Associations of maternal ambient temperature exposures during pregnancy with the risk of preterm birth and the effect modification of birth order during the new baby boom: A birth cohort study in Guangzhou, China.

Maternal exposures to ambient temperatures during pregnancy may increase the preterm birth (PTB) risk; however, which periods have stronger effects remain controversial. The effects of temperature exposure on PTB in first- and second-born neonate groups may be different during the new baby boom that has followed the Two-child Policy in China. We examined a birth cohort of 4928 pregnant women beginning in 2016 in Guangzhou, China. An inverse distance weighted method was used to estimate the temperature exposure at each individual residential address. A distribution lag non-linear model incorporating a Cox proportional hazard model was employed to estimate the effects of temperature exposure on PTB and test the effects modification of birth order related to the new baby boom. A total of 4101 pregnant women were included, of which 234 (5.7%) experienced PTB. Compared with the mean temperature (23.0 °C), we found a significantly higher risks of PTB associated with high temperatures (i.e, 30 °C [95th centile]) from the 4th to 8th, and 22nd to 27th gestational weeks. A peak effect was found during the 6th week (HR = 1.79, 95% CI: 1.26, 2.54) and 24th week (HR = 1.83, 95% CI: 1.27, 2.62). The risks of PTB were reduced for low temperatures (i.e. 14 °C [5th centile] versus 23.0 °C) from the 2nd to 10th and 20th to 26th gestational weeks, and the negative peak effect was found during the 4th week (HR = 0.43, 95% CI: 0.26, 0.72) and 23rd week (HR = 0.59, 95% CI: 0.43, 0.83). Stratification analyses showed that significant effects of 30 °C versus 23 °C on PTB were observed during the 4th to 8th weeks in the second-born neonate, and the peak effect was found in the 6th week (HR = 2.13, 95% CI: 1.31, 3.47). However, we did not find significant effects of 30 °C during the same weeks in the first-born neonate group. Maternal exposures to higher temperatures during pregnancy may increase the risk of PTB, and lower temperatures may decrease the risk of PTB. Stronger effects of temperature exposures during the first trimester on PTB risk were found among the second-born neonates than among the first-born neonates.

Associations of maternal ozone exposures during pregnancy with maternal blood pressure and risk of hypertensive disorders of pregnancy: A birth cohort study in Guangzhou, China.

Although studies have assessed the associations of maternal exposure to ozone (O3) during pregnancy with blood pressure and the risk of hypertensive disorders of pregnancy (HDP), the results were inconsistent. Furthermore, no studies have been conducted in China where the ambient O3 concentration continuedly increased. The present study aimed to estimate the effects of maternal exposure to O3 during pregnancy on the HDP risk, systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse pressure (PP). All participants of pregnant women were selected from the prospective birth cohort study on Prenatal Environments and Offspring Health conducted in Guangzhou, China. A spatiotemporal land-use-regression model was used to estimate individual monthly air pollution exposure from three months before pregnancy to childbirth date. Information on HDP, SBP, DBP and PP was obtained from maternal medical records. A Logistic regression model and a mixed linear model were used to estimate the associations of maternal exposure to O3 with the risk of HDP and blood pressure (SBP, DBP and PP), respectively. We found significant associations of maternal exposure to O3 during the third (OR = 1.31, 95%CI: 1.07, 1.60) and the second month (OR = 1.25, 95%CI: 1.02, 1.51) before pregnancy with the risk of HDP. Observed significantly positive associations of O3 exposures with SBP, DBP and PP during the two months before pregnancy and during the early pregnancy. The peak effects of O3 exposure on SBP, DBP and PP were respectively observed during the second month of pregnancy (ß = 1.07  mmHg, 95%CI: 0.84, 1.31  mmHg), the first month before pregnancy (ß = 0.40  mmHg, 95%CI: 0.21, 0.50  mmHg) and the second month of pregnancy (ß = 0.78  mmHg, 95%CI: 0.59, 0.97  mmHg). Our results suggest that maternal exposure to O3 were positively associated with blood pressure and the risk of HDP, and the period from three months before pregnancy to the first trimester might be the critical exposure window.

Effects of prenatal exposure to air particulate matter on the risk of preterm birth and roles of maternal and cord blood LINE-1 methylation: A birth cohort study in Guangzhou, China.

