Gestational exposures to outdoor air pollutants in relation to low birth weight: A retrospective observational study

Coexposure to ambient air pollution and temperature and its associations with birth outcomes in women undergoing assisted reproductive technology in Fujian, China: A retrospective cohort study

BACKGROUND

The interactions between pollutants and temperature coexposure, the mixing effects and their potential mechanisms remain uncertain.

METHODS

This retrospective cohort study included 11,766 women with infertility who received treatment at Fujian Hospital between 2015 and 2024. The daily mean concentrations of the six pollutants and the relative humidity and temperature data were acquired from the Fujian region. Data on genes were obtained from the Comparative Toxicogenomics Database.

RESULTS

O3 (aOR=0.80, 95 % CI=0.725--0.891) and temperature (aOR=0.936, 95 % CI=0.916--0.957) were negatively correlated with live birth rates. Moreover, PM10 (aOR=1.135, 95 % CI=1.028--1.252) and PM2.5 (aOR=1.146, 95 % CI=1.03--1.274) were positively associated with preterm birth. Among the effects on live births, PM2.5, PM10, NO2, CO, and SO2 had significant synergistic effects with temperature; in addition, O3 had significant antagonistic effects with temperature. A notable trend toward declining live birth rates with elevated concentrations of mixed pollutants was observed. Different infertility patients have different sensitivities to coexposure. Gene enrichment and cell experiments are associated mainly with cellular life activities.

CONCLUSIONS

Individual effects, interactions, and mixed effects between temperature and air pollutants and birth outcomes persist when air pollutant levels are relatively low. AAP may trigger miscarriage through cytotoxic effects.

Effect of environmental air pollutants on placental function and pregnancy outcomes: a molecular insight

Air pollution has become a major health concern, particularly for vulnerable populations such as the elderly, children, and pregnant women. Studies have reported a strong association between prenatal exposure to air pollutants and adverse pregnancy outcomes, including lower birth weight, reduced fetal growth, and an increased frequency of preterm births. This review summarizes the harmful effects of air pollutants, such as particulate matter, on pregnancy and outlines the mechanistic details associated with these adverse outcomes. Particulate pollutant matter may be able to cross the placenta barrier, and alterations in placental functions are central to the detrimental effects of these pollutants. In addition to associations with preeclampsia and gestational hypertension, air pollutants also induce oxidative stress, inflammation, and epigenetic alteration in the placenta. These pollutants can also affect placental homeostasis and endocrine function, contributing to pregnancy complications and possible transgenerational effects. Prenatal air pollution exposure has been linked to reduced cognitive and motor function in infants and newborns, increasing the predisposition to autism spectrum disorders and other neuropsychiatric disorders. This review also summarizes the use of various animal models to study the harmful effects of air pollution on pregnancy and postnatal outcomes. These findings provide valuable insight into the molecular events associated with the process and can aid in risk mitigation and adopting safety measures. Implementing effective environmental protocols and taking appropriate steps may reduce the global disease burden, particularly for developing nations with poor regulatory compliance and large populations of pregnant women.

Alterations in sperm DNA methylation may as a mediator of paternal air pollution exposure and offspring birth outcomes: Insight from a birth cohort study

Paternal exposure to environmental risk factors influences the offspring health. This study aimed to evaluate the association between paternal air pollution exposure mediated by sperm DNA methylation and adverse birth outcomes in offspring. We recruited 1607 fertile men and their partners from 2014 to 2016 and collected semen samples to detect sperm DNA methylation. Multivariate linear regression and weighted quantile sum regression models were used to assess the associations between paternal air pollution exposure and offspring birth outcomes. A critical exposure window was identified. Reduced representation bisulfite sequencing was used to detect sperm DNA methylation. The results demonstrated that high paternal exposure to PM2.5 (β = -211.31, 95% CI: (-386.37, -36.24)), PM10 (β = -178.20, 95% CI: (-277.13, -79.27)), and NO2 (β = -84.22, 95% CI: (-165.86, -2.57)) was negatively associated with offspring's birthweight, especially in boys. Additionally, an early exposure window of 15-69 days before fertilization was recognized to be the key exposure window, which increased the risk of low birth weight and small for gestational age. Furthermore, paternal co-exposure to six air pollutants contributed to lower birthweight (β = -51.91, 95% CI: (-92.72, -11.10)) and shorter gestational age (β = -1.72, 95% CI: (-3.26, -0.17)) and PM2.5 was the most weighted pollutant. Paternal air pollution exposure resulted in 10,328 differentially methylated regions and the IGF2R gene was the key gene involved in the epigenetic process. These differentially methylated genes were predominantly associated with protein binding, transcriptional regulation, and DNA templating. These findings indicate that spermatogenesis is a susceptible window during which paternal exposure to air pollution affects sperm DNA methylation and the birth outcomes of offspring.

