Maternal fine particulate matter (PM2.5) exposure and adverse birth outcomes: an updated systematic review based on cohort studies

Health effects of exposure to urban ambient particulate matter: A spatial-statistical study on 3rd-trimester pregnant women

Pregnant women are highly vulnerable to environmental stressors such as ambient particulate matter (PM). Particularly during their 3rd trimester, their bodies undergo significant oxidative stresses. To further consolidate this dialogue into practice, the current study evaluated healthy pregnant women (n = 150 housewives; 18-40 years old; gestation age >36 weeks) from the highly polluted city of Yazd, Iran, from September to November 2021. The aerosol optical depth (AOD) data retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS) were employed as influencing variables and validated using field-collected PM10 data (r = 0.62, p-value <0.01). The links between blood platelet count, enzymes (SGOT, SGPT, LDH, bilirubin), metabolic products (urea and acid uric) and different combinations of AOD data were assessed using the Generalized Additive Model. The results showed a high temporal variability in AOD (0.94 ± 0.51) but a spatially stable distribution pattern. The mean AOD during the 3rd trimester, followed by that of the three-month peak, were identified as the most significant non-linear predictors, while the mean AOD during the 1st trimester and throughout the entire pregnancy showed no significant associations with any of the biomarkers. Considering the associations found between AOD variables and maternal oxidative stresses, urgent planning is required to improve the urban air quality for sensitive subpopulations.

Maternal urban particulate matter (SRM 1648a) exposure disrupted the cellular immune homeostasis during early life: The potential attribution of altered placental transcriptome profile

Ambient fine particular matter (PM2.5) exposure has been associated with numerous adverse effects including triggering functional disorders of the placenta and inducing immune imbalance in offspring. However, how maternal PM2.5 exposure impacts immune development during early life is not fully understood. In the current study, we exposed mice with low-, middle-, and high-dose PM2.5 during pregnancy to investigate the potential link between the transcriptional changes in the placenta and immune imbalance in mice offspring induced by PM2.5 exposures. Using flow cytometry, we found that the proportions of B cells, CD3+CD4+ T cells, CD3+CD8+ T cells, and macrophage (Mφ) cells were altered in the blood of PM2.5-exposed mice pups but not dendritic cells (DCs) and natural killer cells (NKs). Using bulk RNA sequencing, we found that PM2.5 exposure altered the transcriptional profile which indicated an inhibition of the complement and coagulation cascades in the placenta. Weighted gene co-expression network analysis (WGCNA) revealed the potential crosstalk between the perturbation of placental gene expression and the changes of immune cell subsets in pups on postnatal day 10 (PND10). Specifically, WGCNA identified a cluster of genes including Defb15, Defb20, Defb25, Cst8, Cst12, and Adam7 that might regulate the core immune cell types in PND10 pups. Although the underlying mechanisms of how maternal PM2.5 exposure induces peripheral lymphocyte disturbance in offspring still remain much unknown, our findings here shed light on the potential role of placental dysfunction in these adverse effects.

A scoping review of wildfire smoke risk communications: issues, gaps, and recommendations

BACKGROUND

Wildfire smoke exposure has become a growing public health concern, as megafires and fires at the wildland urban interface increase in incidence and severity. Smoke contains many pollutants that negatively impact health and is linked to a number of health complications and chronic diseases. Communicating effectively with the public, especially at-risk populations, to reduce their exposure to this environmental pollutant has become a public health priority. Although wildfire smoke risk communication research has also increased in the past decade, best practice guidance is limited, and most health communications do not adhere to health literacy principles: readability, accessibility, and actionability. This scoping review identifies peer-reviewed studies about wildfire smoke risk communications to identify gaps in research and evaluation of communications and programs that seek to educate the public.

METHODS

Four hundred fifty-one articles were identified from Web of Science and PubMed databases. After screening, 21 articles were included in the final sample for the abstraction process and qualitative thematic analysis. Ten articles were based in the US, with the other half in Australia, Canada, Italy, and other countries. Fifteen articles examined communication materials and messaging recommendations. Eight papers described communication delivery strategies. Eleven articles discussed behavior change. Six articles touched on risk communications for vulnerable populations; findings were limited and called for increasing awareness and prioritizing risk communications for at-risk populations.

RESULTS

This scoping review found limited studies describing behavior change to reduce wildfire smoke exposure, characteristics of effective communication materials and messaging, and communication delivery strategies. Literature on risk communications, dissemination, and behavior change for vulnerable populations was even more limited.

CONCLUSIONS

Recommendations include providing risk communications that are easy-to-understand and adapted to specific needs of at-risk groups. Communications should provide a limited number of messages that include specific actions for avoiding smoke exposure. Effective communications should use mixed media formats and a wide variety of dissemination strategies. There is a pressing need for more intervention research and effectiveness evaluation of risk communications about wildfire smoke exposure, and more development and dissemination of risk communications for both the general public and vulnerable populations.

Geodetector analysis of individual and joint impacts of natural and human factors on maternal and child health at the provincial scale

This ecological study examined the individual and joint impacts of natural-human factors on the spatial patterns of maternal and child health status in China at the provincial scale in 2020. We considered natural factors (forest coverage, average temperature, and total sulfur dioxide and particulate matter emissions) and human factors (economic development, urbanization, healthcare access, and education level). We combined maternal, infant, and under-five mortality rates into a composite maternal and child health index using the entropy method. The spatial autocorrelation analysis of this index highlighted distinct health patterns across provinces, whereas the geodetector method assessed the effects of natural-human factors on the patterns. A notable east-central-west stepwise decline in health status was observed. Global Moran's I showed positive spatial clustering, with high-high clustering areas in the Yangtze River Delta and low-low clustering areas in western regions. Factor detection identified eight significant natural-human factors impacting maternal and child health, with total sulfur dioxide emission density having the greatest impact. The interaction between average schooling years and total sulfur dioxide emission notably affected maternal and child health patterns. The study concludes that natural-human factors critically affect the spatial distribution of maternal and child health.

Critical research gaps in treating growth faltering in infants under 6 months: A systematic review and meta-analysis

In 2020, 149.2 million children worldwide under 5 years suffered from stunting, and 45.4 million experienced wasting. Many infants are born already stunted, while others are at high risk for growth faltering early after birth. Growth faltering is linked to transgenerational impacts of poverty and marginalization. Few interventions address growth faltering in infants under 6 months, despite a likely increasing prevalence due to the negative global economic impacts of the COVID-19 pandemic. Breastfeeding is a critical intervention to alleviate malnutrition and improve child health outcomes, but rarely receives adequate attention in growth faltering interventions. A systematic review and meta-analysis were undertaken to identify and evaluate interventions addressing growth faltering among infants under 6 months that employed supplemental milks. The review was carried out following guidelines from the USA National Academy of Medicine. A total of 10,405 references were identified, and after deduplication 7390 studies were screened for eligibility. Of these, 227 were assessed for full text eligibility and relevance. Two randomized controlled trials were ultimately included, which differed in inclusion criteria and methodology and had few shared outcomes. Both studies had small sample sizes, high attrition and high risk of bias. A Bangladeshi study (n = 153) found significantly higher rates of weight gain for F-100 and diluted F-100 (DF-100) compared with infant formula (IF), while a DRC trial (n = 146) did not find statistically significant differences in rate of weight gain for DF-100 compared with IF offered in the context of broader lactation and relactation support. The meta-analysis of rate of weight gain showed no statistical difference and some evidence of moderate heterogeneity. Few interventions address growth faltering among infants under 6 months. These studies have limited generalizability and have not comprehensively supported lactation. Greater investment is necessary to accelerate research that addresses growth faltering following a new research framework that calls for comprehensive lactation support.

Ambient fine particulate matter and pregnancy outcomes: An umbrella review

The available evidence on the effects of ambient fine particulate matter (PM2.5) and pregnancy outcomes (birth outcomes and pregnancy complications) has increased substantially. The purpose of this umbrella review is to refine the evidence of the association between birth outcome (birth defects) and PM2.5; and summarize the credibility of existing research on the association between pregnancy complications and PM2.5. We searched PubMed, Web of Science, Embase, and Cochrane databases for relevant systematic reviews and meta-analyses up to March 16, 2022 in accordance with PRISMA guidelines. Two independent investigators conducted data extraction. AMSTAR 2 and GRADE assessment criteria were used to evaluate the methodological and evidence quality. We performed subgroup analyses by trimesters of pregnancy. The review protocol for this study has been registered in PROSPERO (CRD42022325550). This umbrella review identified a total of 41 systematic reviews, including 28 articles evaluating the influence of PM2.5 on birth outcomes and 13 on pregnancy complications. Positive associations between perinatal PM2.5 exposure and adverse birth outcomes were found, including low birth weight, preterm birth, stillbirth, small for gestational age, and birth defects. Pregnant women exposed to PM2.5 had a significantly higher risk of developing hypertensive disorder of pregnancy, gestational diabetes mellitus, gestational hypertension, and preeclampsia. The findings of subgroup analysis demonstrated that the effects of ambient PM2.5 exposure on pregnancy outcomes varied by trimesters. The findings of this extensive umbrella review provide convincing proof that exposure to ambient PM2.5 raises the risks of unfavorable birth outcomes and pregnancy complications. Some associations show considerable disparity between trimesters. These findings have implications for strengthen perinatal health care on air pollution and improving intergenerational equity.

Fine Particulate Matter Metal Composition, Oxidative Potential, and Adverse Birth Outcomes in Los Angeles

BACKGROUND

Although many studies have linked prenatal exposure to PM 2.5 to adverse birth outcomes, little is known about the effects of exposure to specific constituents of PM 2.5 or mechanisms that contribute to these outcomes.

OBJECTIVES

Our objective was to investigate effects of oxidative potential and PM 2.5 metal components from non-exhaust traffic emissions, such as brake and tire wear, on the risk of preterm birth (PTB) and term low birth weight (TLBW).

METHODS

For a birth cohort of 285,614 singletons born in Los Angeles County, California, in the period 2017-2019, we estimated speciated PM 2.5 exposures modeled from land use regression with cokriging, including brake and tire wear related metals (barium and zinc), black carbon, and three markers of oxidative potential (OP), including modeled reactive oxygen species based on measured iron and copper (ROS), OH formation (OP OH ), and dithiothreitol (DTT) loss (OP DTT ). Using logistic regression, we estimated odds ratios (OR) and 95% confidence intervals (CI) for PTB and TLBW with speciated PM 2.5 exposures and PM 2.5 mass as continuous variables scaled by their interquartile range (IQR).

