Risk Of Term Low Birth Weight Research Articles

Interactive effects of maternal exposure to chemical fertilizer and socio-economic status on the risk of low birth weight

BackgroundMaternal exposure to chemical fertilizer and disadvantaged maternal socio-economic status (SES) have been found to associate with increased risk of low birth weight (LBW). However, whether the two factors would interact to elevate the risk of LBW remains unknown. The present study aimed to explore the interactive effects of maternal exposure to chemical fertilizer during pregnancy and low SES on the risk of term LBW (tLBW).MethodsIn this population-based case–control study, 179 tLBW cases (birthweight < 2500 g and gestational age ≥ 37 weeks) and 204 controls (birthweight ≥ 2500 g and gestational age ≥ 37 weeks) were chosen from the Perinatal Health Care Surveillance System of Pingding County, Shanxi Province, China between 2007 and 2012. Data on basic socio-demographic, dietary and lifestyle characteristics and environmental exposure were directly extracted from the system. Maternal exposure to chemical fertilizer was measured at both household level and village level. Household-level exposure was indicated by household chemical fertilizer use in farming during pregnancy and the data was collected by trained healthcare workers after the selection of cases and controls in 2013. Village-level exposure was indicated by annual amount of village chemical fertilizer consumption per acre and the data came from the Annals of National Economics Statistics of Pingding County in 2010. Interactions between maternal exposure to chemical fertilizer and SES were assessed in logistic regressions using relative excess risk due to interaction (RERI), which indicates an additive interaction if larger than 0.ResultsThe combination of low maternal SES and high exposure to village-level chemical fertilizer consumption was associated with increased risk of tLBW (aOR = 2.62, 95%CI: 1.44 ~ 4.77); The combination of low maternal SES and exposure to household chemical fertilizer use was associated with elevated risk of tLBW (aOR = 2.18, 95%CI: 1.24 ~ 3.83). Additive interactions were detected between high exposure to village-level chemical fertilizer consumption and low maternal SES (RERI:1.79, P < 0.001) and between exposure to household chemical fertilizer use and low maternal SES (RERI:0.77, P < 0.05).ConclusionsOur study suggested negative impacts of potential agricultural pollutants on adverse pregnancy outcomes, especially in disadvantaged socio-economic populations.

Associations between seasonal ambient air pollution and adverse perinatal outcomes: a retrospective cohort study in Wenzhou, China.

Prenatal exposure to ambient air pollution has been associated with adverse perinatal outcomes in previous studies. However, few studies have examined the interaction between air pollution and the season of conception on term low birth weight (TLBW) or macrosomia. Birth registry data of singleton live births in Wenzhou, China, between January 2015 and December 2016 were accessed from the Wenzhou Maternal and Child Health Information Management platform, and data on the ambient air pollutants in Wenzhou were obtained from the Chinese Air Quality Online Monitoring and Analysis Platform. Single-/two-pollutant binary logistic regression models were used to assess the associations between ambient air pollutants (PM2.5, PM10, NO2, SO2, and O3) and TLBW/macrosomia, further exploring whether the season of conception interacts with air pollution to impact birth weight. Finally, 213,959 term newborns were selected, including 2452 (1.1%) infants with TLBW and 13,173 (6.1%) infants with macrosomia. In the single-/two-pollutant models, we observed an increased risk of TLBW associated with maternal exposure to PM2.5, PM10, SO2, and NO2 during the entire pregnancy, especially in the 2nd trimester. Maternal exposure to O3 during the 1st trimester was associated with increased macrosomia risk, and O3 exposure during the 3rd trimester was associated with increased TLBW risk. Pregnant women who conceive in the warm season may experience a more adverse ambient air environment that is related to the risks of TLBW. These findings add to the evidence suggesting that air pollution and the season of conception may have synergistic effects on adverse perinatal outcomes, especially TLBW. Further prospective cohort studies are needed to validate our results.

Association of maternal ozone exposure with term low birth weight and susceptible window identification

