Risk of preeclampsia from exposure to particulate matter (PM₂.₅) speciation chemicals during pregnancy

Exposure to ambient black carbon and particulate matter during pregnancy in associations with risk of pre-eclampsia: A meta-analysis based on population-based studies

Air pollution control protocols and policies formulated for PM2.5 and PM10 (particulate matter [PM] with an aerodynamic diameter of ≤2.5 and 10 μm), however, such protocols and policies have not been available for black carbon (BC). A growing number of studies have evaluated the association between long-term exposure to ambient air pollution with BC and PM and pre-eclampsia. We applied a meta-analysis to estimate pooled odds ratios (ORs) and 95 % confidence intervals (CIs) based on four exposure windows (first/second/third trimester and entire pregnancy). 24 studies meeting our selection criteria (8 for BC, 21 and 15 for PM2.5 and PM10) were finally included after screening studies published up to June 22, 2023. An increase of 1 μg/m3 BC during the second trimester and entire pregnancy were associated with a 16 % (OR: 1.16, 95 % CI: [1.02, 1.32]) and a 15 % (OR: 1.15, 95 % CI: [1.03, 1.29]) increased risk of pre-eclampsia, respectively. A 10 μg/m3 increase in second-trimester exposure to PM2.5 and PM10 was associated with a 1 % (OR: 1.01, 95 % CI: [1.00, 1.03]) and a 5 % (OR: 1.05, 95 % CI: [1.01, 1.10]) increased risk of pre-eclampsia. An 11 % (OR: 1.11, 95 % CI: [1.03, 1.21]) increased risk of pre-eclampsia was found to be associated with a 10 μg/m3 increase in PM10 exposure during the entire pregnancy. The results support the potential effect of exposure to ambient particulate pollutants on risk of pre-eclampsia and emphasize the necessity of strategies and protocols for controlling BC. Greater efforts in controlling ambient particulate pollution and especially BC are needed in order to prevent pregnant women from developing pre-eclampsia.

Short-term effects of exposure to ambient PM2.5 and its components on hospital admissions for threatened and spontaneous abortions: A multicity case-crossover study in China

BACKGROUND

The adverse effects of short-term exposure to PM2.5 and its components on hospital admissions for threatened and spontaneous abortions (TSAB) are still controversial.

METHODS

Data on daily hospitalizations for TSAB and PM2.5 and its components, including sulfate (SO42-), nitrate (NO3-), ammonium salt (NH4+), organic matter (OM), and black carbon (BC), were collected from January 2015 to December 2021 (total 2,557 days) in five cities in China. Case-crossover analyses were conducted to investigate the short-term associations between PM2.5 and its components and TSAB. Additionally, the modification effects by age (<35 and ≥35 years), season (cold and warm seasons), and the "Three-Year Action Plan to Win the Blue Sky Defense War" (before and after implementation) on the above associations were further conducted.

RESULTS

For each 10 μg/m3 (1 μg/m3 for BC) increase, the strongest relative risks (95% confidence intervals) of hospitalization for TSAB were 1.011 (1.001-1.021) for PM2.5 in lag02, 1.060 (1.003-1.120) for SO42- in lag02, 1.035 (1.000-1.070) for NO3- in lag02, 1.065 (1.009-1.124) for NH4+ in lag02, 1.047 (1.008-1.088) for OM in lag01 and 1.029 (1.005-1.054) for BC in lag02 (all P <0.05). Furthermore, significant modifying effects of age and the Action Plan were found. The effects of NO3- (lag2), NH4+ (lag2), and BC (lag2) were more pronounced in mothers aged ≥35 years and the effects of PM2.5 (lag4), NO3- (lag4), NH4+ (lag4), OM (lag4), and BC (lag4) was more pronounced in the period before the Action Plan was implemented (all P modification <0.05).

CONCLUSION

Short-term exposure to ambient PM2.5 and its components (SO42-, NO3-, NH4+, OM, and BC) was related to increased risks of hospitalization for TSAB. The effects were more pronounced in mothers aged ≥35 years and the period before the Action Plan.

