Characterizing the emission trends and pollution evolution patterns during the transition period following COVID-19 at an industrial megacity of central China.

After the resumption of work and production following the COVID-19 pandemic, many cities entered a "transition phase", characterized by the gradual recovery of emission levels from various sources. Although the overall PM2.5 emission trends have recovered, the specific changes in different sources of PM2.5 remain unclear. Here, we investigated the changes in source contributions and the evolution pattern of pollution episodes (PE) in Wuhan during the "transition period" and compared them with the same period during the COVID-19 lockdown. We found that vehicle emissions, industrial processes, and road dust exhibited significant recoveries during the transition period, increasing by 5.4%, 4.8%, and 3.9%, respectively, during the PE. As primary emissions increased, secondary formation slightly declined, but it still played a predominant role (accounting for 39.1∼ 43.0% of secondary nitrate). The reduction in industrial activities was partially offset by residential burning. The evolution characteristics of PE exhibited significant differences between the two periods, with PM2.5 concentration persisting at a high level during the transition period. The differences in the evolution patterns of the two periods were also reflected in their change rates at each stage, which mostly depend on the pre-PE concentration level. The transition period shows a significantly higher value (8.4 µg m-3 h-1) compared with the lockdown period, almost double the amount. In addition to local emissions, regional transport should be a key consideration in pollution mitigation strategies, especially in areas adjacent to Wuhan. Our study quantifies the variations in sources between the two periods, providing valuable insights for optimizing environmental planning to achieve established goals.

[Fe(NCMe)6](BF4)2 is a bifunctional catalyst for styrene aziridination by nitrene transfer and heterocycle expansion by subsequent dipolar insertion.

The solvated iron(II) salt [Fe(NCMe)6](BF4)2 (Me = methyl) is shown to be a bifunctional catalyst with respect to aziridination of styrene. The salt serves as an active catalyst for nitrene transfer from PhINTs to styrene to form 2-phenyl-N-tosylaziridine (Ph = phenyl; Ts = tosyl, -S{O}2-p-C6H4Me). The iron(II) salt also acts as a Lewis acid in non-coordinating CH2Cl2 solution, to catalyze heterolytic CN bond cleavage of the aziridine and insertion of dipolarophiles. The 1,3-zwitterionic intermediate is presumably supported by interaction of the metal dication with the anion, and by resonance stabilization of the carbocation. Nucleophilic dipolarophiles then insert to give a five-membered heterocyclic ring. The result is a two-step cycloaddition, formally [2 + 1 + 2], that is typically regiospecific, but not stereospecific. This reaction mechanism was confirmed by conducting a series of one-step, [3 + 2] additions of unsaturated molecules into pre-formed 2-phenyl-N-tosylaziridine, also catalyzed by [Fe(NCMe)6](BF4)2. Relevant substrates include styrenes, carbonyl compounds and alkynes. These yield five-membered heterocylic rings, including pyrrolidines, oxazolidines and dihydropyrroles, respectively. The reaction scope appears limited only by the barrier to formation of the dipolar intermediate, and by the nucleophilicity of the captured dipolarophile. The bifunctionality of an inexpensive, earth-abundant and non-toxic catalyst suggests a general strategy for one-pot construction of heterocyclic rings, as demonstrated specifically for pyrrolidine ring formation.

Assessing the dry impinger method for condensable particulate matter from ultra-low emission coal-fired power plant measurement.

The dry impinger method is commonly used for the determination of condensable particulate matter (CPM) emissions. The coil and chamber condenser is used to build different dry impinger methods for CPM sampling. The comparative analysis of coil and chamber condenser is performed in a laboratory experiment to evaluate the deviation caused by SO2. Results showed that the positive deviation caused by SO2 in the chamber condenser is lower than that in the coil condenser under the same sampling conditions, especially under high humidity flue gas. The CPM emission characteristics from Hanchuan coal-fired power plant (CFPP) determined by both dry impinger methods are also investigated as well. The CPM and its most water-soluble ions (e.g., F-, Cl-, NO3-, SO42-, Na+, Ca2+ and NH4+) measured by method #2 (chamber condenser) are higher than that of method #1 (coil condenser). In addition, the esters in the CPM also increased with the CPM concentrations. Based on above evidences, it can be inferred that the dry impinger method with chamber condenser, will be recommended as the appropriate method for measuring CPM emitted from stationary sources, especially under the high humidity flue gas conditions.