Effects of Gestational Arsenic Exposures on Placental and Fetal Development in Mice: The Role of Cyr61 m6A

BACKGROUND

Several epidemiological investigations demonstrated that maternal arsenic (As) exposure elevated risk of fetal growth restriction (FGR), but the mechanism remains unclear.

OBJECTIVES

This study aimed to investigate the effects of gestational As exposure on placental and fetal development and its underlying mechanism.

METHODS

Dams were exposed to 0.15, 1.5, and 15 mg / L NaAsO 2 throughout pregnancy via drinking water. Sizes of fetuses and placentas, placental histopathology, and glycogen content were measured. Placental RNA sequencing was conducted. Human trophoblasts were exposed to NaAsO 2 (2 μ M ) to establish an in vitro model of As exposure. The mRNA stability and protein level of genes identified through RNA sequencing were measured. N 6 -Methyladenosine (m 6 A ) modification was detected by methylated RNA immunoprecipitation-quantitative real-time polymerase chain reason (qPCR). The binding ability of insulin-like growth factor 2 binding protein 2 to the gene of interest was detected by RNA-binding protein immunoprecipitation-qPCR. Intracellular S-adenosylmethionine (SAM) and methyltransferase activity were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and colorimetry, respectively. In vitro As + 3 methyltransferase (As3MT) knockdown or SAM supplementation and in vivo folic acid (FA) supplementation were used to evaluate the protective effect. A case-control study verified the findings.

RESULTS

Sizes of fetuses (exposed to 1.5 and 15 mg / L NaAsO 2 ) and placentas (exposed to 15 mg / L NaAsO 2 ) were lower in As-exposed mice. More glycogen + trophoblasts accumulated and the expression of markers of interstitial invasion was lower in the 15 mg / L NaAsO 2 -exposed mouse group in comparison with control. Placental RNA sequencing identified cysteine-rich angiogenic inducer 61 (Cyr61) as a candidate gene of interest. Mechanistically, mice and cells exposed to As had lower protein expression of CYR61, and this was attributed to a lower incidence of Cyr61 m 6 A . Furthermore, cells exposed to As had lower methyltransferase activity, suggesting that this could be the mechanism by which Cyr61 m 6 A was affected. Depletion of intracellular SAM, a cofactor for m 6 A methyltransferase catalytic domain, partially contributed to As-induced methyltransferase activity reduction. Either As3MT knockdown or SAM supplementation attenuated As-induced Cyr61 m 6 A down-regulation. In mice, FA supplementation rescued As-induced defective trophoblastic invasion and FGR. In humans, a negative correlation between maternal urinary As and plasma CYR61 was observed in infants who were small for gestational age.

DISCUSSION

Using in vitro and in vivo models, we found that intracellular SAM depletion-mediated Cyr61 m 6 A down-regulation partially contributed to As-induced defective trophoblastic invasion and FGR. https://doi.org/10.1289/EHP12207.

Combined exposure to PM2.5 and PM10 in reductions of physiological development among preterm birth: a retrospective study from 2014 to 2017 in China

Background

Preterm birth (PTB) has been linked with ambient particulate matter (PM) exposure. However, data are limited between physiological development of PTB and PM exposure.

Methods

Trimester and season-specific PM exposure including PM2.5 and PM10 was collected from Jiaxing between January 2014 and December 2017. Information about parents and 3,054 PTB (gestational age < 37 weeks) outcomes such as weight (g), head circumference (cm), chest circumference (cm), height (cm) and Apgar 5 score were obtained from birth records. We used generalized linear models to assess the relationship between PTB physiological developmental indices and PM2.5, PM10 and their combined exposures. A binary logistic regression model was performed to assess the association between exposures and low birth weight (LBW, < 2,500 g).

