Racial Disparities In Preterm Birth Research Articles

The effect of CenteringPregnancy group prenatal care on preterm birth in a low-income population

The purpose of this study was to evaluate the impact of group prenatal care on rates of preterm birth. We conducted a retrospective cohort study of 316 women in group prenatal care that was compared with 3767 women in traditional prenatal care. Women self-selected participation in group care. Risk factors for preterm birth were similar for group prenatal care vs traditional prenatal care: smoking (16.9% vs 20%; P = .17), sexually transmitted diseases (15.8% vs 13.7%; P = .29), and previous preterm birth (3.2% vs 5.4%; P = .08). Preterm delivery (<37 weeks' gestation) was lower in group care than traditional care (7.9% vs 12.7%; P = .01), as was delivery at <32 weeks' gestation (1.3% vs 3.1%; P = .03). Adjusted odds ratio for preterm birth for participants in group care was 0.53 (95% confidence interval, 0.34-0.81). The racial disparity in preterm birth for black women, relative to white and Hispanic women, was diminished for the women in group care. Among low-risk women, participation in group care improves the rate of preterm birth compared with traditional care, especially among black women. Randomized studies are needed to eliminate selection bias.

459: Racial differences in self-reported and biologic measures of chronic stress in pregnancy

Chronic stress has been associated with adverse pregnancy outcomes such as preterm birth. Elevated chronic stress in African-American women may play a role in racial disparities in preterm birth; however, racial differences in maternal stress have not been consistently demonstrated. The objective of this study is to identify differences in self-reported and biologic measures of chronic stress between African-American and Caucasian pregnant women. African-American and Caucasian pregnant women were recruited at an urban university hospital between May 2008 and July 2009. Self-reported stress was measured from 14 to 22 weeks gestation. Blood samples, collected from 14 to 22 weeks and again from 28 to 32 weeks, were analyzed for serum Epstein-Barr Virus (EBV) antibody, C-Reactive Protein (CRP), CRH, and ACTH. 114 (58 Caucasian and 56 African-American) pregnant women were recruited. An equal number of Caucasian and African American women had Medicaid versus private insurance and income was not significantly different by race. African-American women had significantly higher mean CRP levels in the 2nd trimester (2.09 1.07 vs 1.59 .91, p < .01) and 3rd trimester (1.93 1.11 vs. 1.51 1.0, p = .048). African-American women also had significantly elevated ACTH levels in the 2nd trimester (2.94 0.52 vs 2.68 0.53, p = .01) and 3rd trimester (2.85 1.05 vs. 2.41 1.04, p = .03). No differences in EBV or CRH levels were detected. Caucasian women reported higher buffers against stress (p = .04) and African-American women reported higher rates of discrimination (p<.001). Significant differences in self-reported and biologic measures of chronic stress were identified between African American and Caucasian pregnant women regardless of income. African American women had higher levels of CRP and ACTH in the 2nd and 3rd trimester and reported higher rates of discrimination, while Caucasian women reported a higher level of buffers against stress. Future studies should further investigate the racial differences in chronic stress and associations with adverse pregnancy outcomes.

Racial disparities in preterm birth: an overview of the potential role of nutrient deficiencies

To give an overview of the literature for evidence of nutrient deficiencies as contributors to the disparity in preterm birth (PTB) between African-American and Caucasian women. Structured literature survey. We searched MEDLINE to identify observational and experimental studies that evaluated the relation between nutrient intake and/or supplementation and PTB. For nutrients for which studies supported an association, we searched MEDLINE for studies of the prevalence of deficiency in the USA by race. Summarized findings on nutrients for which there is both evidence of a role in PTB and variability in the prevalence of deficiency by race. Nutrient deficiencies for which there are varying levels of evidence for an association with PTB and a greater burden among African-American compared with Caucasian women include deficiencies of iron, folic acid, zinc, vitamin D, calcium and magnesium, and imbalance of ω-3 and ω-6 polyunsaturated fatty acids. There are inadequate high-quality studies that investigate the role of nutrient deficiencies in PTB, their potential interaction with other risks, the proportion of excess risk for which they account, and whether supplementation can reduce the risk of, and racial disparities in, PTB in US populations. Deficiencies of several nutrients have varying levels of evidence of association with PTB and are of greater burden among African-American compared with Caucasian women. Although further research is needed, strategies that improve the nutritional status of African-American women may be a means of addressing a portion of the racial disparity in PTB.

