Research
ajog.org
OBSTETRICS
Investigating racial differences in risk factors for primary cesarean delivery Caroline J. Min, DrPH; Deborah B. Ehrenthal, MD, MPH; Donna M. Strobino, PhD OBJECTIVE: The objective of the study was to investigate differences
in sociodemographic, medical, and obstetric risk factors for primary cesarean delivery between black and white women. STUDY DESIGN: We conducted a retrospective cohort study among
25,251 black and white women delivering a live, singleton infant with vertex presentation at a large, regional hospital between 2004 and 2010. Demographic and clinical data were derived from electronic hospital records. Differences in risk factors for primary cesarean delivery were analyzed using a modified Poisson regression approach stratified by race and parity. RESULTS: Black and white women had a primary cesarean delivery
rate of 24.7% and 22.2%, respectively (P < .001). Black women had an increased risk of cesarean delivery after adjusting for sociodemographic and clinical risk factors (adjusted relative risk [RR], 1.23; 95% confidence interval [CI], 1.17e1.29). Among nulliparas, labor induction had a greater effect on cesarean delivery for black women (adjusted RR, 1.32; 95% CI, 1.20e1.44) than for white women
(adjusted RR, 1.13; 95% CI, 1.07e1.20). Among multiparas, labor induction reduced the risk of cesarean delivery for white women (adjusted RR, 0.63; 95% CI, 0.55e0.72), whereas no association was observed for black women (adjusted RR, 1.08; 95% CI, 0.92e1.28). Advanced maternal age was a stronger risk factor for black women (adjusted RR, 1.72; 95% CI, 1.43e2.08) than for white women (adjusted RR, 1.30; 95% CI, 1.11e1.52) among multiparas only. Among nulliparas, delivery at 37-38 weeks’ gestation reduced the risk of cesarean delivery for black women (adjusted RR, 0.82; 95% CI, 0.73e0.92), whereas no association was observed for white women (adjusted RR, 0.96; 95% CI, 0.90e1.04). CONCLUSION: Labor induction, among nulliparous women, and
advanced maternal age, among multiparous women, are stronger risk factors for primary cesarean delivery for black women than for white women. Key words: advanced maternal age, cesarean delivery, labor induction, racial disparities
Cite this article as: Min CJ, Ehrenthal DB, Strobino DM. Investigating racial differences in risk factors for primary cesarean delivery. Am J Obstet Gynecol 2015;212:xx-xx.
T
otal and primary cesarean delivery rates have been higher for black women than white women in the United States since the mid-1990s.1 In 2012, the primary cesarean delivery rate for black and white women was 26.1% and 23.1%, respectively.2 Repeatedly higher rates among black women are surprising, given their younger age distribution and the association between increasing maternal age and cesarean delivery.3 Studies suggest that blackwhite differences are largely unexplained by sociodemographic, medical, or obstetric risk factors.4-9 Variation
in women’s preferences for delivery, patient-provider communication, or physician decision making have been suggested to play a role in these differences.5-7,9 High rates of cesarean delivery have raised concerns in the United States, especially when considered alongside rates of labor induction, early-term births,10 and other obstetric practices. Maternal risks associated with cesarean delivery include surgical complications, longer hospitalization, and rehospitalization; newborn risks include mild to severe respiratory problems.11,12 Despite
From the Department of Population, Family, and Reproductive Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD (Drs Min and Strobino), and Department of Obstetrics and Gynecology, Christiana Care Health System, Newark, DE (Dr Ehrenthal). Dr Ehrenthal is currently with the Departments of Obstetrics and Gynecology and Population Health Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI. Received Sept. 19, 2014; revised Jan. 8, 2015; accepted Jan. 23, 2015. The authors report no conflict of interest. Corresponding author: Caroline J. Min, DrPH. [email protected] 0002-9378/$36.00 ª 2015 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajog.2015.01.029
efforts to reduce cesarean delivery rates, quality improvement cannot be achieved without addressing persistently higher rates for black women. In this study, we investigated differences between black and white women in sociodemographic, medical, and obstetric risk factors for primary cesarean delivery using electronic clinical data from a regional hospital. Identifying different risk factors, or factors for which the relation is significantly stronger for black women, through the study of a large community population may suggest future areas of research or intervention to reduce disparities.
