Neighborhood socioeconomic status in relation to preterm birth in a U.S. cohort of black women

Environmental justice burden and Black-White disparities in spontaneous preterm birth in Harris County, Texas

Introduction

Given limited evidence of previous studies, we evaluated the role of environmental justice (EJ) burden (i.e., a neighborhood characterized by both increased environmental burden and socioeconomic deprivation) in Black-White disparities in spontaneous preterm birth (sPTB) in Harris County, Texas and compared results that evaluated neighborhood-level socioeconomic deprivation alone.

Methods

We conducted a retrospective analysis using PeriBank, a database and biospecimen repository of gravidae giving birth at two hospitals in the Texas Medical Center. We included 3,703 non-Hispanic Black and 5,475 non-Hispanic white gravidae who were U.S.-born, delivered from August 2011-December 2020, and resided in Harris County, TX. We used data from the U.S. EPA EJScreen to characterize the EJ burden of participant's zip code of residence from fine particulate matter (PM2.5), ozone, and proximity to National Priorities List (NPL) sites and calculated zip-code level Area Deprivation Index (ADI). We assessed the contribution of neighborhood-level variables to the Black-White disparity in sPTB by evaluating attenuation of the odds ratio (OR) representing the effect of race in multivariable logistic regression models, controlling for individual-level characteristics. We also conducted race-stratified analyses between each neighborhood variable and sPTB. Exposure indices were treated as continuous variables; in stratified models, ORs and 95% Confidence Intervals (CIs) are presented per 10-unit increase in the neighborhood variable.

Results

Accounting for individual-level variables, Black gravidae had 79% higher odds of sPTB than white gravidae (OR = 1.79, 95%CI = 1.32, 2.44); the disparity was moderately attenuated when accounting for EJ burden or ADI (ORs ranged from 1.58 to 1.69). Though we observed no association between any of the EJ burden indices and sPTB among white gravidae, we found increased risks among Black gravidae, with ORs of similar magnitude for each EJ variable. For example, Black gravidae experienced 17% increased odds of sPTB associated with a 10-unit increase in the EJ burden index for PM2.5 (OR = 1.17, 95%CI = 0.97, 1.40). No racial differences were observed in the association of ADI with sPTB.

Discussion

Though we observed limited evidence of the contribution of living in EJ neighborhoods to the Black-White disparity in sPTB, our study suggests living in an EJ neighborhood may differentially impact Black and white gravidae.

Association of maternal education, neighborhood deprivation, and racial segregation with gestational age at birth by maternal race/ethnicity and United States Census region in the ECHO cohorts

Background

In the United States, disparities in gestational age at birth by maternal race, ethnicity, and geography are theorized to be related, in part, to differences in individual- and neighborhood-level socioeconomic status (SES). Yet, few studies have examined their combined effects or whether associations vary by maternal race and ethnicity and United States Census region.

Methods

We assembled data from 34 cohorts in the Environmental influences on Child Health Outcomes (ECHO) program representing 10,304 participants who delivered a liveborn, singleton infant from 2000 through 2019. We investigated the combined associations of maternal education level, neighborhood deprivation index (NDI), and Index of Concentration at the Extremes for racial residential segregation (ICERace) on gestational weeks at birth using linear regression and on gestational age at birth categories (preterm, early term, post-late term relative to full term) using multinomial logistic regression.

Results

After adjustment for NDI and ICERace, gestational weeks at birth was significantly lower among those with a high school diploma or less (-0.31 weeks, 95% CI: -0.44, -0.18), and some college (-0.30 weeks, 95% CI: -0.42, -0.18) relative to a master's degree or higher. Those with a high school diploma or less also had an increased odds of preterm (aOR 1.59, 95% CI: 1.20, 2.10) and early term birth (aOR 1.26, 95% CI: 1.05, 1.51). In adjusted models, NDI quartile and ICERace quartile were not associated with gestational weeks at birth. However, higher NDI quartile (most deprived) associated with an increased odds of early term and late term birth, and lower ICERace quartile (least racially privileged) associated with a decreased odds of late or post-term birth. When stratifying by region, gestational weeks at birth was lower among those with a high school education or less and some college only among those living in the Northeast or Midwest. When stratifying by race and ethnicity, gestational weeks at birth was lower among those with a high school education or less only for the non-Hispanic White category.