RESULTS

For both metals and oxidative potential metrics, we estimated increased risks for PTB (ORs ranging from 1.01 to 1.03) and TLBW (ORs ranging from 1.02 to 1.05) per IQR exposure increment that were robust to adjustment for PM 2.5 mass. Associations for PM 2.5 mass, black carbon, metal components, and oxidative potential (especially ROS and OP OH ) with adverse birth outcomes were stronger in Hispanic, Black, and mixed-race or Native American women.

DISCUSSION

Our results indicate that exposure to PM 2.5 metals from brake and tire wear and particle components that contribute to oxidative potential were associated with an increased risk of PTB and TLBW in Los Angeles County, particularly among Hispanic, Black, and mixed-race or Native American women. Thus, reduction of PM 2.5 mass only may not be sufficient to protect the most vulnerable pregnant women and children from adverse effects due to traffic source exposures. https://doi.org/10.1289/EHP12196.

Prenatal PM2.5 exposure increases the risk of adverse pregnancy outcomes: evidence from meta-analysis of cohort studies

Adverse pregnancy outcomes (APOs) are a significant cause of fetal death. A wide range of maternal psychological, social, and environmental factors may contribute to these outcomes. Mounting epidemiological studies have indicated that PM2.5 may result in these unfavorable consequences. Previously published meta-analyses have been updated and extended. Cohort studies were searched from three databases (up to July 24, 2023), and their quality was assessed by Newcastle-Ottawa Scale (NOS). Publication bias was examined by Egger's test and funnel plot. Despite a large number of studies showing similar results, the inconsistencies between these findings require careful generalization before concluding. This meta-analysis included 67 cohort studies from 20 countries, and the findings revealed that maternal PM2.5 exposure and five APOs were correlated significantly throughout pregnancy: preterm birth (PTB) (RR = 1.05; 95% CI: 1.03, 1.07); low birth weight (LBW) (RR = 1.02; 95% CI: 1.01, 1.04); small for gestational age (SGA) (RR = 1.03; 95% CI: 1.01, 1.04); stillbirth (RR = 1.24; 95% CI: 1.06, 1.45); and change in birthweight (weight change = -6.82 g; 95% CI: -11.39, -2.25). A positive association was found between APOs and PM2.5 exposure in this meta-analysis, and the degree of increased risk of APOs varied due to different gestation periods. Therefore, it is necessary to protect pregnant women at specific times.

Prenatal exposure to PM2.5 and its constituents with children's BMI Z-score in the first three years: A birth cohort study

BACKGROUND

Limited studies evaluated the effect of prenatal exposure to fine particulate matter (PM_2.5) on childhood growth and no consensus reached yet. No study explored the effect of prenatal exposure to PM_2.5 and its constituents on childhood growth in a region with high PM_2.5 levels (>50 μg/m³). The present study aimed to examine the association of prenatal exposure to PM_2.5 and its constituents with children's BMI Z-score in the first three years.

METHODS

The present study was based on a birth cohort in Beijing, China, involving 15,745 mothers with their children who were followed to three years old. We estimated prenatal PM_2.5 and its constituents [organic carbon (OC), elemental carbon (EC), sulfate (SO₄^2-), nitrate (NO₃^-), and ammonium (NH₄⁺)] concentrations based on residential addresses at birth. Height (or length) and weight of children were repeatedly measured, and body mass index (BMI) Z-score was calculated at one, two, and three years old. Generalized linear regression and generalized estimating equation were used to examine the associations between prenatal exposure to PM_2.5 and its constituents with BMI Z-score in the first three years.

RESULTS

Prenatal exposure to PM_2.5 and its constituents was generally associated with higher BMI Z-score of children aged one, two, and three years. One IQR increase of PM_2.5, OC, EC, NO₃^-, NH₄⁺, and SO₄^2- (21.30 μg/m³, 11.52 μg/m³, 2.40 μg/m³, 8.28 μg/m³, 2.42 μg/m³, and 8.80 μg/m³, respectively) was associated with 0.13 (95%CI: 0.10, 0.16), 0.24 (95%CI: 0.19, 0.29), 0.12 (95%CI: 0.09, 0.16), 0.13 (95%CI: 0.09, 0.17), 0.11 (95%CI: 0.08, 0.13), and 0.24 (95%CI: 0.19, 0.30) increase in BMI Z-score from one to three years old, respectively.

CONCLUSION

The study suggested that prenatal exposure to PM_2.5 and its constituents was associated with higher BMI Z-score of children in the first three years. Public health policy for controlling harmful PM_2.5 constituents should be developed to promote child health.

Small vulnerable newborns-big potential for impact

Despite major achievements in child survival, the burden of neonatal mortality has remained high and even increased in some countries since 1990. Currently, most neonatal deaths are attributable to being born preterm, small for gestational age (SGA), or with low birthweight (LBW). Besides neonatal mortality, these conditions are associated with stillbirth and multiple morbidities, with short-term and long-term adverse consequences for the newborn, their families, and society, resulting in a major loss of human capital. Prevention of preterm birth, SGA, and LBW is thus critical for global child health and broader societal development. Progress has, however, been slow, largely because of the global community's failure to agree on the definition and magnitude of newborn vulnerability and best ways to address it, to frame the problem attractively, and to build a broad coalition of actors and a suitable governance structure to implement a change. We propose a new definition and a conceptual framework, bringing preterm birth, SGA, and LBW together under a broader umbrella term of the small vulnerable newborn (SVN). Adoption of the framework and the unified definition can facilitate improved problem definition and improved programming for SVN prevention. Interventions aiming at SVN prevention would result in a healthier start for live-born infants, while also reducing the number of stillbirths, improving maternal health, and contributing to a positive economic and social development in the society.

Effects of maternal urban particulate matter SRM 1648a exposure on birth outcomes and offspring growth in mice

The association between exposure to particulate matter (PM) during pregnancy and abnormal birth outcomes is still inconclusive. This study aims to provide more evidence for this public health concern by investigating birth outcomes and the growth of offspring in mice exposed to PM during pregnancy. C57BL/6 J pregnant mice were exposed to PM via nasal drip at three doses or solvent control. The dam weight gain was recorded during pregnancy. The number of pups, pup weight, and placental weight were recorded at embryonic day 18.5 (E18.5) necropsy. For mice that gave birth naturally, we calculated the gestation length and measured the body weight of offspring once a week from the 1st to the 6th week after birth. The results showed that there were no significant differences in maternal body weight gain, conception rate, pregnancy duration, and litter size among different groups. There were no significant differences in fetal weight, placental weight, and fetal/placental weight ratio at E18.5. Weight gain in offspring was reduced after birth. The average body weight of offspring in the high-dose group was significantly lower than that in the control group at weeks 5 in female pups. There were no significant differences in the body weight of male offspring among groups from 1st to the 6th. Together, our study indicated that maternal exposure to PM did not significantly impact birth outcomes of C57BL/6 J mice but affected growth trajectories in offspring after birth in a dose- and fetal sex-dependent manner.

Prenatal exposure to particulate matter and term low birth weight: systematic review and meta-analysis

To evaluate the relationships between maternal particulate matter exposure and offspring birth weight. Studies were categorized into three subgroups: term low birth weight (TLBW) among full-term births and all births (regardless of gestational age) and low birth weight (LBW) among all births, based on the search results of MEDLINE and the Web of Science from the inception of the database to April 2022. Subgroup analyses were conducted based on the economic status, region, exposure assessment, risk of bias, and adjustment. Sixty-one studies involving 34,506,975 singleton live births in 15 countries were analyzed. Overall, the risk of bias for most studies (75%) was low. In 39 of 47 term birth studies, the pooled odds ratio of TLBW among term births for per interquartile range (IQR) increases throughout the entire pregnancy was 1.02 (1.01 to 1.03) for PM2.5 and 1.03 (1.01 to 1.05) for PM10 after adjustment for covariates. No significant relevance was detected across each trimester period for PM2.5. A stronger effect was observed during the second trimester (1.03, 1.01 to 1.06) for PM10. There was no increased risk of TLBW in all births associated with IQR increases in PM2.5 and PM10. LBW was associated with PM2.5 exposure in 4 of 7 studies, but statistical heterogeneity was considerable. In the TLBW subgroup analysis, the effects of PM2.5 and PM10 were both greater in studies conducted in advanced countries, studies with low bias, and studies that adjusted for maternal age, infant sex, and parity. Stronger effects were present for PM2.5 exposure collected from monitoring stations and PM10 exposure interpolated from the inverse distance weighting model. TLBW may be associated with prenatal exposure to particulate matter, but no critical windows were identified. Stronger associations were observed in advanced countries. Future original study designs need to consider the impact of different exposure assessment modalities and all possible confounding factors.

Identifying the critical windows and joint effects of temperature and PM2.5 exposure on small for gestational age

The potential critical windows for extreme ambient temperature, air pollution exposure and small for gestational age (SGA) are still unclear, and no study has explored their joint effects on SGA. In a national multi-center prospective cohort, we included 179,761 pairs of mother-infant from 16 counties of 8 provinces in China during 2014-2018. Daily averaged temperature and PM2.5 concentration were matched to the maternal residential address to estimate personal exposure. Extreme temperature exposures were categorized by a series of percentile in each meteorological and geographic division for the entire pregnancy, each trimester and gestational week (GA-week). Generalized linear mixed models (GLMMs) and distributed lag nonlinear models (DLNMs) were used to estimate the whole pregnancy-, trimester-specific, and weekly-specific associations of extreme temperature and PM2.5 exposures with SGA. Combined effects were evaluated with the relative excess risk due to interaction (RERI) and proportion attributable to interaction (AP). We observed that by referring to temperature at the 41st - 50th percentile, heat (>90th percentile) exposure during 13th - 29th GA-weeks was associated with SGA; odds ratio (OR) and 95 % confidence intervals (CI) was 1.16 (1.06, 1.28). For cold (<=10th percentile), inverse associations were observed during the 1st - 8th GA-weeks. PM2.5 exposure during the 2nd - 5th and 19th - 27th GA-weeks was associated with SGA, with the strongest association in the 2nd GA-week (OR = 1.0017, 95 %CI: 1.0001, 1.0034, for a 10 μg/m3 increase). No interactive effects between ambient temperature and PM2.5 on SGA were observed. Our findings suggest the weekly susceptibility windows for heat and PM2.5 exposure were primarily the gestational weeks within the 2nd trimester, therefore, corresponding protective measures should be conveyed to pregnant women during routine prenatal visits to reduce exposures.

