Effects of Maternal Homelessness, Supplemental Nutrition Programs, and Prenatal PM2.5 on Birthweight

An incomplete picture: A scoping review of how scholars account for race and ethnicity in family homelessness research

Families of color in the United States experience homelessness at a disproportionately higher rate than White families; however, little is known about how scholars account for race and ethnicity in family homelessness research. This scoping review analyzes how researchers examine race and ethnicity in conceptual frameworks, methods, and analysis. Following PRISMA-ScR reporting standards, I searched PubMed, PsycINFO, Scopus, and ERIC for quantitative studies including a housing outcome for homeless service-involved families. I used Covidence to screen for inclusion and extract data, and QuADS to evaluate study quality. Fourteen studies met inclusion criteria. Researchers' articles lacked theory and the context of racism, lacked detail on how race and ethnicity were conceptualized and operationalized, and most (71%) did not disaggregate results. Without putting data within the context of systemic racism and disaggregating outcomes, research will produce incomplete knowledge on family homelessness, leading to ineffective interventions for families of color.

Special Supplemental Nutrition Program for Women, Infants, and Children Enrollment and Adverse Pregnancy Outcomes Among Nulliparous Individuals

OBJECTIVE

To evaluate the relationship between changes in Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) enrollment during pregnancy from 2016 to 2019 and rates of adverse pregnancy outcomes in U.S. counties in 2019.

METHODS

We conducted a serial, cross-sectional ecologic study at the county level using National Center for Health Statistics natality data from 2016 to 2019 of nulliparous individuals eligible for WIC. The exposure was the change in county-level WIC enrollment from 2016 to 2019 (increase [more than 0%] vs no change or decrease [0% or less]). Outcomes were adverse pregnancy outcomes assessed in 2019 and included maternal outcomes (ie, gestational diabetes mellitus [GDM], hypertensive disorders of pregnancy, cesarean delivery, intensive care unit [ICU] admission, and transfusion) and neonatal outcomes (ie, large for gestational age [LGA], small for gestational age [SGA], preterm birth, and neonatal intensive care unit [NICU] admission).

RESULTS

Among 1,945,914 deliveries from 3,120 U.S. counties, the age-standardized rate of WIC enrollment decreased from 73.1 (95% CI, 73.0-73.2) per 100 live births in 2016 to 66.1 (95% CI, 66.0-66.2) per 100 live births in 2019, for a mean annual percent change decrease of 3.2% (95% CI, -3.7% to -2.9%) per year. Compared with individuals in counties in which WIC enrollment decreased or did not change, individuals living in counties in which WIC enrollment increased had lower rates of maternal adverse pregnancy outcomes, including GDM (adjusted odds ratio [aOR] 0.71, 95% CI, 0.57-0.89), ICU admission (aOR 0.47, 95% CI, 0.34-0.65), and transfusion (aOR 0.68, 95% CI, 0.53-0.88), and neonatal adverse pregnancy outcomes, including preterm birth (aOR 0.71, 95% CI, 0.56-0.90) and NICU admission (aOR 0.77, 95% CI, 0.60-0.97), but not cesarean delivery, hypertensive disorders of pregnancy, or LGA or SGA birth.

CONCLUSION

Increasing WIC enrollment during pregnancy at the county level was associated with a lower risk of adverse pregnancy outcomes. In an era when WIC enrollment has decreased and food and nutrition insecurity has increased, efforts are needed to increase WIC enrollment among eligible individuals in pregnancy.

Navigating Homelessness Assistance While Pregnant: A Rapid Qualitative Research-to-Policy Collaboration in Washington, DC

Background

Homelessness during pregnancy contributes to adverse pregnancy and infant outcomes from birth through early childhood. Washington, DC, a microcosm of structural inequities in the United States, has persistent racial disparities in perinatal outcomes and housing insecurity.

Methods

Grounded in a reproductive justice framework, we explored the lived experience of navigating homelessness assistance while pregnant to inform recommendations for a collaborative policy and practice change effort. We conducted 20 individual interviews with DC residents who experienced homelessness during pregnancy. We analyzed the data using thematic analysis and an action-oriented approach.

Results

Our analysis resulted in three main recommendation areas for policy and practice change: (1) timely and meaningful access to safe and stable housing in pregnancy; (2) care coordination for services and referrals that support physical, mental, and social well-being; and (3) access to a living wage and affordable housing.

Discussion

Access to stable housing is critical to ensure that pregnant and parenting people can have and raise children in a safe and sustainable environment-key tenets of reproductive justice. Housing support must be meaningfully accessible, including service delivery that accommodates the complex social histories and competing demands that accompany housing insecurity.

