Combined effects of traffic air pollution and home environmental factors on preterm birth in China

Effect of pregnancy and infancy exposure to outdoor particulate matter (PM1, PM2.5, PM10) and SO2 on childhood pneumonia in preschool children in Taiyuan City, China

There is currently a paucity of research on the effects of early life exposure to particulate matter (PM) of various size fractions on pneumonia in preschool-aged children. We explored the connections between antenatal and postnatal exposure to atmospheric pollutants and diagnosed pneumonia among 4814 offspring children in Taiyuan City, northern China. Outdoor air pollutant concentrations and ambient temperature were collected. A machine learning-based model was utilized to compute daily mean concentrations of PM10, PM2.5, and PM1 at the home address. Associations were calculated using generalized linear mixed models, and stratified analysis was used to detect sensitive subpopulations. We observed significant associations between prenatal exposure to atmospheric pollutants and the incidence of pneumonia in children. For every 10 μg/m3 increase, the odds ratios (ORs) were 1.06 for PM10, 1.15 for PM2.5, 1.24 for PM1, and 1.05 for SO2 for the whole pregnancy period. In mid-pregnancy, the most vital connections were found for PM10, PM2.5, and PM1 exposure. Girls showed higher sensitivity to exposure to PM2.5 and PM10. The most significant connections between PM and pneumonia were observed at high SO2 exposure. Connections between PM1, PM2.5 and pneumonia were stronger in children without environmental tobacco smoke (ETS) at home. Associations between PM10 and pneumonia were stronger in children with ETS at home. The synthesis of the data suggests that exposure to PM10, PM2.5, PM1, and SO2 during pregnancy contributes to an elevated susceptibility to childhood pneumonia. The second trimester period is significant and represents a critical window of vulnerability. PM1 may have the strongest impact. Exposure to SO2 can further enhance the PM related risks of pneumonia. Gender and ETS exposure at home can modify associations between outdoor PM and pneumonia. Further reductions in outdoor PM, especially PM1, are needed to reduce childhood pneumonia in China.

Preterm births attributable to criteria air pollutant exposure in Bangladesh during 2015-2019

Criteria air pollutant exposure impacts human health through various pathways. Preterm birth (PTB) is one of the major adverse birth outcomes (ABO) associated with such exposure. Although numerous global and regional studies have been conducted on this issue, few have recently investigated the impact of major criteria air pollutant exposure on PTBs in Bangladesh, one of the world's most polluted countries with the highest relative PTB rate. In this study, we retrieved high-resolution criteria air pollution data from recent studies and regionally scaled it to 10 km × 10 km resolution. We incorporated the MERRA-2 model, satellite measurements, and exposure-response modeling to quantify the impacts of CO, O3, PM2.5, SO2, and NO2 exposure on PTBs in Bangladesh from 2015 to 2019. We observed the highest all-source CO, O3, PM2.5, SO2, and NO2 exposure in 2018 at 272.8 μg/m3, 88.2 ppbv, 62.9 μg/m3, 20.5 μg/m3, and 11.6 ppbv, respectively. These exposures were associated with 0.18 million [95% confidence interval (95%CI): 0.08-0.29 million] to 0.20 million [95%CI: 0.08-0.32 million] annual total PTBs among 4.3 million annual total live births, indicating an alarming 4.4-4.9% PTB rate exclusively attributable to the exposure to these five criteria air pollutants. Within these PTB estimates, our study found that combined CO, O3, and PM2.5 exposure caused the majority (94.7-95.8%) of the total PTBs, with hotspots in the central and southern regions of Bangladesh. This study provides quantitative evidence of the PTB incidence caused by major criteria air pollutant exposure and discusses the urgency of the targeted reduction of pollutants as well as source control to reduce the risks of PTBs, which is critical for the overall well-being of the overpopulated and underrepresented women and children of Bangladesh.