Results

Results showed that there were 75.5% of low birth weight (LBW) infants in PTB. Decreased PM2.5 and PM10 levels were found in Jiaxing from 2014 to 2017, with a higher PM10 level than PM2.5 each year. During the entire pregnancy, the highest median concentration of PM2.5 and PM10 was in winter (61.65 ± 0.24 vs. 91.65 ± 0.29 μg/m3) followed by autumn, spring and summer, with statistical differences in trimester-specific stages. After adjusting for several potential factors, we found a 10 μg/m3 increase in joint exposure of PM2.5 and PM10 during the entire pregnancy associated with reduced 0.02 week (95%CI: -0.05, -0.01) in gestational age, 7.9 g (95%CI: -13.71, -2.28) in birth weight, 0.8 cm in height (95%CI: -0.16, -0.02), 0.05 cm (95%CI: -0.08, - 0.01) in head circumference, and 0.3 (95%CI: -0.04, -0.02) in Apgar 5 score, except for the chest circumference. Trimester-specific exposure of PM2.5 and PM10 sometimes showed an opposite effect on Additionally, PM2.5 (OR = 1.37, 95%CI: 1.11, 1.68) was correlated with LBW.

Conclusion

Findings in this study suggest a combined impact of fine particulate matter exposure on neonatal development, which adds to the current understanding of PTB risk and health.

The relationship between extreme ambient temperature and small for gestational age: A cohort study of 1,436,480 singleton term births in China

Studies have shown that exposure to extreme ambient temperature can contribute to adverse pregnancy outcomes, however, results across studies have been inconsistent. We aimed to evaluate the relationships between trimester-specific extreme temperature exposures and fetal growth restriction indicated by small for gestational age (SGA) in term pregnancies, and to assess whether and to what extent this relationship varies between different geographic regions. We linked 1,436,480 singleton term newborns (2014-2016) in Hubei Province, China, with a sub-district-level temperature exposures estimated by a generalized additive spatio-temporal model. Mixed-effects logistic regression models were employed to estimate the effects of extreme cold (temperature ≤5th percentile) and heat exposures (temperature >95th percentile) on term SGA in three different geographic regions, while adjusting for the effects of maternal age, infant sex, the frequency of health checks, parity, educational level, season of birth, area-level income, and PM_2.5 exposure. We also stratified our analyses by infant sex, maternal age, urban‒rural type, income categories and PM_2.5 exposure for robustness analyses. We found that both cold (OR:1.32, 95% CI: 1.25-1.39) and heat (OR:1.17, 95% CI: 1.13-1.22) exposures during the third trimester significantly increased the risk of SGA in the East region. Only extreme heat exposure (OR:1.29, 95% CI: 1.21-1.37) during the third trimester was significantly related to SGA in the Middle region. Our findings suggest that extreme ambient temperature exposure during pregnancy can lead to fetal growth restriction. Governments and public health institutions should pay more attention to environmental stresses during gestation, especially in the late stage of the pregnancy.

Cellular mechanisms linking to outdoor and indoor air pollution damage during pregnancy

Pregnancies are a critical window period for environmental influences over the mother and the offspring. There is a growing body of evidence associating indoor and outdoor air pollution exposure to adverse pregnancy outcomes such as preterm birth and hypertensive disorders of pregnancy. Particulate matter (PM) could trigger oxi-inflammation and could also reach the placenta leading to placental damage with fetal consequences. The combination of strategies such as risk assessment, advise about risks of environmental exposures to pregnant women, together with nutritional strategies and digital solutions to monitor air quality can be effective in mitigating the effects of air pollution during pregnancy.

Associations between maternal exposure to ambient air pollution and very low birth weight: A birth cohort study in Chongqing, China

Introduction

There have been many researches done on the association between maternal exposure to ambient air pollution and adverse pregnancy outcomes, but few studies related to very low birth weight (VLBW). This study thus explores the association between maternal exposure to ambient air pollutants and the risk of VLBW, and estimates the sensitive exposure time window.

Methods

A retrospective cohort study analyzed in Chongqing, China, during 2015-2020. The Generalized Additive Model were applied to estimate exposures for each participant during each trimester and the entire pregnancy period.