BackgroundOzone pollution keeps deteriorating in the context of climate change. Maternal ozone exposure may be associated with low birth weight (LBW), but the results are still inconsistent. The identification of the critical exposure windows, a specific period of particular susceptibility during pregnancy, remains unresolved. We aimed to evaluate whether ozone exposure was associated with term LBW and further identify the susceptible exposure windows. MethodsA retrospective cohort study was conducted in Guangzhou, a megacity in the most populous and economically developed city clusters in China. We included 444,096 singleton live births between January 2015 and July 2017. From 11 fixed stations, we collected daily 1-h maximum and 8-h maximum moving average ozone level (O3-1 h and O3-8 h) and calculated exposures for each participant based on their district of residence during pregnancy. We used traditional Logistic regression to estimate the trimester-specific association between ozone exposure and term LBW, and further estimated monthly- and weekly association by distributed lag models (DLMs) with Logistic regression. Odds ratios (ORs) and 95% confidence intervals (CIs) of term LBW were calculated for an interquartile range (IQR) increase in ozone exposure. Stratified analyses and heterogeneity tests were conducted by maternal age and infant sex. ResultsThe incidence of term LBW was 1.9%. During the study period, the mean O3-1 h and O3-8 h levels were 112.6 µg/m3 and 84.5 µg/m3, respectively. Increased O3-1 h (IQR: 90 µg/m3) and O3-8 h (73 µg/m3) exposure during the second trimester were associated with increased risk of term LBW. At a monthly level, the term LBW risk was associated with O3-1 h exposure during the 4th-6th month and O3-8 h exposure during the 6th month. By estimating the weekly-specific association, we observed that critical exposure windows were the 15th- 26th gestational weeks for O3-1 h, and the 20th-26th weeks for O3-8 h, respectively. Estimated ORs and 95% CIs ranged from 1.012 (1.000, 1.024) to 1.023 (1.007, 1.039). When examined by subgroups, the effects were present among women ≥ 35 years or < 25 years old and those with female babies. ConclusionsThis study provides compelling evidence that exposure to O3 was associated with increased risk of term LBW, and gestational weeks 15th- 26th was found to be particularly susceptible. These findings provide a research basis for further mechanism examination, public health interventions, and targeted environmental policy-making.

Length of chronic exposure to particulate matter and adverse birth outcomes: A population-based cohort study

Background/Aim: Previous studies have shown associations between particulate matter (PM) air pollution and adverse birth outcomes. However, most studies focused on relatively short periods of prenatal exposure to PM and in a low to moderate polluted areas. We examined the possible impact of exposure to particulate matter with diameter ≤10 μm (PM10) and ≤2.5 μm (PM2.5) for a number of years before delivery on the occurrence of adverse birth outcomes: term low birth weight (TLBW), preterm delivery (PTB), and small for gestational age (SGA) in a region exposed to long-range dust transport. Methods: This study was based on a cohort of births (N=90,505) that occurred in Israel during 2013-2015. We calculated prenatal PM averages during 1, 5, and 10 years prior to delivery. Logistic regression models with mother-level as a random intercept were used to determine the association between exposure and adverse birth outcomes, adjusting for a priori known covariates. Results: In fully adjusted models, a 10-μg/m3 increase in PM2.5 during 1-, 5- and 10-years prior to delivery was associated with a monotonically increasing risk of TLBW [odds ratio (OR)=1.51 95% confidence interval (CI): (1.14-1.99), 1.54 (1.12-2.14) and 1.70 (1.21-2.41), respectively] and SGA [1.25 (1.03-1.49), 1.43 (1.16-1.77) and 1.45 (1.16-1.80), respectively]. ORs increased with the length of exposure period also for PM10. For example, ORs for TLBW in association with a 20-μg/m3 increase in PM10 over 1-, 5-, and 10-years prior to delivery were 1.25 (1.00-1.58), 1.32 (1.01-1.72) and 1.46 (1.11-1.90), respectively. PTB was not associated with neither PM2.5 nor PM10. For example, the OR for PTB in association with a 10-μg/m3 increase in PM2.5 over 10-years prior to delivery was 1.19 (0.91-1.52).Conclusions The magnitude of the estimated associations between maternal exposure to both PM2.5 and PM10 exposure and birth outcomes increased with the length of the exposure period.

Impact of air pollution exposure during various periods of pregnancy on term birth weight: a large-sample, retrospective population-based cohort study

Previous studies have suggested that maternal exposure to air pollution might affect term birth weight. However, the conclusions are controversial. Birth data of all term newborns born in Xi’an city of Shaanxi, China, from 2015 to 2018 and whose mother lived in Xi’an during pregnancy were selected form the Birth Registry Database. And the daily air quality data of Xi’an city was collected from Chinese Air Quality Online Monitoring and Analysis Platform. Generalized additive models (GAM) and 2-level binary logistic regression models were used to estimate the effects of air pollution exposure on term birth weight, the risk term low birth weight (TLBW), and macrosomia. Finally, 321521 term newborns were selected, including 4369(1.36%) TLBW infants and 24,960 (7.76%) macrosomia. The average pollution levels of PM2.5, PM10, and NO2 in Xi’an city from 2015 to 2018 were higher than national limits. During the whole pregnancy, maternal exposure to PM2.5, PM10, SO2, and CO all significantly reduced the term birth weight and increased the risk of TLBW. However, NO2 and O3 exposure have significantly increased the term birth weight, and O3 even increased the risk of macrosomia significantly. Those effects were also observed in the first and second trimesters of pregnancy. But during the third trimester, high level of air quality index (AQI) and maternal exposure to PM2.5, PM10, SO2, NO2, and CO increased the term birth weight and the risk of macrosomia, while O3 exposure was contrary to this effect. The findings suggested that prenatal exposure to air pollution might cause adverse impacts on term birth weight, and the effects varied with trimesters and pollutants, which provides further pieces of evidence for the adverse effects of air pollution exposure in heavy polluted-area on term birth weight.