Exploring relationships between smoke exposure, housing characteristics, and preterm birth in California

Pregnant people are vulnerable to air pollution exposure, including risk of preterm birth, low birth weight, and stillbirth. Understanding the infiltration of outdoor wildfire smoke into a residential space is critical for the accurate assessment of wildfire smoke exposure and associated health effects in pregnant people. Relying on ambient measurements of wildfire smoke alone can result in exposure misclassification. In this study, we examine the role of physical housing characteristics in the relationship between smoke exposure and preterm birth. In particular, we examine the effect of home size, year of construction, cooling type, and renovation status, as effect modifiers in the relationship between smoke exposure during pregnancy and preterm birth from 2007 to 2015 in California. To do this, we combined data on home characteristics from the California Tax Assessor, birth outcomes from the California birth records database, and the number of smoke days for each pregnancy from the NOAA (National Oceanic and Atmospheric Administration) Hazard Mapping System (HMS). We estimated the association between smoke day exposures and odds of preterm birth using logistic regression models and stratified by air basin and housing characteristics. Our findings reveal that cooling type and renovation status are key factors modifying the smoke exposure-preterm birth relationship. Notably, we found elevated associations for people living in unrenovated homes, those using evaporative cooling systems, and those using central air conditioning units. While we observed elevated odds of preterm birth associated with increasing smoke day exposure for residents of large and new homes, this effect does not significantly differ across home size and age quartiles. This study highlights the need to further examine the relative roles of housing characteristics as well as factors not measured here including behavioral factors, time spent outdoors, window use, and occupational exposures in driving adverse birth outcomes related to wildfire smoke exposure.

Prenatal air pollutant exposure and preterm birth risk in primiparas of advanced maternal age residing in rural Henan province

Direct evidence on the impact of air pollution on preterm birth (PTB) among advanced maternal age (AMA) primiparas is limited. This study examined the association between air pollution and PTB among 6,295 AMA primiparas in rural Henan Province. Logistic regression and distributed lag nonlinear models showed that prenatal exposure to carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide (NO2), and fine particulate matter (PM2.5) was associated with an increased PTB risk among AMA primiparas, while ozone (O3) exposure was inversely related to PTB risk (all P < 0.05). Moreover, the vulnerable periods were identified as gestational weeks 1-6 and 22-28. The education level, smoking status, and season of conception significantly modified the association between PTB and air pollution (P interaction < 0.10) among AMA primiparas. These findings emphasize the impact of air pollution on PTB risk in AMA primiparas, highlighting the need for targeted interventions in vulnerable populations.

The causal impact of fetal exposure to PM2.5 on birth outcomes: Evidence from rural China

This paper investigates the causal impact of fetal exposure to PM2.5 on birth outcomes, including birth weight, the incidence of low birth weight (LBW), and small for gestational age (SGA), based on a nationally representative birth record dataset in a developing country setting. We employed thermal inversion as the instrument variable (IV) for PM2.5 and leveraged the distinctive characteristics of rural China in the 1990 s to address identification challenges. Our IV estimates indicate that higher fetal PM2.5 exposure leads to lower birth weight and elevated probabilities of LBW and SGA. Due to the mortality selection in utero, weak male fetuses were more likely to be screened out by PM2.5 exposure, resulting in a comparatively lower vulnerability among the surviving male infants. Furthermore, infants born to less educated mothers exhibited increased susceptibility, a phenomenon not entirely explained by the sorting behaviors associated with the preference for cleaner air based on socioeconomic status.

Association between gestational exposure and risk of orofacial clefts: a systematic review and meta-analysis

BACKGROUND

The occurrence of orofacial Clefts (OFCs) is a congenital disease caused by many factors. According to recent studies, air pollution has a strong correlation with the occurrence of OFCs. However, there are still some controversies about the current research results, and there is no relevant research to review the latest results in recent years.

OBJECTIVE

In this paper, the authors conducted a systematic review and meta-analysis to explore the correlation between ambient air pollution and the occurrence of neonatal OFCs deformity.

METHODS

We searched Pubmed, Web of science, and Embase databases from the establishment of the database to May 2023. We included observational studies on the relationship between prenatal exposure to fine particulate matter 2.5 (PM2.5), fine particulate matter 10 (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO) and the risk of cleft lip (CL), cleft palate (CP), cleft lip with or without palate (CL/P). the Newcastle-Ottawa quality assessment scale (NOS) was used to evaluate the quality of the literature. Funnel plot and Egger's regression were used to verify the publication bias. Random effect model or fixed effect model was used to estimate the combined relative risk (RR) and 95% confidence interval (95%CI).