Preconceptional stress and racial disparities in preterm birth: an overview.

We reviewed the evidence for three theories of how preconceptional psychosocial stress could act as a contributing determinant of excess preterm birth risk among African American women: early life developmental plasticity and epigenetic programming of adult neuroendocrine systems; blunting, weathering, or dysfunction of neuroendocrine and immune function in response to chronic stress activation through the life course; individuals' adoption of risky behaviors such as smoking as a response to stressful stimuli. Basic science, clinical, and epidemiologic studies indexed in MEDLINE and Web of Science databases on preconceptional psychosocial stress, preterm birth and race were reviewed. Mixed evidence leans towards modest associations between preconceptional chronic stress and preterm birth (for example common odds ratios of 1.2-1.4), particularly in African American women, but it is unclear whether this association is causal or explains a substantial portion of the Black-White racial disparity in preterm birth. The stress-preterm birth association may be mediated by hypothalamic-pituitary-adrenal axis dysfunction and susceptibility to bacterial vaginosis, although these mechanisms are incompletely understood. Evidence for the role of epigenetic or early life programming as a determinant of racial disparities in preterm birth risk is more circumstantial. Preconceptional stress, directly or in interaction with host genetic susceptibility or infection, remains an important hypothesized risk factor for understanding and reducing racial disparities in preterm birth. Future studies that integrate adequately sized epidemiologic samples with measures of stress, infection, and gene expression, will advance our knowledge and allow development of targeted interventions.

526: Unraveling the racial disparity in preterm birth: experiences of discrimination are associated with preterm birth and low birth weight in black women

526: Unraveling the racial disparity in preterm birth: experiences of discrimination are associated with preterm birth and low birth weight in black women

Genetic and Environmental Contributions to Racial Disparities in Preterm Birth

The preterm birth rate exceeds 12% in the United States, and preterm birth continues to be a clinical and public health challenge globally. Even though preterm birth is a major contributor to infant mortality and lifelong morbidity, there are few effective strategies to predict preterm birth and few clinical interventions to prevent it. Genomic research approaches that identify risk factors at the intersection of genetics and the environment will likely provide insights. Both genetic and environmental factors are known to contribute to the racial disparity seen in preterm birth. Through the identification of relevant gene-environment interactions that contribute to preterm birth and may underlie the racial disparity in preterm birth, research that will translate to clinical practice and ultimately prevent a number of preterm births is possible.

Cost of racial disparity in preterm birth: evidence from Michigan.

This study examined the economic costs associated with racial disparity in preterm birth and preterm fetal death in Michigan. Linked 2003 Michigan vital statistics and hospital discharge data were used for data analysis. Thirteen percent of the singleton births among non-Hispanic Blacks were before 37 completed weeks of gestation, compared with only 7.7% among non-Hispanic Whites (risk ratio = 1.66, 95% confidence interval: 1.59-1.72; p<.0001). One thousand one hundred and eighty four (1,184) non-Hispanic Black, singleton preterm births and preterm fetal deaths would have been avoided in 2003 had their preterm birth rate been the same as Michigan non-Hispanic Whites. Economic costs associated with these excess Black preterm births and preterm fetal deaths amounted to $329 million (range: $148 million-$598 million) across their lifespan over and above the costs if they were born at term, including costs associated with the initial hospitalization, productivity loss due to perinatal death, and major developmental disabilities. Hence, racial disparity in preterm birth and preterm fetal death has substantial cost implications for society. Improving pregnancy outcomes for African American women and reducing the disparity between Blacks and Whites should continue to be a focus of future research and interventions.

The genetics of birth timing: insights into a fundamental component of human development.

