Relationship between ambient air pollution and preterm birth: a retrospective birth cohort study in Yan'an, China

Ambient ozone exposure and pregnancy complications and adverse birth outcomes: A systematic review and meta-analysis

BACKGROUND

Ambient ozone pollution is becoming a global health threat under global warming. Evidence on the association between ambient ozone and pregnancy complications and adverse birth outcomes has grown enormously. To provide a comprehensive assessment of the evidence, we performed a systematic review and meta-analysis to outline current epidemiological evidence.

METHODS

A systematic literature search up to January 2024 was conducted in PubMed, Web of Science, Cochrane Library and Embase. We included studies that examined the association of ambient ozone exposure with pregnancy complications and birth outcomes. Data extraction was performed independently. All eligible studies were synthesized qualitatively. A random-effects meta-analysis was used to summarize the available effect estimates that calculated with a 10 μg/m3 exposure. We further evaluated whether geographic location, study design, study quality, and exposure assessments explain the heterogeneity. This study protocol was registered with PROSPERO (CRD42024499445).

RESULTS

A total of 10,940 records were originally searched, 65 articles were finally included. Our results showed that first trimester ozone exposure significantly increased the risk of preeclampsia (pooled odds ratio (OR) = 1.018, 95%CI: 1.006-1.030). For birth outcomes, short-term ozone exposure was associated with the risk of preterm birth, with the pooled OR of 1.005 (95%CI: 1.002-1.008) and 1.003(95%CI:1.000-1.005). First trimester and whole pregnancy ozone exposure were associated with the risk of small for gestational age, with the pooled OR of 1.007 (95%CI: 1.002-1.012) and 1.030 (95%CI: 1.010-1.050), respectively.

CONCLUSION

First trimester ozone exposure was associated with adverse pregnancy complications and adverse birth outcomes. Future investigations that considering local climates and population characteristics are warranted to explore the vulnerability at local and regional levels for tailored preventions.

Exploring the association between atmospheric pollutants and preterm birth risk in a river valley city

Objective

To investigate the association between exposure to atmospheric pollutants and preterm birth in a river valley-type city and its critical exposure windows.

Methods

A retrospective cohort study was used to collect data from the medical records of preterm and full-term deliveries in two hospitals in urban areas of a typical river valley-type city from January 2018 to December 2019. A total of 7,288 cases were included in the study with general information such as pregnancy times, the number of cesarean sections, occupation, season of conception and regularity of the menstrual cycle. And confounding factors affecting preterm birth were inferred using the chi-square test. The effects of exposure to each pollutant, including particulate matter 2.5 (PM2.5), particulate matter 10 (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO) and ozone (O3), during pregnancy on preterm birth and the main exposure windows were explored by establishing a logistic regression model with pollutants introduced as continuous variables.

Results

Maternal age, pregnancy times, number of births, number of cesarean sections, season of conception, complications diseases, comorbidities diseases, hypertension disorder of pregnancy and neonatal low birth weight of the newborn were significantly different between preterm and term pregnant women. Logistic regression analysis after adjusting for the above confounders showed that the risk of preterm birth increases by 0.9, 0.6, 2.4% in T2 and by 1.0, 0.9, 2.5% in T3 for each 10 μg/m3 increase in PM2.5, PM10, NO2 concentrations, respectively. The risk of preterm birth increases by 4.3% in T2 for each 10 μg/m3 increase in SO2 concentrations. The risk of preterm birth increases by 123.5% in T2 and increases by 188.5% in T3 for each 10 mg/m3 increase in CO concentrations.

Conclusion

Maternal exposure to PM2.5, PM10, NO2, CO was associated with increased risk on preterm birth in mid-pregnancy (T2) and late pregnancy (T3), SO2 exposure was associated with increased risk on preterm birth in mid-pregnancy (T2).

The relationship between air pollutants and preterm birth and blood routine changes in typical river valley city

OBJECTIVE

To collect maternal maternity information on preterm births in two tertiary hospitals in the urban area of Baota District, Yan'an City, from January 2018 to December 2020, to explore the long-term and short-term effects of air pollutants (PM2.5, PM10, SO2, NO2, CO and O3) and preterm births, and to explore changes in blood cell counts due to air pollutants.

