Introduction

Across the USA, large and persistent racial inequities in maternal morbidity and mortality have been well documented, with maternal pregnancy complications contributing largely to both [1–3]. Much of this research examines individual level risk, as well as disparities in access to adequate health services and racial bias in healthcare settings [4, 5]. Increasingly, however, there is greater understanding of how structural racism harms health [6], and how broader social and structural factors shape reproductive health inequities in particular [7••, 8, 9•].

Due to historic and ongoing structural racism, manifest in residential segregation and the resulting concentration of poverty and underinvestment in racially and ethnically minoritized communities, health-harming exposures are often concentrated at the neighborhood level for racially marginalized groups [6, 10–16]. In this sense, environmental racism is a core pillar of structural racism, yet environmental epidemiology has too often failed to interrogate and integrate the role of racism as a driver of poor health and health inequities [17]. An environmental justice lens offers an opportunity to examine how neighborhood-level environments can create the conditions for improved maternal health and could contribute to narrowing racial inequities in maternal pregnancy complications [18, 19].

Environmental justice is defined by the Environmental Protection Agency (EPA) and other government agencies as “the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income with respect to the development, implementation and enforcement of environmental laws, regulations and policies” [20]. They further define that fair treatment means “no group of people should bear a disproportionate share of the negative environmental consequences resulting from industrial, governmental and commercial operations or policies” [20].

Most research exploring environmental factors and maternal pregnancy complications has centered on environmental pollutants, from air pollution to toxic waste and environmental chemicals [21,22,23,24,25], with environmental racism commonly understood as the disproportionate concentration of environmental pollutants or hazards in or near communities of color. However, a broader understanding of environmental racism to include the lack of access to beneficial built and social environmental resources such as greenspace, safe and affordable housing, quality education, nutrient-rich food, quality public transportation, treated water, and nature is needed to comprehensively address seemingly intractable inequities. The negative social and built environment consequences resulting from industrial, governmental, and commercial operations or policies are rarely explored in the literature or included in population level environmental justice interventions.

We conducted this scoping review with two primary objectives: (1) to survey the state of the literature exploring the association between neighborhood-level built and social environment factors and maternal pregnancy complications among racially marginalized women in the USA and (2) briefly highlight how an environmental justice framework can be used to offer policy and clinical interventions for maternal health inequities caused by structural racism in built and social environments.

Methods

We searched peer-reviewed literature from January 2017 to January 2022 in databases known to index scholarship on neighborhood context, environmental factors, and maternal pregnancy complications from various sources and fields. These included PubMed, Academic Search Premier, and Environment Index. We also searched the reference lists of related articles to find additional relevant studies when applicable.

We developed a list of broad exposure terms after reviewing the structural racism and neighborhood literature. The broad terms included housing, policing, parks and greenspace, neighborhood segregation, schools, food environment, and public transportation. These broader terms were then broken down to reflect related concepts and cultural adaptions in the literature (i.e., ethnic enclaves vs segregation). Our outcome search terms included gestational diabetes, all maternal hypertension outcomes (gestational hypertension, preeclampsia, eclampsia, and HELLP), and gestational weight gain. We intentionally limited our search to maternal specific complications during pregnancy to center the experiences of birthing people rather than on the infant outcomes. Additionally, maternal specific complications are among the leading causes of severe maternal morbidity and mortality, but many can be intervened upon. Evidence suggests that inequitable distribution in these conditions drive many of the racial disparities we see for acute and chronic conditions that lead to increased mortality and morbidity like maternal hemorrhage and postpartum hypertension [2]. Corresponding MESH terms were identified for each exposure and outcome search term in PubMed, and this was used to develop the search strategy for Academic Search Premier and Environment Index.

To be included in the study, articles had to meet five criteria and be published within the last five years: (1) written in the English language, (2) based in the United States, (3) quantitative (qualitative studies, if any, will be included in discussion for future recommendations) (4) exposure: contextual factor measured at the neighborhood level, beyond environmental pollutants (5) outcome: defined maternal pregnancy complication (individual or at the neighborhood level).

The first and second authors (BB and AG) reviewed abstracts, read all full text articles, and extracted relevant data. Team meetings were used to adjudicate any inclusion discrepancies. Reference review and data extraction were conducted using Covidence web-based software.

Results

Our search returned 1,215 unique abstracts for screening after removal of duplicates. Authors discussed conflicts and agreed on which articles warranted further review. After screening all abstracts and removing duplicates, we reviewed 43 full-text articles. We excluded studies that were outside of the USA [3], not empirical [2], and did not measure social or built environment variables at the neighborhood level [14]. We also excluded studies that did not meet our outcome criteria [5], were intervention-based [1], review papers [1], and full text not available [1]. A total of 16 studies met our full eligibility criteria for inclusion in this review (see Table 1).

Table 1 Characteristics of studies to assess built and social environments in relation to maternal pregnancy complications (n = 16, presented in chronological order)
Full size table

Retrospective cohort/observational study was the design most used to assess the association between neighborhood contextual factors and pregnancy complications [6]. Other studies used cross-sectional [4], prospective cohort [1], case–control [2], exposome-wide association [1], or time-series [1] study designs. One study employed an unclear design.