Trimester-specific ambient PM2.5 exposures and risk of intellectual disability in Utah

Prenatal fine particulate matter (PM2.5) exposure is an understudied risk factor for neurodevelopmental outcomes, including intellectual disability (ID). Associations among prenatal exposures and neurodevelopmental outcomes may vary depending on the timing of exposure. Limited numbers of studies examining PM2.5 and neurodevelopmental outcomes have considered exposures occurring during the preconception period. To address these gaps, we conducted a case-control study of children born in Utah between 2002 and 2008 (n = 1032). Cases were identified using methods developed by the Centers for Disease Control and Prevention's Autism and Developmental Disabilities Monitoring Network and matched with controls on birth year, sex, and birth county. We estimated the daily average PM2.5 concentration during a period spanning 12 weeks before the estimated conception date, as well as during each of the three trimesters at the maternal residential address listed on the child's birth certificate. In a multivariable model, the third (OR: 2.119, CI: 1.123-3.998, p = .021) and fourth (OR: 2.631, CI: 1.750-3.956, p < .001) quartiles for preconception average PM2.5 demonstrated significantly increased risk of ID relative to the first quartile. Second quartile preconception exposure was also associated with increased risk, though it did not reach significance (OR: 1.385, CI: 0.979-1.959, p = .07). The fourth quartile of first trimester average PM2.5 was positive and significant (OR: 2.278, CI: 1.522-3.411, p < .001); the third quartile was positive, but not significant (OR: 1.159, CI: 0.870-1.544, p = .312). Quartiles of second and third trimester were not associated with higher risk of ID. These findings from Utah, which were robust to a variety of sensitivity analyses, provide initial evidence that preconception and prenatal PM2.5 exposure may be associated with ID. Future studies are needed across other geographic locations and populations.

Air Pollution and Birth Outcomes: Health Impact and Economic Value Assessment in Spain

Air pollution is considered an ongoing major public health and environmental issue around the globe, affecting the most vulnerable, such as pregnant women and fetuses. The aim of this study is to estimate the health impact and economic value on birth outcomes, such as low birthweight (LBW), preterm birth (PTB), small for gestational age (SGA), attributable to a reduction of PM₁₀ levels in Spain. Reduction based on four scenarios was implemented: fulfillment of WHO guidelines and EU limits, and an attributable reduction of 15% and 50% in annual PM₁₀ levels. Retrospective study on 288,229 live-born singleton children born between 2009-2010, using data from Spain Birth Registry Statistics database, as well as mean PM₁₀ mass concentrations. Our finding showed that a decrease in annual exposure to PM₁₀ appears to be associated with a decrease in the annual cases of LBW, SGA and PTB, as well as a reduction in hospital cost attributed to been born with LBW. Improving pregnancy outcomes by reducing the number of LBW up to 5% per year, will result in an estimate associated monetary saving of 50,000 to 7,000,000 euros annually. This study agrees with previous literature and highlights the need to implement, and ensure compliance with, stricter policies that regulate the maximum exposure to outdoor PM permitted in Spain, contributing to decreased environmental health risk, especially negative birth outcomes.

Spatiotemporal variation of PM2.5-related preterm birth in China and India during 1990-2019 and implications for emission controls

Preterm birth is the leading threat to neonatal health. The variation of PM_2.5-associated preterm birth in China and India from 1990 through 2019 was estimated in this study. Meanwhile, four mitigation scenarios were proposed, and the corresponding PM_2.5-related preterm birth was projected for 2030. Owing to differences in emission control policies and the effects of various factors (e.g., differences in population-control policies), the PM_2.5 concentration and PM_2.5-associated preterm birth in the two countries presented disparate spatiotemporal characteristics and variation trends during 1990-2019. The 30-year average of annual PM_2.5-associated preterm birth in India was 1018 (95% confidence interval, 718-1289) thousand, which was much larger than in China (280 [196-358] thousand). To fight air pollution, China launched several control strategies in the past two decades, and the nationwide maternal exposure risk dramatically decreased after 2010. In contrast, India's air-pollution control measures and policies have not effectively mitigated the nationwide PM_2.5 pollution. Under current mitigation measures and policies, the projected decrease in maternal exposure risk by 2030 is greater for China than India, and the scope for controlling air pollutant emissions and reducing maternal exposure risk is much large for India. The results of all four scenarios revealed that the annual PM_2.5-associated preterm birth in the two countries is likely to decrease in the future. In particular, if China and India implement more robust emission control strategies than those currently, the number of associated preterm birth is projected to be more than 50% lower in 2030 compared with 2019 rates.

Household polluting cooking fuels and adverse birth outcomes: An updated systematic review and meta-analysis

Background and aim

The current study aimed to clarify the association between household polluting cooking fuels and adverse birth outcomes using previously published articles.

Methods

In this systematic review and meta-analysis, a systematic literature search in PubMed, Embase, Web of Science, and Scopus databases were undertaken for relevant studies that had been published from inception to 16 January 2023. We calculated the overall odds ratio (OR) and 95% confidence interval (CI) for adverse birth outcomes [low birth weight (LBW), small for gestational age (SGA), stillbirth, and preterm birth (PTB)] associated with polluting cooking fuels (biomass, coal, and kerosene). Subgroup analysis and meta-regression were also conducted.

Results

We included 16 cross-sectional, five case-control, and 11 cohort studies in the review. Polluting cooking fuels were found to be associated with LBW (OR: 1.37, 95% CI: 1.24, 1.52), SGA (OR: 1.48, 95% CI: 1.13, 1.94), stillbirth (OR: 1.38, 95% CI: 1.23, 1.55), and PTB (OR: 1.27, 95% CI: 1.19, 1.36). The results of most of the subgroup analyses were consistent with the main results. In the meta-regression of LBW, study design (cohort study: P < 0.01; cross-sectional study: P < 0.01) and sample size (≥ 1000: P < 0.01) were the covariates associated with heterogeneity. Cooking fuel types (mixed fuel: P < 0.05) were the potentially heterogeneous source in the SGA analysis.

Conclusion

The use of household polluting cooking fuels could be associated with LBW, SGA, stillbirth, and PTB. The limited literature, observational study design, exposure and outcome assessment, and residual confounding suggest that further strong epidemiological evidence with improved and standardized data was required to assess health risks from particular fuels and technologies utilized.

Identifying and quantifying PM2.5 pollution episodes with a fusion method of moving window technique and constrained Positive Matrix Factorization

PM_2.5 pollution episodes rapidly and significantly deteriorate the air quality and are a critical concern worldwide. This study developed a fusion method based on the moving window dataset technique and constrained Positive Matrix Factorization (PMF) to differentiate and characterize potential factors in a PM_2.5 episode case assuming having one new contributor. The hourly PM_2.5 compositions of elements, ions and carbonaceous components, were collected from September to December 2020 in Taipei, Taiwan. Constraint targets based on the bootstrap analysis result of a PMF model using a long-term input dataset were imposed on the modeling of each moving window to ensure similar features of the retrieved factors. The constituents of an additionally differentiated factor to the episode, which was identified as regional transport, were stable among each moving window that covered the occurrence of the episode as revealed by the profile matching index. The results showed that the largest contributor to the PM_2.5 mass during the episode period of 12/12/2020 was regional transport (61%), whereas that of 12/13 was the regular pollution of industry/ammonium sulfate related (43%). According to our review of the literature, this study is the first to apply both the moving window technique and constrained PMF to characterize the episode. The findings provide valuable information that can be used to explore the causes of PM_2.5 episodes and implement air pollution control strategies.

The associations of prenatal exposure to PM2.5 and its constituents with fetal growth: A prospective birth cohort in Beijing, China

BACKGROUND

Limited studies investigated the association of prenatal exposure to PM_2.5 and fetal growth measured by ultrasound with inconsistent results. No study evaluated the effect of PM_2.5 constituents on fetal growth in utero. We aimed to investigated whether prenatal exposure to PM_2.5 and its constituents was associated with fetal growth measured by ultrasound.

METHODS

A total of 4319 eligible pregnant women in Peking University Birth Cohort in Tongzhou (PKUBC-T) were included in the study. Based on mothers' residential addresses, we estimated prenatal PM_2.5 concentrations with a satellite-based spatiotemporal model and PM_2.5 constituents concentrations with a modified Community Multiscale Air Quality model. Fetal growth parameters of abdominal circumference (AC), head circumference (HC), and femur length (FL) were measured by ultrasound and then estimated fetal weight (EFW) was calculated. We calculated sex and gestational age-specific fetal growth Z-score and then defined the corresponding fetal undergrowth. Generalized estimating equation was used to investigate the association of PM_2.5 and its constituents with fetal growth Z-score and fetal undergrowth.

RESULTS

Prenatal exposure to PM_2.5, OC, EC, SO₄^2-, NH₄⁺, or NO₃^- was consistently associated with decreased Z-scores of fetal growth parameters (AC, HC, FL, EFW). One IQR increase of PM_2.5, OC, EC, SO₄^2-, NH₄⁺, or NO₃^- was associated with -0.183 [95% confident interval (CI): -0.225, -0.141], -0.144 (95%CI: -0.181, -0.107), -0.123 (95%CI: -0.160, -0.085), -0.035 (95%CI: -0.055, -0.015), -0.095 (95%CI: -0.126, -0.064), and -0.124 (95%CI: -0.159, -0.088) decrease in EFW Z-score, respectively. Prenatal exposure to PM_2.5, OC, EC, SO₄^2-, NH₄⁺, or NO₃^- was also associated with higher risk of fetal AC, HC, FL or EFW undergrowth.

CONCLUSION

The study identified that prenatal exposure to PM_2.5 or its constituents was associated with impaired fetal growth. The findings provided evidence that control measures for PM_2.5 constituents should be implemented for further promoting fetal growth.

Ambient air pollution during pregnancy and DNA methylation in umbilical cord blood, with potential mediation of associations with infant adiposity: The Healthy Start study

BACKGROUND

Prenatal exposure to ambient air pollution has been associated with adverse offspring health outcomes. Childhood health effects of prenatal exposures may be mediated through changes to DNA methylation detectable at birth.

METHODS

Among 429 non-smoking women in a cohort study of mother-infant pairs in Colorado, USA, we estimated associations between prenatal exposure to ambient fine particulate matter (PM2.5) and ozone (O3), and epigenome-wide DNA methylation of umbilical cord blood cells at delivery (2010-2014). We calculated average PM2.5 and O3 in each trimester of pregnancy and the full pregnancy using inverse-distance-weighted interpolation. We fit linear regression models adjusted for potential confounders and cell proportions to estimate associations between air pollutants and methylation at each of 432,943 CpGs. Differentially methylated regions (DMRs) were identified using comb-p. Previously in this cohort, we reported positive associations between 3rd trimester O3 exposure and infant adiposity at 5 months of age. Here, we quantified the potential for mediation of that association by changes in DNA methylation in cord blood.

