases, there can be flaws with accuracy. Additional research should target specific interventions utilized at hospital systems to decrease implicit bias and racism in medicine and their effectiveness in a prospective manor. Research initiatives that validate tools used with the intention of improving implicit bias are needed. This could be accomplished by evaluating measurable outcomes in obstetric disparities before and after introduction of implicit bias and diversity training tools in healthcare.
Non-Hispanic Black patients are disproportionately affected by racial disparities in maternal health and obstetric care. The finding of the current study is supported by literature reporting increased risk of cesarean delivery and cesarean delivery for emergent indications for non-Hispanic Black patients when compared to non-Hispanic White patients.21, 22 The disparity in cesarean delivery rates highlights the need for further research to address and define racial and ethnic disparities in maternal health outcomes in order to initiate changes that will improve maternal health outcomes due to racial disparity in obstetrics.
I want to acknowledge all the authors who contributed to this manuscript and thank them for their time. No funding was sought for this manuscript.
The authors have no relevant financial disclosures or conflicts of interest.
Monique Holod is a fourth year medical student at Rush Medical College.
Dr. Anna McCormick is a Maternal Fetal Medicine (MFM) specialist and associate professor at Rush University Medical Center. She also serves as the Director of Labor and Delivery and the Perinatal Center for the Illinois Department of Health. Her research interests include preeclampsia and health equity.
Dr. Samantha de los Reyes is a Maternal Fetal Medicine (MFM) specialist and assistant professor at Rush University Medical Center. She serves as resident research director and research interests include mentorship and improving the field of MFM.
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