A spatially varying distributed lag model with application to an air pollution and term low birth weight study.

Distributed lag models have been used to identify critical pregnancy periods of exposure (i.e. critical exposure windows) to air pollution in studies of pregnancy outcomes. However, much of the previous work in this area has ignored the possibility of spatial variability in the lagged health effect parameters that may result from exposure characteristics and/or residual confounding. We develop a spatially varying Gaussian process model for critical windows called 'SpGPCW' and use it to investigate geographic variability in the association between term low birth weight and average weekly concentrations of ozone and PM2:5 during pregnancy by using birth records from North Carolina. SpGPCW is designed to accommodate areal level spatial correlation between lagged health effect parameters and temporal smoothness in risk estimation across pregnancy. Through simulation and a real data application, we show that the consequences of ignoring spatial variability in the lagged health effect parameters include less reliable inference for the parameters and diminished ability to identify true critical window sets, and we investigate the use of existing Bayesian model comparison techniques as tools for determining the presence of spatial variability. We find that exposure to PM2:5 is associated with elevated term low birth weight risk in selected weeks and counties and that ignoring spatial variability results in null associations during these periods. An R package (SpGPCW) has been developed to implement the new method.

Term Low Birth Weight or Macrosomia among Immigrant Mothers in Korea

Objective: The aim of this study was to analyze the relationship between maternal origin and risks of term low birth weight (TLBW) or macrosomia in Korea. Methods: Using Korean birth statistics from 2009 to 2015, we examined the association between maternal nationality and risks of TLBW (less than 2.5 kg) or term macrosomia (over 4.0 kg). Birth statistics included singleton live births in women, from 37 to 41 weeks’ gestation, during the period 2009-2015. Immigrant mothers were defined as women born in any country other than Korea, and were grouped by economic level of maternal country of origin. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated with multivariate logistic regression analysis. Results: There were significant differences in neonatal birth weights between Korean mothers and immigrant mothers (3.28±0.38 kg vs. 3.24±0.39 kg, P<0.001). In multivariate logistic regression analysis, the risk of TLBW was significantly higher (OR: 1.268, 95% CI: 1.181-1.361, P<0.001) and the risk of macrosomia was significantly lower (OR: 0.607, 95% CI: 0.518-0.71, P<0.001), in mothers from low and lower middle income countries, compared to Korean mothers. The risk of macrosomia was significantly higher (OR: 1.387, 95% CI: 1.228-1.566, P<0.001) and the risk of TLBW was significantly lower (OR: 0.879, 95% CI: 0.81-0.954), in mothers from high and upper middle income countries, compared to Korean mothers. Conclusion: After adjustment for relevant characteristics, the risk of TLBW was higher in immigrant mothers from low and lower middle income countries, but the risk of macrosomia was higher in immigrant mothers from high and upper middle income country. Prenatal care and education needs to consider the origin of immigrant mothers.