[Effect of WESP on Emission Characteristics of Condensable Particulate Matter from Ultra-low Emission Coal-fired Power Plants].

In order to study the effect of wet electrostatic precipitators(WESP) on emission characteristics of condensable particulate matter (CPM) from ultra-low emission coal-fired power plants that are under different capacity conditions, a set of CPM sampling devices was built based on US EPA Method 202, and an ultra-low emission coal-fired power plant was detected. This study evaluated the emission level of the CPM from the flue gas of coal-fired power plants, the effects of different unit capacity conditions on the CPM emission concentrations, and the removal efficiency of WESP for different components of the CPM. The results suggested that the emission concentrations of the CPM from ultra-low emission power plants were 27.27 mg·m-3 and 28.71 mg·m-3under the conditions of 75% and 100% capacity, respectively. The removal efficiencies of WESP for the CPM were 35.59% and 27.59%, respectively. SO42- was the main component of water-soluble ions of the CPM. The proportion of SO42- in inorganic components of the CPM reached more than 65% under different capacity conditions. In addition, the removal efficiency of WESP for Cl-, K+, Ca2+, Mg2+, Na+, and other inorganic ions reached 30%-50%, but the mass concentrations of SO42- and NO3- increased.

Development of an E. coli strain for cell-free ADC manufacturing.

Recent advances in cell-free protein synthesis have enabled the folding and assembly of full-length antibodies at high titers with extracts from prokaryotic cells. Coupled with the facile engineering of the Escherichia coli translation machinery, E. coli based in vitro protein synthesis reactions have emerged as a leading source of IgG molecules with nonnatural amino acids incorporated at specific locations for producing homogeneous antibody-drug conjugates (ADCs). While this has been demonstrated with extract produced in batch fermentation mode, continuous extract fermentation would facilitate supplying material for large-scale manufacturing of protein therapeutics. To accomplish this, the IgG-folding chaperones DsbC and FkpA, and orthogonal tRNA for nonnatural amino acid production were integrated onto the chromosome with high strength constitutive promoters. This enabled co-expression of all three factors at a consistently high level in the extract strain for the duration of a 5-day continuous fermentation. Cell-free protein synthesis reactions with extract produced from cells grown continuously yielded titers of IgG containing nonnatural amino acids above those from extract produced in batch fermentations. In addition, the quality of the synthesized IgGs and the potency of ADC produced with continuously fermented extract were indistinguishable from those produced with the batch extract. These experiments demonstrate that continuous fermentation of E. coli to produce extract for cell-free protein synthesis is feasible and helps unlock the potential for cell-free protein synthesis as a platform for biopharmaceutical production.

Nonlinear response of SIA to emission changes and chemical processes over eastern and central China during a heavy haze month.

This study used a chemical transport model to investigate the response of secondary inorganic aerosols (SIA) to chemical processes and its precursor emissions over northern and southern city-clusters of China in January 2014. Unexpectedly, SIA concentrations with low levels of precursor emissions were much higher over the southern regions than those over the northern region with high levels of precursor emissions, based on ground observations and high-precision simulations. The sensitivity analysis of chemical processes suggests that the gas-phase chemistry was a critical factor determining the SIA pattern, especially the higher efficiency of nitrogen conversion to nitrate in southern cities controlled by favorable meteorological elements than that in northern city. However, the heterogeneous process led to the decrease of SIA in southern regions by 3% to 36% and the increasing of SIA in NCP by 26.9%, mainly attributing to the impact on nitrate. The reason was that sulfate enhancement by the heterogeneous reactions can compete ammonia (NH3) and the excessive nitric acid converted into nitrogen oxide (NOx), leading to nitrate decrease in southern regions under NH3-deficient regimes. Moreover, through sensitivity experiments of precursor emission reduction by 20%, NH3 control was found to be the most effective for reducing SIA concentrations comparing to sulfur dioxide (SO2) and NOx reduction and a more remarkable decrease of SIA was in southern regions by 10% to 15% than that in northern region by 6.7%. The effect of the synergy control of precursors emission varied in different city-clusters, inferring that the control strategy aimed at improving air quality should be implemented based on specific characteristics of precursors emission in different regions of China.

A Spatial-Temporal Resolved Validation of Source Apportionment by Measurements of Ambient VOCs in Central China.