Health Equity Implications

This study informed the development of strategic recommendations, catalyzed a new model for multisector collaboration, and influenced a system-wide practice change to expand access to robust housing supports for pregnant people. Policy and practice change require sustained leveraging of political will to promote economic justice and ensure that residents can achieve safe, sustainable, and affordable housing.

Associations of household unmet basic needs and health outcomes among very low birth weight children

OBJECTIVE

We examined associations of past year household hardships (housing, energy, food, and healthcare hardships) with postnatal growth, developmental risk, health status, and hospitalization among children 0-36 months born with very low birth weight (VLBW) and the extent that these relationships differed by receipt of child supplemental security income (SSI).

STUDY DESIGN

We examined cross-sectional data from 695 families. Growth was measured as weight-for-age z-score change. Developmental risk was defined as ≥1 concerns on the "Parents' Evaluation of Developmental Status" screening tool. Child health status was categorized as excellent/good vs. fair/poor. Hospitalizations excluded birth hospitalizations.

RESULTS

Compared to children with no household hardships, odds of developmental risk were greater with 1 hardship (aOR 2.0 [1.26, 3.17]) and ≥2 hardships (aOR) 1.85 [1.18, 2.91], and odds of fair/poor child health (aOR) 1.59 [1.02, 2.49] and hospitalizations (aOR) 1.49 [1.00, 2.20] were greater among children with ≥2 hardships. In stratified analysis, associations of hardships and developmental risk were present for households with no child SSI and absent for households with child SSI.

CONCLUSION

Household hardships were associated with developmental risk, fair/poor health status, and hospitalizations among VLBW children. Child SSI may be protective against developmental risk among children living in households with hardships.

Risk of delivery complications among pregnant people experiencing housing insecurity

BACKGROUND

Housing insecurity is increasingly being recognized as an important social determinant of health. Pregnant individuals experiencing housing insecurity may represent a particularly vulnerable subset of this population, but few studies have examined this population nationally. In particular, racial and ethnic minority individuals may be at risk for poor outcomes within this group because of structural racism and discrimination. The introduction of the International Classification of Diseases, Tenth Revision, Clinical Modification diagnosis codes related to social determinants of health represent a new opportunity to identify patients with housing insecurity nationally.

OBJECTIVE

This study aimed to evaluate the prevalence of and delivery outcomes for pregnant people experiencing housing insecurity, both nationally and by race and ethnicity.

STUDY DESIGN

This was a retrospective cohort study using data from the 2016 to 2018 National Inpatient Sample. Delivery hospitalizations for people experiencing housing insecurity were identified using the International Classification of Diseases, Tenth Revision, Clinical Modification diagnosis code Z59. Among hospitals that coded at least 1 delivery for a patient with housing insecurity, logistic regression models were used to assess the odds of severe maternal morbidity associated with housing insecurity, adjusting for clinical risk and pregnancy characteristics.

RESULTS

Of 539,950 delivery hospitalizations, 1820 hospitalizations (0.3%) were for patients with housing insecurity. Compared to deliveries for patients with housing security, deliveries for patients with housing insecurity were more likely for patients who identified as Black (34.8% vs 18.1%; P<.001) and who had Medicaid insurance (83.5% vs 46.2%; P<.001). People with housing insecurity were more likely to have comorbidities and higher-risk pregnancies, including higher rates of substance use disorders (54.0% vs 6.9%), major mental health disorders (37.5% vs 8.7%), preeclampsia with severe features (7.4% vs 4.3%), and preterm birth <37 weeks gestation (23.7% vs 11.6%) (all P<.001). In regression analyses, patients with housing insecurity had more than twice the odds of severe maternal morbidity than patients with housing security during the delivery hospitalization (odds ratio, 2.17; 95% confidence interval, 1.75-2.68). After adjusting for clinical risk and pregnancy characteristics, the differences were attenuated overall (adjusted odds ratio, 1.17; 95% confidence interval, 0.94-1.47) and among racial and ethnic groups (White patients: adjusted odds ratio, 1.39; 95% confidence interval, 0.95-2.03; Black patients: adjusted odds ratio, 1.05; 95% confidence interval, 0.73-1.52; Hispanic patients: adjusted odds ratio, 1.04; 95% confidence interval, 0.59-1.84; Asian or Pacific Islander or Native American or other race patients: adjusted odds ratio, 1.08; 95% confidence interval, 0.45-2.58).

CONCLUSION

Pregnant individuals experiencing housing insecurity were more likely to be from groups that have been marginalized historically, had higher rates of comorbidities, and worse delivery outcomes. After risk adjustment, differences in the odds of severe maternal mortality were attenuated. Screening for housing insecurity may identify these patients earlier and connect them to services that could improve disparities in outcomes.