The timing of birth necessitates the coupling of fetal maturation with the onset of parturition, and occurs at characteristic, but divergent gestations between mammals. Preterm birth in humans is an important but poorly understood outcome of pregnancy that uncouples fetal maturation and birth timing. The etiology of preterm birth is complex, involving environmental and genetic factors whose underlying molecular and cellular pathogenic mechanisms remain poorly understood. Animal models, although limited by differences with human physiology, have been crucial in exploring the role of various genetic pathways in mammalian birth timing. Studies in humans of both familial aggregation and racial disparities in preterm birth have contributed to the understanding that preterm birth is heritable. A significant portion of this heritability is due to polygenic causes with few true Mendelian disorders contributing to preterm birth. Thus far, studies of the human genetics of preterm birth using a candidate gene approach have met with limited success. Emerging research efforts using unbiased methods may yield promising results if concerns about study design can be adequately addressed. The findings from this frontier of research may have direct implications for the allocation of public health and clinical resources as well as spur the development of more effective therapeutics.

Black-White Preterm Birth Disparity: A Marker of Inequality

The racial disparity in preterm birth (PTB) is a persistent feature of perinatal epidemiology. Its consistency is not only an outcome of reproductive interest but may function as a persistent inequality to which women are exposed over time. Herein we sought to analyze exposure to area-level PTB disparity and its association with individual-level PTB risk. Using geocoded birth records (1999-2001) and year 2000 census data for Wake County, North Carolina, we created a tract-level PTB disparity variable for each woman in our study area, comprising all births in her tract excluding her birth. Multilevel random intercept models for exposure to neighborhood PTB disparity and odds of PTB were fit. Exposure to area-level PTB disparity was associated with increased odds of PTB for all women. After adjustment for maternal and neighborhood covariates, odds of delivering preterm increased by 25%, 26%, and 36% for the second, third, and fourth quartiles of exposure to PTB disparity (odds ratio [OR]=1.25, 95% confidence interval [CI]: 1.00-1.57; OR=1.26, 95% CI: 1.01-1.58; and OR=1.36, 95% CI: 1.06-1.75, respectively). Exposure to persistent inequality, in the form of PTB disparity, appears associated with individual-level PTB risk. Knowing where PTB disparity is greatest has implications for PTB prevention policy efforts to buffer adverse conditions.

Racial disparity in bacterial vaginosis: the role of socioeconomic status, psychosocial stress, and neighborhood characteristics, and possible implications for preterm birth

Racial disparity in preterm birth is one of the most salient, yet least well-understood health disparities in the United States. The preterm birth disparity may be due to differences in how women experience their racial identity in light of neighborhood factors, psychosocial stress, or the prevalence of or response to genital tract infections such as bacterial vaginosis (BV). The latest research emphasizes a need to explore all these factors simultaneously. This cross-sectional study of parous women in King County, Washington, USA investigated the effects of household income, psychosocial stress, and neighborhood socioeconomic characteristics on risk of BV after accounting for known individual-level risk factors. Relevant demographic, socioeconomic, and medical data were linked to U.S. census socioeconomic data by geocoding subjects' residential addresses. It was found that having a low income was significantly associated with an increased prevalence of BV among African American but not White American women. A higher number of stressful life events was significantly associated with higher BV prevalence among both African American and White American women. However, perceived stress was not related to BV risk among either group of women. Among White American women, neighborhood socioeconomic status (SES) was univariately associated with increased BV prevalence by principal components analysis, but was no longer significant after adjusting for individual-level risk factors. No neighborhood SES effects were observed for African American women. These results suggest that both the effects of individual- and neighborhood-level risk factors for BV may differ importantly by racial group, and stressful life events may have physiological effects independent of perceived stress.