Understanding the sources of volatile organic compounds (VOCs) is essential in the implementation of abatement measures of ground-level ozone and secondary organic aerosols. In this study, we conducted offline VOC measurements at residential, industrial, and background sites in Wuhan City from July 2016 to June 2017. Ambient samples were simultaneously collected at each site and were analyzed using a gas chromatography-mass spectrometry/flame ionization detection system. The highest mixing ratio of total VOCs was measured at the industrial site, followed by the residential, and background sites. Alkanes constituted the largest percentage (>35%) in the mixing ratios of quantified VOCs at the industrial and residential sites, followed by oxy-organics and alkenes (15-25%).The values of aromatics and halohydrocarbons were less than 15%. By contrast, the highest values of oxy-organics accounted for more than 30%. The model of positive matrix factorization was applied to identify the VOC sources and quantify the relative contributions of various sources. Gasoline-related emission (the combination of gasoline exhaust and gas vapor) was the most important VOC-source in the industrial and residential areas, with a relative contribution of 32.1% and 40.4%, respectively. Industrial process was the second most important source with a relative contribution ranging from 30.0% to 40.7%. The relative contribution of solvent usage was 6.5-22.3%. Meanwhile, the relative contribution of biogenic emission was only within the range of 2.0-5.0%. These findings implied the importance of controlling gasoline-related and industrial VOC emissions in reducing the VOC emissions in Wuhan.

Effect of residential exposure to green space on maternal blood glucose levels, impaired glucose tolerance, and gestational diabetes mellitus.

BACKGROUND: Residential surrounding green spaces can affect human health. However, limited studies have examined their impacts on maternal blood glucose homeostasis outcomes. OBJECTIVE: We examined the associations of residential exposure to green space with maternal blood glucose levels, gestational impaired glucose tolerance (IGT), and gestational diabetes mellitus (GDM). METHODS: Pregnant women were recruited from a prospective birth cohort between October 2012 and September 2015. Exposure to green space was calculated as the mean value of the normalized difference vegetation index (NDVI) within a 300-m circular buffer area surrounding each residence. Maternal glucose was measured between 24 and 28 weeks of gestation, and gestational IGT and GDM were diagnosed using valid methods. We estimated the associations of residential NDVI with maternal glucose levels using multiple linear regression models with adjustment for age, education, BMI, passive smoking during pregnancy, parity, season of conception, income, and urbancity. We estimated the relative risks of residential NDVI with IGT and GDM using a generalized estimating equation model with modified Poisson regression. The mediation effects of residential exposure to air pollution and maternal physical activity were assessed using causal mediation analysis. RESULTS: Of 6807 pregnant women, 751 (11.3%) and 604 (8.8%) were diagnosed with IGT and GDM, respectively. One SD increment of residential NDVI was associated with a decrease of 0.06 mmol/L (95% CI: -0.07, -0.05), 0.09 mmol/L (95% CI: -0.13, -0.05), and 0.06 mmol/L (95% CI: -0.09, -0.03) in maternal fasting glucose levels, 1-h glucose levels, and 2-h glucose levels, respectively, as well as reduced risks of incident IGT (RR: 0.92, 95% CI: 0.86, 0.99) and GDM (RR: 0.85, 95% CI: 0.79, 0.92). The association between residential NDVI and maternal fasting glucose levels was partly mediated by maternal exposure to PM2.5. CONCLUSION: Living with higher levels of green space was significantly associated with decreased maternal glucose levels and attenuated risks of incident maternal IGT and GDM. Our findings provide evidence linking green space to better maternal glucose outcomes. More studies are needed to further explore the maternal and child health benefits related to our findings.

Residential exposure to green space and early childhood neurodevelopment.