Critical windows of susceptibility for the effects of prenatal exposure to heat and heat variability on gestational growth

BACKGROUND

Studies have shown that prenatal heat exposure may impact fetal growth, but few studies have examined the critical windows of susceptibility. As extreme heat events and within season temperature variability is expected to increase in frequency, it is important to understand how this may impact gestational growth.

OBJECTIVES

We investigated associations between various measures of weekly prenatal heat exposure (mean and standard deviation (SD) of temperature and heat index (HI), derived using temperature in °C and dew point) and term birthweight or odds of being born small for gestational age (SGA) to identify critical windows of susceptibility.

METHODS

We analyzed data from mother-child dyads (n = 4442) in the Boston-based Children's HealthWatch cohort. Birthweights were collected from survey data and electronic health records. Daily temperature and HI values were obtained from 800 m gridded spatial climate datasets aggregated by the PRISM Climate Group. Distributed lag-nonlinear models were used to assess the effect of the four weekly heat metrics on measures of gestational growth (birthweight, SGA, and birthweight z-scores). Analyses were stratified by child sex and maternal homelessness status during pregnancy.

RESULTS

HI variability was significantly associated with decreased term birthweight during gestational weeks 10-29 and with SGA for weeks 9-26. Cumulative effects for these time periods were -287.4 g (95% CI: -474.1 g, -100.8 g for birthweight and 4.7 (95% CI: 1.6, 14.1) for SGA. Temperature variability was also significantly associated with decreased birthweight between weeks 15 and 26. The effects for mean heat measures on term birthweight and SGA were not significant for any gestational week. Stratification by sex revealed a significant effect on term birthweight in females between weeks 23-28 and in males between weeks 9-26. Strongest effects of HI variability on term birthweight were found in children of mothers who experienced homelessness during pregnancy. Weekly HI variability was the heat metric most strongly associated with measures of gestational growth. The effects observed were largest in males and those who experienced homelessness during pregnancy.

DISCUSSION

Given the impact of heat variability on birthweight and risk of SGA, it is important for future heat warnings to incorporate measure of heat index and temperature variability.

Maternal, Infant, and Child Health Outcomes Associated With the Special Supplemental Nutrition Program for Women, Infants, and Children : A Systematic Review

BACKGROUND

The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) is intended to improve maternal and child health outcomes. In 2009, the WIC food package changed to better align with national nutrition recommendations.

PURPOSE

To determine whether WIC participation was associated with improved maternal, neonatal-birth, and infant-child health outcomes or differences in outcomes by subgroups and WIC enrollment duration.

DATA SOURCES

Search (January 2009 to April 2022) included PubMed, Embase, CINAHL, ERIC, Scopus, PsycInfo, and the Cochrane Central Register of Controlled Trials.

STUDY SELECTION

Included studies had a comparator of WIC-eligible nonparticipants or comparison before and after the 2009 food package change.

DATA EXTRACTION

Paired team members independently screened articles for inclusion and evaluated risk of bias.

DATA SYNTHESIS

We identified 20 observational studies. We found: moderate strength of evidence (SOE) that maternal WIC participation during pregnancy is likely associated with lower risk for preterm birth, low birthweight infants, and infant mortality; low SOE that maternal WIC participation may be associated with a lower likelihood of inadequate gestational weight gain, as well as increased well-child visits and childhood immunizations; and low SOE that child WIC participation may be associated with increased childhood immunizations. We found low SOE for differences in some outcomes by race and ethnicity but insufficient evidence for differences by WIC enrollment duration. We found insufficient evidence related to maternal morbidity and mortality outcomes.

LIMITATION

Data are from observational studies with high potential for selection bias related to the choice to participate in WIC, and participation status was self-reported in most studies.

CONCLUSION

Participation in WIC was likely associated with improved birth outcomes and lower infant mortality, and also may be associated with increased child preventive service receipt.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality. (PROSPERO: CRD42020222452).

The Intersection of Immigrant and Environmental Health: A Scoping Review of Observational Population Exposure and Epidemiologic Studies

BACKGROUND

Transnational immigration has increased since the 1950s. In countries such as the United States, immigrants now account for > 15 % of the population. Although differences in health between immigrants and nonimmigrants are well documented, it is unclear how environmental exposures contribute to these disparities.

OBJECTIVES

We summarized current knowledge comparing immigrants' and nonimmigrants' exposure to and health effects of environmental exposures.

METHODS

We conducted a title and abstract review on articles identified through PubMed and selected those that assessed environmental exposures or health effects separately for immigrants and nonimmigrants. After a full text review, we extracted the main findings from eligible studies and categorized each article as exposure-focused, health-focused, or both. We also noted each study's exposure of interest, study location, exposure and statistical methods, immigrant and comparison groups, and the intersecting socioeconomic characteristics controlled for.