An exposure-response meta-analysis of ambient PM2.5 during pregnancy and preeclampsia

Relationships between PM_2.5 exposure and preeclampsia have been the focus of four recent systematic reviews and meta-analyses. We expand on knowledge gaps in these reviews by characterizing the shape of the exposure-outcome relationship, and by assessing the heterogeneity in these associations by study characteristics. Studies of PM_2.5 and preeclampsia were identified from reviews, and confounder-adjusted estimates were extracted. Estimates were derived using a random-effects model. Potential non-linearity was evaluated using a one-stage dose-response meta-analysis. Contrary to previous meta-analyses reporting stronger relationships, the overall adjusted relative risk (RR) for a 10 μg/m³ average increase in PM_2.5 during pregnancy and preeclampsia was modest and not statistically significant (RR: 1.07, 95% CI: 0.99-1.15). This was mainly attributable to inclusion/exclusion decisions for studies made during this review. In addition, there was no evidence of non-linearity, and no important sub-group differences by characteristics such as region, exposure assessment, participant exclusions, and early versus late-onset preeclampsia. Overall, our analysis suggests a modest relationship between ambient PM_2.5 and preeclampsia. We provide details on inclusion and exclusion decisions that were lacking in previous studies, and report novel investigations of non-linearity and heterogeneity.

Exposure to chemical components of fine particulate matter and ozone, and placenta-mediated pregnancy complications in Tokyo: a register-based study

BACKGROUND

Maternal exposure to fine particulate matter (PM_2.5) was associated with pregnancy complications. However, we still lack comprehensive evidence regarding which specific chemical components of PM_2.5 are more harmful for maternal and foetal health.

OBJECTIVE

We focused on exposure over the first trimester (0-13 weeks of gestation), which includes the early placentation period, and investigated whether PM_2.5 and its components were associated with placenta-mediated pregnancy complications (combined outcome of small for gestational age, preeclampsia, placental abruption, and stillbirth).

METHODS

From 2013 to 2015, we obtained information, from the Japan Perinatal Registry Network database, on 83,454 women who delivered singleton infants within 23 Tokyo wards (≈627 km²). Using daily filter sampling of PM_2.5 at one monitoring location, we analysed carbon and ion components, and assigned the first trimester average of the respective pollutant concentrations to each woman.

RESULTS

The ORs of placenta-mediated pregnancy complications were 1.14 (95% CI = 1.08-1.22) per 0.51 μg/m³ (interquartile range) increase of organic carbon and 1.11 (1.03-1.18) per 0.06 μg/m³ increase of sodium. Organic carbon was also associated with four individual complications. There was no association between ozone and outcome.

SIGNIFICANCE

There were specific components of PM_2.5 that have adverse effects on maternal and foetal health.

Trimester-Specific Association of Maternal Exposure to Fine Particulate Matter and its Components With Birth and Placental Weight in Japan

OBJECTIVE

We investigated which trimester of exposure to PM2.5 and its components was associated with birth and placental weight, and the fetoplacental weight ratio.

METHODS

The study included 63,990 women who delivered singleton term births within 23 Tokyo wards between 2013 and 2015. Each day, we collected fine particles on a filter, and analyzed their chemical constituents, including carbons and ions. Trimester-specific exposure to each pollutant was estimated based on the average daily concentrations.

RESULTS

Over the third trimester, sulfate exposure tended to be inversely associated with birth weight, and decreased placental weight (difference for highest vs lowest quintile groups = -6.7 g, 95% confidence interval = -12.5 to -0.9). For fetoplacental weight ratio, there was no relationship.

CONCLUSIONS

Sulfate exposure over the third trimester may reduce birth weight, particularly placental weight.

Air pollution and pre-eclampsia; associations and potential mechanisms

INTRODUCTION

Air pollution has significant negative health impacts, particularly on the cardiovascular system. The aims of this narrative review were to identify whether there is an association between air pollution and the incidence of pre-eclampsia, and the potential mechanisms by which any effects may be mediated.

METHODS

We undertook a literature search using Google Scholar, PubMed, the Cochrane Library and NICE Evidence. The primary eligibility criterion was articles correlating exposure to air pollution with incidence of pre-eclampsia.

RESULTS

Meta-analyses currently show a positive association between pre-eclampsia and exposure to both particulate matter PM_2.5 and nitrogen dioxide, but no significant associations with ambient ozone or carbon monoxide exposure. No meta-analysis has been performed for exposure to sulfur dioxide. Variability in terms of quantification of exposure, the exposure period and co-founders among the studies makes comparisons complex. Adverse effects on trophoblast invasion and placental vascularisation, and increases in oxidative stress and anti-angiogenic factors, such as sFlt-1, in response to air pollution provide pathways by which exposure may contribute to the pathophysiology of pre-eclampsia. So far, studies have not discriminated between the early- and late-onset forms of the syndrome.