BACKGROUND: A few studies reported that exposure to high levels of residential surrounding green spaces was associated with better cognitive development in primary school children. However, no studies have been conducted to examine such association in early childhood. OBJECTIVES: We investigated the association between residential exposure to green space and early childhood neurodevelopment, and further explored the mediation effects of traffic-related air pollution and maternal physical activity on this association. METHODS: We enrolled 1312 pregnant women between January 2012 and October 2015 and their children were followed up until an age of 2 years. We measured residential exposure to green space by calculating averaged normalized difference vegetation index (NDVI) within a 300 meter buffer area surrounding residential address at birth. The neurodevelopment, which included mental development index (MDI) and psychomotor development index (PDI), was assessed using Bayley Scales of Infant Development for each child at about 24 months. The associations of residential exposure to NDVI with early childhood MDI score and PDI score were evaluated using multiple linear regression models. The mediation effects of traffic-related air pollution and maternal physical activities on those associations were estimated by causal mediation analyses. RESULTS: Exposure to higher levels of residential surrounding green spaces was associated with increased early childhood PDI score (adjusted changes for one SD increment of NDVI: 3.28 (95% CI: 2.15, 4.41)) and MDI score (adjusted changes for one SD increment of NDVI: 1.97 (95% CI: 0.63, 3.30). These associations were more pronounced in children of mothers whose pre-pregnancy BMI were lower than 24 kg/m2. Further mediation analyses indicated that reduced levels of traffic-related air pollution explained 13.6% to 28.0% of the association between exposure to green space and early childhood PDI score. CONCLUSION: Exposure to higher levels of residential surrounding green spaces was associated with better early childhood neurodevelopment. The association between exposure to green space and early childhood psychomotor development might be partly explained by reduced levels of traffic-related air pollution.

Prenatal exposure to fine particulate matter, maternal hemoglobin concentration, and fetal growth during early pregnancy: associations and mediation effects analysis.

BACKGROUND: Fetal essential organ development is completed during early pregnancy which is important for fetal and postnatal health. However, the effect of exposure to PM2.5 on fetal growth during early pregnancy is less studied and the related mechanisms are largely unknown. METHODS: We conducted a birth cohort study of 1945 pregnant women with measurement of the fetal crown to rump length (CRL) by ultrasound between the gestational age of 11 and 14 weeks. We estimated residential exposures of PM2.5 from the date of LMP to the date of ultrasound examination using a spatial-temporal land use regression model. Maternal hemoglobin concentration was examined by maternal blood samples during the same gestational period or ±1 week of the ultrasound examination. The associations of exposure to PM2.5 with maternal hemoglobin concentration, and exposure to PM2.5 with fetal CRL during early pregnancy were estimated by multiple linear regression models. The mediation effect of maternal hemoglobin concentration on the association between exposure to PM2.5 and fetal CRL was explored by a casual mediation analysis. RESULTS: One IQR increment of prenatal exposure to PM2.5 was associated with a 0.929 g/L (95% CI: 0.068, 1.789) increase in maternal hemoglobin concentration, and associated with a -0.082 cm (95% CI: 0.139, -0.025) decrease in fetal CRL. One g/L increment of maternal hemoglobin concentration was associated a -0.011 cm (95% CI: 0.014, -0.008) decrease in fetal CRL. The mediation analysis indicated that 12.1% of the total effect of prenatal exposure to PM2.5 on reducing fetal CRL was mediated by increased maternal hemoglobin concentration. CONCLUSION: Exposure to PM2.5 was associated with reduced fetal growth during early pregnancy and elevated maternal hemoglobin concentration mediated this association.

Exposure to ambient fine particulate matter during pregnancy and gestational weight gain.

BACKGROUND: Gestational weight gain (GWG) is increasingly reported to be associated with adverse birth outcomes. However, the effect of PM2.5 exposure during pregnancy on GWG is unknown. OBJECTIVES: We investigated the associations between the exposure to PM2.5 and GWGs during three pregnancy trimesters based on a prospective birth cohort. METHODS: Data were obtained from 2029 pregnant women who participated in a birth cohort between January 2013 and October 2014 in Wuhan, China. A spatial-temporal land use regression model was used to estimate the trimester and overall pregnancy exposures of PM2.5 of each pregnant woman. The relationships between PM2.5 exposure and GWG were estimated using linear mixed models. RESULTS: The median value of GWG was 2.0 kg (interquartile range (IQR): 4.0) in the first trimester, 6.5 kg (IQR: 3.5) in the second trimester, and 7.0 kg (IQR: 3.5) in the third trimester, respectively. The exposure to PM2.5 was peaked in the first trimester (median concentration: 117.3 µg/m3 (IQR: 71.9)). After adjustment for potential confounders, each 10 µg/m3 increase in PM2.5 was consistently associated with increases in GWG in overall pregnancy (0.14 kg, 95% confidence interval (CI): 0.12, 0.17), the first (0.15 kg, 95%CI: 0.12, 0.18), second (0.15 kg, 95%CI: 0.10, 0.19) and third trimester (0.13 kg, 95%CI: 0.09, 0.17). Further stratified analysis indicated that pregnant women who delivered in spring or summer gained more body weight associated with PM2.5 exposure. CONCLUSIONS: This study provides evidence on the effect of exposure to PM2.5 on GWG and it is the first report on the importance of reducing the ambient PM2.5 in controlling of GWG in pregnant women.