Conclusion

In this study, maternal education was consistently associated with shorter duration of pregnancy and increased odds of preterm birth, including in models adjusted for NDI and ICERace.

Influence of Neighborhood Socioeconomic Status on Adverse Outcomes in Pregnancy

PURPOSE

To evaluate whether ZIP-code level neighborhood socioeconomic status (SES) is associated with adverse pregnancy outcomes.

METHODS

A retrospective study of 2009-2014 Oregon Health and Science University (OHSU) births with maternal ZIP codes in one of 89 Portland metropolitan area ZIP codes. Deliveries with ZIP codes outside of the Portland metro area were excluded. Deliveries were stratified by SES based on ZIP code median household income: low (below 10th percentile), medium (11th-89th percentile), and high (above 90th percentile). Univariate analysis and multivariable logistic regression with medium SES as the reference group evaluated perinatal outcomes and strength of association between SES and adverse events.

RESULTS

This study included 8118 deliveries with 1654 (20%) classified as low SES, 5856 (72%) medium SES, and 608 (8%) high SES. The low SES group was more likely to be younger, have a higher maternal BMI, have increased tobacco use, identify as Hispanic or Black, and less likely to have private insurance. Low SES was associated with a significantly increased risk of preeclampsia (RR 1.23 95% CI 1.01-1.49), but this was no longer significant after adjusting for confounders (aRR 1.23 95% CI .971-1.55). High SES was negatively associated with gestational diabetes mellitus (GDM), even after adjusting for confounders (aRR 0.710, 95% CI 0.507-0.995).

CONCLUSION

In the Portland metropolitan area, high SES was associated with a lower risk of GDM. Low SES was associated with a higher risk of preeclampsia before accounting for covariates. ZIP code-based risk assessment may be a useful indicator in detecting healthcare disparities.

Protective Places: the Relationship between Neighborhood Quality and Preterm Births to Black Women in Oakland, California (2007-2011)

Black women have the highest incidence of preterm birth (PTB). Upstream factors, including neighborhood context, may be key drivers of this increased risk. This study assessed the relationship between neighborhood quality, defined by the Healthy Places Index, and PTB among Black women who lived in Oakland, California, and gave birth between 2007 and 2011 (N = 5418 women, N = 107 census tracts). We found that, compared with those living in lower quality neighborhoods, women living in higher quality neighborhoods had 20-38% lower risk of PTB, independent of confounders. Findings have implications for place-based research and interventions to address racial inequities in PTB.

Racial and geographic variation in effects of maternal education and neighborhood-level measures of socioeconomic status on gestational age at birth: Findings from the ECHO cohorts

Preterm birth occurs at excessively high and disparate rates in the United States. In 2016, the National Institutes of Health (NIH) launched the Environmental influences on Child Health Outcomes (ECHO) program to investigate the influence of early life exposures on child health. Extant data from the ECHO cohorts provides the opportunity to examine racial and geographic variation in effects of individual- and neighborhood-level markers of socioeconomic status (SES) on gestational age at birth. The objective of this study was to examine the association between individual-level (maternal education) and neighborhood-level markers of SES and gestational age at birth, stratifying by maternal race/ethnicity, and whether any such associations are modified by US geographic region. Twenty-six ECHO cohorts representing 25,526 mother-infant pairs contributed to this disseminated meta-analysis that investigated the effect of maternal prenatal level of education (high school diploma, GED, or less; some college, associate's degree, vocational or technical training [reference category]; bachelor's degree, graduate school, or professional degree) and neighborhood-level markers of SES (census tract [CT] urbanicity, percentage of black population in CT, percentage of population below the federal poverty level in CT) on gestational age at birth (categorized as preterm, early term, full term [the reference category], late, and post term) according to maternal race/ethnicity and US region. Multinomial logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CIs). Cohort-specific results were meta-analyzed using a random effects model. For women overall, a bachelor's degree or above, compared with some college, was associated with a significantly decreased odds of preterm birth (aOR 0.72; 95% CI: 0.61-0.86), whereas a high school education or less was associated with an increased odds of early term birth (aOR 1.10, 95% CI: 1.00-1.21). When stratifying by maternal race/ethnicity, there were no significant associations between maternal education and gestational age at birth among women of racial/ethnic groups other than non-Hispanic white. Among non-Hispanic white women, a bachelor's degree or above was likewise associated with a significantly decreased odds of preterm birth (aOR 0.74 (95% CI: 0.58, 0.94) as well as a decreased odds of early term birth (aOR 0.84 (95% CI: 0.74, 0.95). The association between maternal education and gestational age at birth varied according to US region, with higher levels of maternal education associated with a significantly decreased odds of preterm birth in the Midwest and South but not in the Northeast and West. Non-Hispanic white women residing in rural compared to urban CTs had an increased odds of preterm birth; the ability to detect associations between neighborhood-level measures of SES and gestational age for other race/ethnic groups was limited due to small sample sizes within select strata. Interventions that promote higher educational attainment among women of reproductive age could contribute to a reduction in preterm birth, particularly in the US South and Midwest. Further individual-level analyses engaging a diverse set of cohorts are needed to disentangle the complex interrelationships among maternal education, neighborhood-level factors, exposures across the life course, and gestational age at birth outcomes by maternal race/ethnicity and US geography.