The Association of PM2.5 and Greenness with Term Low Birth Weight

OPS 31: Health effects of multiple environmental stressors, Room 412, Floor 4, August 27, 2019, 1:30 PM - 3:00 PM Background/Aim: Pregnancy exposure to air pollution, particularly PM2.5, has been associated with increased risks of adverse pregnancy outcomes such as preterm delivery and low birth weight. Growing attention has been devoted to investigating the health benefit of exposure to natural environments, including greenness, on pregnancy outcomes. However, the roles of air pollution and greenness exposures on pregnancy outcomes are unclear. Here, we investigated whether greenness exposure modified the relationship between PM2.5 and term low birth weight (TLBW) in a large cohort in Taiwan. Methods: This is a hospital-based cohort study. We obtained data from the Chang Gung Research Database and identified 14,543 live infants born after 37 gestational weeks at the Chang Gung Memorial Hospital between 2010 and 2012. Kriging interpolation method and land-use regression models were applied to estimate daily PM2.5 concentration and monthly PM2.5 concentration, respectively. Greenness exposure was estimated based on the global Moderate Resolution Imaging Spectroradiometer Normalized Difference Vegetation Index (NDVI) database. Logistic regressions were used to estimate marginal and joint effects of PM2.5 and greenness exposures on TLBW. Results: The incidence of TLBW was 3.2%. We found that first trimester PM2.5 exposure was significantly associated with TLBW (the OR at the top quartile of PM2.5 compared with the lowest quartile was 1.84, 95%CI=1.17-2.90). Additionally, the top quartile of NDVI was associated with decreased risk of TLBW compared with the lowest quartile (OR=0.87, 95%CI=0.65-1.16), but not statistically significant. We did not find evidence of significant interaction on a multiplicative scale between PM2.5 and NDVI on TLBW (interaction OR=0.98, 95%CI=0.86-1.12). Conclusions: Our study indicated that first trimester PM2.5 exposure was associated with TLBW, but did not find the join effect of PM2.5 and greenness exposures on TLBW. It will be of importance to further investigate the effect of greenness exposure on pregnancy outcomes.

Exposure to coarse particulate matter during gestation and term low birthweight in California: Variation in exposure and risk across region and socioeconomic subgroup

Despite evidence that particulate matter with an aerodynamic diameter ≤10 μm (PM10) or ≤2.5 μm (PM2.5) are associated with several adverse birth outcomes, research on the association between coarse particulate matter (PM10–2.5) and birth outcomes is scarce, and results have been inconsistent. Furthermore, the literature is unclear whether associations between PM10 and adverse birth outcomes were driven by PM2.5 alone or also by PM10–2.5 exposure. Research on the variation in exposure to and risk from PM10–2.5 across populations is also needed to identify potentially vulnerable subgroups. We used birth certificate and ambient air monitoring data in California from 2002 to 2013 to develop a retrospective cohort study of pregnant women and their infants. Averaged gestational and trimester-specific exposures of PM10–2.5 and PM2.5 were calculated for mothers whose residential zip code tabulation areas were within a 20 km radius of monitors. We assessed the relationship between prenatal exposure to PM10–2.5 and term low birthweight (TLBW) using logistic and linear regression, adjusting for maternal and paternal demographic, environmental, temporal, and health-related covariates. We also conducted analyses stratified by socioeconomic characteristics and regions. We found a relationship between PM10–2.5 exposure during pregnancy and TLBW after controlling for PM2.5 exposure: odds ratio for second quartile of exposure: 1.00 (95% confidence interval: 0.98, 1.03), third quartile: 1.03 (1.00, 1.06), fourth quartile: 1.04 (1.01, 1.07), compared to the first quartile. Associations were strong among Non-Hispanic Black mothers, mothers living in the Central Valley, and fathers without a college degree. Exposure to and risk from PM10–2.5 were heterogeneous across California indicating environmental justice implications. We also found that paternal characteristics were associated with the risk of TLBW even after controlling for maternal characteristics. In addition to PM10–2.5 total mass, further research is needed on the components of PM10–2.5 which may be driving these associations.

Associations between maternal exposure to chemical fertilizers during pregnancy and the risk of offspring's low birth weights

Objective: To explore the association between the consumption of chemical fertilizers and the risk of low birth weight (LBW), to provide references for prevention programs on LBW and to improve the birth outcomes. Methods: Stratified multivariate logistic regression method was used in this study involving 153 preterm LBW infants, 179 term LBW infants and 204 normal control infants that were randomly selected from the birth monitoring data between October 2007 and September 2012 in Pingding county, Shanxi province. Associations between the risk of LBW and maternal exposure to chemical fertilizers during pregnancy were identified. A normal control group was set up to compare results between preterm and term LBW groups. Results: Totally, 18 749 infants were born between 2007 and 2012, with the total incidence rates of LBW as 48.5‰, preterm LBW as 19.4‰, and term LBW as 29.1‰. Concerning the case control study on preterm LBW, after adjustment for confounding factors, the risk of preterm LBW appeared 2.51 (95%CI: 1.05-5.99) times higher in villages with annual consumption of chemical fertilizer ≥100 tons than those villages that using chemical fertilizer less than 50 tons. No significant statistical associations were found between the amounts of household chemical fertilizer consumption and the risks of preterm LBW. Regarding the case control study on term LBW, after adjustment for confounding factors, in villages with ≥100 tons annual consumption of chemical fertilizers, the risk of term LBW was 4.03 (95%CI: 1.63-9.92) times of the risk in villages where the annal use of chemical fertilizers was less than 50 tons. There was no significant association between household consumption of chemical fertilizers and the risk of term LBW. Conclusions: Maternal exposure to chemical fertilizers during pregnancy was associated with the risk of LBW. Our findings suggested that the amount of chemical fertilizer consumption in rural areas seemed also associated with the risks of other adverse pregnancy outcomes. Women should avoid the chance of exposure to chemical fertilizers during pregnancy and the consumption of chemical fertilizers should be carefully managed.

