Ambient Air Pollution and Risk of Gestational Hypertension

Exposure to Volatile Organic Compounds and Blood Pressure in NHANES 2011 to 2018

BACKGROUND

Volatile organic compounds (VOCs) are ubiquitous environmental pollutants. Exposure to VOCs is associated with cardiovascular disease risk factors, including elevated blood pressure in susceptible populations. However, research in the general population, particularly among nonsmoking adults, is limited. We hypothesized that higher VOC exposure is associated with higher blood pressure and hypertension, among nonsmokers.

METHODS

We included 4 cycles of data (2011-2018) of nonsmoking adults (n=4430) from the National Health and Nutrition Examination Survey. Urinary VOC metabolites were measured by ultraperformance liquid chromatography-mass spectrometry, adjusted for urine dilution, and log-transformed. We estimated mean differences in blood pressure using linear models and prevalence ratio of stage 2 hypertension using modified Poisson models with robust standard errors. Models were adjusted for age, sex, race and ethnicity, education, body mass index, estimated glomerular filtration rate, and National Health and Nutrition Examination Survey cycle.

RESULTS

Participants were 54% female, with a median age of 48 years, 32.3% had hypertension, and 7.9% had diabetes. The mean differences (95% CI) in systolic blood pressure were 1.61 (0.07-3.15) and 2.46 (1.01-3.92) mm Hg when comparing the highest with the lowest quartile of urinary acrolein (N-acetyl-S-[2-carboxyethyl]-L-cysteine) and 1,3-butadiene (N-acetyl-S-[3,4-dihydroxybutyl]-L-cysteine) metabolites. The prevalence ratios for hypertension were 1.06 (95% CI, 1.02-1.09) and 1.05 (95% CI, 1.01-1.09) when comparing the highest with lowest quartiles of urinary acrolein (N-acetyl-S-[2-carboxyethyl]-L-cysteine) and 1,3-butadiene (N-acetyl-S-[3,4-dihydroxybutyl]-L-cysteine), respectively.

CONCLUSIONS

Exposure to VOCs may be a relevant yet understudied environmental contributor to cardiovascular disease risk in the nonsmoking, US population.

Crohn's Disease Mortality and Ambient Air Pollution in New York City

BACKGROUND

The worldwide increase in Crohn's disease (CD) has accelerated alongside rising urbanization and accompanying decline in air quality. Air pollution affects epithelial cell function, modulates immune responses, and changes the gut microbiome composition. In epidemiologic studies, ambient air pollution has a demonstrated relationship with incident CD and hospitalizations. However, no data exist on the association of CD-related death and air pollution.

METHODS

We conducted an ecologic study comparing the number of CD-related deaths of individuals residing in given zip codes, with the level of air pollution from nitric oxide, nitrogen dioxide, sulfur dioxide (SO2), and fine particulate matter. Air pollution was measured by the New York Community Air Survey. We conducted Pearson correlations and a Poisson regression with robust standard errors. Each pollution component was modeled separately.

RESULTS

There was a higher risk of CD-related death in zip codes with higher levels of SO2 (incidence rate ratio [IRR], 1.16; 95% confidence interval [CI], 1.06-1.27). Zip codes with higher percentage of Black or Latinx residents were associated with lower CD-related death rates in the SO2 model (IRR, 0.58; 95% CI, 0.35-0.98; and IRR, 0.13; 95% CI, 0.05-0.30, respectively). There was no significant association of either population density or area-based income with the CD-related death rate.

CONCLUSIONS

In New York City from 1993 to 2010, CD-related death rates were higher among individuals from neighborhoods with higher levels of SO2 but were not associated with levels of nitric oxide, nitrogen dioxide, and fine particulate matter. These findings raise an important and timely public health issue regarding exposure of CD patients to environmental SO2, warranting further exploration.

Urinary Volatile Organic Compound Metabolites are Associated with High Blood Pressure Among Non-smoking Participants in the National Health and Nutrition Examination Survey (2011-2018)

Background

Volatile organic compounds (VOCs) are ubiquitous environmental pollutants. Exposure to VOCs is associated with cardiovascular disease (CVD) risk factors, including elevated blood pressure (BP) in susceptible populations. However, research in the general population, particularly among non-smoking adults, is limited. We hypothesized that higher VOC exposure is associated with higher BP and hypertension, among non-smokers.

Methods

We included four cycles of data (2011-2018) of non-smoking adults (n=4,430) from the National Health and Nutrition Examination Survey (NHANES). Urinary VOC metabolites were measured by ultra-performance liquid chromatography-mass spectrometry, adjusted for urine dilution, and log-transformed. We estimated mean differences in BP using linear models and prevalence ratio of stage 2 hypertension using modified Poisson models with robust standard errors. Models were adjusted for age, sex, race and ethnicity, education, body mass index, estimated glomerular filtration rate and NHANES cycle.

Results

Participants were 54% female, with a median age of 48 years, 32.3% had hypertension, and 7.9% had diabetes. The mean differences (95% CI) in systolic BP were 1.61 (0.07, 3.15) and 2.46 (1.01, 3.92) mmHg when comparing the highest to lowest quartile of urinary acrolein (CEMA) and 1,3-butadiene (DHBMA) metabolites. The prevalence ratios (PR) for hypertension were 1.06 (1.02, 1.09) and 1.05 (1.01, 1.09) when comparing the highest to lowest quartiles of urinary acrolein (CEMA) and 1,3-butadiene (DHBMA), respectively.