RESULTS

We conducted a title and abstract review on 3,705 articles, a full text review on 84, and extracted findings from 50 studies. There were 43 studies that investigated exposure (e.g., metals, organic compounds, fine particulate matter, hazardous air pollutants) disparities, but only 12 studies that assessed health disparities (e.g., mortality, select morbidities). Multiple studies reported higher exposures in immigrants compared with nonimmigrants. Among immigrants, studies sometimes observed exposure disparities by country of origin and time since immigration. Of the 50 studies, 43 were conducted in North America.

DISCUSSION

The environmental health of immigrants remains an understudied area, especially outside of North America. Although most identified studies explored potential exposure disparities, few investigated subsequent differences in health effects. Future research should investigate environmental health disparities of immigrants, especially outside North America. Additional research gaps include the role of immigrants' country of origin and time since immigration, as well as the combined effects of immigrant status with intersecting socioeconomic characteristics, such as race/ethnicity, income, and education attainment. https://doi.org/10.1289/EHP9855.

The immigrant birthweight paradox in an urban cohort: Role of immigrant enclaves and ambient air pollution

BACKGROUND

Foreign-born Black and Latina women on average have higher birthweight infants than their US-born counterparts, despite generally worse socioeconomic indicators and prenatal care access, i.e., "immigrant birthweight paradox" (IBP). Residence in immigrant enclaves and associated social-cultural and economic benefits may be drivers of IBP. Yet, enclaves have been found to have higher air pollution, a risk factor for lower birthweight.

OBJECTIVE

We investigated the association of immigrant enclaves and children's birthweight accounting for prenatal ambient air pollution exposure.

METHODS

In the Boston-based Children's HealthWatch cohort of mother-child dyads, we obtained birthweight-for-gestational-age z-scores (BWGAZ) for US-born births, 2006-2015. We developed an immigrant enclave score based on census-tract percentages of foreign-born, non-citizen, and linguistically-isolated households statewide. We estimated trimester-specific PM_2.5 concentrations and proximity to major roads based residential address at birth. We fit multivariable linear regressions of BWGAZ and examined effect modification by maternal nativity. Analyses were restricted to nonsmoking women and term births.

RESULTS

Foreign-born women had children with 0.176 (95% CI: 0.092, 0.261) higher BWGAZ than US-born women, demonstrating the IBP in our cohort. Immigrant enclave score was not associated with BWGAZ, even after adjusting for air pollution exposures. However, this association was significantly modified by maternal nativity (p_interaction = 0.014), in which immigrant enclave score was positively associated with BWGAZ for only foreign-born women (0.090, 95% CI: 0.007, 0.172). Proximity to major roads was negatively associated with BWGAZ (-0.018 per 10 m, 95% CI: -0.032, -0.003) and positively correlated with immigrant enclave scores. Trimester-specific PM_2.5 concentrations were not associated with BWGAZ.

SIGNIFICANCE

Residence in immigrant enclaves was associated with higher birthweight children for foreign-born women, supporting the role of immigrant enclaves in the IBP. Future research of the IBP should account for immigrant enclaves and assess their spatial correlation with potential environmental risk factors and protective resources.

Both parents matter: a national-scale analysis of parental race/ethnicity, disparities in prenatal PM2.5 exposures and related impacts on birth outcomes

BACKGROUND

Most U.S. studies that report racial/ethnic disparities in increased risk of low birth weight associated with air pollution exposures have been conducted in California or northeastern states and/or urban areas, limiting generalizability of study results. Few of these studies have examined maternal racial/ethnic groups other than Non-Hispanic Black, non-Hispanic White and Hispanic, nor have they included paternal race. We aimed to examine the independent effects of PM_2.5 on birth weight among a nationally representative sample of U.S. singleton infants and how both maternal and paternal race/ethnicity modify relationships between prenatal PM_2.5 exposures and birth outcomes.

METHODS

We used data from the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B), a longitudinal nationally representative cohort of 10,700 U.S. children born in 2001, which we linked to U.S.EPA's Community Multi-scale Air Quality (CMAQ)-derived predicted daily PM2.5 concentrations at the centroid of each Census Bureau Zip Code Tabulation Area (ZCTA) for maternal residences. We examined relationships between term birthweight (TBW)_, term low birthweight rate (TLBW) and gestational PM_2.5 pollutant using multivariate regression models. Effect modification of air pollution exposures on birth outcomes by maternal and paternal race was evaluated using stratified models. All analyses were conducted with sample weights to provide national-scale estimates.