RESULTS

We identified several DMRs for each pollutant and period of pregnancy. The greatest number of significant DMRs were associated with third trimester PM2.5 (21 DMRs). No single CpGs were associated with air pollutants at a false discovery rate <0.05. We found that up to 8% of the effect of 3rd trimester O3 on 5-month adiposity may be mediated by locus-specific methylation changes, but mediation estimates were not statistically significant.

CONCLUSIONS

Differentially methylated regions in cord blood were identified in association with maternal exposure to PM2.5 and O3. Genes annotated to the significant sites played roles in cardiometabolic disease, immune function and inflammation, and neurologic disorders. We found limited evidence of mediation by DNA methylation of associations between third trimester O3 exposure and 5-month infant adiposity.

Maternal short-term exposure to NO2 during pregnancy and its relationship with Doppler markers of placental function

BACKGROUND

Maternal exposure to air pollution has been associated with poor obstetric outcomes. However, the available evidence on the impact of maternal exposure to air pollution on placental function is still scarce and is based on estimated ambient levels of air pollutants.

OBJECTIVE

To evaluate the association between short-term maternal exposure to NO₂ based on the objective personal measure of NO₂ exposure and Doppler markers of placental function.

METHODS

This study was based on a prospective cohort of 101 pregnant women, recruited at Hospital Sant Joan de Déu, Barcelona (Spain), between January 2017 and April 2018. NO₂ diffusion tubes were worn by pregnant women to measure personal exposure to NO₂ between weeks 28 and 32 of their pregnancy. Placental function was evaluated at the 32nd week of gestation by Doppler evaluation of mean uterine arteries pulsatility index (PI), umbilical artery PI, middle cerebral artery PI, cerebroplacental ratio (CPR) and ductus venosus PI. Linear regression models were applied to estimate the association of personal NO₂ exposure and Doppler markers of placental function (one at a time), controlled for relevant covariates.

RESULTS

Higher personal exposure to NO₂ was significantly associated with lower mean uterine artery PI. Each one-interquartile range (IQR) increase in the exposure to NO ₂ was associated with -0.07 (95% confidence intervals (CIs): -0.12, -0.02) decrease in uterine arteries PI. We also observed some suggestions for an inverse association between this exposure and CPR. A one-IQR increase in NO₂ was associated with -0.18 (95% CIs: -0.37, 0.01) decrease in CPR. The findings for the rest of Doppler markers were not conclusive.

CONCLUSIONS

Maternal exposure to NO₂ could interfere with Doppler markers of placental function, potentially indicating a certain degree of cerebral vasodilatation with a decrease of mean uterine arteries PI.

Associations between seasonal ambient air pollution and adverse perinatal outcomes: a retrospective cohort study in Wenzhou, China

Prenatal exposure to ambient air pollution has been associated with adverse perinatal outcomes in previous studies. However, few studies have examined the interaction between air pollution and the season of conception on term low birth weight (TLBW) or macrosomia. Birth registry data of singleton live births in Wenzhou, China, between January 2015 and December 2016 were accessed from the Wenzhou Maternal and Child Health Information Management platform, and data on the ambient air pollutants in Wenzhou were obtained from the Chinese Air Quality Online Monitoring and Analysis Platform. Single-/two-pollutant binary logistic regression models were used to assess the associations between ambient air pollutants (PM_2.5, PM₁₀, NO₂, SO₂, and O₃) and TLBW/macrosomia, further exploring whether the season of conception interacts with air pollution to impact birth weight. Finally, 213,959 term newborns were selected, including 2452 (1.1%) infants with TLBW and 13,173 (6.1%) infants with macrosomia. In the single-/two-pollutant models, we observed an increased risk of TLBW associated with maternal exposure to PM_2.5, PM₁₀, SO₂, and NO₂ during the entire pregnancy, especially in the 2nd trimester. Maternal exposure to O₃ during the 1st trimester was associated with increased macrosomia risk, and O₃ exposure during the 3rd trimester was associated with increased TLBW risk. Pregnant women who conceive in the warm season may experience a more adverse ambient air environment that is related to the risks of TLBW. These findings add to the evidence suggesting that air pollution and the season of conception may have synergistic effects on adverse perinatal outcomes, especially TLBW. Further prospective cohort studies are needed to validate our results.

Prenatal exposure to ambient air pollution and adverse birth outcomes: An umbrella review of 36 systematic reviews and meta-analyses

Multiple systematic reviews and meta-analyses linked prenatal exposure to ambient air pollutants to adverse birth outcomes with mixed findings, including results indicating positive, negative, and null associations across the pregnancy periods. The objective of this study was to systematically summarise systematic reviews and meta-analyses on air pollutants and birth outcomes to assess the overall epidemiological evidence. Systematic reviews with/without meta-analyses on the association between air pollutants (NO₂, CO, O₃, SO₂, PM_2.5, and PM₁₀) and birth outcomes (preterm birth; stillbirth; spontaneous abortion; birth weight; low birth weight, LBW; small-for-gestational-age) up to March 30, 2022 were included. We searched PubMed, CINAHL, Scopus, Medline, Embase, and the Web of Science Core Collection, systematic reviews repositories, grey literature databases, internet search engines, and references of included studies. The consistency in the directions of the effect estimates was classified as more consistent positive or negative, less consistent positive or negative, unclear, and consistently null. Next, the confidence in the direction was rated as either convincing, probable, limited-suggestive, or limited non-conclusive evidence. Final synthesis included 36 systematic reviews (21 with and 15 without meta-analyses) that contained 295 distinct primary studies. PM_2.5 showed more consistent positive associations than other pollutants. The positive exposure-outcome associations based on the entire pregnancy period were more consistent than trimester-specific exposure averages. For whole pregnancy exposure, a more consistent positive association was found for PM_2.5 and birth weight reductions, particulate matter and spontaneous abortion, and SO₂ and LBW. Other exposure-outcome associations mostly showed less consistent positive associations and few unclear directions of associations. Almost all associations showed probable evidence. The available evidence indicates plausible causal effects of criteria air pollutants on birth outcomes. To strengthen the evidence, more high-quality studies are required, particularly from understudied settings, such as low-and-middle-income countries. However, the current evidence may warrant the adoption of the precautionary principle.

Ambient fine particulate matter exposure disrupts placental autophagy and fetal development in gestational mice

Recent studies have shown that some adverse pregnancy outcomes, especially intrauterine growth restriction (IUGR), are associated with gestational exposure to ambient fine particulate matter (PM_2.5). However, potential mechanism remains to be elucidated. In the present study, pregnant C57BL/6 mice were randomly assigned to be exposed to either filtered air or ambient PM_2.5 in the gestation period via a concentrated whole-body exposure system. We found that gestational PM_2.5 exposure exerted no effect on implantation, preterm delivery, as well as fetal resorption and death. However, in utero fetal exposure to PM_2.5 showed a significant reduction in body weight and crown-rump length on GD13 and GD18. Meanwhile, maternal blood sinusoid in placenta was markedly reduced along with abnormal expression of placental nutrient transporters and growth hormone in dams exposed to PM_2.5. Additional tests showed gestational PM_2.5 exposure decreased autophagy-related protein levels and inhibited autophagy flux mainly on GD15. Correspondingly, AMPK/mTOR signaling pathway, a critical negative regulator of autophagy, was activated in placenta on GD15 by PM_2.5 exposure as well. These findings provide evidences that placental developmental disorder caused by autophagy inhibition might be an important mechanism for the growth restriction caused by PM_2.5 exposure.

Portable HEPA Filter Air Cleaner Use during Pregnancy and Children's Cognitive Performance at Four Years of Age: The UGAAR Randomized Controlled Trial

BACKGROUND

Developmental exposure to air pollution is associated with diminished cognitive abilities in observational studies, but no randomized controlled trial has examined the effect of reducing air pollution on cognition in children.

OBJECTIVES

We sought to quantify the impact of reducing exposure to particulate matter (PM) during pregnancy on children's cognitive performance at 4 y of age.

METHODS

In this single-blind, parallel-group, randomized controlled trial in Ulaanbaatar, Mongolia, we randomly assigned 540 nonsmoking pregnant women (268 intervention and 272 control) to receive 1-2 portable high-efficiency particulate air (HEPA) filter air cleaners or no air cleaners. The air cleaners were used from a median of 11 wk gestation until the end of pregnancy. The primary outcome was full-scale intelligence quotient (FSIQ) assessed using the Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition (WPPSI-IV) when children were a median of 48 months old. We imputed missing outcome data using multiple imputation with chained equations, and our primary analysis was by intention to treat.

RESULTS

After excluding known miscarriages, stillbirths, neonatal deaths, and medical conditions that impeded cognitive testing and imputation, 475 (233 control and 242 intervention) children were included in our analyses. In an unadjusted analysis, the mean FSIQ of children who were randomly assigned to the intervention group was 2.5 points [95% confidence interval (CI): -0.4, 5.4 points] higher than that of children in the control group. After adjustment to account for an imbalance in preterm birth between groups, the effect estimate increased to 2.8 points (95% CI: -0.1, 5.7).

CONCLUSIONS

Reducing PM air pollution during pregnancy may improve cognitive performance in childhood. https://doi.org/10.1289/EHP10302.

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.