Conclusions

Exposure to VOCs may be relevant yet understudied environmental contributors to CVD risk in the non-smoking, US population.

Increased Risk of Gestational Hypertension by Periconceptional Exposure to Ambient Air Pollution and Effect Modification by Prenatal Depression

BACKGROUND

Air pollution has been associated with gestational hypertension (GH) and preeclampsia, but susceptible windows of exposure and potential vulnerability by comorbidities, such as prenatal depression, remain unclear.

METHODS

We ascertained GH and preeclampsia cases in a prospective pregnancy cohort in Los Angeles, CA. Daily levels of ambient particulate matters (with a diameter of ≤10 μm [PM10] or ≤2.5 μm [PM2.5]), nitrogen dioxide, and ozone were averaged for each week from 12 weeks preconception to 20 gestational weeks. We used distributed lag models to identify susceptible exposure windows, adjusting for potential confounders. Analyses were additionally stratified by probable prenatal depression to explore population vulnerability.

RESULTS

Among 619 participants, 60 developed preeclampsia and 42 developed GH. We identified a susceptible window for exposure to PM2.5 from 1 week preconception to 11 weeks postconception: higher exposure (5 µg/m3) within this window was associated with an average of 8% (95% CI, 1%-15%) higher risk of GH. Among participants with probable prenatal depression (n=179; 32%), overlapping sensitive windows were observed for all pollutants from 8 weeks before to 10 weeks postconception with increased risk of GH (PM2.5, 16% [95% CI, 3%-31%]; PM10, 39% [95% CI, 13%-72%]; nitrogen dioxide, 65% [95% CI, 17%-134%]; and ozone, 45% [95% CI, 9%-93%]), while the associations were close to null among those without prenatal depression. Air pollutants were not associated with preeclampsia in any analyses.

CONCLUSIONS

We identified periconception through early pregnancy as a susceptible window of air pollution exposure with an increased risk of GH. Prenatal depression increases vulnerability to air pollution exposure and GH.

Assessment of the association between ambient air pollution and stillbirth in the UK: Results from a secondary analysis of the MiNESS case-control study

OBJECTIVE

We examined whether the risk of stillbirth was related to ambient air pollution in a UK population.

DESIGN

Prospective case-control study.

SETTING

Forty-one maternity units in the UK.

POPULATION

Women who had a stillbirth ≥28 weeks' gestation (n = 238) and women with an ongoing pregnancy at the time of interview (n = 597).

METHODS

Secondary analysis of data from the Midlands and North of England Stillbirth case-control study only including participants domiciled within 20 km of fixed air pollution monitoring stations. Pollution exposure was calculated using pollution climate modelling data for NO2 , NOx and PM2.5 . The association between air pollution exposure and stillbirth risk was assessed using multivariable logistic regression adjusting for household income, maternal body mass index (BMI), maternal smoking, Index of Multiple Deprivation quintile and household smoking and parity.

MAIN OUTCOME MEASURE

Stillbirth.

RESULTS

There was no association with whole pregnancy ambient air pollution exposure and stillbirth risk, but there was an association with preconceptual NO2 exposure (adjusted odds ratio [aOR] 1.06, 95% CI 1.01-1.08 per microg/m3 ). Risk of stillbirth was associated with maternal smoking (aOR 2.54, 95% CI 1.38-4.71), nulliparity (aOR 2.16, 95% CI 1.55-3.00), maternal BMI (aOR 1.05, 95% CI 1.01-1.08) and placental abnormalities (aOR 4.07, 95% CI 2.57-6.43).

CONCLUSIONS

Levels of ambient air pollution exposure during pregnancy in the UK, all of were beneath recommended thresholds, are not associated with an increased risk of stillbirth. Periconceptual exposure to NO2 may be associated with increased risk but further work is required to investigate this association.

Co-exposure to phthalates and polycyclic aromatic hydrocarbons and the risk of gestational hypertension in Chinese women

Phthalates (PAEs) and polycyclic aromatic hydrocarbons (PAHs) are frequently detected in females of reproductive age. Many studies have found that environmental PAE and PAH levels are independent risk factors for gestational hypertension. However, exposure to both components is a more realistic scenario. To better assess the health effects of PAEs and PAHs in pregnant women, we explored the associations of exposure to both individual and combined PAEs and PAHs with gestational hypertension. This nested case-control study was a component of a prospective cohort study conducted in Beijing, China. We included 206 women with gestational hypertension and 214 pregnant controls. We used gas chromatography/tandem mass spectrometry (GC-MS/MS) to detect 8 PAEs and 13 PAHs in > 80 % of all collected hair samples. Multiple linear regression models were employed to test the individual associations between each component and gestational hypertension. A quantile-based g-computation (qgcomp) model and a weighted quantile sum (WQS) regression model were used to estimate whether exposure to both PAEs and PAHs increased the risk of gestational hypertension. The individual exposure analyses revealed that diethyl phthalate (DEP), diisobutyl phthalate (DIBP) (both PAEs), benzo(k)fluoranthene (BKF), anthracene, (ANT), and benzo(a)pyrene (BAP) (all PAHs) were positively associated with increased risk of gestational hypertension. In mixed-effect analyses, the qgcomp model indicated that co-exposure to PAEs and PAHs increased the risk of gestational hypertension (odds ratio = 2.01; 95 % confidence interval: 1.02, 3.94); this finding was verified by the WQS regression model. Our findings support earlier evidence that both PAEs and PAHs increase the risk of gestational hypertension, both individually and in combination. This suggests that reductions in exposure to endocrine system-disrupting chemicals such as PAEs and PAHs might reduce the risk of gestational hypertension.