Maternal exposure to ambient air pollutant and risk of oral clefts in Wuhan, China.

Maternal exposure to ambient air pollution has been related to oral clefts in offspring; however, the epidemiologic evidence is equivocal. Especially, the association between high levels of exposure to ambient air pollution during pregnancy and oral clefts remains unclear. The objective of this study was to evaluate whether high levels of maternal exposure to PM2.5, PM10, O3, CO and SO2 are related to increased risk of oral clefts in Wuhan, China. A population-based study was conducted using cohort of 105,927 live-born infants, fetal deaths, and stillbirths during a two-year period from 2011 to 2013. For each participant, weekly and monthly averages of daily mean concentrations for each pollutant were estimated. Multiple logistic regression analyses were constructed to quantify the adjusted odds ratios (aORs) for the relationship between each air pollutant and oral clefts while controlling for key covariates. Using monthly averages, a cleft lip with or without cleft palate (CLP) was associated with PM2.5 (aORs 2nd month = 1.34, CI:1.19-1.49; aORs 3rd month=1.14, CI:1.02-1.28), PM10 (aORs 2nd month = 1.11, CI:1.00-1.23) and CO (aORs 2nd month = 1.31, CI:1.14-1.51; aORs 3rd month = 1.17, CI:1.03-1.33). A cleft palate only (CPO) was associated with PM2.5 (aORs 2nd month = 1.24, CI: 1.03-1.48), and O3 (aORs 2nd month = 1.21, CI: 1.03-1.42; aORs 3rd month = 1.18, CI: 1.02-1.37). Our findings reveal an association between air pollutants exposure and the risk of oral clefts. Future studies are needed to confirm these associations, and clarify the causality related to specific pollutants during the most relevant vulnerable exposure time windows for oral clefts during pregnancy.

Association between prenatal care utilization and risk of preterm birth among Chinese women.

It is recognized that prenatal care plays an important role in reducing adverse birth. Chinese pregnant women with medical condition were required to seek additional health care based on the recommended at least 5 times health care visits. This study was to estimate the association between prenatal care utilization (PCU) and preterm birth (PTB), and to investigate if medical conditions during pregnancy modified the association. This population-based case control study sampled women with PTB as cases; one control for each case was randomly selected from women with term births. The Electronic Perinatal Health Care Information System (EPHCIS) and a questionnaire were used for data collection. The PCU was measured by a renewed Prenatal Care Utilization (APNCU) index. Logistic regression models were used to estimate odds ratios (OR) and the 95% confidence interval (95% CI). Totally, 2393 women with PTBs and 4263 women with term births were collected. In this study, 695 (10.5%) women experienced inadequate prenatal care, and 5131 (77.1%) received adequate plus prenatal care. Inadequate PCU was associated with PTB (adjusted OR: 1.41, 95% CI: 1.32-1.84); the similar positive association was found between adequate plus PCU and PTB. Among women with medical conditions, these associations still existed; but among women without medical conditions, the association between inadequate PCU and PTB disappeared. Our data suggests that women receiving inappropriate PCU are at an increased risk of having PTB, but it does depend on whether the woman has a medical condition during pregnancy.

Source tagging modeling study of heavy haze episodes under complex regional transport processes over Wuhan megacity, Central China.

Wuhan as a megacity of Central China was suffering from severe particulate matter pollution according to previous observation studies, however, the mechanism behind the pollution formation especially the impact of regional chemical transport is still unclear. This study, carried out on the Nested Air Quality Prediction Modeling System (NAQPMS) coupled with an on-line source-tagging module, explores different roles regional transport had in two strong haze episodes over Wuhan in October 2014 and quantitatively assesses the contributions from local and regional sources to PM2.5 concentration. Validation of predictions based on observations shows modeling system good skills in reproducing key meteorological and chemical features. The first short-time haze episode occurred on 12 October under strong northerly winds, with a hourly PM2.5 peak of 180 µg m-3, and was found to be caused primarily by the long-range transport from the northern regions, which contributed 60.6% of the episode's PM2.5 concentration (versus a total of 32.7% from sources in and near Wuhan). The second episode lasted from the 15-20 October under stable regional large-scale synoptic conditions and weak winds, and had an hourly PM2.5 peak of 231.0 µg m-3. In this episode, both the long-distance transport from far regions and short-range transport from the Wuhan-cluster were the primary causes of the haze episode and account for 24.8% and 29.2% of the PM2.5 concentration respectively. Therefore, regional transport acts as a crucial driver of haze pollution over Wuhan through not only long-range transfer of pollutants, but also short-range aerosol movement under specific meteorological conditions. The present findings highlight the important role of regional transport in urban haze formation and indicate that the joint control of multi city-clusters are needed to reduce the particulate pollution level in Wuhan.