Results

For each 10 μg/m³ increase in PM_2.5 during pregnancy, the relative risk of VLBW increased on the first trimester, with RR = 1.100 (95% CI: 1.012, 1.195) in the single-pollutant model. Similarly, for each 10 μg/m³ increase in PM₁₀, there was a 12.9% (RR = 1.129, 95% CI: 1.055, 1.209) increase for VLBW on the first trimester in the single-pollutant model, and an 11.5% (RR = 1.115, 95% CI: 1.024, 1.213) increase in the multi-pollutant model, respectively. The first and second trimester exposures of NO₂ were found to have statistically significant RR values for VLBW. The RR values on the first trimester were 1.131 (95% CI: 1.037, 1.233) and 1.112 (95% CI: 1.015, 1.218) in the single-pollutant model and multi-pollutant model, respectively; The RR values on the second trimester were 1.129 (95% CI: 1.027, 1.241) and 1.146 (95% CI: 1.038, 1.265) in the single-pollutant model and multi-pollutant model, respectively. The RR of O3 exposure for VLBW on the entire trimester was 1.076 (95% CI: 1.010-1.146), and on the second trimester was 1.078 (95% CI: 1:016, 1.144) in the single-pollutant model.

Conclusion

This study indicates that maternal exposure to high levels of PM_2.5, PM₁₀, NO₂, and O₃ during pregnancy may increase the risk of very low birth weight, especially for exposure on the first and second trimester. Reducing the risk of early maternal exposure to ambient air pollution is thus necessary for pregnant women.

Gestational exposure to ambient particulate matter and preterm birth: An updated systematic review and meta-analysis

Previous studies on gestational particulate matter (PM) exposure and preterm birth (PTB) showed inconsistent results, and no study systematically examined the short-term effect of PM exposure on PTB subtypes. To investigate both long- and short-term effects of the evidence to date in general population, we searched for epidemiological studies on PM exposure and PTB that published in PubMed, Web of Science, Embase and Cochrane Library up to March 31, 2022. The protocol for this review was registered with PROSPERO (CRD42021265202). Heterogeneity was assessed by Cochran's Q test and I² statistic. Publication bias was evaluated using funnel plots and Egger's tests. Subgroup analysis, meta-regression and sensitivity analysis were performed. Of 16,801 records, 84 eligible studies were finally included. The meta-analysis of long-term effect showed that per 10 μg/m³ increase in PM_2.5 and PM₁₀ during entire pregnancy were associated with PTB, the pooled odds ratios (ORs) were 1.084 (95% CI: 1.055-1.113) and 1.034 (95% CI: 1.018-1.049). Positive associations were found between PM_2.5 in second trimester and PTB subtypes. For the short-term exposure, we observed that PTB was positively associated with a 10 μg/m³ increment in PM_2.5 on lag day 2 and 3, the pooled ORs and 95% CIs were 1.003 (1.001-1.004) and 1.003 (1.001-1.005), with I² of 65.30% and 76.60%. PM₁₀ exposure on ave day 1 increased the risk of PTB, the pooled OR was 1.001 (95% CI: 1.000, 1.001). We also found that PM₁₀ exposure in 2 weeks prior to birth increased PTB risk. Our results support the hypothesis of both long- and short-term PM_2.5 exposure increase the risk of PTB. Further well-designed longitudinal studies and investigations into potential biological mechanisms are warranted.

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.

Assessing the effect of fine particulate matter on adverse birth outcomes in Huai River Basin, Henan, China, 2013-2018

Previous studies have indicated that maternal exposure to particles with aerodynamic diameter <2.5 μm (PM_2.5) is associated with adverse birth outcomes. However, the critical exposure windows remain inconsistent. A retrospective cohort study was conducted in Huai River Basin, Henan, China during 2013-2018. Daily PM_2.5 concentration was collected using Chinese Air Quality Reanalysis datasets. We calculated exposures for each participant based on the residential address during pregnancy. Binary logistic regression was used to examine the trimester-specific association of PM_2.5 exposure with preterm birth (PTB), low birth weight (LBW) and term LBW (tLBW), and we further estimated monthly and weekly association using distributed lag models. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for each 10 μg/m³ increase in PM_2.5 exposure. Stratified analyses were performed by maternal age, infant gender, parity, and socioeconomic status (SES). In total, 196,780 eligible births were identified, including 4257 (2.2%) PTBs, 3483 (1.8%) LBWs and 1770 (0.9%) tLBWs. Maternal PM_2.5 exposure during the second trimester were associated with the risk of PTB and LBW. At the monthly level, the PTB and LBW risks were associated with PM_2.5 exposure mainly in the 4th -6th month. By estimating the weekly-specific association, we observed that critical exposure windows of PM_2.5 exposure and PTB were in the 18th- 27th gestational weeks. Stronger associations were found in younger, multiparous mothers and those with a female baby and in low SES. In conclusion, the results indicate that maternal PM_2.5 exposure during the second trimester was associated with PTB and LBW. Younger, multiparous mothers and those with female babies and in low SES were susceptible.