Effects of Air Pollution Exposure during Preconception and Pregnancy on Gestational Diabetes Mellitus

This study aimed to investigate the association between air pollution and gestational diabetes mellitus (GDM) in small- and medium-sized cities, identify sensitive periods and major pollutants, and explore the effects of air pollution on different populations. A total of 9820 women who delivered in Handan Maternal and Child Health Hospital in the Hebei Province from February 2018 to July 2020 were included in the study. Logistic regression and principal component logistic regression models were used to assess the effects of air pollution exposure during preconception and pregnancy on GDM risk and the differences in the effects across populations. The results suggested that each 20 μg/m3 increase in PM2.5 and PM10 exposure during preconception and pregnancy significantly increased the risk of GDM, and a 10 μg/m3 increase in NO2 exposure during pregnancy was also associated with the risk of GDM. In a subgroup analysis, pregnant women aged 30-35 years, nulliparous women, and those with less than a bachelor's education were the most sensitive groups. This study provides evidence for an association between air pollution and the prevalence of GDM, with PM2.5, PM10, and NO2 as risk factors for GDM.

Effects of Particulate Matter on the Risk of Gestational Hypertensive Disorders and Their Progression

Associations between particulate matter (PM) and gestational hypertensive disorders (GHDs) are well documented, but there is no evidence on the associations between PM and GHD progression, especially among those with assisted reproductive technology (ART) conceptions. To explore the effects of PM on the risk of GHDs and their progression among pregnant women with natural or ART conception, we enrolled 185,140 pregnant women during 2014-2020 in Shanghai and estimated the associations during different periods using multivariate logistic regression. During the 3 months of preconception, 10 μg/m³ increases in PM concentrations were associated with increased risks of gestational hypertension (GH) (PM_2.5: aOR = 1.076, 95% CI: 1.034-1.120; PM₁₀: aOR = 1.042, 95% CI: 1.006-1.079) and preeclampsia (PM_2.5: aOR = 1.064, 95% CI: 1.008-1.122; PM₁₀: aOR = 1.048, 95% CI: 1.006-1.092 ) among women with natural conception. Furthermore, for women with ART conceptions who suffered current GHD, 10 μg/m³ increases in PM concentrations in the third trimester elevated the risk of progression (PM_2.5: aOR = 1.156, 95% CI: 1.022-1.306 ; PM₁₀: aOR = 1.134, 95% CI: 1.013-1.270). In summary, women with natural conception should avoid preconceptional PM exposure to protect themselves from GH and preeclampsia. For women with ART conceptions suffering from GHD, it is necessary to avoid PM exposure in late pregnancy to prevent the disease from progressing.

Associations between short-term and long-term exposure to particulate matter and preterm birth

Despite the longstanding evidence on the effect of air pollutants on preterm birth (PTB), few studies have focused on its subtypes, including spontaneous preterm birth (sPTB) and medically indicated preterm birth (miPTB). Most studies evaluated only the short-term or long-term effects of particulate matter (PM) on PTB. Thus, we designed this study, based on a cohort of 179,385 women, to evaluate both short- and long-term effects of PM with diameters ≤2.5 μm and ≤10 μm (PM_2.5 and PM₁₀) on PTB, sPTB and miPTB in Shanghai. Generalized additive models (GAMs) were applied to evaluate short-term effects. Lagged effects were identified using different lag structures. Exposure-response correlation curves were plotted using GAMs after adjustment for confounders. ORs and 95% CIs were calculated using logistic regression to estimate the long-term effect after adjustment for confounders. There was 5.67%, 3.70% and 1.98% daily incidence of PTB, sPTB, and miPTB on average. Every 10 μg/m³ increase in PM_2.5 and PM₁₀ was positively associated with PTB and sPTB at lag 2 day. The exposure-response curves (lag 2 day) indicated a rapid increase in sPTB for PM_2.5 and a linear increase for PM₁₀, in PTB for PM_2.5 and PM₁₀ at concentrations over 100 μg/m³. Regarding long-term exposure, positive associations were found between 10 μg/m³ increases in PM_2.5 and PM₁₀ in 3rd trimester and greater odds of sPTB (aOR: 1.042, 95% CI: 1.018-1.065, and 1.018, 95% CI:1.002-1.034), and during the 3 months before conception and miPTB (aOR: 1.023, 95% CI: 1.003-1.042, and 1.017, 95% CI: 1.000-1.036). Acute exposure to PM_2.5 and PM₁₀ at lag 2 day and chronic exposure in 3rd trimester was significantly associated with sPTB, while miPTB was related to chronic exposure during the 3 months before pregnancy. These findings indicate that susceptibility windows of PM exposure can be influenced by different underlying etiologies of PTB.