DISCUSSION

Future prospective studies using personal air pollution monitors and blood biomarkers of pre-eclampsia would strengthen the associations. Interactions between pollutants are poorly documented, and at present there is minimal informed advice available to women on the need to avoid exposure to air pollutants during pregnancy.

The impact of particulate matter 2.5 on the risk of preeclampsia: an updated systematic review and meta-analysis

There is increasing and inconsistent evidence of a linkage between maternal exposure to particulate matter 2.5 (PM2.5) and preeclampsia. Therefore, this study was conducted to investigate this relationship. Electronic databases including PubMed, Embase, Web of Science, and Cochrane Library were searched to identify articles published from inception to March 23, 2020, which showed a correlation between PM2.5 and preeclampsia. Finally, 9 of 523 initial studies were deemed eligible for inclusion. A random effect model was adopted to calculate the standardized odds ratio (OR) and 95% confidence interval (CI). Based on potential effect modification, subgroup analyses were further performed. Meta-analysis showed that maternal exposure to PM2.5 (per 10 μg/m3 increment) elevated the risk of preeclampsia (OR = 1.32, 95% CI 1.10 to 1.58%). Compared with other pregnancy trimesters, the third trimester of pregnancy seems to be the period in which women are more susceptible to PM2.5. Significant effect modification of the correlation between PM2.5 exposure and preeclampsia according to multiple pregnancies, pregnancy stage, maternal-related disease history, and sample size was not observed. The results demonstrated that maternal exposure to PM2.5 may predispose pregnant women to develop preeclampsia, especially in the third trimester of pregnancy. Therefore, more efforts should be made to improve air quality to maintain the health of pregnant women.

Urban-Related Environmental Exposures during Pregnancy and Placental Development and Preeclampsia: a Review

PURPOSE OF REVIEW

To summarize the current knowledge of the pathophysiological implications and the clinical role of urban-related environmental exposures in pregnancy.

RECENT FINDINGS

The ongoing urbanization worldwide is leading to an increasing number of pregnant women being exposed to higher levels of urban-related environmental hazards such as air pollution and noise and, at the same time, having less contact with natural environments. Pregnancy represents a particular and vulnerable life period both for women and their children. Extensive physiological and metabolic changes, as well as changes to the cardiovascular and respiratory systems during pregnancy, could result in increased sensitivity to damage by environmental factors. Exposure to air pollution and noise is associated with placental dysfunction and damage, which, in turn, could lead to maternal complications such as preeclampsia. In contrast, more contact with greenspace during pregnancy seems to mitigate these adverse impacts. These findings open up new challenges for our understanding of the potential effect of urban living on placental function and preeclampsia, and offer new clinical and research opportunities.

Temperature and preeclampsia: Epidemiological evidence that perturbation in maternal heat homeostasis affects pregnancy outcome

INTRODUCTION

This study aims to determine the association between temperature and preeclampsia and whether it is affected by seasonality and rural/urban lifestyle.

METHODS

This cohort study included women who delivered at our medical center from 2004 to 2013 (31,101 women, 64,566 deliveries). Temperature values were obtained from a spatiotemporally resolved estimation model performing predictions at a 1×1km spatial resolution. In "Warm" pregnancies >50% of gestation occurred during the spring-summer period. In cold pregnancies >50% of gestation occurred during the fall and winter. Generalized estimating equation multivariable models were used to estimate the association between temperature and incidence of preeclampsia.

RESULTS

1) The incidence of preeclampsia in at least one pregnancy was 7% (2173/64,566); 2) during "warm" pregnancies, an elevation of one IQR of the average temperature in the 1st or the 3rd trimesters was associated with an increased risk to develop preeclampsia [patients with Jewish ethnicity: 1st trimester: relative risk (RR) of 2.38(95%CI 1.50; 3.80), 3rd trimester 1.94(95%CI 1.34;2.81); Bedouins: 1st trimester: RR = 2.91(95%CI 1.98;4.28), 3rd trimester: RR = 2.37(95%CI 1.75;3.20)]; 3) In "cold" pregnancies, an elevation of one IQR of average temperature was associated with a lower risk to develop preeclampsia among patients with Bedouin-Arab ethnicity RR = 0.68 (95% CI 0.49-0.94) for 1st trimester and RR = 0.62 (95% CI 0.44-0.87) for 3rd trimester.