BACKGROUND: Epidemiological studies have found that increased risk of preterm birth (PTB) is associated with higher prenatal exposure to PM10 and PM2.5, but few studies have been conducted to assess the impacts of extremely fine particulate matter (PM1) which may have more toxic effects than other types of ambient particulate air pollution (PM). Several studies have separately investigated the associations between DNA methylation and PTB risk and PM. Maternal LINE-1 methylation level negatively correlated with prenatal exposure to PM and risk of PTB. A comprehensive picture is lacking regarding the associations between prenatal exposure to PM, LINE-1 methylation, and risk of PTB. OBJECTIVES: This study aimed to estimate the effects of exposure to ambient PM (PM10, PM2.5, and PM1) of different sizes during pregnancy on risk of PTB, identify susceptible exposure windows, and illustrate the roles of LINE-1 methylation in the associations between PM and PTB risk. METHODS: The Birth Cohort Study on Prenatal Environments and Offspring Health (PEOH) has been ongoing since 2016 in Guangzhou, China. A total of 4928 pregnant women were recruited during early pregnancy, and 4278 (86.8%) were successfully followed-up. Each individual weekly exposure to PM10 and PM2.5 from 3 months before pregnancy to childbirth was assessed using a spatiotemporal land use regression model, and the weekly PM1 exposure was estimated by employing a generalized additive model. Maternal and cord blood LINE-1 methylation levels (%5mC) were tested using bisulfite-PCR pyrosequencing. A distributed lag nonlinear model incorporated with a Cox proportional hazard model was applied to assess the effect of weekly-specific maternal PM exposure on PTB risk, and a multiple-linear regression model was employed to investigate the associations between PM exposure and LINE-1 methylation levels of maternal and cord bloods. We also assessed the associations between LINE-1 methylation levels and PTB risk by using a logistic regression model. RESULTS: The risk of PTB was positively associated with PM2.5 and PM1 concentrations during the 12th to 20th gestational weeks, and the strongest association was in the fourth quartile (Q4) versus the first quartile (Q1) and observed during the 16th gestational week (PM2.5: harzard ratio [HR] = 1.18, 95%CI: 1.04-1.35, IQR = 11.94 µg/m3. PM1: HR = 1.20, 95%CI: 1.03-1.39, IQR = 11.36 µg/m3). We observed significantly negative associations of PM10(ß = -0.51%5mC per 10 µg/m3, P = 0.014), PM2.5 (ß = -0.66%5mC per 10 µg/m3, P = 0.032) and PM1 (ß = -0.67%5mC per 10 µg/m3, P = 0.032) concentrations with cord blood LINE-1 methylation levels, and a negative association between PM1 concentration and maternal LINE-1 methylation level (ß = -0.86%5mC per 10 µg/m3, P = 0.034). CONCLUSION: Higher prenatal exposure to PM1 and PM2.5 during the 12th to 20th gestational weeks was associated with increased risk of PTB. Maternal and fetal LINE-1 methylation alternation might be an underlying mechanism of PM that increasing the risk of PTB.

The associations of air pollution exposure during pregnancy with fetal growth and anthropometric measurements at birth: a systematic review and meta-analysis.

Fetal growth has been demonstrated to be an important predictor of perinatal and postnatal health. Although the effects of maternal exposure to air pollution during pregnancy on fetal growth have been investigated using ultrasound in many previous studies, the results were inconsistent and disputable. We aimed to qualitatively and quantitatively investigate the associations of air pollution exposure during different periods of pregnancy with fetal growth and anthropometric measurements at birth. We searched for all studies investigating the associations of air pollution exposure during pregnancy with fetal growth and birth anthropometric measurements in English and Chinese databases published before July 31, 2017. A random-effects model was employed in the meta-analysis to estimate the pooled effects of each 10 µg/m3 increment in air pollutant exposure. The ACROBAT-NRSI tool was applied to assess the quality of each included study, and the GRADE tool was employed to assess the overall quality of the meta-analysis. Maternal PM2.5 exposure (10 µg/m3) during the entire pregnancy was negatively associated with head circumference at birth (ß = - 0.30 cm, 95% CI - 0.49, - 0.10), and NO2 exposure during the entire pregnancy was significantly linked to shorter length at birth (ß = - 0.03 cm, 95% CI - 0.05, - 0.02). Maternal exposure to higher NO2 and PM2.5 during pregnancy may impair neonatal head circumference and length development, respectively. More studies are needed to confirm the effects of NO2 and PM2.5 and to identify the sources and major toxic components of PMs.

Modification Effects of Population Expansion, Ageing, and Adaptation on Heat-Related Mortality Risks Under Different Climate Change Scenarios in Guangzhou, China.

(1) Background: Although the health effects of future climate change have been examined in previous studies, few have considered additive impacts of population expansion, ageing, and adaptation. We aimed to quantify the future heat-related years of life lost (YLLs) under different Representative Concentration Pathways (RCP) scenarios and global-scale General Circulation Models (GCMs), and further to examine relative contributions of population expansion, ageing, and adaptation on these projections. (2) Methods: We used downscaled and bias-corrected projections of daily temperature from 27 GCMs under RCP2.6, 4.5, and 8.5 scenarios to quantify the potential annual heat-related YLLs in Guangzhou, China in the 2030s, 2060s, and 2090s, compared to those in the 1980s as a baseline. We also explored the modification effects of a range of population expansion, ageing, and adaptation scenarios on the heat-related YLLs. (3) Results: Global warming, particularly under the RCP8.5 scenario, would lead to a substantial increase in the heat-related YLLs in the 2030s, 2060s, and 2090s for the majority of the GCMs. For the total population, the annual heat-related YLLs under the RCP8.5 in the 2030s, 2060s, and 2090s were 2.2, 7.0, and 11.4 thousand, respectively. The heat effects would be significantly exacerbated by rapid population expansion and ageing. However, substantial heat-related YLLs could be counteracted by the increased adaptation (75% for the total population and 20% for the elderly). (4) Conclusions: The rapid population expansion and ageing coinciding with climate change may present an important health challenge in China, which, however, could be partially counteracted by the increased adaptation of individuals.