Fossil-fuel and combustion-related air pollution and hypertension in the Sister Study

Hypertension is a leading risk factor for disease burden, with more than 200 million disability-adjusted life-years attributed to high blood pressure in 2015. While outdoor air pollution is associated with cardiovascular disease, the joint effect of exposure to air pollution from combustion products on hypertension has rarely been studied. We conducted a cross-sectional analysis to explore the association between combustion-related air pollution and hypertension. Census-tract levels of ambient concentrations of nine fossil-fuel and combustion-related air toxics (biphenyl, naphthalene, polycyclic organic matter, diesel emissions, 1,3-butadiene, acetaldehyde, benzene, acrolein, and formaldehyde) from the 2005 National Air Toxics Assessment database and NO2 from 2005 monitoring data were linked to baseline residential addresses of 47,467 women in the Sister Study cohort. Hypertension at enrollment (2003-2009) was defined as high systolic (≥140 mm Hg) or diastolic (≥90 mm Hg) blood pressure or taking antihypertensive medication. We used log-binomial regression and quantile-based g-computation to estimate the individual and joint effects of fossil-fuel and combustion-related air pollution on hypertension. Comparing the highest to lowest quartiles, diesel emissions (prevalence ratio (PR) = 1.05, 95% confidence interval (CI) = 1.01,1.08), 1,3-butadiene (PR = 1.04, 95%CI = 1.00,1.07), acetaldehyde (PR = 1.08, 95%CI = 1.04,1.12), benzene (PR = 1.05, 95%CI = 1.02,1.08), formaldehyde (PR = 1.08, 95%CI = 1.04,1.11), and NO2 (PR = 1.08, 95%CI = 1.05,1.12) were individually associated with higher prevalence of hypertension. The PR for the joint effect of increasing all ambient air toxics and NO2 by one quartile was 1.02 (95%CI = 1.01,1.04). Associations varied by race/ethnicity, with stronger associations observed among women reporting races/ethnicities (Hispanic/Latina, non-Hispanic Black and other) other than non-Hispanic White. In conclusion, we found that air pollution from fossil fuel and combustion may be a risk factor for hypertension.

Associations of pregnancy complications with ambient air pollution in China

BACKGROUND

Gestational hypertension (GH), preeclampsia (PE), and gestational diabetes mellitus (GDM) are common pregnancy complications and can result in maternal and prenatal morbidity and mortality. Air pollution exposure could adversely impact pregnancy complications; however, evidence remains limited in China, where ambient air pollution is relatively severe.

OBJECTIVE

This study aims to examine the associations of GH, PE, and GDM with exposure to six air pollutants (PM_2.5, PM₁₀, SO₂, NO₂, O₃, and CO) during pregnancy.

METHODS

Leveraging a multicenter birth cohort study among pregnant women in 24 hospitals from 15 provinces in China, we obtained data for maternal characteristics and pregnancy outcomes. We generated ambient concentrations of the six air pollutants using a combination of chemical transport model simulations with monitoring data. We used multivariable logistic regression models to estimate the effects on pregnancy complications from exposure to six air pollutants in each trimester and the entire pregnancy.

RESULTS

Among the total 3754 pregnant women in this study, the prevalences of GH, GDM, and PE were 2.6 %, 11.2 %, and 0.7 %, respectively. GH risk increased 11.9 % (95 % CI, -8.5 %, 36.8 %) and 13.8 % (1.4 %, 27.8 %) per 10 μg/m³ increases in PM_2.5 and PM₁₀ in the entire pregnancy, respectively. PM_2.5 and PM₁₀ exposures in the first trimester were significantly associated with an increased risk of GDM. Exposure to O₃, SO₂, NO₂, and CO in early pregnancy could be associated with GDM risk. Geographic region and season of conception may influence the associations of GH and PE with air pollution.

CONCLUSIONS

Ambient particulate matter pollution adversely affects GH, GDM, and PE among Chinese pregnant women. Since most regions of China still suffer from hazardous levels of air pollution, our findings indicate importance of better protecting pregnant women from the risk of air pollution.

Effect of PM2.5 exposure on gestational hypertension, fetal size in preeclampsia-like rats

Studies have shown intriguing associations between gestational PM_2.5 exposure and preeclampsia (PE), as well as fetal growth restriction (FGR). This study investigated the impact of PM_2.5 exposure on gestational hypertension and fetal outcome in a preeclampsia-like rat model. Pregnant Sprague Dawley rats were exposed to either filtered (FA) or PM_2.5-contaminated air during the whole pregnancy period. A PE-like rat model was established by intraperitoneal injection of L-NAME (300 mg/kg) from gestational day (GD) 12 to until GD20. Systolic blood pressure (SBP), weight gain, pup weight and placental weight were measured. The percentages of rat Treg/Th17 cells and Th17-related cytokines were examined by flow cytometry. Gene expression profiles were analyzed by microarray, and the expression of differentially expressed genes was validated by qRT-PCR. The results showed that maternal PM_2.5 exposure had no effect on SBP but was associated with low birth weight (LBW) and a higher labyrinth/basal zone ratio. The percentages of splenic Th17 cells from the PM_2.5 group of PE-like rats were higher than those from the FA or PM_2.5 groups of healthy controls. A significantly decreased Treg/Th17 cell ratio was found in the PM_2.5 group of PE-like rats. The mRNA expression of Foxp3 was downregulated, while the mRNA expression of RORα and RORγτ was upregulated after PM_2.5 exposure. Furthermore, we observed that both the mRNA and protein levels of TNF-a, CCL2, CCL3 and CCR1 increased in the PM_2.5 groups. Our study suggested that systemic inflammation may contribute to the development of FGR associated with PM_2.5 exposure throughout pregnancy.