Symptoms of anxiety and depression during pregnancy and their association with low birth weight in Chinese women: a nested case control study.

This study is a nested case control study from a population-based cohort study conducted in Wuhan, China. The aim is to estimate the association between symptoms of depression during pregnancy (DDP), anxiety during pregnancy(ADP), and depression with anxiety during pregnancy (DADP) and low birth weight (LBW) and to examine the extent to which preterm birth (PTB) moderates these associations. Logistic regression analyses were used to model associations between DDP, ADP, and DADP and LBW. Models were stratified by the presence or absence of PTB to examine moderating effects. From the cohort study, 2853 had a LBW baby (cases); 5457 pregnant women served as controls. Women with DDP or ADP only were not at higher risk of having a LBW baby, but DADP was associated with increased risk of LBW (crude OR 1.41, 95% CI 1.17-1.70; adjusted OR 1.29, 95% CI 1.07-1.57), and the significant association was particularly evident between DADP and LBW in PTB, but not in full-term births. Our data suggests that DADP is related to an increased risk of LBW and that this association is most present in PTBs.

Ozone and Other Air Pollutants and the Risk of Congenital Heart Defects.

The objective of this study was to evaluate whether high levels of maternal exposure to O3, SO2, NO2, CO are related to increased risk of congenital heart defects (CHDs) in Wuhan, China. The study included mothers living in the central districts of Wuhan during pregnancy over the two-year period from June 10, 2011 to June 9, 2013. For each study participant, we assigned 1-month averages of O3, SO2, NO2 and CO exposure based on measurements obtained from the nearest exposure monitor to the living residence of mothers during their early pregnancy period. In one-pollutant model, we observed an increased risk of CHDs, ventricular septal defect (VSD), and tetralogy of fallot (TF) with increasing O3 exposure. In two-pollutant model, associations with all CHDs, VSD, and TF for O3 were generally consistent compared to the models that included only O3, with the strongest aORs observed for exposures during the third month of pregnancy. We also observed a positive association between CO exposures during the third month of pregnancy and VSD in two pollution model.Our results contribute to the small body of evidence regarding air pollution exposure and CHDs, but confirmation of these associations will be needed in future studies.

Maternal Prepregnancy Body Mass Index and Small for Gestational Age Births in Chinese Women.

BACKGROUND: Both high and low prepregnancy body mass index (BMI) has been associated with small for gestational age births (SGA; birthweight below the population specific 10th centile for the gestational age), but results remain inconsistent. We examined the association between maternal BMI and SGA, and evaluated if the associations were modified by preterm birth (being born prior to 37 weeks) status. METHODS: A population-based cohort study was conducted in Wuhan, China from June 2011, to June 2013. Women who delivered a non-malformed livebirth (n = 76 695) were included using the Wuhan Maternal and Child Health Management Information System. Log-binomial regression models were used to analyse the associations between prepregnancy BMI, categorized using thresholds adapted to the Chinese population, and SGA. Stratified analyses were used to examine the relationship of prepregnancy BMI to preterm-SGA and term-SGA. RESULTS: Of the 76 695 live births, 3058 (4.0%) were delivered preterm. For babies born at term, prepregnancy underweight (<18.5 kg/m2 ) was associated with an increased risk of SGA, the adjusted risk ratio (RR) was 1.41 (95% confidence interval (CI) 1.33, 1.49), whereas, being overweight (24.0-27.9 kg/m2 ) was associated with a decreased risk (RR 0.84, 95% CI 0.74, 0.94). For babies born preterm, prepregnancy underweight was not associated with risk of SGA, but being overweight was associated with an increased risk (RR 1.57, 95% CI 1.04, 2.35). CONCLUSIONS: These data suggest that the association of overweight and underweight prepregnancy BMI and SGA differs depending on whether the baby is full term or preterm.