RESULTS

A total of eleven studies were included in this study, including four cohort studies and seven case-control studies, including 22,453 cases of OFCs. Ten studies had low risk of bias and only one study had high risk of bias. Three studies reported that PM2.5 was positively correlated with CL and CP, with a combined RR and 95%CI of 1.287(1.174,1.411) and 1.267 (1.105,1.454). Two studies reported a positive correlation between O3 and CL, with a combined RR and 95%CI of 1.132(1.047,1.225). Two studies reported a positive correlation between PM10 and CL, with a combined RR and 95%CI of 1.108 (1.017,1.206). No association was found between SO2, CO, NO2 exposure during pregnancy and the risk of OFCs.

CONCLUSION

The results of this study showed that there was a significant statistical correlation between exposure to PM10, PM2.5, O3 and the risk of OFCs in the second month of pregnancy. Exposure assessment, research methods and mechanisms need to be further explored.

Trends and risk of recurrent preterm birth in pregnancy cohorts in rural Bangladesh, 1990-2019

INTRODUCTION

A history of preterm birth reportedly increases the risk of subsequent preterm birth. This association has primarily been studied in high-income countries and not in low-income settings in transition with rapidly descending preterm birth figures. We evaluated the population-based trends of preterm births and recurrent preterm births and the risk of preterm birth recurrence in the second pregnancy based on prospectively studied pregnancy cohorts over three decades in Matlab, Bangladesh.

METHODS

A population-based cohort included 72 160 live births from 1990 to 2019. We calculated preterm birth and recurrent preterm birth trends. We assessed the odds of preterm birth recurrence based on a subsample of 14 567 women with live-born singletons in their first and second pregnancies. We used logistic regression and presented the associations by OR with a 95% CI.

RESULTS

The proportion of preterm births decreased from 25% in 1990 to 13% in 2019. The recurrent preterm births had a similar, falling pattern from 7.4% to 3.1% across the same period, contributing 27% of the total number of preterm births in the population. The odds of second pregnancy preterm birth were doubled (OR 2.18; 95% CI 1.96 to 2.43) in women with preterm birth compared with the women with term birth in their first pregnancies, remaining similar over the study period. The lower the gestational age at the first birth, the higher the odds of preterm birth in the subsequent pregnancy (test for trend p<0.001).

CONCLUSION

In this rural Bangladeshi setting, recurrent preterm births contributed a sizeable proportion of the total number of preterm births at the population level. The increased risk of recurrence remained similar across three decades when the total proportion of preterm births was reduced from 25% to 13%.

The influence of air pollution on gestational age at delivery and birthweight in patients with or without respiratory allergy: A nested case-control study

INTRODUCTION

Air pollution is a current major health issue. The burden of airborne pollutants and aeroallergen levels varies throughout the year, as well as their interaction and consequences. Prenatal exposure during pregnancy has been associated with adverse perinatal outcomes. The aim of this study was to evaluate the impact of air pollutants on perinatal outcomes in patients with or without respiratory allergy.

MATERIAL AND METHODS

Nested case-control retrospective study on 3006 pregnant women. Correlations between concentrations of common pollutants in each trimester of pregnancy and on average during the whole pregnancy and both gestational age at delivery and birthweight were studied. Pearson's correlation coefficient and binary logistic regression were used.

RESULTS

In general, pollutants correlated more strongly with birthweight than with gestational age at delivery. Nine-month NO2 , SO2 , CO, and benzene, and second-trimester CO negatively correlated with birthweight, whereas only first-trimester NO2 showed a very mild correlation with gestational age at delivery. Negative correlations between pollutants and birthweight were much stronger in the respiratory allergy group (n = 43; 1.4%) than in the non-allergic group. After adjustments, the most significant predictive pollutant of birthweight was SO2 in both groups. The best predictive model was much stronger in the allergic group for third-trimester SO2 (R2  = 0.12, p = 0.02) than in the non-allergic group for total SO2 (R2  = 0.002, p = 0.02). For each unit that SO2 increased, birthweight reduced by 3.22% vs. 1.28% in each group, respectively.

CONCLUSIONS

Air pollutant concentrations, especially SO2 , negatively influenced birthweight. The impact of this association was much stronger and more relevant in the group of women with respiratory allergies.

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.