RESULTS

The majority of mothers were White (61%). Fourteen percent of mothers identified as Black, 21% as Hispanic, 3% Asian American and Pacific Islander (AAPI) and 1% American Indian and Alaskan Native (AIAN). Fathers were also racially/ethnically diverse with 55% identified as White Non-Hispanic, 10% as Black Non-Hispanic, 19% as Hispanic, 3% as AAPI and 1% as AIAN. Results from the chi-square and ANOVA tests of significance for racial/ethnic differences indicate disparities in prenatal exposures and birth outcomes by both maternal and paternal race/ethnicity. Prenatal PM_2.5 was associated with reduced birthweights during second and third trimester and over the entire gestational period in adjusted regression models, although results did not reach statistical significance. In models stratified by maternal race and paternal race, one unit increase in PM_2.5 was statistically significantly associated with lower birthweights among AAPI mothers, -5.6 g (95% CI:-10.3, -1.0 g) and AAPI fathers, -7.6 g (95% CI: -13.1, -2.1 g) during 3^rd trimester and among births where father's race was not reported, -14.2 g (95% CI: -24.0, -4.4 g).

CONCLUSIONS

These data suggest that paternal characteristics should be used, in addition to maternal characteristics, to describe the risks of adverse birth outcomes. Additionally, our study suggests that serious consideration should be given to investigating environmental and social mechanisms, such as air pollution exposures, as potential contributors to disparities in birth outcomes among AAPI populations.

Household unmet basic needs in the first 1000 days and preterm birth status

OBJECTIVE

To examine the relationship of individual and composite number of unmet basic needs (housing, energy, food, and healthcare hardships) in the past year with preterm birth status among children aged 0-24 months.

STUDY DESIGN

We examined cross-sectional 2011-18 data of 17,926 families with children aged 0-24 months. We examined children born <31 weeks', 31-33 weeks', and 34-36 weeks' gestation versus term (≥37 weeks) using multivariable multinomial logistic regression.

RESULTS

At least 1 unmet basic need occurred among ≥60% of families with preterm children, compared to 56% of families with term children (p = 0.007). Compared to term, children born ≤30 weeks' had increased odds of healthcare hardships (aOR 1.28 [1.04, 1.56]) and children born 34-36 weeks' had increased odds of 1 (aOR 1.19 [1.05, 1.35]) and ≥2 unmet needs (aOR 1.15 [1.01, 1.31]).

CONCLUSION

Unmet basic needs were more common among families with preterm, compared to term children.

Maternal exposure to ambient PM2.5 and term birth weight: A systematic review and meta-analysis of effect estimates

Effect estimates of prenatal exposure to ambient PM_2.5 on change in grams (β) of birth weight among term births (≥37 weeks of gestation; term birth weight, TBW) vary widely across studies. We present the first systematic review and meta-analysis of evidence regarding these associations. Sixty-two studies met the eligibility criteria for this review, and 31 studies were included in the meta-analysis. Random-effects meta-analysis was used to assess the quantitative relationships. Subgroup analyses were performed to gain insight into heterogeneity derived from exposure assessment methods (grouped by land use regression [LUR]-models, aerosol optical depth [AOD]-based models, interpolation/dispersion/Bayesian models, and data from monitoring stations), study regions, and concentrations of PM_2.5 exposure. The overall pooled estimate involving 23,925,941 newborns showed that TBW was negatively associated with PM_2.5 exposure (per 10 μg/m³ increment) during the entire pregnancy (β = -16.54 g), but with high heterogeneity (I² = 95.6%). The effect estimate in the LUR-models subgroup (β = -16.77 g) was the closest to the overall estimate and with less heterogeneity (I² = 18.3%) than in the other subgroups of AOD-based models (β = -41.58 g; I² = 95.6%), interpolation/dispersion models (β = -10.78 g; I² = 86.6%), and data from monitoring stations (β = -11.53 g; I² = 97.3%). Even PM_2.5 exposure levels of lower than 10 μg/m³ (the WHO air quality guideline value) had adverse effects on TBW. The LUR-models subgroup was the only subgroup that obtained similar significant of negative associations during the three trimesters as the overall trimester-specific analyses. In conclusion, TBW was negatively associated with maternal PM_2.5 exposures during the entire pregnancy and each trimester. More studies based on relatively standardized exposure assessment methods need to be conducted to further understand the precise susceptible exposure time windows and potential mechanisms.

Postnatal exposure to PM2.5 and weight trajectories in early childhood

BACKGROUND

Inconsistent evidence has assessed the impact of air pollution exposure on children's growth trajectories. We investigated the role of 90-day average postnatal fine particulate matter (PM2.5) exposures by estimating the magnitude of effects at different ages, and the change in child weight trajectory by categories of exposure.

METHODS

We obtained weight values from electronic health records at each hospital visit (males = 1859, females = 1601) from birth to 6 years old children recruited into the Boston-based Children's HealthWatch cohort (2009-2014). We applied mixed models, adjusting for individual and maternal confounders using (1) varying-coefficient models allowing for smooth non-linear interaction between age and PM2.5, (2) factor-smooth interaction between age and PM2.5 quartiles. Additionally, we stratified by sex and low birthweight (LBW) status (≤2500 g).