Fine Particulate Air Pollution and Adverse Birth Outcomes: Effect Modification by Regional Nonvolatile Oxidative Potential.

Background:Prenatal exposure to fine particulate matter air pollution with aerodynamic diameter () has been associated with preterm delivery and low birth weight (LBW), but few studies have examined possible effect modification by oxidative potential.Objectives:The aim of this study was to evaluate if regional differences in the oxidative potential of modify the relationship between and adverse birth outcomes.Methods:A retrospective cohort study was conducted using 196,171 singleton births that occurred in 31 cities in the province of Ontario, Canada, from 2006 to 2012. Daily air pollution data were collected from ground monitors, and city-level oxidative potential was measured. We used random-effects meta-analysis to combine the estimates of effect from regression models across cities on preterm birth, term LBW, and term birth weight and used meta-regression to evaluate the modifying effect of oxidative potential.Results:An interquartile increase () in first-trimester was positively associated with term LBW among women in the highest quartile of glutathione (GSH)-related oxidative potential [; 95% confidence interval (CI): 1.10, 1.48], but not the lowest quartile (; 95% CI: 0.87, 1.14; ). on the day of delivery also was associated with preterm birth among women in the highest quartile of GSH-related oxidative potential [; 95% CI: 1.01, 1.04], but not the lowest quartile [; 95% CI: 0.95, 1.00; ]. Between-city differences in ascorbate (AA)-related oxidative potential did not significantly modify associations with .Conclusions:Between-city differences in GSH-related oxidative potential may modify the impact of on the risk of term LBW and preterm birth. https://doi.org/10.1289/EHP2535

Exposure to fine particulate matter during pregnancy and risk of term low birth weight in Jinan, China, 2014-2016.

Existing studies exploring the association between low birth weight (LBW) and maternal fine particulate matter (aerodynamic diameter<2.5μm, PM2.5) exposure have presented equivocal results, and one of the possible reasons for this finding might be due to relatively low maternal exposures. In addition, relatively narrow maternal exposure windows to PM2.5 have not been well established for LBW. We employed a nested matched case-control design among 43,855 term births in a large maternity and child care hospital in Jinan, China. A total of 369 cases were identified, and four controls per case matched by maternal age were randomly selected among those with normal birth weight (n=1,476) from 2014 to 2016. Ambient air monitoring data on continuous measures of PM2.5, nitrogen dioxide (NO2), and sulfur dioxide (SO2) (24-h average concentrations) from 2013 to 2016 were collected from thirteen local monitoring stations. An inverse distance weighting method based on both home and work addresses was adopted to estimate the individual daily exposures to these air pollutants during pregnancy by weighting the average of the twelve nearest monitoring stations within 30km of each 100m×100m grid cell by an inverse squared distance, and then the average exposure concentrations for gestational months, trimesters and the entire pregnancy were calculated. Adjusted conditional logistic regression models were used to estimate the odds ratios (ORs) per 10μg/m3 increment in PM2.5 and by PM2.5 quartiles during different gestational periods. In this study, the estimated mean values of PM2.5, NO2, and SO2 exposure during the entire pregnancy were 88.0, 54.6, and 63.1μg/m3, respectively. Term low birth weight (TLBW) increased in association with per 10μg/m3 increment in PM2.5 for the 8th month [OR=1.13, 95% confidence interval (CI): 1.04, 1.22], the 9th month (OR=1.06, 95% CI: 0.99, 1.15), the third trimester (OR=1.17, 95% CI: 1.05, 1.29), and the entire pregnancy (OR=1.38, 95% CI: 1.07, 1.77) in models adjusted for one pollutant (PM2.5). In models categorizing the PM2.5 exposure by quartiles, comparing the second, third, and highest with the lowest PM2.5 exposure quartile, the PM2.5 was positively associated with TLBW during the 8th month (OR: 1.77, 95% CI: 1.09, 2.88; OR: 1.77, 95% CI: 1.03, 3.04; OR: 1.92, 95% CI: 1.04, 3.55, respectively) and for the 9th month, only association for exposure in the third versus the lowest quartile was significant (OR: 1.91, 95% CI: 1.02, 3.58). The study provides evidence that exposure to PM2.5 during pregnancy might be associated with the risk of TLBW in the context of very high pollution level of PM2.5, and the 8th and 9th months were identified as potentially relevant exposure windows.