Six of the eligible studies included some measure of neighborhood food access/environment as a primary exposure, and five assessed neighborhood-level exposures of greenspace. Other studies used neighborhood-level residential segregation [2], crime [3], local expenditures [1], physical disorder [1], and proximity to roadways [1] as primary exposures. Studies assessed a variety of pregnancy complications. Outcomes included gestational diabetes, preeclampsia, eclampsia, gestational weight gain, and maternal morbidity. Among included studies, hypertensive disorders of pregnancy (HDP) were the most frequently studied outcome.

Three of the six studies that focused on the food environment examined living in neighborhoods classified by the USDA as “food deserts.” Pedersen et al. found that living in a food desert, characterized by the USDA as a low-income census tract that also has low access to food outlets, was associated with higher odds of experiencing a pregnancy morbidity and when examined separately the same association was also seen for preeclampsia [25]. Using the same measure but differing distances, neither Rammah et al. nor Tipton et al. found the same association when examining hypertensive disorders. However, Banner et al. did find that living in a food desert was associated with lower odds for gestational diabetes [22, 26]. Banner et al. developed a neighborhood asset index and found that pregnant individuals living in neighborhoods with low assets (high poverty/low retail) had higher BMI and C-reactive protein concentrations-cardiometabolic factors closely related to maternal pregnancy complications [27]. While Black women reported lower levels of assets compared to white women in the study, these relationships were not modified by race or ethnicity [27]. Two studies examined food access and gestational weight gain. Assibey-Mensah found that a higher number of grocery stores within 3 km was associated with lower odds of having excessive or inadequate gestational weight gain [28]. Grobman et al. found that living within a half-mile of culturally specific foods, specifically a Mexican restaurant, was associated with lower odds of excessive weight gain [29].

The studies focused on greenspace, walkability, and access to recreational facilities also showed varying results. Most studies found an inverse association with pregnancy related complications, while others found no association. Of those examining hypertensive disorders, Giuntella and Weber et al. conducted two studies that found that living in a neighborhood with higher percentages or higher density of greenspace (within a 100 or 500 m buffer) was associated with reduction in odds of maternal hypertension, specifically super imposed preeclampsia and severe preeclampsia [30, 31]. In one study, Weber et al. also found that these associations differed by neighborhood-level socioeconomic status [31]. Using the same measure of higher density of greenspace, but variable distances, Weber and Choe et al. found no association [32, 33]. Despite Weber et. al finding no association between greenspace and hypertension, they did show that living within 500 m of a recreational facility (parks, playgrounds, fishing, etc.) was associated with lower odds of gestational hypertension [32]. Hu et al. used a different measure of greenspace and found that living in neighborhoods with less available greenspace per person, less accessible greenspace within a 10-min walk, and less total available greenspace were associated with higher odds of gestational diabetes and preeclampsia [34].

When comparing ability to access greenspace within a 10-min walk, women in neighborhoods comprised predominantly of low-income Black residents were more likely to develop preeclampsia or gestational diabetes than neighborhoods comprised predominantly of high-income white residents [34]. When examining general walkability and proximity to parks in relation to gestational weight gain, Grobman et al. found an inverse association, where increases in walkability score and number of parks were associated with reduced odds in both excessive and inadequate weight gain [28]. Weber et al. also explored proximity to highways and found that living within close proximity of a major roadway was associated with higher odds of gestational diabetes, but no association for hypertensive disorders [32].

Of the studies that explored neighborhood contextual factors of the social environment, four explored crime, violence, or physical disorder, and two studies examined residential segregation. Galin et al. focused on crime, finding that living in neighborhoods with higher rates of violence and crime is associated with increased risk of excessive gestational weight gain [35]; among Asian and Pacific Islander women, they found that high exposure of neighborhood violence was associated with reduced risk of inadequate weight gain as well as increased risk of excessive weight gain [35].

Two studies examined neighborhood-level crime and maternal hypertension. Choe et al. found a positive association between increasing neighborhood crime and maternal hypertension, specifically when examining burglary and forcible sex offenses [33]. Galin et al. found a similar positive association between living in a neighborhood with high crime rates and odds of hypertensive disorders of pregnancy, particularly assaults and incivilities [36]. Another study done by Mayne et al. examined neighborhood physical disorder which was also shown to be associated with an increased prevalence for hypertensive disorders of pregnancy [37]. Both studies on segregation examined maternal hypertension and found positive associations. One study done by Mayne et al. found that residential segregation was associated with a higher prevalence ratio of hypertensive disorders of pregnancy among Black women living in the high poverty neighborhoods [38]. The other study, by Mayne et al. examined segregation through the practice of “redlining” and found that living in neighborhoods that were previously deemed “hazardous” was associated with higher odds of maternal hypertension compared to neighborhoods that were deemed “best” [39].

Expenditures on various neighborhood assets like policing, education, and greenspace was examined by Hollenbach et al. They documented that increases in spending on policing in a locality were associated with higher odds of severe maternal morbidity, while increases in spending on transportation and housing resulted in reduction of odds of severe morbidity [40].