PM2.5-Related Neonatal Infections: A Global Burden Study from 1990 to 2019

Background: Long-term exposure to fine particulate matter (PM2.5) may increase the risk of neonatal infections. To show the effects of PM2.5 on neonatal infections as well as the trends of the effect, we studied the burden measured by the age-standardized mortality rate (ASMR) and the age-standardized disability-adjusted life years rate (ASDR) and its trends with the socio-demographic index in 192 countries and regions from 1990 to 2019. Methods: This is a retrospective study that uses the Global Burden of Disease Study 2019 database. The age-standardized mortality rate and age-standardized disability-adjusted life years rate are used to measure the burden of PM2.5-related neonatal infections in different countries and regions. The annual percentage changes and the average annual percentage changes are used to reflect the trends over the years (1990–2019) and are calculated using a Joinpoint model. The relationship of the socio-demographic index with the ASMR and ASDR is calculated and described using Gaussian process regression. Results: With the rapid increase in the global annual average of PM2.5, the global burden of PM2.5-related neonatal infections has increased since 1990, especially in early neonates, boys, and low-middle SDI regions. Globally, the ASMR and ASDR of PM2.5-related neonatal infections in 2019 were 0.21 (95% CI: 0.14, 0.31) and 19.06 (95% CI: 12.58, 27.52) per 100,000 people, respectively. From 1990 to 2019, the ASMR and ASDR increased by 72.58% and 73.30%, and their average annual percentage changes were 1.9 (95% CI: 1.3, 2.6) and 2.0 (95% CI: 1.3, 2.6), respectively. When the socio-demographic index was more than 0.60, it was negatively related to the burden of PM2.5-related neonatal infections. Surprisingly, the burden in low SDI regions was lower than it was in low-middle and middle SDI regions, while high-middle and high-SDI regions showed decreasing trends. Interpretation: Boys bore a higher PM2.5-related neonatal burden, with male fetuses being more likely to be affected by prenatal exposure to PM2.5 and having less of a biological survival advantage. Poverty was the root cause of the burden. Higher SDI countries devoted more resources to improving air quality, the coverage of medical services, the accessibility of institutional delivery, and timely referral to reduce the disease burden. The burden in low SDI regions was lower than that in low-middle and middle SDI regions. One reason was that the benefits of medical services were lower than the harm to health caused by environmental pollution in low-middle and middle SDI regions. Moreover, the underreporting of data is more serious in low SDI countries. Conclusions: In the past 30 years, the global burden of PM2.5-related neonatal infections has increased, especially in early neonates, boys, and low-middle SDI regions. The huge difference compared to higher SDI countries means that lower SDI countries have a long way to go to reduce the disease burden. Policy makers should appropriately allocate medical resources to boys and early newborns and pay more attention to data under-reporting in low SDI countries. In addition, it is very necessary to promulgate policies to prevent and control air pollution in countries with large and increasing exposure to PM2.5 pollution.

Association of exposure to fine particulate matter wave over the preconception and pregnancy periods with adverse birth outcomes: Results from the project ELEFANT

BACKGROUND

No study has explored the effects of sustained maternal exposure to high-level ambient fine particulate matter (PM_2.5) within a short period, i.e., PM_2.5 wave, on adverse birth outcomes, though increasing epidemiological studies demonstrated that exposure to single days of high ambient PM_2.5 could increase risks of adverse birth outcomes. In this study, we aim to evaluate associations of maternal PM_2.5 wave exposure around pregnancy with preterm birth (PTB), small for gestational age (SGA), and large for gestational age (LGA).

METHODS

Totally 10,916 singleton pregnant women from all 16 districts in Tianjin, China, and their followed-up birth outcomes were included in this study. We defined PM_2.5 wave as at least 2 consecutive days with daily average PM_2.5 concentration exceeding 75 μg/m³, and 90th, 92.5th, 95th, 97.5th, 99th percentiles of PM_2.5 distribution during the study period in Tianjin, respectively. Cox proportional hazard model was applied to evaluate the durational effects of PM_2.5 wave during each exposure window on PTB, SGA, and LGA after adjusting for potential confounders.

RESULTS

Exposure to PM_2.5 wave over the preconception and pregnancy periods was associated with increased risks of adverse birth outcomes. For PTB, the strongest association was found during the first trimester when PM_2.5 wave was defined as at least 4 consecutive days with daily average PM_2.5 concentration >90th (HR, 10.46; 95% CI, 6.23-17.54); and for SGA (HR, 6.23; 95% CI, 3.34-11.64) and LGA (HR, 4.70; 95% CI, 3.35-6.59), the strongest associations both were found when PM_2.5 wave was defined as at least 2 consecutive days with daily average PM_2.5 concentration >99th. Additionally, the risks of adverse birth outcomes generally increased at higher PM_2.5 thresholds or longer durations of PM_2.5 wave.

CONCLUSION

Prolonged exposure to high-level PM_2.5 over preconception and pregnancy periods was associated with increasing risks of PTB, SGA and LGA.

Impact of airborne total suspended particles (TSP) and fine particulate matter (PM2.5 )-induced developmental toxicity in zebrafish (Danio rerio) embryos

Airborne total suspended particles (TSP) and particulate matter (PM_2.5 ) threaten global health and their potential impact on cardiovascular and respiratory diseases are extensively studied. Recent studies attest premature deaths, low birth weight, and congenital anomalies in the fetus of pregnant women exposed to air pollution. In this regard, only few studies have explored the effects of TSP and PM_2.5 on cardiovascular and cerebrovascular development. As both TSP and PM_2.5 differ in size and composition, this study is attempted to assess the variability in toxicity effects between TSP and PM_2.5 on the development of cardiovascular and cerebrovascular systems and the underlying mechanisms in a zebrafish model. To explore the potential toxic effects of TSP and PM_2.5 , zebrafish embryos/larvae were exposed to 25, 50, 100, 200, and 400 μg/ml of TSP and PM_2.5 from 24 to 120 hpf (hours post-fertilization). Both TSP and PM_2.5 exposure increased the rate of mortality, malformations, and oxidative stress, whereas locomotor behavior, heart rate, blood flow velocity, development of cardiovasculature and neurovasculature, and dopaminergic neurons were reduced. The expression of genes involved in endoplasmic reticulum stress (ERS), Wnt signaling, and central nervous system (CNS) development were altered in a dose- and time-dependent manner. This study provides evidence for acute exposure to TSP and PM_2.5 -induced cardiovascular and neurodevelopmental toxicity, attributed to enhanced oxidative stress and aberrant gene expression. Comparatively, the effects of PM_2.5 were more pronounced than TSP.

Associations of perinatal exposure to PM2.5 with gestational weight gain and offspring birth weight

BACKGROUND

PM_2.5 have been associated with weight change in animal models and non-pregnant populations. Evidence of associations between PM_2.5 and gestational weight gain (GWG), an important determinant of course and outcomes of pregnancy, and subsequent birth outcomes is limited.

METHODS

The study was conducted among a subset of participants from the Omega Study, a prospective pregnancy cohort. Exposure to PM_2.5 (μg/m³) was ascertained for participants (N = 855) based on their residential address using a validated national spatiotemporal model. Adjusted multivariable linear regression models were used to estimate associations of trimester-specific and pregnancy-month PM_2.5 exposures with early (<20 weeks gestation), late (≥20 weeks gestation), and total GWG and infant birth weight. Stratified models and product terms were used to examine whether pre-pregnancy BMI (ppBMI) and infant sex modified the associations.

RESULTS

Average monthly PM_2.5 exposure during the first, second, and third trimesters were 7.3 μg/m³, 7.9 μg/m³, and 7.7 μg/m³, respectively. Higher third trimester PM_2.5 exposure was associated with higher late (0.40 kg per 5 μg/m (McDowell et al., 2018); 95%CI: 0.12, 0.67) and total (0.35 kg; 95%CI: 0.01, 0.70) GWG among participants with normal ppBMI. Higher second month PM_2.5 exposure was associated with lower early (-0.70 kg; 95%CI: 1.22, -0.18), late (-0.84 kg; 95% CI: 1.54, -0.14), and total (-1.70 kg; 95%CI: 2.57, -0.82) GWG among participants with overweight/obese ppBMI. Product terms between PM_2.5 and ppBMI were significant for second month PM_2.5 exposure and early (p-value = 0.01) and total GWG (p-value<0.01). Higher third trimester PM_2.5 exposure was associated with higher birth weight, though higher fourth month PM_2.5 exposure was associated with lower birth weight, particularly among those with normal ppBMI and male infants.

CONCLUSIONS

Associations of PM_2.5 with GWG vary by exposure window and ppBMI, while associations of PM_2.5 with birth weight potentially vary by exposure window, ppBMI and infant sex. Further exploration of associations between PM_2.5 and maternal/child health outcomes are needed.

Neighborhood environmental exposures and incidence of attention deficit/hyperactivity disorder: A population-based cohort study

BACKGROUND

Emerging studies have associated low greenspace and high air pollution exposure with risk of child attention deficit/hyperactivity disorder (ADHD). Population-based studies are limited, however, and joint effects are rarely evaluated. We investigated associations of ADHD incidence with greenspace, air pollution, and noise in a population-based birth cohort.

METHODS

We assembled a cohort from administrative data of births from 2000 to 2001 (N ∼ 37,000) in Metro Vancouver, Canada. ADHD was identified by hospital records, physician visits, and prescriptions. Cox proportional hazards models were applied to assess associations between environmental exposures and ADHD incidence adjusting for available covariates. Greenspace was estimated using vegetation percentage derived from linear spectral unmixing of Landsat imagery. Fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) were estimated using land use regression models; noise was estimated using a deterministic model. Exposure period was from birth until the age of three. Joint effects of greenspace and PM_2.5 were analysed in two-exposure models and by categorizing values into quintiles.

RESULTS

During seven-year follow-up, 1217 ADHD cases were diagnosed. Greenspace was associated with lower incidence of ADHD (hazard ratio, HR: 0.90 [0.81-0.99] per interquartile range increment), while PM_2.5 was associated with increased incidence (HR: 1.11 [1.06-1.17] per interquartile range increment). NO₂ (HR: 1.01 [0.96, 1.07]) and noise (HR: 1.00 [0.95, 1.05]) were not associated with ADHD. There was a 50% decrease in the HR for ADHD in locations with the lowest PM_2.5 and highest greenspace exposure, compared to a 62% increase in HR in locations with the highest PM_2.5 and lowest greenspace exposure. Effects of PM_2.5 were attenuated by greenspace in two-exposure models.

CONCLUSIONS

We found evidence suggesting environmental inequalities where children living in greener neighborhoods with low air pollution had substantially lower risk of ADHD compared to those with higher air pollution and lower greenspace exposure.