Perinatal outcomes associated with maternal HIV infection: a systematic review and meta-analysis

The HIV pandemic affects 36·9 million people worldwide, of whom 1·5 million are pregnant women. 91% of HIV-positive pregnant women reside in sub-Saharan Africa, a region that also has very poor perinatal outcomes. We aimed to establish whether untreated maternal HIV infection is associated with specific perinatal outcomes. We did a systematic review and meta-analysis of the scientific literature by searching PubMed, CINAHL (Ebscohost), Global Health (Ovid), EMBASE (Ovid), and the Cochrane Central Register of Controlled Trials and four clinical trial databases (WHO International Clinical Trials Registry Platform, the Pan African Clinical Trials Registry, the ClinicalTrials.gov database, and the ISRCTN Registry) for studies published from Jan 1, 1980, to Dec 7, 2014. Two authors independently reviewed the studies retrieved by the scientific literature search, identified relevant studies, and extracted the data. We investigated the associations between maternal HIV infection in women naive to antiretroviral therapy and 11 perinatal outcomes: preterm birth, very preterm birth, low birthweight, very low birthweight, term low birthweight, preterm low birthweight, small for gestational age, very small for gestational age, miscarriage, stillbirth, and neonatal death. We included prospective and retrospective cohort studies and case-control studies reporting perinatal outcomes in HIV-positive women naive to antiretroviral therapy and HIV-negative controls. We used a random-effects model for the meta-analyses of specific perinatal outcomes. We did subgroup and sensitivity analyses and assessed the effect of adjustment for confounders. This systematic review and meta-analysis is registered with PROSPERO, number CRD42013005638. Of 60,750 studies identified, we obtained data from 35 studies (20 prospective cohort studies, 12 retrospective cohort studies, and three case-control studies) including 53 623 women. Our meta-analyses of prospective cohort studies show that maternal HIV infection is associated with an increased risk of preterm birth (relative risk 1·50, 95% CI 1·24-1·82), low birthweight (1·62, 1·41-1·86), small for gestational age (1·31, 1·14-1·51), and stillbirth (1·67, 1·05-2·66). Retrospective cohort studies also suggest an increased risk of term low birthweight (2·62, 1·15-5·93) and preterm low birthweight (3·25, 2·12-4·99). The strongest and most consistent evidence for these associations is identified in sub-Saharan Africa. No association was identified between maternal HIV infection and very preterm birth, very small for gestational age, very low birthweight, miscarriage, or neonatal death, although few data were available for these outcomes. Correction for confounders did not affect the significance of these findings. Maternal HIV infection in women who have not received antiretroviral therapy is associated with preterm birth, low birthweight, small for gestational age, and stillbirth, especially in sub-Saharan Africa. Research is needed to assess how antiretroviral therapy regimens affect these perinatal outcomes. None.

Maternal Occupational Exposure To Extremely Low Frequency Magnetic Fields And Electrical Shocks And Birth Outcomes Across Europe

Background: Previous epidemiological studies have assessed adverse reproductive effects from maternal exposure to extremely low frequency magnetic fields (ELF-MF) exposure showing inconsistent results. The aim of this study is to assess the association between maternal occupational exposure to ELF-MF and electrical shocks during pregnancy and birth outcomes across Europe. Methods: We used a pooled dataset of 186,433 mother-child pairs enrolled in 12 birth cohorts throughout Europe. Occupational exposure to ELF-MF and electrical shocks was estimated based on individual data on information on the mother's occupation during pregnancy and linkage with job exposure matrices. Outcomes assessed included birthweight, gestational age, preterm birth, term low birthweight, small for gestational age, and infant sex ratio. Analyses were adjusted for several potentially confounding variables. We performed meta-analyses of cohort-specific estimates and explored heterogeneity. Results: Twenty two percent of women were exposed to medium levels of ELF-MF during pregnancy and 0.4% to high levels, whereas 5.9% of women were exposed to a medium risk of electrical shocks and 0.7% to a high risk. Exposure to high levels of ELF-MF during pregnancy was associated with a higher risk of term low birthweight (OR 1.99, 95%CI 1.00;3.99) compared to low levels of ELF-MF. Exposure to high risk of electrical shocks during pregnancy had a longer gestational length of 0.91 days (95%CI 0.07;1.68) compared to low risk of electrical shocks. Associations were consistent across cohorts with little heterogeneity. No associations were found with the other birth outcomes. Results were similar when both exposures were assessed together. Conclusions: This large study suggests that exposure to high levels of ELF-MF during pregnancy might be associated with impaired fetal growth at birth, whereas exposure to high risk of electrical shocks during pregnancy seems to be associated with longer gestational age.