Association between air pollutants and birth defects in Xiamen, China

Objective

To explore the relationship between common air pollution and common birth defects, and to provide reference for the prevention of birth defects.

Methods

We conducted a case-control study in Xiamen, a city in southeastern China from 2019 to 2020. Logistics regression was used to analyze the relationship between sulfur dioxide(SO₂), fine particulate matter 2.5(PM_2.5), nitrogen dioxide(NO₂), ozone(O₃), carbon monoxide(CO) and the occurrence of common birth defects such as congenital heart disease, facial cleft, and finger deformity.

Results

SO₂ significantly increased the risk of birth defects such as congenital heart disease, cleft lip and/or cleft palate, and ear deformity in the first and second months of pregnancy.

Conclusion

Exposure to common air pollutants increases the risk of birth defects, and SO₂ significantly affects the occurrence of birth defects in the first two months of pregnancy.

Air pollution exposure and the risk of macrosomia: Identifying specific susceptible months

Birth weight is an important indicator of future growth and development for newborns. Few studies investigated the potential effects of air pollutants on macrosomia and their susceptible windows. We included 38,971 singleton full-term births from Beijing HaiDian Maternal and Child Health Hospital between 2014 and 2018, and assessed the associations of air pollutants exposure during preconception and pregnancy with macrosomia as well as the corresponding susceptible windows. The concentrations of air pollutants (PM_2.5, PM₁₀, SO₂, NO₂, CO and O₃) for participants were calculated by the data from the nearest monitoring stations. Distributed lag models (DLM) incorporating logistic regression models were used to estimate the associations between air pollutants exposure during the 3 months before conception and pregnancy period and the risk of macrosomia, identifying susceptible windows of air pollutants. Weighted quantile sum (WQS) regression was applied to estimate the joint effect of air pollutants. A 10 μg/m³ increase in PM_2.5 exposure from 3rd to 8th gestational month was positively associated with the risk of macrosomia, with the strongest effect in the 6th month (OR = 1.010, 95 % CI: 1.002-1.019). For a 10 μg/m³ increase in SO₂, the windows of significant exposure were from the 1st preconception month to the 3rd gestational month, with the strongest effect in the 2nd month (OR = 1.030, 95 % CI: 1.010-1.049). We also observed the significant positive associations were in the 5th-8th gestational months for PM₁₀, the 8th-9th gestational months for NO₂ and the 3rd-7th gestational months for CO respectively. WQS regression also indicated a positive association between co-exposure to air pollutants and macrosomia. Our results suggest air pollution exposure is associated with increased risk of macrosomia. The windows of exposure for susceptibility to the risk of macrosomia vary between air pollutants. The susceptible exposure windows were middle and late pregnancy for PM, CO and NO₂, while for SO₂, early pregnancy is the window of vulnerability. Our findings provide the evidence that air pollution exposure is an independent risk factor for macrosomia and a basis for targeted environment policy.

Association between trimester-specific exposure to thirteen endocrine disrupting chemicals and preterm birth: Comparison of three statistical models

BACKGROUND

Growing evidence indicated that maternal exposure to some endocrine disrupting chemicals (EDCs) may increase the risk of preterm birth (PTB). However, few studies have evaluated the joint effect of EDCs on PTB.

OBJECTIVES

This study aimed to evaluate the associations of maternal EDCs mixture in the 1st, 2nd, and 3rd trimesters during pregnancy with PTB, and identify the vital components that mainly contribute to PTB.

METHODS

This study included 847 pregnant women that provided urine samples for all three trimesters. Urinary concentrations of thirteen EDC metabolites (four phthalates, two parabens, three phenols, and four benzotriazoles and benzothiazoles) were examined. Logistic regression model, quantile g-computation and Bayesian kernel machine regression (BKMR) models were applied to study the association.

RESULTS

Logistic regression model suggested that only bisphenol A (BPA) in the 1st trimester significantly increased the OR of PTB after adjusting for BPA exposure in the 2nd and 3rd trimesters. Quantile g-computation model identified that urinary EDCs mixture in the 1st trimester were positively associated with PTB [OR (95 % CI): 1.98 (1.10, 3.58)], and the most heavily weighted component for PTB was BPA (26 %), followed by mono-2ethylhexyl phthalate (MEHP) (22 %). BKMR model determined a significant association between EDCs mixture in the 1st trimester and PTB when all EDC concentrations were at or above their 55th percentile compared with the median. The BKMR model found that BPA and MEHP were associated with an increase in the estimated probability of PTB, when the other EDCs were held to their 50th and 75th percentiles, respectively, in the 1st trimester.