RESULTS

Using varying-coefficient models, we found that PM2.5 significantly modified the association between age and weight in males, with a positive association in children younger than 3 years and a negative association afterwards. In boys, for each 10 µg/m3 increase in PM2.5 we found a 2.6% increase (95% confidence interval = 0.8, 4.6) in weight at 1 year of age and a -0.6% (95% confidence interval = -3.9, 2.9) at 5 years. We found similar but smaller changes in females, and no differences comparing growth trajectories across quartiles of PM2.5. Most of the effects were in LBW children and null for normal birthweight children.

CONCLUSIONS

This study suggests that medium-term postnatal PM2.5 may modify weight trajectories nonlinearly in young children, and that LBW babies are more susceptible than normal-weight infants.

Housing instability and adverse perinatal outcomes: a systematic review

OBJECTIVE

Our objective was to conduct a systematic review of the published literature on housing instability during pregnancy and adverse pregnancy outcomes and perinatal healthcare utilization.

DATA SOURCES

We performed a systematic search in November 2020 using Embase, MEDLINE, Cochrane Library, and Scopus using terms related to housing instability during pregnancy, adverse pregnancy outcomes, and perinatal healthcare utilization. The search was limited to the United States.

STUDY ELIGIBILITY CRITERIA

Studies examining housing instability (including homelessness) during pregnancy and adverse pregnancy outcomes (including preterm birth, low birthweight neonates, and maternal morbidity) and perinatal healthcare utilization were included.

METHODS

Two authors screened abstracts and full-length articles for inclusion. The final cohort consisted of 14 studies. Two authors independently extracted data from each article and assessed the study quality using the Grading of Recommendations, Assessment, Development, and Evaluation tool. Risk of bias was assessed using the National Institutes of Health Study Quality Assessment Tools.

RESULTS

All included studies were observational, including retrospective cohort (n=10, 71.4%), cross-sectional observational (n=3, 21.4%), or prospective cohort studies (n=1, 7.1%). There was significant heterogeneity in the definitions of housing instability and homelessness. Most of the studies only examined homelessness (n=9, 64.3%) and not lesser degrees of housing instability. Housing instability and homelessness during pregnancy were significantly associated with preterm birth, low birthweight neonates, neonatal intensive care unit admission, and delivery complications. Among studies examining perinatal healthcare utilization, housing instability was associated with inadequate prenatal care and increased hospital utilization. All studies exhibited moderate, low, or very low study quality and fair or poor internal validity.

CONCLUSION

Although data on housing instability during pregnancy are limited by the lack of a standardized definition, a consistent relationship between housing instability and adverse pregnancy outcomes has been suggested by this systematic review. The evaluation and development of a standardized definition and measurement of housing instability among pregnant individuals is warranted to address future interventions targeted to housing instability during pregnancy.

Living in a block group with a higher eviction rate is associated with increased odds of preterm delivery

BACKGROUND

Housing instability is associated with adverse pregnancy outcomes. Recent studies indicate that eviction, which may affect a larger segment of the population than other forms of housing instability, is also associated with adverse pregnancy outcomes. However, these studies evaluate eviction across large areas, such as counties, so it remains unclear whether these patterns extend to individual-level pregnancy outcomes.

METHODS

We used data on a cohort of all singleton live births at a single Chicago hospital between March 2008 and March 2018 to investigate the associations between block-group eviction rates and individual adverse pregnancy outcomes. Eviction data were obtained from the Eviction Lab at Princeton University. Generalised estimating equations were used to estimate associations and account for correlations among individuals living in the same block groups.

RESULTS

Individuals living in block groups in the highest quartile for eviction filing rate were 1.17 times as likely to deliver preterm (95% CI: 1.08 to 1.27) and 1.13 times as likely to deliver a small for gestational age infant (95% CI: 1.03 to 1.25) as compared with individuals living in block groups in the lowest quartile. Further, tests for linear trend indicated that for each quartile increase in eviction filing rate, there was a corresponding increase in odds of adverse outcomes (p<0.05). Results were strongest in magnitude for those with low neighbourhood and individual socioeconomic status, who are most likely to be renters and affected by local eviction policies.

CONCLUSION

Our results suggest that individuals living in block groups with higher eviction rates are more likely to deliver preterm. Future research should explore associations of individual experience with eviction on adverse pregnancy outcomes and examine whether policies to improve tenant protections also impact pregnancy outcomes.