The Relationship between Racial Identity, Income, Stress and C-Reactive Protein among Parous Women: Implications for Preterm Birth Disparity Research

The persistent racial disparity in preterm birth (PTB)remains one of the most obvious yet poorly understood health disparities in the United States, and current evidence suggests that maternal stress, infection and inflammation may play an important role in the etiology of PTB. In this context, we assessed the complex relationships among racial identity; socioeconomic status (SES); psychosocial factors; and serum C-reactive protein (CRP), an inflammatory biomarker, among parous women in King County, WA. African-American women consistently reported a higher number of stressful life events than white American women (4.6 vs. 2.9, p < 0.001), as well as slightly higher levels of perceived stress and lower social support (24.7 vs. 22.2, p = 0.011, and 3.4 vs. 3.6, p = 0.06, respectively). In the multivariate analysis, African-American race, low-income status and their interaction were all independently associated with CRP; when further adjusted for proximal psychosocial, behavioral and infectious factors, race and income associations were significantly reduced. Stressful life events score was the single best proximal predictor of CRP levels (beta = 0.07 per event,p < 0.001), while perceived stress and social support were not significantly related to CRP. These results support the hypothesis that differences in CRP by racial identity and income may be mediated by differences in proximal risk factors, including stressful life events and health behaviors such as smoking. Objective life event stressors may be important to consider in future studies investigating a potential inflammatory etiology for preterm birth.

Are Racial Disparities in Preterm Birth Larger in Hypersegregated Areas?

The causes of the racial/ethnic disparity in preterm birth (PTB) remain largely unknown; traditional risk factors such as smoking and prenatal care fail to account for it. The authors examined whether living in metropolitan areas (MAs) with high levels of residential racial segregation along multiple dimensions (hypersegregation) was associated with higher rates of PTB or larger racial disparities in PTB and whether segregation modified the established race-age association in PTB. The authors merged 2000 natality data (n = 1,944,703) with US Census measures of Black-White hypersegregation. They executed two-level hierarchical logistic regression analyses among White and Black mothers in 237 MAs to estimate the odds of PTB by hypersegregation, race, and age, after controlling for covariates. In unadjusted and adjusted models, Black infants in hypersegregated MAs were more likely to be preterm than Black infants in nonhypersegregated MAs (p < 0.001). Black-White PTB disparities were larger in hypersegregated areas than in nonhypersegregated areas (p < 0.001), and the age-race association with PTB was modified by hypersegregation (p < 0.001). Living in a hypersegregated MA had a more pronounced association with PTB among older Black women, and racial disparities in PTB were larger in hypersegregated areas among older mothers (p < 0.001). Since over 40% of Black childbearing women live in hypersegregated areas, residential segregation may be an important social determinant of racial birth disparities.

652: Paternal influence on preterm birth racial disparities

MetroHealth Medical Center Case Western Reserve University, Cleveland, Ohio OBJECTIVE: To determine if racial disparities in preterm birth are influenced by the race of the father. STUDY DESIGN: Deliveries with complete information on maternal and paternal race, gestational age, and maternal education were obtained from 2004 birth certificate data. Deliveries were grouped by race of the mother and father: both white (WW), both black (BB), white mother and black father (WB), black mother and white father (BW). Rates of preterm birth (PTB) 37 weeks were calculated for each racial combination. Rates for each racial combination were stratified by maternal high school education or maternal high school education as a marker for social economic status (SES). Chi square testing and Mantel-Haenszel tests were used to test for significance. RESULTS: 2,292,499 deliveries met study criteria (1,888,807 WW), (52,213 WB), (14,411 BW), (337,068 BB). Overall, 12.04% of deliveries were PTB. PTB varied by race. Rates were lowest for WW (11.15%) and highest for BB (16.89%) (figure p .0001). Rates for WB (12.2%) and BW (14.9%) couples fell in between BB and WW couples. When stratified by maternal education, PTB rates were higher in mothers with less education (OR 1.14 p .0002). However, the relative order of PTB among racial groups remained the same within each educational strata.

The contribution of preterm birth to the Black-White infant mortality gap, 1990 and 2000.

We evaluated whether the decline of the racial disparity in preterm birth during the last decade was commensurate with a decline in the contribution of preterm birth to the infant mortality gap. We used linked files of 1990 and 2000 data on US infant births and deaths to partition the gap between Black and White infant mortality rates into differences in the (1) distribution of gestational age and (2) gestational age-specific mortality rates. Between 1990 and 2000, the Black-White infant mortality rate ratio did not change significantly (2.3 vs 2.4). Excess deaths among preterm Black infants accounted for nearly 80% of the Black-White infant mortality gap in both 1990 and 2000. The narrowing racial disparity in the preterm birth rate was counterbalanced by greater mortality reductions in White than in Black preterm infants. Extremely preterm birth (<28 weeks) was 4 times higher in Black infants and accounted for more than half of the infant mortality gap. Substantial reductions in the Black-White infant mortality gap will require improved prevention of extremely preterm birth among Black infants.