CONCLUSIONS

The results of mixture analysis models indicated that exposure to higher EDCs mixture in the 1st trimester may increase the risk of PTB. BPA was considered as the most contributing factor for PTB among the detected EDCs.

The causal and independent effect of ozone exposure during pregnancy on the risk of preterm birth: Evidence from northern China

The concentration of ozone (O₃) in the environment is gradually increasing, but there are limited reports on the exposure to O₃ during pregnancy on the risk of adverse birth outcomes. Our study aimed to examine the causal and independent effect of O₃ exposure during pregnancy on the risk of preterm birth (PTB) and to identify the critical window. Based on the baseline population of the birth cohort in Jinan, northern China, we obtained the individual exposure for each subject during pregnancy of ambient 8-h moving average O₃ through the inverse distance weighting model. The effect of O₃ exposure during pregnancy on PTB was evaluated through the time-dependent Cox proportional-hazard models. And we assessed the causal relationship by controlling unknown confounding factors using the instrumental variable (IV) analysis, estimated the independent effect by principal component analysis, and identified the critical window period of exposure through the distributed lag model. Among 6501 subjects, 285 mothers delivered prematurely. The median (IQR) of O₃ concentration during pregnancy was 109.51 (23.54) μg/m³. The high level of O₃ exposure (>173.64 μg/m³) increased the risk of PTB, with HR of 1.92 (95% CI: 1.38-2.66). Furthermore, the HR (95% CI) of the O₃ estimated value calculated by the IV (wind speed) on the risk of PTB was 2.63 (1.41-4.88). In addition, the high level of O₃ exposure was associated with the risk of PTB in the 13th-18th gestational weeks. Therefore, the high level of O₃ exposure during pregnancy may independently increase the risk of PTB, which may be a causal effect. The 13th to 18th week of gestation is a critical window for preventing this risk.

Association between ambient PM2.5 and outpatient visits of children's respiratory diseases in a megacity in Central China

Objective

To explore the relationship between ambient PM_2.5 level and outpatient visits of children with respiratory diseases in a megacity, Zhengzhou, in central China.

Methods

We collected daily outpatient visit data, air pollutant data, and meteorological data at the monitoring points of Zhengzhou from the time period 2018 to 2020 and used Spearman's rank correlation to analyze the correlation between children's respiratory outpatient visits and air pollutants and meteorological factors. Generalized additive models were used to analyze the association between PM_2.5 exposures and children's respiratory outpatient visits. A stratified analysis was further carried out for the seasons.

Results

From 2018 to 2020, the total number of outpatients with children's respiratory diseases was 79,1107, and the annual average concentrations of PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃-8h in Zhengzhou were respectively 59.48 μg/m³, 111.12 μg/m³, 11.10 μg/m³, 47.77 μg/m³, 0.90 mg/m³ and 108.81 μg/m³. The single-pollutant model showed that the risk of outpatient visits for children with respiratory disease increased by 0.341% (95%CI: 0.274-0.407%), 0.532% (95%CI: 0.455-0.609%) and 0.233% (95%CI: 0.177-0.289%) for every 10 μg/m³ increase in PM_2.5 with a 3-day lag, 1-day lag, and 1-day lag respectively for the whole year, heating period, and non-heating period. The multi-pollutant model showed that the risk of PM_2.5 on children's respiratory disease visits was robust. The excess risk of PM_2.5 on children's respiratory disease visits increased by 0.220% (95%CI: 0.147-0.294%) when SO₂ was adjusted. However, the PM_2.5 effects were stronger during the heating period than during the non-heating period.

Conclusion

The short-term exposure to PM_2.5 was significantly associated with outpatient visits for children's respiratory diseases. It is therefore necessary to strengthen the control of air pollution so as to protect children's health.

The type of previous abortion modifies the association between air pollution and the risk of preterm birth

BACKGROUND

Air pollution and previous abortion have been reported to be related to preterm birth (PTB). But rare study examined the effect of air pollution on PTB risk among mothers with previous abortion.