Linking air pollution data and adverse birth outcomes: environmental public health tracking in New York State.

Studies investigating associations between ambient air pollution and fetal growth and gestational duration have reported inconclusive findings. The study goal was to use the Environmental Public Health Tracking Network to describe the association between exposure to particulate matter (PM2.5) and ozone and term low birth weight (TLBW) in New York State. Birth data for the years 2001-2006 were linked to Census data and hierarchical Bayesian modeled air pollution data. Daily 8-hour maximums for ozone and daily average PM2.5 estimates were averaged by trimester and exposure quartiles. The Environmental Public Health Tracking Academic Center for Excellence at Rutgers University partnered with New York and several other states to create a statistical program that uses logistic regression to determine the association between air pollution exposure and TLBW. There were no consistent dose-response relationships between the pollutants and TLBW. Ozone exposure was associated with a higher risk of TLBW only in the first trimester, but these results were not statistically significant. Exposure to the third quartile of ozone for the full gestational period had negative associations with TLBW (odds ratio = 0.86; 95% confidence interval, 0.81-0.92). Collaboration within the Environmental Public Health Tracking Network to share methods and data for research proved feasible and efficient in assessing the relationship of air pollutants to adverse birth outcomes. This study finds little evidence to support positive associations between exposure to ozone or PM2.5 and TLBW in New York State.

The effects of air pollution on adverse birth outcomes

BackgroundAir pollution has been shown to have adverse effects on many health outcomes including cardiorespiratory diseases and cancer. However, evidence on the effects of prenatal exposure is still limited. The purpose of this retrospective cohort study is to evaluate the effects of prenatal exposure to air pollutants including particulate matter with aerodynamic diameter less than 2.5μm (PM2.5) and ozone (O3) on the risk of adverse birth outcomes (ABOs) including term low birth weight (LBW), preterm delivery (PTD) and very PTD (VPTD). Methodssingleton births from 2004 to 2005 in Florida were included in the study (N=423,719). Trimester-specific exposures to O3 and PM2.5 at maternal residence at delivery were estimated using the National Environmental Public Health Tracking Network data, which were interpolated using Hierarchical Bayesian models. ResultsAfter adjustment for potential confounders such as demographics, medical and lifestyle factors PM2.5 exposures in all trimesters were found to be significantly and positively associated with the risk of all ABOs. Second-trimester exposure had the strongest effects. For an interquartile range (IQR) increase in PM2.5 during the second trimester, the risk of term LBW, PTD and VPTD increased by 3% [95% confidence interval (CI): 1–6%)], 12% (11–14%) and 22% (18–25%), respectively. O3 was also found to be positively associated with PTD and VPTD with the strongest effects over the whole pregnancy period [3% (1–5%) for PTD and 13% (7–19%) for VPTD for each IQR increase]. However, O3 was observed to have protective effects on term LBW. Results were consistent for multi-pollutant models. ConclusionPM2.5 has consistent adverse effects on ABOs whereas O3 has inconsistent effects. These findings warrant further investigation.

Residential proximity to major roads and term low birth weight: the roles of air pollution, heat, noise, and road-adjacent trees.

Maternal residential proximity to roads has been associated with adverse pregnancy outcomes. However, there is no study investigating mediators or buffering effects of road-adjacent trees on this association. We investigated the association between mothers' residential proximity to major roads and term low birth weight (LBW), while exploring possible mediating roles of air pollution (PM(2.5), PM(2.5-10), PM(10), PM(2.5) absorbance, nitrogen dioxide, and nitrogen oxides), heat, and noise and buffering effect of road-adjacent trees on this association. This cohort study was based on 6438 singleton term births in Barcelona, Spain (2001-2005). Road proximity was measured as both continuous distance to and living within 200 m from a major road. We assessed individual exposures to air pollution, noise, and heat using, respectively, temporally adjusted land-use regression models, annual averages of 24-hour noise levels across 50 m and 250 m, and average of satellite-derived land-surface temperature in a 50-m buffer around each residential address. We used vegetation continuous fields to abstract tree coverage in a 200-m buffer around major roads. Living within 200 m of major roads was associated with a 46% increase in term LBW risk; an interquartile range increase in heat exposure with an 18% increase; and third-trimester exposure to PM(2.5), PM(2.5-10), and PM10 with 24%, 25%, and 26% increases, respectively. Air pollution and heat exposures together explained about one-third of the association between residential proximity to major roads and term LBW. Our observations on the buffering of this association by road-adjacent trees were not consistent between our 2 measures of proximity to major roads. An increased risk of term LBW associated with proximity to major roads was partly mediated by air pollution and heat exposures.