Amniotic Fluid Interleukin-1β and Interleukin-8 Concentrations: Racial Disparity in Preterm Birth

The purpose of this study is to examine the racial differences between interleukin (IL)-1beta and IL-8 concentrations in the amniotic fluid of black and white women with spontaneous preterm birth (PTB). In this study, 350 amniotic fluid samples were collected: 165 PTB cases (<36 weeks' gestation; 52 blacks and 113 whites) and 185 controls (normal term delivery >37 weeks' gestation; 87 blacks and 98 whites). Amniotic fluid IL-1beta and IL-8 concentrations were measured by immunoassay. Wilcoxon nonparametric test was performed for statistical analysis. In data stratified by race, the median IL-1beta concentration was significantly higher in black cases (80 pg/mL) compared to black controls (23.7 pg/mL; P < .0001), and the difference was nonsignificant in white cases (25.5 pg/mL) compared to white controls (21.3 pg/mL; P = .1). IL-8 concentration was not higher in black cases (742.2 pg/mL) compared to black controls (731.4 pg/mL; P = .9), whereas it was higher in white cases (1362.3 pg/mL) compared to white controls (533.5 pg/mL; P = .0005). Between races, IL-1beta was significantly higher in blacks (P < .0001) than in whites in PTB, whereas no significant difference was noticed in IL-8 concentration between races (P = .1). In PTB, the cytokine footprint differs in the amniotic fluid between racial groups. IL-1beta is higher in black and IL-8 in white PTB. These differences in the amniotic fluid cytokine concentration might not explain the racial disparity in the PTB rate, but they are suggestive of different processes of PTB in whites and blacks.

Genetic Influences on Preterm Birth

The high prevalence, increasing frequency, and adverse outcomes for mothers and infants of preterm birth have led to heightened awareness of this public health concern. The causes of preterm birth are likely to be multifactorial, with genetic, infectious, nutritional, behavioral, and other environmental contributors. Because of important differences in the physiology of human pregnancy and that of nonprimate mammals, extrapolation of mechanisms from animal model systems to humans has had limited impact on the understanding of human prematurity. This review summarizes work from many groups that implicates important genetic contributions to human preterm birth. These efforts use epidemiological, classical genetic, and more recently, genomic science approaches to determine pregnancies at risk for preterm delivery and to facilitate an understanding of the substantial racial disparity in preterm birth. Data revealing racial and familial predispositions to prematurity, along with genetic polymorphisms conferring increased preterm birth, promise new insights into the understanding and treatment of this critical problem.

Differences in the Placental Membrane Cytokine Response: a Possible explanation for the Racial Disparity in Preterm Birth

The prematurity rate is higher in African-Americans (AA) compared with Caucasians (C). As spontaneous preterm labor has been hypothesized to be a host inflammatory response disease racial differences in human placental membrane inflammatory cytokine and prostaglandin pathway gene expression patterns between AA and C were examined in this report. Placental membranes (amniochorion) collected from AA and C women from cesareans at term were maintained in an organ explant system and stimulated with endotoxin (lipopolysaccharide, LPS). Microarray analysis and enzyme-linked immunosorbent assay was performed on mRNAs and culture media from AA- and C-derived membranes to document any differences in mRNA expression and protein production of IL-1, IL-6, IL-8, IL-10 and expression of cyclooxygenase 1 (COX-1), COX-2 and 15-hydroxyprostaglandin dehydrogenase (PGDH). Increased mRNA expression of IL-1, IL-8 and COX-2 in AA and IL-6, IL-10, COX-1 and PGDH in C were documented after LPS stimulation. Concentration of IL-1 was significantly higher in media derived from AA whereas IL-6 and IL-10 concentrations were higher in C with no differences observed in IL-8 after LPS stimulation compared with respective unstimulated controls. These data document ethnic diversity in placental membrane immune response.