Relationship Between Common Mental Disorder Symptoms During Pregnancy and Preterm Birth Among Chinese Women in Wuhan.

Objectives Few studies focus on the symptoms of common mental disorders during pregnancy (CMDP) and risk of preterm birth subtypes (PTB). The purpose of this study was to estimate the association between CMDP and PTB, and to examine whether or not the association between CMDP and PTB varies with the subtype of PTB in Chinese. Methods This population-based case control study, conducted in Wuhan, China, defined cases as every pregnant woman who had a PTB among all births in Wuhan, from June 10, 2011, to June 9, 2013. The same number of pregnant women who had term births was randomly selected as controls. The Electronic Perinatal Health Care Information System, a questionnaire designed for the study, provided data about the participants. Logistic regression analyses were used to model associations between CMDP and PTB, and to test associations between CMDP and two subtypes of PTB. Results The study recruited 8616 cases and an equal number of controls. We successfully collected maternal information on 6656 cases and controls for a response rate of 77.3 %. The incidence of PTB in Wuhan was 4.5 %. Spontaneous preterm births (SPTB) accounted for 60.1 %, and medically induced preterm births (IPTB) accounted for 39.9 % of preterm births. The prevalence rate of CMDP was 15.8 %. CMDP was slightly associated with PTB (crude OR 1.16, 95 % CI 1.01-1.32; adjusted OR 1.15, 95 % CI 1.00-1.32), further analyses showed CMDP was associated with IPTB (aOR 1.25, 95 % CI 1.04-1.50), but not with SPTB. Conclusion Our data suggest that CMDP is related to an increased risk of PTB, and that this association is primarily due to IPTB rather than SPTB.

Maternal exposure to air pollutant PM2.5 and PM10 during pregnancy and risk of congenital heart defects.

Maternal exposure to ambient air pollution has increasingly been linked to congenital heart defects (CHDs). The objective of this study was to evaluate whether high levels of maternal exposure to PM2.5 and PM10 are related to increased risk of CHDs in Wuhan, China. We conducted a cohort study with a total of 105,988 live-born infants, stillbirths, and fetal deaths. The study included mothers living in the urban district of Wuhan during pregnancy over the 2-year period from 10 June 2011 to 9 June 2013. For each study participant, we assigned 1-month and 1-week averages of PM10 and PM2.5 exposure based on measurements obtained from the nearest exposure monitor to the living residence of mothers during their early pregnancy period. Logistic regression analyses were conducted to calculate the adjusted odds ratios (aORs) and 95% confidence intervals (CI) for the association between exposure to these ambient air pollutants during early pregnancy and CHDs. We observed an increased risk of CHDs, particularly ventricular septal defect (VSD), with increasing PM2.5 exposure. Using 1-week averages, we also observed significant monotonically increasing associations between PM2.5 exposure during weeks 7-10 of pregnancy and risk of VSD, with aORs ranging from 1.11 to 1.17 (95% CI: 1.02-1.20, 1.03-1.22, 1.05-1.24, and 1.08-1.26 separately) per a 10 µg/m(3) change in PM2.5 concentration. Our study contributes to the small body of knowledge regarding the association between in utero exposure to air pollution and CHDs, but confirmation of these associations will be needed in future studies.

Ambient Air Pollution and Adverse Pregnancy Outcomes in Wuhan, China.