The relationship between the neighborhood built and social environment and hypertensive disorders of pregnancy: A scoping review

BACKGROUND

Theory and limited empirical research suggest that the neighborhood environment influences maternal health outcomes. The goal of this scoping review is to summarize extant research considering the impact of the built and social environment of resident neighborhood on hypertensive disorders of pregnancy (HDP) globally.

METHODS

We performed a systematic search of the literature using four databases, PubMed, Web of Science, CINAHL, and Embase on July 15, 2020. We excluded articles not in English, that did not consider one or more HDP as a primary or secondary outcome, and that did not include an element of the neighborhood built or social environment as an exposure. We applied a modified version of the Effective Public Health Practice Project Quality Assessment Tool for Quantitative Studies to evaluate quality of included studies.

RESULTS

Our search identified 11,385 unique abstracts for screening. Following exclusions, we included 64 articles in the final review. The majority of articles measured an element of the built environment (70.3% (44)), most commonly traffic-related air pollution (42.2% (27)). A third of articles (31.3% (20)) considered an element of the neighborhood social environment, most commonly neighborhood deprivation (10.9% (7)). Global quality ratings were mostly moderate (29.7% (19)) or weak (68.8% (44)), primarily due to inattention to neighborhood-level confounding.

CONCLUSION

Critical gaps remain in understanding how the resident neighborhood may impact HDP. Future research should focus on designing high-quality studies incorporating elements of both the built and social environment to holistically understand how context may impact maternal health.

Particulate matter and hypertensive disorders in pregnancy: systematic review and meta-analysis

OBJECTIVES

We aimed to quantitatively synthesize the association between maternal exposure to particulate matter (PM; including PM <2.5 μm and PM <10 μm) and hypertensive disorders in pregnancy (HDP; including gestational hypertension [GH] and pre-eclampsia) and to explore the influence of certain factors on the outcome.

STUDY DESIGN

Meta-analysis was used to quantitatively synthesize the results of similar independent studies.

METHODS

Original documents were identified by searching six electronic bibliographic databases from their inceptions to August 17, 2021. Then we performed meta-analysis to combine the effect estimates if at least three estimates reported the same exposure and outcome and used stratified analysis to evaluate the impact of exposure assessment method, data source, and study area on heterogeneity. In addition, we used the 95% prediction interval to evaluate the potential effects of exposure in random effects meta-analysis.

RESULTS

The overall meta-analysis showed that the risk of HDP was significantly associated with per 5 μg/m³ increase in PM_2.5 exposure during T1 and PM₁₀ exposure during T, with odds ratios [ORs] 1.06 (95% confidence interval [CI]: 1.01-1.12) and 1.04 (95% CI: 1.02-1.07), respectively. The results also showed that PM_2.5 exposure during T1 and T2 and PM₁₀ exposure during T1 increased the incidence of GH; the summary ORs were 1.11 (95% CI: 1.01-1.23), 1.16 (95% CI: 1.05-1.29), and 1.04 (95% CI: 1.02-1.07), respectively. Subgroup analyses showed that the pooled effects were generally significant or more apparent in studies using models to assess exposure, studies whose data derived from birth registers, and studies in Europe.

CONCLUSIONS

This meta-analysis showed that PM exposure was associated with increased HDP risks, and the association varied by study area, data source, and exposure assessment method. With the continuous improvement of research design and exposure assessment, future research may find higher risks.

Early Gestational Exposure to Inhaled Ozone Impairs Maternal Uterine Artery and Cardiac Function

Exposure to air pollutants such as ozone (O3) is associated with adverse pregnancy outcomes, including higher incidence of gestational hypertension, preeclampsia, and peripartum cardiomyopathy; however, the underlying mechanisms of this association remain unclear. We hypothesized that O3 exposures during early placental formation would lead to more adverse cardiovascular effects at term for exposed dams, as compared with late-term exposures. Pregnant Sprague Dawley rats were exposed (4 h) to either filtered air (FA) or O3 (0.3 or 1.0 ppm) at either gestational day (GD)10 or GD20, with longitudinal functional assessments and molecular endpoints conducted at term. Exposure at GD10 led to placental transcriptional changes at term that were consistent with markers in human preeclampsia, including reduced mmp10 and increased cd36, fzd1, and col1a1. O3 exposure, at both early and late gestation, induced a significant increase in maternal circulating soluble FMS-like tyrosine kinase-1 (sFlt-1), a known driver of preeclampsia. Otherwise, exposure to 0.3 ppm O3 at GD10 led to several late-stage cardiovascular outcomes in dams that were not evident in GD20-exposed dams, including elevated uterine artery resistance index and reduced cardiac output and stroke volume. GD10 O3 exposure proteomic profile in maternal hearts characterized by a reduction in proteins with essential roles in metabolism and mitochondrial function, whereas phosphoproteomic changes were consistent with pathways involved in cardiomyopathic responses. Thus, the developing placenta is an indirect target of inhaled O3 and systemic maternal cardiovascular abnormalities may be induced by O3 exposure at a specific window of gestation.