Prepregnancy Body Mass Index, Vaginal Inflammation, and the Racial Disparity in Preterm Birth

The authors sought to quantify the overall and race/ethnic-specific relations between prepregnancy body mass index and both preterm birth and vaginal inflammation. Data from a cohort of 11,392 women who enrolled in the multicenter Vaginal Infections and Prematurity Study (1984-1989) at 23-26 weeks' gestation were used. Compared with a prepregnancy body mass index of 22, a body mass index of 16 increased the risk of preterm birth by 90% (odds ratio = 1.9, 95% confidence interval (CI): 1.5, 2.6), and a body mass index of 18 increased the risk by 40% (odds ratio = 1.4, 95% CI: 1.2, 1.7). Ethnicity substantially modified the magnitude of the body mass index effect and the shape of the preterm birth risk curve, with underweight having a greater impact on preterm birth among Blacks and Hispanics than among Whites. Low body mass index increased the risk of a high level of neutrophils (> 5 per oil immersion field) and a high vaginal pH measurement (> or = 5.0) among Black women; for a body mass index of 16 versus 22, the odds ratio = 1.7 (95% CI: 1.1, 2.6). Compared with Black women with a body mass index of 22, Blacks with a body mass index of 16 had a 1.7-fold increased risk for a high level of neutrophils and a high vaginal pH measurement, while those with a body mass index of 18 had a 1.3-fold increased risk.

Neighborhood Crime, Deprivation, and Preterm Birth

Significant racial disparity in preterm birth (PTB; birth at <37 weeks' gestation) exists, poorly explained by Individual-level factors. This research explores whether neighborhood crime contributes to the racial disparity in PTB. Geocoded Wake County, NC, birth records and crime-report data for 1999 to 2001 were merged with US Census data (2000). Race-stratified logistic and multilevel logistic models produced odds ratios (ORs) and 95% confidence intervals (CIs) for block-group violent, theft, property, and vice crime rates and singleton PTB. A total of 13,960 women resided in a 114-block-group crime area. Non-Hispanic black women were more likely than non-Hispanic white women to deliver preterm (12.8% versus 6.7%), live in economically deprived block groups (42.2% versus 19.3% in the highest deprivation quartile), and experience more crime (32.0% versus 3.8% in the highest violent-crime-rate quartile). Quartiles of violent, theft, property, and vice crimes were associated with PTB in unadjusted models. Living in very high violent-crime-rate block-group quartiles was suggestive of increased odds of PTB for white and black non-Hispanic women (OR = 1.5; 95% CI, 0.9-2.6; and OR = 1.4; 95% CI, 1.0-2.1, respectively) in adjusted models. Other crime effects were attenuated after adjustment. Differential neighborhood exposures may contribute to racial disparity in PTB.

Racial disparities in elevated prenatal depressive symptoms among black and white women in eastern north Carolina.

Black women have an increased risk for preterm birth compared with white women, and prior research indicated that maternal prenatal depressive symptoms are associated with increased risk for preterm outcomes among black women. Race-related differences in prenatal depression could be of etiologic significance in understanding racial disparities in preterm birth. Our study focused on Center for Epidemiologic Studies' Depression Scale (CES-D) scores of pregnant black and white women. Women were administered the CES-D at the time of their first visit to hospital-based prenatal clinics. Two cutoff scores for the CES-D were used: 16 or higher, which indicates "significant" depressive symptoms, and 23 or higher, which indicates major depressive disorder. For the sample of 1163 women, mean CES-D scores were significantly higher among black (17.4) than white (13.7) women. Of black women, 49% had CES-D scores higher than 15 compared with 33.5% of white women. Also, 27.5% of black women had scores higher than 22 compared with 16% of white women. After adjustment for maternal age, marital status, and education, odds ratios for race for both CES-D cutoff scores were approximately 1.5. Results of this study indicate that black women have greater rates of prenatal depression than white women.