CONCLUSIONS

1) Elevated averaged temperature during the 1st or 3rd trimesters in "warm" pregnancies confer an increased risk for the development of preeclampsia, especially in nomadic patients; 2) Of interest, during cold pregnancies, elevated averaged temperature was associated with a lower risk to develop preeclampsia for nomadic patients. 3) These findings suggest temperature might be associated with perturbations in maternal heat homeostasis resulting in reallocation of energy resources and their availability to the fetus that may increase the risk for preeclampsia. This observation is especially relevant in the context of global warming and its effects on maternal/fetal reproductive health.

Wintertime Wood Smoke, Traffic Particle Pollution, and Preeclampsia

Previous studies have reported associations between ambient fine particle concentrations and preeclampsia; however, the impact of particulate pollution on early- and late-onset preeclampsia is understudied. Furthermore, few studies have examined the association between source-specific particles such as markers of traffic pollution or wood combustion on adverse pregnancy outcomes. Electronic medical records and birth certificate data were linked with land-use regression models in Monroe County, New York for 2009 to 2013 to predict monthly pollutant concentrations for each pregnancy until the date of clinical diagnosis during winter (November-April) for 16 116 births. Up to 30% of ambient wintertime fine particle concentrations in Monroe County, New York is from wood combustion. Multivariable logistic regression was used to separately estimate the odds of preeclampsia (all, early-, and late-onset) associated with each interquartile range increase in fine particles, traffic pollution, and woodsmoke concentrations during each gestational month, adjusting for maternal characteristics, birth hospital, temperature, and relative humidity. Each 3.64 µg/m3 increase in fine particle concentration was associated with an increased odds of early-onset preeclampsia during the first (odds ratio, 1.35 [95% CI, 1.08-1.68]), second (odds ratio, 1.51 [95% CI, 1.23-1.86]), and third (odds ratio, 1.25 [95% CI, 1.06-1.46]) gestational months. Increases in traffic pollution and woodsmoke during the first gestational month were also associated with increased odds of early-onset preeclampsia. Increased odds of late-onset preeclampsia were not observed. Our findings suggest that exposure to wintertime particulate pollution may have the greatest effect on maternal cardiovascular health during early pregnancy.

Association of childhood pulmonary tuberculosis with exposure to indoor air pollution: a case control study

Background

Crude measures of exposure to indicate indoor air pollution have been associated with the increased risk for acquiring tuberculosis. Our study aimed to determine an association between childhood pulmonary tuberculosis (PTB) and exposure to indoor air pollution (IAP), based on crude exposure predictors and directly sampled and modelled pollutant concentrations.

Methods

In this case control study, children diagnosed with PTB were compared to children without PTB. Questionnaires about children’s health; and house characteristics and activities (including household air pollution) and secondhand smoke (SHS) exposure were administered to caregivers of participants. A subset of the participants’ homes was sampled for measurements of PM₁₀ over a 24-h period (n = 105), and NO₂ over a period of 2 to 3 weeks (n = 82). IAP concentrations of PM₁₀ and NO₂ were estimated in the remaining homes using predictive models. Logistic regression was used to look for association between IAP concentrations, crude measures of IAP, and PTB.

Results

Of the 234 participants, 107 were cases and 127 were controls. Pollutants concentrations (μg/m³) for were PM₁₀ median: 48 (range: 6.6–241) and NO₂ median: 16.7 (range: 4.5–55). Day-to-day variability within- household was large. In multivariate models adjusted for age, sex, socioeconomic status, TB contact and HIV status, the crude exposure measures of pollution viz. cooking fuel type (clean or dirty fuel) and SHS showed positive non-significant associations with PTB. Presence of dampness in the household was a significant risk factor for childhood TB acquisition with aOR of 2.4 (95% CI: 1.1–5.0). The crude exposure predictors of indoor air pollution are less influenced by day-to-day variability. No risk was observed between pollutant concentrations and PTB in children for PM₁₀ and NO₂.