Association between Maternal Exposure to Ambient Air Pollution and the Risk of Preterm Birth: A Birth Cohort Study in Chongqing, China, 2015-2020

Recent study results on the association between maternal exposure to ambient air pollution with preterm birth have been inconsistent. The sensitive window of exposure and influence level of air pollutants varied greatly. We aimed to explore the association between maternal exposure to ambient air pollutants and the risk of preterm birth, and to estimate the sensitive exposure time window. A total of 572,116 mother–newborn pairs, daily concentrations of air pollutants from nearest monitoring stations were used to estimate exposures for each participant during 2015–2020 in Chongqing, China. We applied a generalized additive model and estimated RRs and 95% CIs for preterm birth in each trimester and the entire pregnancy period. In the single-pollutant model, we observed that each 10 μg/m³ increase in PM_2.5 had a statistically significant effect on the third trimester and entire pregnancy, with RR = 1.036 (95% CI: 1.021, 1.051) and RR = 1.101 (95% CI: 1.075, 1.128), respectively. Similarly, for each 10 μg/m³ increase in PM₁₀, there were 2.7% (RR = 1.027, 95% CI: 1.016, 1.038) increase for PTB on the third trimester, and 3.8% (RR = 1.038, 95% CI: 1.020, 1.057) increase during the whole pregnancy. We found that for each 10 mg/m³ CO increases, the relative risk of PTB increased on the first trimester (RR = 1.081, 95% CI: 1.007, 1.162), second trimester (RR = 1.116, 95% CI: 1.035, 1.204), third trimester (RR = 1.167, 95% CI: 1.090, 1.250) and whole pregnancy (RR = 1.098, 95% CI: 1.011, 1.192). No statistically significant RR was found for SO₂ and NO₂ on each trimester of pregnancy. Our study indicates that maternal exposure to high levels of PM_2.5 and PM₁₀ during pregnancy may increase the risk for preterm birth, especially for women at the late stage of pregnancy. Statistically increased risks of preterm birth were associated with CO exposure during each trimester and entire pregnancy. Reducing exposure to ambient air pollutants for pregnant women is clearly necessary to improve the health of infants.

Length of PM2.5 exposure and alterations in the serum metabolome among women undergoing infertility treatment

Background:

Both acute and chronic exposure to fine particulate matter (PM_2.5) have been linked to negative health outcomes. Studies have used metabolomics to describe the biological pathways linking PM_2.5 with disease but have focused on a single exposure window. We compared alterations in the serum metabolome following various short- and long-term PM_2.5 exposures.

Methods:

Participants were women undergoing in vitro fertilization at a New England fertility clinic (n = 200). Women provided their residential address and provided a blood sample during controlled ovarian stimulation. PM_2.5 exposure was estimated in the 1, 2, and 3 days, 2 weeks, and 3 months prior to blood collection using a validated spatiotemporal model. We utilized liquid chromatography with high-resolution mass spectrometry. We used generalized linear models to test for associations between metabolomic features and PM_2.5 exposures after adjusting for potential confounders. Significant features (P < 0.005) were used for pathway analysis and metabolite identification.

Results:

We identified 17 pathways related to amino acid, lipid, energy, and nutrient metabolism that were solely associated with acute PM_2.5 exposure. Fifteen pathways, mostly, pro-inflammatory, anti-inflammatory, amino acid, and energy metabolism, were solely associated with long-term PM_2.5 exposure. Seven pathways were associated with the majority of exposure windows and were mostly related to anti-inflammatory and lipid metabolism. Among the significant features, we confirmed seven metabolites with level-1 evidence.

Conclusions:

We identified serum metabolites and metabolic pathways uniquely associated with acute versus chronic PM_2.5 exposure. These different biologic pathways may help explain differences in disease states when investigating different lengths of PM_2.5 exposure.

Interaction of PM2.5 and pre-pregnancy body mass index on birth weight: A nationwide prospective cohort study

BACKGROUND

Fine particulate matter (PM_2.5), one of the most common air pollutants worldwide, has been associated with many adverse birth outcomes in some studies. Pre-pregnancy body mass index (BMI) is an important indicator of maternal obesity that may also contribute to a wide range of birthweight outcomes. Both PM_2.5 and maternal obesity have been found associated with issues on neonatal birthweight respectively, and more attentions and interests are focusing on their combined effect on pregnancy outcomes.

PURPOSE

To explore the modifying effect of pre-pregnancy BMI on the association between gestational PM_2.5 and birthweight; to investigate the interactive effect between gestational PM_2.5 and pre-pregnancy BMI on birthweight among pregnant women during three trimesters and the whole pregnancy.

METHODS

This nationwide cohort study used the National Free Preconception Health Examination Project (NFPHEP) data collected from January 1, 2010, to December 31, 2012. A total population of 248,501 Chinese women from 220 counties registered this project. Pre-pregnancy BMI as a common anthropometric examination was collected during preconception investigation, and gestational PM_2.5 was derived from a hindcast model for historical PM_2.5 estimation from satellite-retrieved aerosol optic depth. Subgroup analysis was conducted to explore a potential modifying effect on the association between PM_2.5 and birthweight during pregnancy by four pre-pregnancy BMI subgroups. Interaction analysis by introducing product terms to multivariable linear regression was also used to examine whether there was an interactive relationship between PM_2.5 and pre-pregnancy BMI.

RESULTS

Totally, 193,461 participants were included in our study. The average concentration of PM_2.5 was 75.33 μg/m³. Higher exposure of PM_2.5 during the entire pregnancy was associated with higher birthweight (17.15 g per 10 μg/m3; 95% CI:16.15, 18.17). Each 10 μg/m³ increase in PM_2.5 during the first, second, and third trimesters was associated with increases in birthweight by 14.93 g (95%CI: 13.96, 15.89), 13.75 g (95% CI: 12.81, 14.69), and 8.79 g (95% CI: 8.09, 9.49), respectively. Higher pre-pregnancy BMI per kg/m² was associated with an increase of birthweight by 7.012 g (95% CI: 6.121, 7.902). Product terms between PM_2.5 and pre-pregnancy BMI were significant for the first, second trimesters, and the entire duration of pregnancy.

CONCLUSIONS

Our results found both gestational PM_2.5 exposure and pre-pregnancy BMI respectively correlated with the increase of birthweight. A negative interaction between pre-pregnancy BMI and gestational PM_2.5 was discovered in term of birthweight gain. Avoidance of high-dose exposure to PM_2.5 during the early and middle stages of pregnancy and pre-pregnancy overweight/obesity may help prevent high birthweight.

The correlation between chronic exposure to particulate matter and spontaneous abortion: A meta-analysis

BACKGROUND

Spontaneous abortion (SAB) brings serious physical and psychological sequelae to women and their families. Though a growing body of individual studies have suggested the possible linkage between chronic particulate matter (PM) exposure and risks of SAB, the provided results were rather contradictory. We therefore performed an evidence-based meta-analysis.

METHODS

We systematically searched the PubMed, EMBASE and Web of Science databases for available studies published before February 1, 2021 which reported associations between PM exposure and SAB. Corresponding models were applied to combine relative risks (RRs) and their confidence intervals (CIs) from eligible studies according to heterogeneity test. The GRADEpro app was used to evaluate the certainty of evidence. Sensitivity analyses and a publication bias assessment were also utilized to determine the stability of results.

RESULTS

Of the initial 2358 citations, 6 papers examining the chronic effects of PM exposure were deemed eligible and a total population of approximately 723,000 was observed. Pooled RR for SAB risks associated with a 10 μg/m³ increase in fine particulate matter (PM_2.5) and particulate matter ≤ 10 μm in aerodynamic diameter (PM₁₀) were 1.20 (95%CI: 1.01-1.40) and 1.09 (95%CI: 1.02-1.15), respectively. The GRADE results of PM_2.5 and PM₁₀ were both categorized as "moderate" certainty evidence.

CONCLUSION

Our findings revealed a significant increase of SAB hazards related with maternal PM exposure, and this study may therefore provide new evidence for personal protection to improve reproductive health.

Maternal Secondhand Smoke Exposure Enhances Macrosomia Risk Among Pregnant Women Exposed to PM2.5: A New Interaction of Two Air Pollutants in a Nationwide Cohort

Background: Fine particulate matter (PM_2.5) is one of the most common outdoor air pollutants, and secondhand smoking (SHS) is an important source of inhalable indoor air pollution. Previous studies were controversial and inconsistent about PM_2.5 and SHS air pollutants on neonatal birth weight outcomes, and no studies assessed the potential interactive effects between PM_2.5 and SHS on birth weight outcomes. Purpose: To investigate the interaction between gestational PM_2.5 and SHS air pollution exposure on the risk of macrosomia among pregnant women and examine the modifying effect of SHS exposure on the association of PM_2.5 air pollution and birth weight outcomes during pregnancy. Methods: Research data were derived from the National Free Preconception Health Examination Project (NFPHEP), which lasted 3 years from January 1, 2010, to December 31, 2012. At least 240,000 Chinese women from 220 counties were enrolled in this project. PM_2.5 exposure concentration was obtained using a hindcast model specific for historical PM_2.5 estimation from satellite-retrieved aerosol optic depth. Different interaction models about air pollution exposure on birth weight outcomes were established, according to the adjustment of different confounding factors and different pregnancy stages. The establishment of interaction models was based on multivariable logistic regression, and the main confounding factors were maternal age at delivery and pre-pregnancy body mass index (BMI) of participants. SHS subgroups analysis was conducted to further confirm the results of interaction models. Results: In total, 197,877 participants were included in our study. In the full-adjusted interaction model, maternal exposure to PM_2.5 was associated with an increased risk of macrosomia in whole, the first-, second-, and third trimesters of pregnancy (p < 0.001). The interactive effect was statistically significant between maternal exposure to PM_2.5 and SHS on the risk of macrosomia in the whole (interaction p < 0.050) and the first-trimester pregnancy (interaction p < 0.050), not in the second (interaction p > 0.050) or third trimester (interaction p > 0.050) of pregnancy. The higher frequency of SHS exposure prompted the stronger interaction between the two air pollutants in the whole pregnancy and the first-trimester pregnancy. Conclusions: In the whole and first-trimester pregnancy, maternal exposure to SHS during pregnancy enhanced the risk of macrosomia among pregnant women exposed to PM_2.5 air pollutants, and the interaction became stronger with the higher frequency of SHS exposure.