Paternal DNA Methylation May Be Associated With Gestational Age at Birth

Background:

How epigenetic modifications of DNA are associated with gestational age at birth is not fully understood. We investigated potential effects of differential paternal DNA methylation (DNAm) on offspring gestational age at birth by conducting an epigenome-wide search for cytosine-phosphate-guanine (CpG) sites.

Methods:

Study participants in this study consist of male cohort members or partners of the F1-generation of the Isle of Wight Birth Cohort (IoWBC). DNAm levels in peripheral blood from F1-fathers (n = 92) collected around pregnancy of their spouses were analyzed using the Illumina 450K array. A 5-step statistical analysis was performed. First, a training-testing screening approach was applied to select CpG sites that are potentially associated with gestational age at birth. Second, functional enrichment analysis was employed to identify biological processes. Third, by centralizing on biologically informative genes, Cox proportional hazards models were used to assess the hazard ratios of individual paternal CpGs on gestational age adjusting for confounders. Fourth, to assess the validity of our results, we compared our CpG-gestational age correlations within a Born into Life Study in Sweden (n = 15). Finally, we investigated the correlation between the detected CpGs and differential gene expression in F2 cord blood in the IoWBC.

Results:

Analysis of DNAm of fathers collected around their partner’s pregnancy identified 216 CpG sites significantly associated with gestational age at birth. Functional enrichment pathways analyses of the annotated genes revealed 2 biological pathways significantly related to cell-cell membrane adhesion molecules. Differential methylation of 9 cell membrane adhesion pathway-related CpGs were significantly associated with gestational age at birth after adjustment for confounders. The replication sample showed correlation coefficients of 2 pathway-related CpGs with gestational age at birth within 95% confidence intervals of correlation coefficients in IoWBC. Finally, CpG sites of protocadherin (PCDH) gene clusters were associated with gene expression of PCDH in F2 cord blood.

Conclusions:

Our findings suggest that differential paternal DNAm may affect gestational age at birth through cell-cell membrane adhesion molecules. The results are novel but require future replication in a larger cohort.

Low birthweight in second children after nurse home visiting

OBJECTIVE

To examine low birthweight and preterm birth of second children born to home-visited first-time mothers.

SUBJECTS

Women were previously recruited for a randomized controlled trial of the home visiting model disseminated as Nurse-Family Partnership. 512 of these women had second children within 18 years of the first child's birth, and were included in our sample.

RESULTS

The intervention was associated with a lower likelihood of low birthweight for second children (odds ratio: 0.51, 95% CI: 0.27, 0.97), an effect apparent only if the first-born had low birthweight and mediated by close birth spacing. These moderation and mediation patterns were similar in the preterm birth outcome.

CONCLUSION

A home visiting program provided for first-born children reduced low birthweight for second-born children, if the first-born had low birthweight. This finding implies a broader impact than previously documented, because few studies have included these second children.

A review of recent literature on materialist and psychosocial models for racial and ethnic disparities in birth outcomes in the US, 2000-2014

OBJECTIVE

Material and psychosocial factors exacerbate racial disparities in health outcomes. This review sought to ascertain recent knowledge of the effects of materialist and psychosocial factors on differences in low birthweight (LBW) and preterm delivery (PTD) outcomes between Black and White mothers.

DESIGN

Search and review was conducted for studies that examined: (a) neighborhood-level deprivation as an indicator of material conditions, and (b) racial discrimination or occupational stressors as indicators of psychosocial stress. The outcomes of interest were LBW and PTD.