METHODS

Daily average mass concentration data of six air pollutants in the urban area of Yan'an City from January 1, 2017 to December 31, 2020 were collected from the monitoring station in Baota District, Yan'an City. Meteorological information was obtained from the Meteorological Bureau of Yan'an City, including temperature,relative humidity and wind speed for the time period. The mass concentration of air pollutants in each exposure window of pregnant women was assessed by the nearest monitoring station method, and conditional logistic regression was used to analyze the relationship between air pollutants and preterm births, as well as the lagged and cumulative effects of air pollutants. Multiple linear regression was used to explore the relationship between air pollutants and blood tests after stepwise linear regression was used to determine confounders for each blood test.

RESULTS

The long-term effects of pollutants showed that PM2.5, PM10, SO2, NO2and CO were risk factors for preterm birth. In the two-pollutant model, PM2.5, PM10, SO2 and NO2 mixed with other pollutants were associated with preterm birth. The lagged effect showed that PM2.5, PM10, SO2, NO, and CO were associated with preterm birth; the cumulative effect showed that other air pollutants except O3 were associated with preterm birth. The correlation study between air pollutants and blood indicators showed that air pollutants were correlated with leukocytes, monocytes, basophils, erythrocytes, hs-CRPand not with CRP.

CONCLUSION

Exposure to air pollutants is a risk factor for preterm birth. Exposure to air pollutants was associated with changes in leukocytes, monocytes, basophils and erythrocytes and hs-CRP.

Independent and interaction effects of prenatal exposure to high AQI and extreme Humidex on the risk of preterm birth: A large sample population study in northern China

The combined effects of air pollution and extreme temperature on PTB remain unclear. To evaluate the independent effect and interaction effect of prenatal extreme exposure to air quality index (AQI) and Humidex, on PTB. Based on the National Health Care Data Platform of Shandong University, women who gave birth in 2019-2020 were selected for the study. First, the independent effects of AQI and Humidex on PTB were assessed by logistic regression model. Subsequently, the interaction effects of AQI and Humidex on PTB were estimated separately by calculation of the relative excess risk of interaction (RERI). A total of 34365 pregnant women were included and 1975 subjects were diagnosed with PTB. We observed a significant increase in the odds of PTB associated with maternal high AQI exposure, with an OR of 1.70 (95% CI: 1.59, 1.81). Similarly, extreme exposure to Humidex also demonstrated an elevated PTB odds, with a low Humidex OR of 2.48 (95% CI: 2.23, 2.76) and a high Humidex OR of 1.48 (95% CI: 1.31, 1.67). Finally, we observed an interaction between high AQI and extreme Humidex during the 1st trimester. Interaction effects were noted between high AQI and low Humidex throughout the entire trimester and the 2nd trimester. This study suggests that prenatal exposure to high AQI and extreme Humidex could increase the odds of PTB, with effects exhibiting the sensitivity window and a cumulative trend. Additionally, there is an interaction between AQI and Humidex.

Relationship Between Outdoor Air Pollutant Exposure and Premature Delivery in China- Systematic Review and Meta-Analysis

Objective: Preterm birth (PTB) is considered as a public health problem and one of the main risk factors related to the global disease burden. The purpose of this study aims to explore the influence of exposure to major air pollutants at different pregnancies on PTB. Methods: The relationship between air pollutants and PTB in China was collected from cohort studies and case-control studies published before 30 April 2022. Meta-analysis was carried out with STATA 15.0 software. Results: A total of 2,115 papers were retrieved, of which 18 papers met the inclusion criteria. The comprehensive effect of pollutant exposure and PTB were calculated. PM2.5 during entire pregnancy and O3 exposure during third trimester were positively associated with preterm birth. Every 10 μg/m3 increase in the average concentration of PM2.5 during the whole pregnancy will increase the risk of premature delivery by 4%, and every 10 μg/m3 increase in the average concentration of O3 in the third trimester will increase the risk of premature delivery by 1%. Conclusion: Exposure to PM2.5 entire prenatal pregnancy and O3 in third trimester is associated with an increased risk of preterm birth occurrence.

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.