Background: Several recent studies have suggested that maternal exposures to air pollution and temperature extremes might contribute to low birth weight (LBW), preterm birth (PTB), and other outcomes that can adversely affect infant health. At the time the current study began, most other studies had been conducted in the United States or Europe. Dr. Zhengmin Qian proposed to extend work he had done on ambient particulate air pollution and daily mortality in Wuhan, China (Qian et al. 2010), as part of the HEIsponsored Public Health and Air Pollution in Asia program, to study adverse birth outcomes. Wuhan is the capital city of Hubei province, has a large population of about 6.4 million within the urban study area, experiences temperature extremes, and generally has higher air pollution levels than those observed in the United States and Europe, thus providing a good opportunity to explore questions about air pollution and health. Approach: Qian and colleagues planned a cohort and nested case­control design with four specific aims, examining whether increased exposures to air pollutants (PM2.5, PM10, SO2, NO2, O3, and CO) during vulnerable pregnancy periods were associated with increased rates of PTB, LBW (<2500 g), or intrauterine growth retardation (IUGR, defined as having a birth weight below the 10th percentile of singleton live births in Wuhan) after adjusting for major risk factors and whether the associations were confounded by copollutant exposures, affected by residual confounding, or modified by temperature extremes, socioeconomic status (SES), or secondhand smoke (SHS) exposure. The cohort study included 95,911 births that occurred from June 10, 2011, to June 9, 2013, and met typical prespecified inclusion criteria used in other birth outcome studies. The case­control study included 3146 cases (PTB, LBW, or both, but not IUGR) and 4263 controls (matched to the cases by birth month) for whom investigators were able to complete home visits and questionnaires. The investigators obtained air pollution and daily weather data for August 2010 to June 2013 from nine monitoring stations representing background air pollution sites in seven Wuhan inner-city districts. Only two of these stations provided PM2.5 data. For the cohort study, the investigators assigned exposures to mothers according to the daily mean concentrations from the monitor nearest the residential community in which the mother lived at the time of the birth. For the case­control study, they assigned exposures based on the inverse distance weighted average of daily mean concentrations from the three nearest monitors, for all but PM2.5 for which the method was not specified. They also collected data on various factors that might confound or modify the impact of the pollutants on the adverse outcomes, including data collected in the cohort from mothers at the time of delivery and, in the case­control study, from questionnaires administered to mothers. In the case­control study, covariates representing SES (as indicated by the mother's educational attainment and household income) and SHS exposures were of particular interest. The primary statistical analyses of the pollutant associations with PTB, LBW, and IUGR were conducted using logistic regression models. In the cohort study, exposures during the pregnancy period of interest (full term, trimesters, and selected months) were included as continuous variables. In the case­control study, the exposures were modeled as binary variables (i.e., above or below the median pollutant concentrations). Numerous sensitivity analyses were conducted. Results and interpretation: Although originally planning a nested case­control study, the investigators encountered challenges that led them to analyze the cohort and case­control studies using different ways of assigning exposures and characterizing them in their statistical models. These decisions precluded direct comparisons between the sets of results, making it difficult to answer the questions about residual confounding that nested case­control studies are designed to answer. The odds ratios from the two study designs using different exposures also have different interpretations. Still, one can ask whether the sets of findings were qualitatively consistent with each other or with those of similar studies. There were some similarities. Both studies suggested that increased PM(2.5), PM(10), CO, and O(3) exposures over the full pregnancy were associated with small increases in the odds of PTB (the case­control study also showed an association with NO2) and that increased PM(2.5) exposures were associated with significantly increased odds of LBW. However, most of the other pollutants had no effect on LBW, except CO in the cohort study and O(3) in the case­control study, both of which increased the odds of LBW. The exposures over the entire pregnancy were generally associated with decreased odds of IUGR. Adjustments for potential confounders were greatest for the delivery covariates. The investigators found no systematic association of any of these outcomes with particular trimesters or months, another result that differed from those of some other studies. They found little evidence that their main results were confounded or modified by the presence of copollutants, although with the exception of O3, most of the pollutants were highly correlated, making it difficult to disentangle the effects of individual pollutants. Could the two sets of data be analyzed in a more comparable way, as in a standard nested case­control study? At the Committee's request, the investigators reanalyzed the case­control data using the same exposures and models as in the cohort study. The results were strikingly different from those using the inverse distance weighted exposures, modeled as binary variables ­ the pollutants had either no effect or an apparent beneficial effect on PTB and LBW. The Committee was not convinced by the explanations offered for these differences, leaving the reasons for them unresolved. Conclusions: This study set out to answer important questions about the effects of air pollution exposure on three measures of adverse birth outcomes ­ LBW, PTB, and IUGR ­ in a large cohort of mothers and newborns in Wuhan, China. Given the cohort size, high pollution levels and temperatures, and detailed covariate data, the investigators were well poised to address these questions. They sought to pattern their work on other studies of birth outcomes, were very responsive to Committee questions, and provided many additional analyses and explanations. In the Committee's view, however, the study was unable to address with confidence several of its specific aims. Most important, the differences in results when the case­control data were analyzed with different exposure metrics remain unexplained, raising concerns about the ability to draw conclusions from subsequent analyses assessing residual confounding and effect modification by temperature extremes, SES, and SHS exposure. Consequently, any individual findings from the cohort and case­control studies should be considered suggestive rather than conclusive, and should be interpreted carefully together.