Placental gene networks at the interface between maternal PM2.5 exposure early in gestation and reduced infant birthweight

BACKGROUND

A growing body of evidence links maternal exposure to particulate matter <2.5 μM in diameter (PM2.5) and deviations in fetal growth. Several studies suggest that the placenta plays a critical role in conveying the effects of maternal PM2.5 exposure to the developing fetus. These include observed associations between air pollutants and candidate placental features, such as mitochondrial DNA content, DNA methylation and telomere length. However, gaps remain in delineating the pathways linking the placenta to air pollution-related health effects, including a comprehensive profiling of placental processes impacted by maternal PM2.5 exposure. In this study, we examined alterations in a placental transcriptome-wide network in relation to maternal PM2.5 exposure prior to and during pregnancy and infant birthweight.

METHODS

We evaluated PM2.5 exposure and placental RNA-sequencing data among study participants enrolled in the Rhode Island Child Health Study (RICHS). Daily residential PM2.5 levels were estimated using a hybrid model incorporating land-use regression and satellite remote sensing data. Distributed lag models were implemented to assess the impact on infant birthweight due to PM2.5 weekly averages ranging from 12 weeks prior to gestation until birth. Correlations were assessed between PM2.5 levels averaged across the identified window of susceptibility and a placental transcriptome-wide gene coexpression network previously generated using the WGCNA R package.

RESULTS

We identified a sensitive window spanning 12 weeks prior to and 13 weeks into gestation during which maternal PM2.5 exposure is significantly associated with reduced infant birthweight. Two placental coexpression modules enriched for genes involved in amino acid transport and cellular respiration were correlated with infant birthweight as well as maternal PM2.5 exposure levels averaged across the identified growth restriction window.

CONCLUSION

Our findings suggest that maternal PM2.5 exposure may alter placental programming of fetal growth, with potential implications for downstream health effects, including susceptibility to cardiometabolic health outcomes and viral infections.

Confounding by Socioeconomic Status in Epidemiological Studies of Air Pollution and Health: Challenges and Opportunities

BACKGROUND

Despite a vast air pollution epidemiology literature to date and the recognition that lower-socioeconomic status (SES) populations are often disproportionately exposed to pollution, there is little research identifying optimal means of adjusting for confounding by SES in air pollution epidemiology, nor is there a strong understanding of biases that may result from improper adjustment.

OBJECTIVE

We aim to provide a conceptualization of SES and a review of approaches to its measurement in the U.S. context and discuss pathways by which SES may influence health and confound effects of air pollution. We explore bias related to measurement and operationalization and identify statistical approaches to reduce bias and confounding.

DISCUSSION

Drawing on the social epidemiology, health geography, and economic literatures, we describe how SES, a multifaceted construct operating through myriad pathways, may be conceptualized and operationalized in air pollution epidemiology studies. SES varies across individuals within the contexts of place, time, and culture. Although no single variable or index can fully capture SES, many studies rely on only a single measure. We recommend examining multiple facets of SES appropriate to the study design. Furthermore, investigators should carefully consider the multiple mechanisms by which SES might be operating to identify those SES indicators that may be most appropriate for a given context or study design and assess the impact of improper adjustment on air pollution effect estimates. Last, exploring model contraction and expansion methods may enrich adjustment, whereas statistical approaches, such as quantitative bias analysis, may be used to evaluate residual confounding. https://doi.org/10.1289/EHP7980.

Are the effects of air pollution on birth weight modified by infant sex and neighborhood socioeconomic deprivation? A multilevel analysis in Paris (France)

Adverse birth outcomes related to air pollution are well documented; however, few studies have accounted for infant sex. There is also scientific evidence that the neighborhood socioeconomic profile may modify this association even after adjusting for individual socioeconomic characteristics. The objective is to analyze the association between air pollution and birth weight by infant sex and neighborhood socioeconomic index. All birth weights (2008-2011) were geocoded at census block level. Each census block was assigned a socioeconomic deprivation level, as well as daily NO2 and PM10 concentrations. We performed a multilevel model with a multiple statistical test and sensible analysis using the spline function. Our findings suggest the existence of a differential association between air pollution and BW according to both neighborhood socioeconomic level and infant sex. However, due to multiple statistical tests and controlling the false discovery rate (FDR), all significant associations became either not statistically significant or borderline. Our findings reinforce the need for additional studies to investigate the role of the neighborhood socioeconomic which could differentially modify the air pollution effect.