Association between ambient air pollution and high-risk pregnancy: A 2015-2018 national population-based cohort study in Korea

BACKGROUND

Several studies have indicated that prenatal exposure to ambient air pollution is associated with an increased risk of gestational diabetes mellitus, hypertensive disorder during pregnancy, preterm birth, and stillbirth. However, no previous study has focused on the association between the number of pregnancy complications and exposure to ambient air pollution.

OBJECTIVES

To investigate the association between prenatal exposure to ambient air pollutants and the number of pregnancy complications in high-risk pregnancies.

METHODS

We collected data on gestational diabetes mellitus, hypertensive disorder during pregnancy, preterm birth, and stillbirth from the National Health Information Databases, provided by the Korean National Health Insurance Service.R To assess individual-level exposure to air pollutants, a spatial prediction model and area-averaging approach were used.

RESULTS

From 2015 to 2018, data of 789,595 high-risk pregnancies were analyzed. The ratio of gestational diabetes mellitus in the country was the highest, followed by preterm birth, hypertensive disorder during pregnancy, and stillbirth. Approximately 71.7% of pregnant women (566,143) presented with one pregnancy complication in identical pregnancies, 27.5% (216,714) presented with two, and 0.9% (6738) presented with three or more. Multiple logistic regression models with adjustments for age, residence, and income variables indicated that the risk of having two or more pregnancy complications was positively associated with the exposure to higher levels of PM₁₀ (odds ratio [OR], 1.11; 95% confidence interval [CI], 1.09-1.12) and PM_2.5 (OR, 1.14; 95% CI, 1.12-1.15). The highest quartile presented higher odds of two or more pregnancy complications compared with the lower three quartiles of PM₁₀, PM_2.5, CO, NO₂, and SO₂ exposures (p < 0.001).

CONCLUSION

The results indicate that the risk of pregnancy complications is positively associated with the exposure to the high concentrations of PM₁₀, PM_2.5, CO, NO₂, and SO₂.

Air pollution exposure and risk of adverse obstetric and neonatal outcomes among women with type 1 diabetes

AIMS/HYPOTHESIS

Women with type 1 diabetes have increased risk for poor obstetric outcomes. Prenatal air pollution exposure is also associated with adverse outcomes for women and infants. We examined whether women with type 1 diabetes are more vulnerable than other women to pollution-associated risks during pregnancy.

METHODS

In singleton deliveries from the Consortium on Safe Labor (2002-2008), obstetric and neonatal outcomes were compared for women with type 1 diabetes (n = 507) and women without autoimmune disease (n = 204,384). Preconception, trimester, and whole pregnancy average air pollutant exposure (ozone (O₃), carbon monoxide (CO), particulate matter >10 μm (PM₁₀), PM > 2.5 μm (PM_2.5), sulfur dioxide (SO₂), nitrogen oxides (NO_x)) were estimated using modified Community Multiscale Air Quality models. Poisson regression models with diabetes*pollutant interaction terms estimated relative risks and 95% confidence intervals for adverse outcomes, adjusted for maternal characteristics and geographic region.

RESULTS

For whole pregnancy exposure to SO₂, women with type 1 diabetes had 15% increased risk (RR:1.15 95%CI:1.01,1.31) and women without autoimmune disease had 5% increased risk (RR:1.05 95%CI:1.05,1.06) for small for gestational age birth (p_interaction = 0.09). Additionally, whole pregnancy O₃ exposure was associated with 10% increased risk (RR:1.10 95%CI:1.02,1.17) among women with type 1 diabetes and 2% increased risk (RR:1.02 95%CI:1.00,1.04) among women without autoimmune disease for perinatal mortality (p_interaction = 0.08). Similar patterns were observed between PM_2.5 exposure and spontaneous preterm birth.

CONCLUSIONS

Pregnant women with type 1 diabetes may be at greater risk for adverse outcomes when exposed to air pollution than women without autoimmune disease.

Air Pollution Measurements and Land-Use Regression in Urban Sub-Saharan Africa Using Low-Cost Sensors—Possibilities and Pitfalls

Air pollution is recognized as the most important environmental factor that adversely affects human and societal wellbeing. Due to rapid urbanization, air pollution levels are increasing in the Sub-Saharan region, but there is a shortage of air pollution monitoring. Hence, exposure data to use as a base for exposure modelling and health effect assessments is also lacking. In this study, low-cost sensors were used to assess PM2.5 (particulate matter) levels in the city of Adama, Ethiopia. The measurements were conducted during two separate 1-week periods. The measurements were used to develop a land-use regression (LUR) model. The developed LUR model explained 33.4% of the variance in the concentrations of PM2.5. Two predictor variables were included in the final model, of which both were related to emissions from traffic sources. Some concern regarding influential observations remained in the final model. Long-term PM2.5 and wind direction data were obtained from the city’s meteorological station, which should be used to validate the representativeness of our sensor measurements. The PM2.5 long-term data were however not reliable. Means of obtaining good reference data combined with longer sensor measurements would be a good way forward to develop a stronger LUR model which, together with improved knowledge, can be applied towards improving the quality of health. A health impact assessment, based on the mean level of PM2.5 (23 µg/m3), presented the attributable burden of disease and showed the importance of addressing causes of these high ambient levels in the area.