OBJECTIVE

To estimate the effect of air pollution on PTB and the potential effect modification of previous abortion on such an association in rural part of Henan province (China).

METHOD

Based on National Free Preconception Health Examination Project (NFPHEP), information from the medical records of 57,337 mothers with previous abortion were obtained. An inverse distance-weighted model was used to estimate exposure levels of air pollutants. The effect of air pollution on the risk of PTB was estimated with a multiple logistic regression model. Stratified and interaction analyses were undertaken to explore the potential effect modification of previous abortion on this association.

RESULTS

The risk of PTB was positively associated with exposure to levels of nitrogen dioxide (NO₂; OR: 1.03; 95%CI: 1.02-1.04)], and sulfur dioxide (SO₂; 1.04; 1.02-1.07), and negatively associated with ozone (O₃) exposure (0.97; 0.97-0.98) during the entire pregnancy. Besides, we observed a positive effect of carbon monoxide (CO) exposure during the third trimester of pregnancy on PTB (1.14; 1.01-1.29). The type of previous abortion could modify the effect of air pollution on the PTB risk (P-_interaction < 0.05). Compared with mothers with previous induced abortion, mothers with previous spontaneous abortion carried a higher risk of PTB induced by NO₂, CO, and O₃.

CONCLUSIONS

The risk of PTB was positively associated with levels of NO₂, SO₂ and CO, and negatively associated with the O₃ level. The types of previous abortion could modify the effect of air pollution on PTB. Mothers who had an abortion previously, especially spontaneous abortion, should avoid exposure to air pollution to improve their pregnancy outcome.

A time series analysis of ambient air pollution and low birth weight in Xuzhou, China

The objective of this study was to examine the relationship between weekly specific maternal air pollution exposures and low birth weight. We fitted a distributed lag nonlinear model (DLNM) to analyze the nonlinear exposure-response association and delayed effects of air pollutants on the risk for low birth weight. The model assumed that all live births have 40 gestational weeks.The 1st week lag was the 40th gestational week, and 40th lag week was the 1st gestational week.The study included 71,809 live births (from July 1, 2016, to June 30, 2019), of which 2,391 (3.33%) exhibited low birth weight. The results demonstrated that exposure of pregnant women to PM10 at lag 22-30 weeks was significantly associated with low birth weight risk, with the greatest impact at the lag 30 week. Exposure to SO2 at lag 29-37 weeks was significantly associated with low birth weight risk. The sensitive exposure window for NO2 began at lag 25-37 weeks of pregnancy. The lag 6-10 weeks constituted the susceptible exposure window for O3. Therefore we concluded that maternal exposures to PM10, SO2, NO2, and O3 were associated with increased risk for low birth weight.

Prenatal exposure to air pollution and the risk of macrosomia: Identifying windows of susceptibility

This study explores the effects of prenatal exposure to air pollution on the risk of macrosomia and its window of susceptibility. We conducted a retrospective cohort study utilizing records of birth certificates for all full-term live newborns born in Xi'an city, China from January 1, 2015, to December 31, 2018.Weekly- and trimester-specific exposures of PM2.5, PM10, NO2, and O3 during pregnancy were calculated by inverse distance weighting (IDW) based on their residences. Cox proportional hazard model and distributed lag models (DLMs) were performed to estimate the effects of air pollution exposure during pregnancy on macrosomia risk and its window of susceptibility. In total, 318,323 full-term newborns were identified, including 24,996 (7.8%) cases of macrosomia. An IQR increase in PM2.5 exposure (45.46 μg/m3) from the 33rd until the 37th weeks of gestation was positively associated with an elevated risk of macrosomia, with the strongest effect in the 37th weeks (HR = 1.007, 95%CI: 1.002-1.013). The window of susceptibility for NO2 exposure on macrosomia risk was in the 29th-35th gestational weeks, with the strongest effect in the 34th weeks (IQR = 21.96 μg/m3, HR = 1.006, 95%CI:1.000-1.013). For prenatal exposure to O3, 5th-24th weeks of gestation was identified as susceptible windows for elevated risk of macrosomia, with the strongest associations observed in the 15th weeks (IQR = 80.53 μg/m3, HR = 1.022, 95%CI: 1.011-1.033). However, we did not observe any associations between weekly exposure of PM10 and macrosomia. Our findings imply that the windows of susceptibility to PM2.5 and NO2 exposure on macrosomia are mainly in late pregnancy, whereas the windows of susceptibility to O3 exposure are in early and middle pregnancy.