Maternal air pollution exposure increases the risk of preterm birth: Evidence from the meta-analysis of cohort studies

Preterm birth (PTB), a major public health impact, has been shown to be associated with prenatal air pollution exposure, but the results are still inconsistent. This meta-analysis was performed to quantitatively evaluate the correlation between maternal air pollutant exposure and PTB, and provide evidence of higher grade to help improving the pregnancy outcomes. Databases including Web of Science and PubMed were searched to retrieve eligible studies published up to October 2020. The quality of the articles was assessed by the Newcastle-Ottawa Quality Score (NOS), after which the pooled estimate of the effect was calculated. The robustness of the joint estimates was confirmed by sensitivity analysis of excluded studies one by one, and the sources of heterogeneity were discussed by stratification analysis. Egger's and Begg's tests were performed to examine publication bias. Sixty studies that met the eligible criteria were finally included in this study. The findings showed combined relative risks of 1.032-1.070 for PTB, 0.859-1.081 for moderate PTB, 1.119-1.194 for very PTB and 1.128-1.259 for extremely PTB when mothers were exposed to PM_2.5, PM₁₀, NO₂, O₃, SO₂, CO and NO_x during pregnancy, while the sensitive windows varied for different air pollutants. Notably, PM_2.5 exposure in only the 2nd trimester, NO₂ exposure in only the 3rd trimester, and O₃ exposure in all three trimesters were positively associated with PTB, while NO₂ exposure in the 1st trimester was negatively associated with PTB. In addition, exposure of PM_2.5 and PM₁₀ in the 2nd trimester was positively associated with moderate PTB, and in the 1st and 2nd trimesters were positively associated with very PTB. These findings demonstrated that PM_2.5, PM₁₀, O₃, NO₂ were associated with PTB (including moderate PTB, very PTB, and/or extremely PTB), while NO_x was not, and the relationship between CO and SO₂ and PTB was not stable.

Portable HEPA filter air cleaner use during pregnancy and children's body mass index at two years of age: The UGAAR randomized controlled trial

IMPORTANCE

Gestational exposure to particulate matter (PM) air pollution may increase the risk of childhood obesity, but the impact of reducing air pollution during pregnancy on obesity-related outcomes in childhood has not been examined.

OBJECTIVE

To assess the impact of reducing gestational PM exposure on body mass index (BMI) at two years of age.

METHODS

In this single-blind, parallel group randomized controlled trial in Ulaanbaatar Mongolia, we randomly assigned 540 pregnant women to receive 1-2 portable high efficiency particulate air (HEPA) filter air cleaners or no air cleaners. We measured height and weight when children were a mean age of 23.8 months. Our primary outcome was age- and sex-specific BMI z-score based on the World Health Organization 2007 Growth Charts. Secondary outcomes included age- and sex-specific weight z score, overweight/obesity (defined as BMI z-score > 2.00), and catch-up growth (defined using various cut-offs to identify children with relatively low birth weight for sex and gestational age and relatively high age- and sex-specific weight in childhood). We imputed missing outcome data using multiple imputation with chained equations and our primary analysis was by intention to treat (ITT). We estimated intervention effects on continuous and binary outcomes using linear and logistic regression, respectively.

RESULTS

After excluding known miscarriages, still births, and neonatal deaths our analysis included 480 children (235 control and 245 intervention). The mean (SD) child BMI z score was 0.79 (1.0); 9.8% of children were overweight or obese. The mean BMI z score of children who were randomly assigned to the intervention group was 0.16-units lower (95% CI: -0.35, 0.04) than children in the control group. The intervention was also associated with reductions in overweight/obesity (odds ratio = 0.59; 95% CI: 0.31, 1.12). Catch-up growth occurred less frequently in the intervention group, but effect estimates varied depending on the specific definition of catch-up growth and confidence intervals consistently spanned no effect.

CONCLUSIONS

We found that the use of portable air cleaners during pregnancy was associated with improvements in obesity-related outcomes, although some effect estimates lacked precision. Reducing PM exposure during pregnancy may lead to improvements in cardiometabolic health in childhood.

Ambient fine particulate matter air pollution and the risk of preterm birth: A multicenter birth cohort study in China

Preterm birth (PTB), defined as live birth before the 37th week of gestation, is believed to have profound impacts on the infant's health in later life. Air pollution has been suggested to be a potential risk factor of PTB, but the evidence was inconsistent. In this multicenter birth cohort study, we aimed to examine the association between fine particulate matter (PM_2.5) exposure during pregnancy and PTB in China. A total of 5976 live births were identified between Jan. 2009 and Feb. 2011 from 8 provinces in China. Residential exposures to PM_2.5 were assigned based on satellite remote sensing estimates. Cox proportional hazards regressions were employed to explore the correlation for each trimester as well as the entire pregnancy. A total of 443 (7.4%) preterm births were observed. The average PM_2.5 during pregnancy was 57.2 ± 8.8 μg/m³. We found exposure to PM_2.5 during the whole pregnancy (hazard ratio, HR = 1.262; 95% CI: 1.087-1.465) and in the first trimester (HR = 1.114; 95% CI: 1.007-1.232) was associated with higher risk of PTB. The associations of PM_2.5 were stronger for subjects with older maternal or paternal age, lower maternal pre-pregnancy BMI, and lower family income. This study adds supports to the cumulating evidence linking PM_2.5 exposure and elevated PTB risk. Measures of air pollution reduction are needed during pregnancy, especially at early stage of pregnancy to prevent adverse birth outcomes.

Mid-pregnancy PM2.5 exposure affects sex-specific growth trajectories via ARRDC3 methylation

Prenatal particulate matter <2.5 μm (PM_2.5) is associated with adverse birth growth. However, the longitudinal growth impacts have been little studied, and no mechanistic relationships have been described. We investigated the association between prenatal PM_2.5 exposure and growth trajectories, and the possible role of epigenetics. We enrolled 1313 neonates with PM_2.5 data measured by ordinary kriging from the COhort for Childhood Origin of Asthma and allergic diseases, followed up at 1, 3, and 5 years to evaluate growth. Differential DNA methylation and pyrosequencing of cord blood leukocytes was evaluated according to the prenatal PM_2.5 levels and birth weight (BW). PM_2.5 exposure during the second trimester (T2) caused the lowest BW in both sexes, further adjusted for indoor PM_2.5 levels [female, aOR 1.39 (95% CI 1.05-1.83); male, aOR 1.36 (95% CI 1.04-1.79)]. Bayesian distributed lag models with indoor PM_2.5 adjustments revealed a sensitive window for BW effects at 10-26 weeks gestation, but only in females. Latent class mixture models indicated that a persistently low weight-for-height percentile trajectory was more prevalent in the highest PM_2.5 exposure quartile at T2 in females, compared to a persistently high trajectory (36.5% vs. 20.3%, P = 0.022). Also, in the females only, the high PM_2.5 and low BW neonates showed significantly greater ARRDC3 methylation changes. ARRDC3 methylation was also higher only in females with low weight at 5 years of age. Higher fetal PM_2.5 exposure during T2 may cause a decreased growth trajectory, especially in females, mediated by ARRDC3 hyper-methylation-associated energy metabolism.

Weekly-specific ambient fine particular matter exposures before and during pregnancy were associated with risks of small for gestational age and large for gestational age: results from Project ELEFANT

BACKGROUND

Investigations on the potential effects of ambient fine particulate matter (PM2.5) on large for gestational age (LGA) are limited. Furthermore, no study has explored weekly-specific susceptible exposure windows for small for gestational age (SGA) and LGA. This study evaluated the associations of exposure to ambient PM2.5 over the preconception and entire-pregnancy periods with risks of SGA and LGA, as well as explored critical weekly-specific exposure windows.

METHODS

10 916 singleton pregnant women with 24-42 completed gestational weeks from the Project Environmental and LifEstyle FActors iN metabolic health throughout life-course Trajectories between 2014 and 2016 were included in this study. Distributed lag models (DLMs) incorporated in Cox proportional-hazards models were applied to explore the associations of maternal exposure to weekly ambient PM2.5 throughout 12 weeks before pregnancy and pregnancy periods with risks of SGA and LGA after controlling for potential confounders.

RESULTS

For a 10-μg/m3 increase in maternal exposure to PM2.5, positive associations with SGA were observed during the 1st to 9th preconceptional weeks and the 1st to 2nd gestational weeks (P<0.05), with the strongest association in the 5th preconceptional week [hazard ratio (HR), 1.06; 95% confidential interval (CI), 1.03-1.09]. For LGA, positive associations were observed during the 1st to 12th preconceptional weeks and the 1st to 5th gestational weeks (P<0.05), with the strongest association in the 7th preconceptional week (HR, 1.10; 95% CI, 1.08-1.12).

CONCLUSIONS

Exposure to high-level ambient PM2.5 is associated with increased risks of both SGA and LGA, and the most susceptible exposure windows are the preconception and early-pregnancy periods.

High particulate matter burden by cigarillos: A laser spectrometric analysis of second-hand smoke of common brands with and without filter

Although the global tobacco market of cigarillos is substantial, little is known about their particulate matter (PM) emissions. For exposure risk assessment of cigarillos, the PM fractions PM10, PM2.5, and PM1 of eight cigarillo brands (four with filters) and a reference cigarette were measured. For this purpose, second-hand smoke was generated by an automatic smoke pump in a measuring chamber with a volume of 2.88 m³. The mean particle concentrations of the cigarillos ranged from 2783 μg/m³ to 6686 μg/m³ for PM10, from 2767 μg/m³ to 6585 μg/m³ for PM2.5, and from 2441 to 4680 μg/m³ for PM1. Mean concentrations of the reference cigarette for PM10, PM2.5, and PM1 were 4400 μg/m³, 4335 μg/m³, and 3289 μg/m³, respectively. Filter-tipped cigarillos showed between 5% and 38% lower PM10 and PM2.5 levels, respectively, and between 4% and 30% lower PM1 levels. Our findings show generally high PM emissions for all investigated tobacco products. Therefore, the declaration of PM amounts to government authorities should be mandatory for all tobacco products. Policymakers should ensure that corresponding information will be provided in the future.

Exposure to ambient particulate matter and biomass burning during pregnancy: associations with birth weight in Thailand

BACKGROUND

There is a growing evidence that exposure to ambient particulate air pollution during pregnancy is associated with adverse birth outcomes, including reduced birth weight (BW). The objective of this study was to quantify associations between BW and exposure to particulate matter (PM) and biomass burning during pregnancy in Thailand.

METHODS

We collected hourly ambient air pollutant data from ground-based monitors (PM with diameter of <10 µm [PM₁₀], Ozone [O₃], and nitrogen dioxide [NO₂]), biomass burning from satellite remote sensing data, and individual birth weight data during 2015-2018. We performed a semi-ecological analysis to evaluate the association between mean trimester exposure to air pollutants and biomass burning with BW and low-birth weight (LBW) (<2500 g), adjusting for gestation age, sex, previous pregnancies, mother's age, heat index, season, year, gaseous pollutant concentrations, and province. We examined potential effect modification of PM₁₀ and biomass burning exposures by sex.