Menopausal Symptoms in Underserved and Homeless Women Living in Extreme Temperatures in the Southwest

Background: Little is known about menopausal symptoms in underserved women. Aim: To better understand self-reported menopausal symptoms in underserved and homeless women living in extreme heat during different seasons. Methods: A cross-sectional study, including the Greene Climacteric Scale (GCS), climate-related questions, and demographics was administered June to August of 2017 and December to February 2018 to women 40-65 years of age. Results: In 104 predominantly Hispanic (56%), uninsured (53%), menopausal (56%), and mid-aged (50 ± 9.5) women, 57% reported any bother, while 20% of these women reported "quite a bit" or "extreme" bother from hot flushes. The total GCS score was a mean of 41 ± 15.0; out of 63 indicating significant symptoms, the psychological and somatic clusters were highest. Women did not think temperature outside influenced their menopausal symptoms at either time point (69% in winter vs. 57% in summer, p = 0.23). In multivariable analyses after adjusting for race, body mass index, and living situation neither season nor temperature was associated with self-reported hot flush bother. While one-third of women reported becoming ill from the heat, 90% of women reported not seeking care from a doctor for their illness. Conclusion: Menopausal, underserved, homeless women living in Arizona reported few vasomotor symptoms regardless of season, and endorsed psychological and somatic complaints. Socioeconomic factors may influence types of bothersome menopausal symptoms in this population of women.

Application of the navigation guide systematic review methodology to evaluate prenatal exposure to particulate matter air pollution and infant birth weight

Low birth weight is an important risk factor for many co-morbidities both in early life as well as in adulthood. Numerous studies report associations between prenatal exposure to particulate matter (PM) air pollution and low birth weight. Previous systematic reviews and meta-analyses report varying effect sizes and significant heterogeneity between studies, but did not systematically evaluate the quality of individual studies or the overall body of evidence. We conducted a new systematic review to determine how prenatal exposure to PM2.5, PM10, and coarse PM (PM2.5-10) by trimester and across pregnancy affects infant birth weight. Using the Navigation Guide methodology, we developed and applied a systematic review protocol [CRD42017058805] that included a comprehensive search of the epidemiological literature, risk of bias (ROB) determination, meta-analysis, and evidence evaluation, all using pre-established criteria. In total, 53 studies met our inclusion criteria, which included evaluation of birth weight as a continuous variable. For PM2.5 and PM10, we restricted meta-analyses to studies determined overall as "low" or "probably low" ROB; none of the studies evaluating coarse PM were rated as "low" or "probably low" risk of bias, so all studies were used. For PM2.5, we observed that for every 10 µg/m3 increase in exposure to PM2.5 in the 2nd or 3rd trimester, respectively, there was an associated 5.69 g decrease (I2: 68%, 95% CI: -10.58, -0.79) or 10.67 g decrease in birth weight (I2: 84%, 95% CI: -20.91, -0.43). Over the entire pregnancy, for every 10 µg/m3 increase in PM2.5 exposure, there was an associated 27.55 g decrease in birth weight (I2: 94%, 95% CI: -48.45, -6.65). However, the quality of evidence for PM2.5 was rated as "low" due to imprecision and/or unexplained heterogeneity among different studies. For PM10, we observed that for every 10 µg/m3 increase in exposure in the 3rd trimester or the entire pregnancy, there was a 6.57 g decrease (I2: 0%, 95% CI: -10.66, -2.48) or 8.65 g decrease in birth weight (I2: 84%, 95% CI: -16.83, -0.48), respectively. The quality of evidence for PM10 was rated as "moderate," as heterogeneity was either absent or could be explained. The quality of evidence for coarse PM was rated as very low/low (for risk of bias and imprecision). Overall, while evidence for PM2.5 and course PM was inadequate primarily due to heterogeneity and risk of bias, respectively, our results support the existence of an inverse association between prenatal PM10 exposure and low birth weight.

Prenatal Ambient Particulate Matter Exposure and Longitudinal Weight Growth Trajectories in Early Childhood

Air pollution exposure during pregnancy has been associated with impaired fetal growth and postnatal weight gain, but few studies have examined the effect on weight growth trajectories. We examine the association between validated 1 km² resolution particulate matter (PM_2.5) concentrations, averaged over pregnancy, and sex-specific growth trajectories from birth to age six of participants in the Boston-based Children's HealthWatch cohort (4797 participants, 84,283 measures). We compared weight trajectories, predicted using polynomial splines in mixed models, between prenatal PM_2.5 above or below the median (9.5 µg/m³), and examined birth weight as an effect modifier. Females exposed to average prenatal PM_2.5 ≥ 9.5 µg/m³ had higher weights compared to females exposed to < 9.5 µg/m³ throughout the study period (0.16 kg at 24 months, 0.61 kg at 60 months). In males, higher prenatal PM_2.5 exposure was associated with significantly lower weights after 24 months of age, with differences increasing with time (-0.17 at 24 months, -0.72 kg at 60 months). Associations were more pronounced among low birth weight (<2500 g) females, but did not differ by birth weight status in males. Our findings demonstrate the complex association between air pollution exposures and childhood weight trajectories and emphasize the importance of sex-stratified analyses.