Should we adjust for delivery hospital in studies of air pollution and pregnancy outcomes?

Background:

In conducting a study of ambient air pollution and pregnancy outcome in New York City, we identified delivery hospital as a potential confounder, given its association with both maternal residence and therefore air pollution exposure, and with clinical practices and as a potential marker of outcome misclassification in the coding of pregnancy complications. Motivated by evidence that adjustment for delivery hospital affected associations between air pollution and pregnancy outcome, we undertook a detailed empirical examination of the role of delivery hospital that warrants consideration by others addressing this topic.

Methods:

In a study of air pollution and pregnancy outcome, we identified births from 2008 to 2010 to residents of New York City and, after restrictions, included 238,960 in the analysis. Air pollution exposure estimates for ambient fine particles (PM_2.5) and nitrogen dioxide (NO₂) were derived from a community-wide exposure study and assigned based on geocoded maternal residence. We examined the impact of adjusting for delivery hospital and explored the relationship between delivery hospital and both exposure and pregnancy outcomes.

Results:

Statistical adjustment for delivery hospital markedly attenuated the relationship of air pollution with birth weight and gestational hypertension, with smaller effects on preterm birth and preeclampsia. Delivery hospital was associated with estimated maternal air pollution levels after adjusting for individual-level patient characteristics, more strongly for PM_2.5 than for NO₂. Delivery hospital predicted pregnancy outcome after adjustment for individual attributes, with larger hospitals and those that managed a greater volume of complicated cases having lower birth weight, more medically indicated preterm births, and more diagnosed gestational hypertension. Evaluation through the use of directed acyclic graphs illustrates the potential for adjustment for hospital to reduce residual spatial confounding, but also indicates the possibility of introducing bias through adjustment of a mediator.

Conclusions:

Based on these results, delivery hospital warrants closer consideration in studies of air pollution and other spatial factors in relation to pregnancy outcomes. The possibility of confounding by delivery hospital needs to be balanced with the risk of adjusting for a mediator of the air pollution—pregnancy outcome association in studies of this type.

Air Pollution Exposure Monitoring among Pregnant Women with and without Asthma

Background: We monitored exposure to fine particulates (PM_2.5), ozone, nitrogen dioxide (NO₂), and ambient temperature for pregnant women with and without asthma. Methods: Women (n = 40) from the Breathe—Well-Being, Environment, Lifestyle, and Lung Function Study (2015–2018) were enrolled during pregnancy and monitored for 2–4 days. Daily pollutants were measured using personal air monitors, indoor air monitors, and nearest Environmental Protection Agency’s stationary monitors based on GPS tracking and home address. Results: Personal-monitor measurements of PM_2.5, ozone, and NO₂ did not vary by asthma status but exposure profiles significantly differed by assessment methods. EPA stationary monitor-based methods appeared to underestimate PM_2.5 and temperature exposure and overestimate ozone and NO₂ exposure. Higher indoor-monitored PM_2.5 exposures were associated with smoking and the use of gas appliances. The proportion of waking-time during which personal monitors were worn was ~56%. Lower compliance was associated with exercise, smoking, being around a smoker, and the use of a prescription drug. Conclusions: Exposure did not vary by asthma status but was influenced by daily activities and assessment methods. Personal monitors may better capture exposures but non-compliance merits attention. Meanwhile, larger monitoring studies are warranted to further understand exposure profiles and the health effects of air pollution during pregnancy.

Adverse Effects of Exposure to Fine Particulate Matters and Ozone on Gestational Hypertension

Gestational hypertension (GH) is a common complication during pregnancy. GH is regarded as a potential public health challenge for pregnant women and infants. Limited evidence has linked ambient air pollution to an increased GH risk. However, most of the studies were conducted in developed countries, with inconsistent results obtained. The present study was performed to explore whether exposure to particulate matters with an aerodynamic diameter &lt; 2.5 (PM_2.5) and ozone (O₃) was related to elevated odds of GH in a Chinese population. This population-based cohort study involved 38 115 pregnant women in Wuhan, China. All information was collected from the Wuhan Maternal and Child Health Management Information System, using standardized quality control. The daily air pollutant data for PM_2.5 and O₃ were obtained from the 20 monitoring stations of the Wuhan Environmental Monitoring Center during 2014. The nearest monitor approach was applied to individual exposure assessment of PM_2.5 and O₃ for each participant. After adjusting for major confounders and other air pollutants, a 10 µg/m³ increase in PM_2.5 and O₃ concentrations was found to correlate to a 1.14-fold [95% confidence interval (95% CI): 1.09, 1.20] and a 1.05-fold (95% CI: 1.02, 1.07) increase in GH risk, respectively. Additionally, stronger relationships between GH risk and PM_2.5 and O₃ exposure were observed in women who conceived in winter and summer, respectively. These findings suggest that air pollutants may contribute to the development of GH.