The Asian Games, air pollution and birth outcomes in South China: An instrumental variable approach

We estimate the effects of air-pollution exposure on low birthweight, birthweight, and prematurity risk in South China, for all expectant mothers and by maternal age group and child sex. We do so by exploiting exogenous improvement in air quality during the 2010 Guangzhou Asian Games, when strict regulations were mandated to assure better air quality. We use daily air-pollution levels collected from monitoring stations in Guangzhou, the Asian Games host city, and Shenzhen, a nearby control city, between 2009 and 2011. We first show that air quality during the Asian Games significantly improved in Guangzhou, relative to Shenzhen. Next, using birth-certificate data for both cities for 2009-2011 and using expected pregnancy overlap with the Asian Games as an instrumental variable, we study the effects of three pollutants (PM₁₀, SO₂, and NO₂) on birth outcomes. Four main conclusions emerge: 1) air pollutants significantly reduce average birthweight and increase preterm risk; 2) for birthweight, late pregnancy is most sensitive to PM₁₀ exposure, but there is not consistent evidence of a sensitive period for other pollutants and outcomes; 3) for birthweight, babies of mothers who are at least 35 years old show more vulnerability to all three air pollutants; and 4) male babies show more vulnerability than female babies to PM₁₀ and SO₂, but birthweights of female babies are more sensitive than those of male babies to NO₂.

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.

Short-term effect of NO2 on outpatient visits for dermatologic diseases in Xinxiang, China: a time-series study

OBJECTIVES

As the largest organ of the human body, the skin is the major exposure route of NO₂. However, the evidence for a relationship between NO₂ exposure and dermatologic diseases (DMs) is limited. This time-series study was conducted to assess the short-term effect of nitrogen dioxide (NO₂) exposure on DMs outpatient visits in Xinxiang, China.

METHODS

Daily recordings of NO₂ concentrations, meteorological data, and the outpatient visits data for DMs were collected in Xinxiang from January 1st, 2015, to December 31st, 2018. The analysis method used was based on the generalized additive model (GAM) with quasi-Poisson regression to investigate the relationship between NO₂ exposure and DMs outpatient visits. Several covariates, such as long-term trends, seasonality, and weather conditions were controlled.

RESULTS

A total of 164,270 DMs outpatients were recorded. A 10 μg/m³ increase in NO₂ concentrations during the period was associated with a 1.86% increase in DMs outpatient visits (95% confidence intervals [Cl]: 1.06-2.66%). The effect was stronger (around 6 times) in the cool seasons than in warmer seasons and younger patients (< 15 years of age) appeared to be more vulnerable.

CONCLUSIONS

The findings of this study indicate that short-term exposure to NO₂ increases the risk of DMs in Xinxiang, China, especially in the cool seasons. Policymakers should implement more stringent air quality standards to improve air quality.

Association between humidifier disinfectant exposure during infancy and subsequent neuropsychiatric outcomes during childhood: a nation-wide cross-sectional study

Background

The purpose was to determine the association between infant exposure to humidifier disinfectant (HD) with neuropsychiatric problems in pre-school children.

Methods

A total of 2,150 children (age 4–11 months) were enrolled in the Panel Study of Korean Children (PSKC) study. The Korean version of the Child Behavior Checklist (CBCL) was used for assessments of neuropsychiatric problems. 1,113 children who participated in all the first to third PSKC studies and answered a question about HD exposure were finally enrolled.

Results

There were 717 (64.5%) children in non-HD group who were not exposed to HD and 396 (35.5%) in HD group with former exposure to HD. Exposure to HD was associated with total neuropsychiatric problems (adjusted odds ratio, aOR = 1.54, 95% CI = 1.15–2.06), being emotionally reactive (aOR = 1.55, 95% CI = 1.00–2.39), having attention problems (aOR = 1.96, 95% CI = 1.10–3.47), having oppositional defiant problems (aOR = 1.70, 95% CI = 1.07–2.71), and having attention deficit/hyperactivity problems (aOR = 11.57, 95% CI = 1.03–2.38). The risks for neuropsychiatric problems were clearly increased in boy, firstborn, and secondary smoker.