RESULTS

Material and psychosocial factors significantly and negatively affected Blacks more than Whites, and were associated with increased adverse outcomes. Of five studies with a homogeneous Black study sample, three reported no effect on outcomes in women exposed to material or psychosocial factors.

CONCLUSION

Through this review we find that in comparison to White women, Black women are at higher risk of adverse outcomes due to both psychosocial stress and meso-level deprivation, after accounting for personal factors. A better understanding of effects on health outcomes of material and psychosocial factors in Black women is needed. Further investigation into materialist and psychosocial factors, will allow us to better understand the factors driving PTD and LBW disparities in the US.

Neighborhood Disadvantage and Preterm Delivery in Urban African Americans: The Moderating Role of Religious Coping

Evidence suggests that neighborhood disadvantage predicts preterm delivery (PTD). However, the design of most existing studies precludes within-group analyses, which would allow the identification segments of the population at highest risk, as well as preventive factors. African Americans (AA) are disproportionately affected by PTD, are disproportionately concentrated in disadvantaged neighborhoods, and frequently use religious coping in response to chronic stressors. Our objective was to examine the association between neighborhood disadvantage and PTD, and whether religious coping moderated the associations, among postpartum AA women. Addresses from participants of the Life Influences on Fetal Environments Study (n=1387) were geocoded and linked to data from the American Community Survey. An index of neighborhood disadvantage was derived from a principal components analysis of the following variables: % below poverty, % unemployed, % receiving public assistance income, % college educated, % AA, % female-headed households, % owner occupied homes, median income, and median home value. Three domains of religious coping were assessed: organizational (church attendance), non-organizational (praying for self and asking others for prayer), and personal or subjective (experiences, perceptions, and sentiments about religion), and all were dichotomized as frequent/infrequent or satisfied/not satisfied. Preterm delivery was defined as birth before 37 completed weeks of gestation. Prevalence ratios and 95% confidence intervals were estimated with log binomial regression models. Neighborhood disadvantage did not predict PTD rates in the overall sample. However, there was evidence of moderation by asking others for prayer (P for asking for prayer X disadvantage index interaction term: 0.01). Among women who infrequently asked others for prayer, neighborhood disadvantage was positively associated with PTD rates (adjusted Prevalence ratio: 1.28, 95% Confidence Interval: 1.01, 1.63), and a null association was found for those who frequently asked others for prayer. No evidence of moderation by the other religious coping variables was present. Non-organizational religious coping may buffer against the adverse effects of neighborhood disadvantage on PTD rates, among urban AA women. Future research should examine the mechanisms of the reported relationships.

Association of neighborhood context with offspring risk of preterm birth and low birthweight: A systematic review and meta-analysis of population-based studies

Findings from studies investigating associations of residential environment with poor birth outcomes have been inconsistent. In a systematic review and meta-analysis, we examined associations of neighborhood disadvantage with preterm birth (PTB) and low birthweight (LBW), and explored differences in relationships among racial groups. Two reviewers searched English language articles in electronic databases of published literature. We used random effects logistic regression to calculate odds ratios (and 95% confidence intervals) relating neighborhood disadvantage with PTB and LBW. Neighborhood disadvantage, most disadvantaged versus least disadvantaged neighborhoods, was defined by researchers of included studies, and comprised of poverty, deprivation, racial residential segregation or racial composition, and crime. We identified 1314 citations in the systematic review. The meta-analyses included 7 PTB and 14 LBW cross-sectional studies conducted in the United States (U.S.). Overall, we found 27% [95%CI: 1.16, 1.39] and 11% [95%CI: 1.07, 1.14] higher risk for PTB and LBW among the most disadvantaged compared with least disadvantaged neighborhoods. No statistically significant association was found in meta-analyses of studies that adjusted for race. In race-stratified meta-analyses models, we found 48% [95%CI: 1.25, 1.75] and 61% [95%CI: 1.30, 2.00] higher odds of PTB and LBW among non-Hispanic white mothers living in most disadvantaged neighborhoods compared with those living in least disadvantaged neighborhoods. Similar, but less strong, associations were observed for PTB (15% [95%CI: 1.09, 1.21]) and LBW (17% [95%CI: 1.10, 1.25]) among non-Hispanic black mothers. Neighborhood disadvantage is associated with PTB and LBW, however, associations may differ by race. Future studies evaluating causal mechanisms underlying the associations, and racial/ethnic differences in associations, are warranted.