Associations between prenatal exposure to air pollution, small for gestational age, and term low birthweight in a state-wide birth cohort

A range of health effects, including adverse pregnancy outcomes, have been associated with exposure to ambient concentrations of particulate matter (PM) and ozone (O3). The objective of this study was to determine whether maternal exposure to fine particulate matter (PM2.5) and O3 during pregnancy is associated with the risk of term low birthweight and small for gestational age infants in both single and co-pollutant models. Term low birthweight and small for gestational age were determined using all birth certificates from North Carolina from 2003 to 2005. Ambient air concentrations of PM2.5 and O3 were predicted using a hierarchical Bayesian model of air pollution that combined modeled air pollution estimates from the EPA׳s Community Multi-Scale Air Quality (CMAQ) model with air monitor data measured by the EPA׳s Air Quality System. Binomial regression, adjusted for multiple potential confounders, was performed. In adjusted single-pollutant models for the third trimester, O3 concentration was positively associated with small for gestational age and term low birthweight births [risk ratios for an interquartile range increase in O3: 1.16 (95% CI 1.11, 1.22) for small for gestational age and 2.03 (95% CI 1.80, 2.30) for term low birthweight]; however, inverse or null associations were observed for PM2.5 [risk ratios for an interquartile range increase in PM2.5: 0.97 (95% CI 0.95, 0.99) for small for gestational age and 1.01 (95% CI 0.97, 1.06) for term low birthweight]. Findings were similar in co-pollutant models and linear models of birthweight. These results suggest that O3 concentrations in both urban and rural areas may be associated with an increased risk of term low birthweight and small for gestational age births.

Mediator Role of Air Pollution, Heat, and Noise on the Association Between Maternal Residential Proximity to Major Roads and Term Low Birth Weight

BACKGROUND: Maternal residential proximity to major roads has been associated to a range of adverse pregnancy outcomes; however, there is no available study investigating mediators of such an association. AIMS: To investigate the association between term low birth weight (LBW) and maternal residential proximity (200m) to major roads and to explore mediating roles of air pollution (PM2.5, PM2.5-10, PM10, PM2.5 absorbance, NO2, NOx), heat, and noise in this association. METHODS: This study was based on 6,487 singleton term births occurred in Barcelona (2001-2005). We assessed individual exposures to air pollution, noise, and heat using respectively temporally-adjusted land use regression models, average of environmental noise levels across 50m and 250m buffers based on the European Noise Directive strategic noise map, and average of satellite-derived land surface temperature in 50m buffer around each residential address. The association between term LBW and proximity to major roads and mediator, we used logistic regressions, adjusted for relevant covariates. We assessed the mediating role of air pollution, heat, and noise exposures by quantifying the change in the OR for the proximity to major roads after including the mediators (one at a time) alongside the indicator of the proximity to major roads in fully-adjusted models. RESULTS: Proximity to major roads and an interquartile-range increase in heat exposure and the third trimester exposure to PM2.5, PM2.5-10, and PM10 were associated with respectively 46%, 22%, 24%, 25%, and 26% increase in term LBW risk. 19.7% and 11.8% of our observed association between residential proximity to major roads and term LBW could be explained byair pollution (PM2.5) and heat exposures respectively. Air pollution (PM2.5) and heat together could explain about one-third of this association. CONCLUSION: Our observed increased risk of term LBW associated with proximity to major roads was partly mediated by air pollution and heat exposures.

Association Between Trihalomethane Concentrations in Drinking Water and Adverse Pregnancy Outcome in Taiwan

ISEE-0059 Background and Objective: Chlorination has been the major strategy for disinfection of drinking water in Taiwan. Recently there has been interest in the relationship between by-products of disinfection of drinking water and pregnancy outcomes including low birth weight and preterm delivery. Methods: We performed a study to examine the effects of exposure to total trihalomethanes (TTHMs) on the risk of term low birth weight (TLBW), small for gestational age (SGA), and preterm delivery in Taiwan. TTHMs data was available for 65 municipalities in Taiwan. Results: The study population comprised 90,848 women residing in the 65 municipalities who had a first parity singleton birth between January 1, 2000 and December 31, 2002, and for which complete information on maternal age, education, gestational age, birth weight, and sex of the baby were available. Maternal TTHMs exposure was estimated from the TTHMs concentration for the municipality of residence at birth. Conclusion: The study results provide no evidence of an increased risk of TLBW, SGA, and preterm delivery at the relatively low concentrations of TTHMs in Taiwan's drinking water.