Conclusions

Exposure to HD during early childhood had a potential association with subsequent behavioral abnormalities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02825-7.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Single-cell RNA sequencing reveals heterogeneity and differential expression of decidual tissues during the peripartum period

Objectives

The decidua is a tissue that contacts both maternal and foetal components and is pivotal to labour onset due to its location. Due to the heterogeneity of decidual tissue, it is challenging to study its role in the peripartum period. Herein, we analysed the transcriptomes of peripartum decidua at single‐cell resolution.

Materials and methods

Single‐cell RNA sequencing was performed for 29 231 decidual cells before and after delivery to characterize the transcriptomes.

Results

Eight major cell types (including endothelial cells, fibroblasts) and subtypes of decidual stromal cells, extravillous trophoblasts and T cells were identified and found to have various functions. Compared with before delivery, the activation of decidual stromal cell, extravillous trophoblast and T‐cell subtypes to different degrees was observed after delivery. Furthermore, the activation involved multiple functions, such as cell proliferation, and several pathways, such as the activator protein 1 pathway. The results of pseudotemporal ordering showed differentiation of decidual stromal cell and extravillous trophoblast subtypes, suggesting inhomogeneity of these subgroups in decidualization (decidual stromal cell) and invasion (extravillous trophoblast).

Conclusions

The peripartum decidual tissue is heterogeneous. This study revealed changes in the decidua and its components at single‐cell resolution; these findings provide a new perspective for the study of peripartum decidua.

Serum apolipoprotein A-II and alpha-2-antiplasmin levels in midtrimester can be used as predictors of preterm delivery

OBJECTIVE

To identify serum protein markers in midtrimester that predict preterm delivery.

METHODS

A retrospective case-control study randomly selected patients that experienced spontaneous preterm birth and healthy control patients that experienced a normal delivery at term. A proteomic analysis was undertaken using the data-independent acquisition method.

RESULTS

A total of 30 singleton pregnant women were randomly selected from 12 800 pregnant women: 15 women had a spontaneous preterm birth (group Y) and 15 age- and body mass index-matched women gave birth at term (group D). All of the patients provided serum at 15-20 weeks of gestation. A total of 39 differentially expressed proteins were identified. Compared with group D, 24 proteins were upregulated and 15 were downregulated in the preterm group Y. Using Kyoto Encyclopedia of Genes and Genomes pathway enrichment, the 24 upregulated proteins were significantly enriched in the complement and coagulation cascade pathways. Search Tool for the Retrieval of Interacting Genes Furthermore (STRING) analysis showed that apolipoprotein A-II (apoA-II) and alpha-2-antiplasmin (α2-AP), two upregulated proteins, were key nodes in the STRING protein-protein network.

CONCLUSIONS

These findings suggest that apoA-II and α2-AP might be new markers for predicting preterm delivery in the midtrimester.

Early-life exposure to air pollution and childhood allergic diseases: an update on the link and its implications

INTRODUCTION

Although mounting evidence has linked environmental factors with childhood allergies, some specific key issues still remain unclear: what is the main environmental factor? what is the critical timing window? And whether these contribute to the development of disease?

AREAS COVERED

This selective review summarizes recent epidemiological studies on the association between early-life exposure to indoor/outdoor air pollution and childhood allergic diseases. A literature search was conducted in the PubMed and Web of Science for peer-reviewed articles published until April 2020. Exposure to the traffic-related air pollutant, NO₂, exposure during pregnancy and early postnatal periods is found to be associated with childhood allergies, and exposure during different trimesters causes different allergic diseases. However, exposure to classical air pollutants (PM₁₀ and SO₂) also contributes to childhood allergy in developing countries. In addition, early-life exposure to indoor renovation and mold/dampness significantly increases the risk of allergy in children. A synergistic effect between indoor and outdoor air pollution is found in the development of allergic diseases.

EXPERT OPINION

Early-life exposure to outdoor air pollution and indoor environmental factors plays an important role in the development of childhood allergic diseases, and the synergy between indoor and outdoor exposures increases allergy risk. The available findings support the hypothesis of the 'fetal origins of childhood allergy,' with new implications for the effective control and early prevention of childhood allergies.