RESULTS

There were 83,931 eligible births with a mean pregnancy PM₁₀ exposure of 39.7 µg/m³ (standard deviation [SD] = 7.7). The entire pregnancy exposure was associated with reduced BW both for PM₁₀ (-6.81 g per 10 µg/m³ increase in PM₁₀ [95% CI = -12.52 to -1.10]) and biomass burning (-6.34 g per 1 SD increase in fires/km² [95% CI = -11.35 to -1.34]) only after adjustment for NO₂. In contrast with these findings, a reduced odds ratio (OR) of LBW was associated with PM₁₀ exposure only in trimesters one and two, with no relationship across the entire pregnancy period. Associations with biomass burning were limited to increased ORs of LBW with exposure in trimester three, but only for male births.

CONCLUSION

Based on our results, we encourage further investigation of air pollution, biomass burning and BW in Thailand and other low-income and middle-income countries.

Preterm birth and PM2.5 in Puerto Rico: evidence from the PROTECT birth cohort

BACKGROUND

Preterm birth (PTB, birth before 37 weeks of gestation) has been associated with adverse health outcomes across the lifespan. Evidence on the association between PTB and prenatal exposure to air pollutants is inconsistent, and is especially lacking for ethnic/racial minority populations.

METHODS

We obtained data on maternal characteristics and behaviors and PTB and other birth outcomes for women participating in the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) cohort, who lived in municipalities located along the North Coast of Puerto Rico. We assessed pre-natal PM_2.5 exposures for each infant based on the nearest US Environmental Protection Agency monitor. We estimated prenatal phthalate exposures as the geometric mean of urinary measurements obtained during pregnancy. We then examined the association between PM_2.5 and PTB using modified Poisson regression and assessed modification of the association by phthalate exposure levels and sociodemographic factors such as maternal age and infant gender.

RESULTS

Among 1092 singleton births, 9.1% of infants were born preterm and 92.9% of mothers had at least a high school education. Mothers had a mean (standard deviation) age of 26.9 (5.5) years and a median (range) of 2.0 (1.0-8.0) pregnancies. Nearly all women were Hispanic white, black, or mixed race. Median (range) prenatal PM_2.5 concentrations were 6.0 (3.1-19.8) μ g/m³. Median (interquartile range) prenatal phthalate levels were 14.9 (8.9-26.0) and 14.5 (8.4-26.0), respectively, for di-n-butyl phthalate (DBP) and di-isobutyl phthalate (DiBP). An interquartile range increase in PM_2.5 was associated with a 1.2% (95% CI 0.4, 2.1%) higher risk of PTB. There was little difference in PTB risk in strata of infant sex, mother's age, family income, history of adverse birth outcome, parity, and pre-pregnancy body mass index. Pregnancy urinary phthalate metabolite levels did not modify the PM_2.5-PTB association.

CONCLUSION

Among ethnic minority women in Puerto Rico, prenatal PM_2.5 exposure is associated with a small but significant increase in risk of PTB.

A bibliometric and visualized analysis of research progress and frontiers on health effects caused by PM2.5

Fine particulate matter (PM2.5) is one of the major air pollutants. A large number of epidemiological and experimental studies have shown that PM2.5 pollution can cause adverse health consequences, which has attracted more public attention. In order to have a deeper and more structured understanding of the research progress and frontiers on the impact of PM2.5 on health, in this study, we used the bibliometrics software CiteSpace to analyze the relevant literature in this field. The results show that since 2000, the relevant literature has increased steadily, especially in the last 5 years, and the number of publications in China has increased rapidly. The United States has the most publications. The Chinese Academy of Sciences and Professor Joel Schwartz are the most published institution and author, respectively, and many articles have been published in the journal of Environmental Health Perspectives. Over time, studies on the health effects of PM2.5 have gradually deepened. In addition to a more comprehensive study of its harmful effects, the related molecular mechanisms have also been further explored. We believe that countries and regions should strengthen cooperation and jointly solve the harm caused by PM2.5 through the integration of multiple disciplines and fields. In addition, the adverse health consequences and its related mechanisms caused by exposure to ultrafine particle, different chemical components of PM2.5, as well as the intervention of the health effects caused by PM2.5 need to be further studied.

Ambient and household air pollution on early-life determinants of stunting-a systematic review and meta-analysis

Stunting is an important risk factor for early growth and health implications throughout the life course, yet until recently, studies have rarely focused on populations exposed to high levels of particulate matter pollution or on developing countries most vulnerable to stunting and its associated health and developmental impacts. We systematically searched for epidemiologic studies published up to 15 August 2020 that examined the association between ambient and household particulate exposure and postnatal stunting (height-for-age z-score) and prenatal determinants (small for gestational age or SGA, or equivalent) of stunting. We conducted the literature search in PUBMED, MEDLINE, EMBASE, and Web of Science databases in August 2020, using keywords including, but not limited to, "particulate matter," "indoor/household air pollution," and "adverse birth outcomes," to identify relevant articles. Forty-five studies conducted in 29 countries met our inclusion criteria for meta-analysis. We found significant positive associations between SGA and a 10 μg/m³ increase in fine particulate matter (PM_2.5) exposure over the entire pregnancy [OR = 1.08; 95% confidence interval (CI): 1.03-1.13], with similar SGA impact during the second and third trimesters, and from high exposure quartile of PM_2.5 exposure during the entire pregnancy. A 19% increased risk of postnatal stunting (95% CI: 1.10, 1.29) was also associated with postnatal exposure to household air pollution. Our analysis shows consistent, significant, and noteworthy evidence of elevated risk of stunting-related health outcomes with ambient PM_2.5 and household air pollution exposure. This evidence reinforces the importance of promoting clean air as part of an integrated approach to preventing stunting.

Nutraceuticals with anti-inflammatory and anti-oxidant properties as intervention for reducing the health effects of fine particulate matter: Potential and Prospects

Air pollution, especially particulate matter pollution adversely affects human health. A growing pool of evidence has emerged which underscores the potential of individual-level nutritional interventions in attenuating the adverse health impact of exposure to PM2.5. Although controlling emission and reducing the overall levels of air pollution remains the ultimate objective globally, the sustainable achievement of such a target and thus consequent protection of human health will require a substantial amount of time and concerted efforts worldwide. In the meantime, smaller-scale individual-level interventions that can counter the inflammatory or oxidative stress effects triggered by exposure to particulate matter may be utilized to ameliorate the health effects of PM2.5 pollution. One such intervention is incorporation of nutraceuticals in the diet. Here, we present a review of the evidence generated from various in vitro, in vivo and human studies regarding the effects of different anti-inflammatory and antioxidant nutraceuticals in ameliorating the health effects of particulate matter air pollution. The studies discussed in this review suggest that these nutraceuticals when consumed as a part of the diet, or as additional supplementation, can potentially negate the cellular level adverse effects of exposure to particulate pollution. The potential benefits of adopting a non-pharmacological diet-based approach to air pollution-induced disease management have also been discussed. We argue that before a nutraceuticals-based approach can be used for widespread public adoption, further research, especially human clinical trials, is essential to confirm the beneficial action of relevant nutraceuticals and to explore the safe limits of human supplementation and the risk of side effects. Future research should focus on systematically translating bench-based knowledge regarding nutraceuticals gained from in-vitro and in-vivo studies into clinically usable nutritional guidelines.

Associations of adverse pregnancy outcomes with high ambient air pollution exposure: Results from the Project ELEFANT

BACKGROUND

Investigations on the potential effects of high air pollution exposure before pregnancy on adverse pregnancy outcomes are limited, and it is unknown whether air quality standards looser than that set by World Health Organization (WHO) still can provide sufficient protection pregnant women from adverse pregnancy outcomes.

OBJECTIVES

To evaluate the potential effects of high ambient air pollution around pregnancy on preterm birth (PTB) and low birth weight (LBW), and assess the risk of PTB and LBW associated with air pollutants with reference to different air quality standards of WHO and China.

METHODS

Our study leveraged 10,960 pregnant women from the Project ELEFANT. Daily average particulate matter with an aerodynamic diameter of ≤2.5 μm (PM_2.5) and ≤10 μm (PM₁₀), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), carbon monoxide (CO) and ozone (O₃) concentrations were collected based on Chinese Air Quality Reanalysis datasets. Hazard ratios (HR) of PTB and LBW were estimated for maternal PM_2.5, PM₁₀, NO₂, SO₂, CO and O₃ exposures and related proportions of days with daily average air pollution concentrations exceeding air quality standards of WHO and China around pregnancy using Cox proportional hazards regression models with adjustment for potential confounders.

RESULTS

Ambient PM_2.5, PM₁₀, NO₂, SO₂ and CO exposure during the before pregnancy and pregnancy period were both significantly and positively associated with increased risk of PTB, PTB subtypes and LBW. A 10% increase in proportion of days with daily average PM_2.5 exceeding 25 μg/m³ over the entire pregnancy was most apparently associated with risk of PTB (HR, 12.66; 95% CI, 8.20-19.53) and LBW (HR, 17.42; 95% CI, 6.88-44.10) among all PM_2.5 proportion variables based on different air quality standards.

CONCLUSION

Air quality standards of WHO are necessary to be implemented to control for risks of adverse pregnancy outcomes associated with ambient air pollution in areas with high air pollution levels.

Environmental Exposure during Pregnancy: Influence on Prenatal Development and Early Life: A Comprehensive Review

Preconception and prenatal exposure to environmental contaminants may affect future health. Pregnancy and early life are critical sensitive windows of susceptibility. The aim of this review was to summarize current evidence on the toxic effects of environment exposure during pregnancy, the neonatal period, and childhood. Alcohol use is related to foetal alcohol spectrum disorders, foetal alcohol syndrome being its most extreme form. Smoking is associated with placental abnormalities, preterm birth, stillbirth, or impaired growth and development, as well as with intellectual impairment, obesity, and cardiovascular diseases later in life. Negative birth outcomes have been linked to the use of drugs of abuse. Pregnant and lactating women are exposed to endocrine-disrupting chemicals and heavy metals present in foodstuffs, which may alter hormones in the body. Prenatal exposure to these compounds has been associated with pre-eclampsia and intrauterine growth restriction, preterm birth, and thyroid function. Metals can accumulate in the placenta, causing foetal growth restriction. Evidence on the effects of air pollutants on pregnancy is constantly growing, for example, preterm birth, foetal growth restriction, increased uterine vascular resistance, impaired placental vascularization, increased gestational diabetes, and reduced telomere length. The advantages of breastfeeding outweigh any risks from contaminants. However, it is important to assess health outcomes of toxic exposures via breastfeeding. Initial studies suggest an association between pre-eclampsia and environmental noise, particularly with early-onset pre-eclampsia. There is rising evidence of the negative effects of environmental contaminants following exposure during pregnancy and breastfeeding, which should be considered a major public health issue.