Conclusion

Our study suggests increased risk of childhood tuberculosis disease when children are exposed to SHS, dirty cooking fuel, and dampness in their homes. Yet, HIV status, age and TB contact are the most important risk factors of childhood PTB in this population.

Current Methods and Challenges for Epidemiological Studies of the Associations Between Chemical Constituents of Particulate Matter and Health

Epidemiological studies have been critical for estimating associations between exposure to ambient particulate matter (PM) air pollution and adverse health outcomes. Because total PM mass is a temporally and spatially varying mixture of constituents with different physical and chemical properties, recent epidemiological studies have focused on PM constituents. Most studies have estimated associations between PM constituents and health using the same statistical methods as in studies of PM mass. However, these approaches may not be sufficient to address challenges specific to studies of PM constituents, namely assigning exposure, disentangling health effects, and handling measurement error. We reviewed large, population-based epidemiological studies of PM constituents and health and describe the statistical methods typically applied to address these challenges. Development of statistical methods that simultaneously address multiple challenges, for example, both disentangling health effects and handling measurement error, could improve estimation of associations between PM constituents and adverse health outcomes.

Association between maternal aluminum exposure and the risk of congenital heart defects in offspring

BACKGROUND

Aluminum (Al) is the third most common element in the earth' s crust and has been reported to be teratogenic. However, there is lack of understanding about the association between maternal aluminum exposure and the risks of birth defects such as congenital heart defects (CHDs).

METHODS

A multi-center, hospital-based case-control study was performed at four maternal and child tertiary hospitals in China. A total of 223 cases with CHDs and 223 controls without any abnormalities were recruited according to the inclusion and matching criteria. Hair samples were prepared and measured by inductively coupled plasma mass spectrometry (ICP-MS). The correlation between CHDs and maternal aluminum concentrations was estimated by a 1:1 conditional logistic regression.

RESULTS

The geometric mean and median of hair aluminum levels in isolated or multiple CHD cases was significantly higher than in controls (p < 0.05). A significant association was found between increased hair aluminum concentrations and the risk of total CHDs in offspring (adjusted odds ration [aOR], 2.32; 95% confidence interval [CI], 1.72-3.13), especially in some subtypes of CHDs, such as septal defects (aOR, 2.17; 95% CI, 1.15-4.10), conotruncal defects (aOR, 5.42; 95%CI, 2.43-12.10), and right ventricular outflow track obstruction (aOR, 2.43; 95% CI, 1.08-5.44). However, there was no statistically significant association with left ventricular outflow track obstruction (aOR, 1.66; 95% CI, 0.95-2.88).

CONCLUSION

A high maternal aluminum concentration may significantly increase the risk of delivering a child with a CHD, such as a septal defect, conotruncal heart defect and right-side obstruction.

A register-based study of the association between air pollutants and hypertensive disorders in pregnancy among the Japanese population

BACKGROUND

Ambient air pollution is hypothesized to be a risk factor for hypertensive disorders in pregnancy, one of the major pregnancy complications. Past studies have reported the supporting evidence, however this mainly referred to the Western population, and results from trimester-specific analysis have been varied. In this study, we focused on exposure during the first trimester of pregnancy (placental development stage), and tested the hypothesis among the Japanese population.

METHODS

We drew on data from the Japan Perinatal Registry Network database, and studied 36,620 singleton pregnant women without medical complications, in western Japan (Kyushu and Okinawa districts) between 2005 and 2010. In addition, data on ozone, suspended particulate matter (SPM), nitrogen dioxide (NO2), and sulfur dioxide (SO2) concentrations were obtained. The nearest monitoring station to the respective birthing hospital was used as a reference point for assigning average concentrations of each pollutant during the first trimester of pregnancy for each woman. The logistic regression model was applied to assess the association between quintiles of each pollutant and hypertensive disorders in pregnancy.

RESULTS

Mean concentrations during the first trimester were 41.3 ppb for ozone, 27.4 μg/m(3) for SPM, 11.8 ppb for NO2, and 3.2 ppb for SO2. High exposure to ozone was associated with an increased risk of hypertensive disorders in pregnancy (for highest quintile vs. lowest: odds ratio=1.20, 95% confidence interval=1.01-1.42). With regard to SPM, NO2 and SO2, we did not obtain the results with constant directionality.

CONCLUSIONS

Ozone exposure during early pregnancy may be a risk factor for hypertensive disorders in pregnancy.