Discussion

Our scoping review of the literature found that the research examining the association between neighborhood-level built and social environment factors and maternal pregnancy complications is sparse, especially in relation to structural racism for racially marginalized groups. When excluding environmental pollution and toxins, we identified only 16 studies in the last five years that fit our criteria of neighborhood-level environmental exposure, with the majority focused on built environment factors, and in particular proximity to greenspace and food access. Fewer papers were identified that focused on contextual neighborhood-level social environmental factors—with crime and physical disorder most examined. Collectively, these studies provide important information on the association between built and social environmental features and maternal pregnancy complications. These connections should be further explored in the literature, to complement studies exclusively focused on environmental hazards and pollutants.

In our exploration and synthesis of the literature, we identified a few important gaps. First, there has been limited exploration of other factors in the built environment that disproportionately impact racially marginalized communities such as access to safe and treated water, housing quality and access, transportation, and highway construction [41••, 42–44]. We do acknowledge however that this gap may primarily reflect our exclusion criteria (the fact that exposure had to be a contextual factor measured at the neighborhood level, beyond environmental pollutants).

Secondly, considerable research is still needed to examine the social environment, especially in relation to structural racism. There are many adverse social environmental factors that disproportionately impact racially marginalized neighborhoods over the life course. These conditions result from industrial, governmental, and commercial operations or policies such as over policing and hyper surveillance, poor school quality and inadequate educational access, unaffordable housing, mortgage discrimination, and acculturation. Such factors are not currently explored and likely interact and intersect with other forms of environmental racism to impact maternal pregnancy complications [45–51].

Understanding the social environment can help us move away from the narrative that “biological race” is a meaningful risk factor that increases risk of maternal pregnancy complications [9•, 52], but rather towards an understanding that the social environment plays a large role in access and exposure to key determinants of health, thus shaping health behaviors [9•]. Exploring some of these factors may also help elucidate why we see disparities for racially marginalized groups and inform policy solutions to combat them. Finally, these associations need to be explored critically in various racially marginalized groups and through a structural racism lens. Most of the studies included racially diverse samples but did not stratify analyses, examine interactions, or explicitly engage with an intersectional analysis. This specific examination is necessary given the historical and continued context of divestment at the neighborhood level for racially marginalized communities and that these associations may not behave the same in white populations or neighborhoods.

The available literature also points to a critical need to apply an environmental justice lens to guide future research on built and social environment factors and maternal pregnancy complications. Utilizing an environmental justice framework will help elucidate the numerous practices, policies, and environmental consequences at the neighborhood level that disproportionately burden racially marginalized groups and shape maternal health outcomes [53]. It will also point to why we see aggregation of social determinants of health at the neighborhood level and inform population health and clinical interventions. Additionally, as the environmental justice framework hinges on identifying solutions and tools to advance equity for the groups most impacted by the environmental racism [18], examining practices in the social and built environment and their harms on maternal pregnancy complications directly can be a useful way to inform policy solutions for equity. For example, Muchomba et al.’s study on municipal spending highlights that where and how we invest funding at the local level has lasting impacts for health outcomes [40]. As racially marginalized, over surveilled, and harassed communities call for diversion of funding away from policing into neighborhood level infrastructure and resources [54], examining these studies on the built and social environment through a structural racism and environmental justice framework shows how spending practices at the neighborhood level, specifically reallocation of funds from policing and into community infrastructure like greenspace, grocery stores, schools. and affordable housing, can be potentially meaningful environmental justice interventions for maternal morbidity and counteract the health impacts of over policing, discriminatory housing practices, and inequitable investment in education in racially minoritized communities [55–58].

Conclusion

We have witnessed a galvanization around sustainability and environmental health from industrial, government, and commercial agencies over the last decade in response to climate change and depleting natural resources. This shift has been critical in thinking about a sustainable planet and future. As we continue to invest in understanding the impacts of our environments on pregnancy and inter-generational wellbeing, it is necessary to examine the built and social environments that create racially disparate incidence in maternal pregnancy complications. A narrow definition of the environment, which does not consider the overlapping ways in which the built and social environment intersect with the more traditional understanding of environmental pollution and harm to shape reproductive health outcomes, is likely to result in interventions that are similarly narrow in scope and impact. To address injustices and disparities in maternal morbidity caused by inequitable environments, clinical interventions and policies should incorporate the Environmental Justice Principles outlined at the First National People of Color Environmental Leadership Summit in 1991 [18]. While all principles should be considered, particular attention should be given to the following: Principle 2, which requires public policy be based on mutual respect and justice, free from discrimination and bias; Principle 7, which requires equal participation in decision-making by impacted communities; and Principle 13, which underscores informed consent and the end to experimental reproductive or medical procedures on people of color. In addition, Principle 3 and Principle 12, which focus on the responsible uses of land and renewable resources, and the need for integrated urban and rural ecological policies, respectively, are foundational for any work that protects the health of our planet for humans and other living beings. More actionable research that bridges the literature on structural racism and environmental justice is needed as a first step to fundamentally address the stark racial inequities in maternal health outcomes and pregnancy complications.