Differential Effect of Ambient Air Pollution Exposure on Risk of Gestational Hypertension and Preeclampsia

Although ambient air pollution may increase hypertension risk through endothelial damage and oxidative stress, evidence is inconsistent regarding its effect on hypertension in pregnancy. Prior research has evaluated a limited scope of pollution species and often not differentiated preeclampsia, which may have a placental origin, from gestational hypertension. Among 49 607 women with at least 2 singleton deliveries in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Consecutive Pregnancies Study (2002-2010), we estimated criteria pollutant and volatile organic compound levels during pregnancy using Community Multiscale Air Quality models and abstracted gestational hypertension and preeclampsia diagnoses from medical records. Generalized estimating equations accounted for repeat pregnancies and adjusted for ambient temperature and maternal age, race/ethnicity, body mass index, smoking, alcohol, parity, insurance, marital status, and asthma. Air pollution levels were low to moderate (eg, median 41.6 ppb [interquartile range, 38.9-43.7 ppb] for ozone and 35.1 ppb [28.9-40.3 ppb] for nitrogen oxides). Higher levels of most criteria pollutants during preconception and the first trimester were associated with lower preeclampsia risk, while higher second-trimester levels were associated with greater gestational hypertension risk. For example, an interquartile increase in first-trimester carbon monoxide was associated with a relative risk of 0.88 (95% CI, 0.81-0.95) for preeclampsia and second-trimester carbon monoxide a relative risk of 1.14 (95% CI, 1.07-1.22) for gestational hypertension. Volatile organic compounds, conversely, were not associated with gestational hypertension but consistently associated with higher preeclampsia risk. These findings further suggest air pollution may affect the development of hypertension in pregnancy, although differing causes of preeclampsia and gestational hypertension may alter these relationships.

Ambient Volatile Organic Compounds and Racial/Ethnic Disparities in Gestational Diabetes Mellitus: Are Asian/Pacific Islander Women at Greater Risk?

US Asian/Pacific Islander (API) communities experience high air pollution levels. APIs may be predisposed to pancreatic β-cell dysfunction and have the highest prevalence of gestational diabetes mellitus (GDM) compared with other racial/ethnic groups. Exposure to high levels of volatile organic compounds (VOCs) impairs pancreatic β-cell function, leading to insulin resistance, but racial/ethnic differences in this association are unexamined. We analyzed singleton deliveries (n = 220,065) from the Consortium on Safe Labor (2002-2008). Exposure to 14 VOCs in each hospital referral region was based on modified Community Multiscale Air Quality models. Logistic regression estimated odds ratios for GDM associated with high (≥75th percentile) versus low (<75th percentile) VOC exposure 3 months before conception and during the first trimester of pregnancy. Preconception and first-trimester exposure to high VOC levels was associated with increased odds of GDM among whites and APIs. GDM risk was significantly higher for APIs than whites for most VOCs. Preconception benzene exposure was associated with 29% (95% confidence interval: 12, 47) increased odds of GDM among whites compared with 45% (95% confidence interval: 16, 81) increased odds among APIs. These findings highlight environmental health disparities affecting pregnant women. Increased focus on GDM risk in US API communities is warranted.

The association of traffic-related air and noise pollution with maternal blood pressure and hypertensive disorders of pregnancy in the HOME study cohort

Traffic-related air and noise pollution may increase the risk for cardiovascular disorders, especially among susceptible populations like pregnant women. The objective of this study was to evaluate the association of exposure to traffic-related air pollution and traffic noise with blood pressure in pregnant women. We extracted systolic blood pressure (SBP) and diastolic blood pressure (DBP) at ≥20 weeks gestation, as well as hypertensive disorders of pregnancy from medical records in the HOME Study, a prospective pregnancy and birth cohort from Cincinnati, OH (n = 370). We estimated exposure to elemental carbon attributable to traffic (ECAT),1 a marker of traffic-related air pollution, at women's residences at ~20 weeks gestation using a validated land use regression model and traffic noise using a publicly available transportation noise model. We used linear mixed models and modified Poisson regression adjusted for covariates to examine associations of ECAT and traffic noise with blood pressure and hypertensive disorders of pregnancy risk, respectively. In adjusted models, we found a 1.6 (95% CI = 0.02, 3.3; p = 0.048) mm Hg increase in SBP associated with an interquartile range increase in ECAT concentration; the association was stronger after adjusting for traffic noise (1.9 mm Hg, 95% = 0.1, 3.7; p = 0.035). ECAT concentrations were not significantly associated with DBP or hypertensive disorders of pregnancy, and traffic noise was not associated with SBP, DBP, or hypertensive disorders of pregnancy. There was no evidence of a joint effect of traffic noise and ECAT on any outcome. In this cohort, higher residential traffic-related air pollution exposure at ~20 weeks gestation was associated with higher SBP in late pregnancy. It is important for future studies of traffic-related air or noise pollution to jointly consider both exposures and neighborhood characteristics given their correlation and potential cumulative impact on cardiovascular health.