Changes of Ecosystem Service Value in a Coastal Zone of Zhejiang Province, China, during Rapid Urbanization.

Gains and losses in ecosystem service values (ESV) in coastal zones in Zhejiang Province during rapid urbanization were analyzed in terms of land-use changes. Decision-making on coastal development based on ESV estimation is significant for the sustainable utilization of coastal resource. In this study, coastal land-use changes in Zhejiang Province during rapid urbanization were discussed based on remote-sensing derived land-use maps created in the years 1990, 2000 and 2010. The ESV changes in coastal zones in Zhejiang Province from 1990 to 2010 were estimated by using the established ESV estimation model. The analysis results demonstrate the following: (1) with the continuous acceleration of urbanization, land-use types in coastal zones in Zhejiang Province changed significantly from 1990 to 2010, demonstrated by considerable growth of urban construction land and reduction of forest land and farmland; (2) in the study period, the total ESV in coastal zones in Zhejiang Province continuously decreased in value from RMB 35.278 billion to 29.964 billion, a reduction of 15.06%; (3) in terms of the spatial distribution of ESV, the ESVs in coastal zones in Zhejiang Province were generally converted from a higher ESV to a lower ESV; (4) estimates of ESV for the three years 1990, 2000 and 2010 appear to be relatively stable; and (5) land-use intensity in coastal zones in Zhejiang Province continuously increased during the 20 years. The spatial distribution of land-use intensity was consistent with that of the ESV change rate. Disordered land-use changes from forestland and farmland to urban construction land was a major cause of ESV loss.

Tempo-Spatial Variations of Ambient Ozone-Mortality Associations in the USA: Results from the NMMAPS Data.

Although the health effects of ambient ozone have been widely assessed, their tempo-spatial variations remain unclear. We selected 20 communities (ten each from southern and northern USA) based on the US National Morbidity, Mortality, and Air Pollution Study (NMMAPS) dataset. A generalized linear model (GLM) was used to estimate the season-specific association between each 10 ppb (lag0-2 day average) increment in daily 8 h maximum ozone concentration and mortality in every community. The results showed that in the southern communities, a 10 ppb increment in ozone was linked to an increment of mortality of -0.07%, -0.17%, 0.40% and 0.27% in spring, summer, autumn and winter, respectively. For the northern communities, the excess risks (ERs) were 0.74%, 1.21%, 0.52% and -0.65% in the spring, summer, autumn and winter seasons, respectively. City-specific ozone-related mortality effects were positively related with latitude, but negatively related with seasonal average temperature in the spring, summer and autumn seasons. However, a reverse relationship was found in the winter. We concluded that there were different seasonal patterns of ozone effects on mortality between southern and northern US communities. Latitude and seasonal average temperature were identified as modifiers of the ambient ozone-related mortality risks.

Associations of Short-Term and Long-Term Exposure to Ambient Air Pollutants With Hypertension: A Systematic Review and Meta-Analysis.

Hypertension is a major disease of burden worldwide. Previous studies have indicated that air pollution might be a risk factor for hypertension, but the results were controversial. To fill this gap, we performed a meta-analysis of epidemiological studies to investigate the associations of short-term and long-term exposure to ambient air pollutants with hypertension. We searched all of the studies published before September 1, 2015, on the associations of ozone (O3), carbon monoxide (CO), nitrogen oxide (NO2 and NOX), sulfur dioxide (SO2), and particulate matter (PM10 and PM2.5) with hypertension in the English electronic databases. A pooled odds ratio (OR) for hypertension in association with each 10 µg/m(3) increase in air pollutant was calculated by a random-effects model (for studies with significant heterogeneity) or a fixed-effect model (for studies without significant heterogeneity). A total of 17 studies examining the effects of short-term (n=6) and long-term exposure (n=11) to air pollutants were identified. Short-term exposure to SO2 (OR=1.046, 95% confidence interval [CI]: 1.012-1.081), PM2.5 (OR=1.069, 95% CI: 1.003-1.141), and PM10 (OR=1.024, 95% CI: 1.016-1.032) were significantly associated with hypertension. Long-term exposure (a 10 µg/m(3) increase) to NO2 (OR=1.034, 95% CI: 1.005-1.063) and PM10 (OR=1.054, 95% CI: 1.036-1.072) had significant associations with hypertension. Exposure to other ambient air pollutants (short-term exposure to NO2, O3, and CO and long-term exposure to NOx, PM2.5, and SO2) also had positive relationships with hypertension, but lacked statistical significance. Our results suggest that short-term or long-term exposure to some air pollutants may increase the risk of hypertension.