M ATERIALS
AND
M ETHODS
We conducted a retrospective cohort study of deliveries at a private, not-forprofit hospital from 2004 through 2010 with the following maternal and infant characteristics: live, singleton birth with vertex presentation; birthweight of 500 g or greater; 23 or more completed weeks’ gestation; and
MONTH 2015 American Journal of Obstetrics & Gynecology
1.e1
Research
ajog.org
Obstetrics
TABLE 1
Sociodemographic and clinical characteristics and primary cesarean delivery rates by race Distribution, n (%)
Cesarean delivery, %
Characteristic
White
Black
P value
Total
17,698 (100.0)
7553 (100.0)
—
a
Total
P valueb
White
Black
P valuec
23.0
—
22.2
24.7
< .001
< .001
Maternal age, y
< .001
ajog.org
OBSTETRICS
Investigating racial differences in risk factors for primary cesarean delivery Caroline J. Min, DrPH; Deborah B. Ehrenthal, MD, MPH; Donna M. Strobino, PhD OBJECTIVE: The objective of the study was to investigate differences
in sociodemographic, medical, and obstetric risk factors for primary cesarean delivery between black and white women. STUDY DESIGN: We conducted a retrospective cohort study among
25,251 black and white women delivering a live, singleton infant with vertex presentation at a large, regional hospital between 2004 and 2010. Demographic and clinical data were derived from electronic hospital records. Differences in risk factors for primary cesarean delivery were analyzed using a modified Poisson regression approach stratified by race and parity. RESULTS: Black and white women had a primary cesarean delivery
rate of 24.7% and 22.2%, respectively (P < .001). Black women had an increased risk of cesarean delivery after adjusting for sociodemographic and clinical risk factors (adjusted relative risk [RR], 1.23; 95% confidence interval [CI], 1.17e1.29). Among nulliparas, labor induction had a greater effect on cesarean delivery for black women (adjusted RR, 1.32; 95% CI, 1.20e1.44) than for white women
(adjusted RR, 1.13; 95% CI, 1.07e1.20). Among multiparas, labor induction reduced the risk of cesarean delivery for white women (adjusted RR, 0.63; 95% CI, 0.55e0.72), whereas no association was observed for black women (adjusted RR, 1.08; 95% CI, 0.92e1.28). Advanced maternal age was a stronger risk factor for black women (adjusted RR, 1.72; 95% CI, 1.43e2.08) than for white women (adjusted RR, 1.30; 95% CI, 1.11e1.52) among multiparas only. Among nulliparas, delivery at 37-38 weeks’ gestation reduced the risk of cesarean delivery for black women (adjusted RR, 0.82; 95% CI, 0.73e0.92), whereas no association was observed for white women (adjusted RR, 0.96; 95% CI, 0.90e1.04). CONCLUSION: Labor induction, among nulliparous women, and
advanced maternal age, among multiparous women, are stronger risk factors for primary cesarean delivery for black women than for white women. Key words: advanced maternal age, cesarean delivery, labor induction, racial disparities
Cite this article as: Min CJ, Ehrenthal DB, Strobino DM. Investigating racial differences in risk factors for primary cesarean delivery. Am J Obstet Gynecol 2015;212:xx-xx.
T
otal and primary cesarean delivery rates have been higher for black women than white women in the United States since the mid-1990s.1 In 2012, the primary cesarean delivery rate for black and white women was 26.1% and 23.1%, respectively.2 Repeatedly higher rates among black women are surprising, given their younger age distribution and the association between increasing maternal age and cesarean delivery.3 Studies suggest that blackwhite differences are largely unexplained by sociodemographic, medical, or obstetric risk factors.4-9 Variation
in women’s preferences for delivery, patient-provider communication, or physician decision making have been suggested to play a role in these differences.5-7,9 High rates of cesarean delivery have raised concerns in the United States, especially when considered alongside rates of labor induction, early-term births,10 and other obstetric practices. Maternal risks associated with cesarean delivery include surgical complications, longer hospitalization, and rehospitalization; newborn risks include mild to severe respiratory problems.11,12 Despite
From the Department of Population, Family, and Reproductive Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD (Drs Min and Strobino), and Department of Obstetrics and Gynecology, Christiana Care Health System, Newark, DE (Dr Ehrenthal). Dr Ehrenthal is currently with the Departments of Obstetrics and Gynecology and Population Health Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI. Received Sept. 19, 2014; revised Jan. 8, 2015; accepted Jan. 23, 2015. The authors report no conflict of interest. Corresponding author: Caroline J. Min, DrPH. [email protected] 0002-9378/$36.00 ª 2015 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.ajog.2015.01.029
efforts to reduce cesarean delivery rates, quality improvement cannot be achieved without addressing persistently higher rates for black women. In this study, we investigated differences between black and white women in sociodemographic, medical, and obstetric risk factors for primary cesarean delivery using electronic clinical data from a regional hospital. Identifying different risk factors, or factors for which the relation is significantly stronger for black women, through the study of a large community population may suggest future areas of research or intervention to reduce disparities.
M ATERIALS
AND
M ETHODS
We conducted a retrospective cohort study of deliveries at a private, not-forprofit hospital from 2004 through 2010 with the following maternal and infant characteristics: live, singleton birth with vertex presentation; birthweight of 500 g or greater; 23 or more completed weeks’ gestation; and
MONTH 2015 American Journal of Obstetrics & Gynecology
1.e1
Research
ajog.org
Obstetrics
TABLE 1
Sociodemographic and clinical characteristics and primary cesarean delivery rates by race Distribution, n (%)
Cesarean delivery, %
Characteristic
White
Black
P value
Total
17,698 (100.0)
7553 (100.0)
—
a
Total
P valueb
White
Black
P valuec
23.0
—
22.2
24.7
< .001
< .001
Maternal age, y
< .001
