The use of ultrasound measurements in environmental epidemiological studies of air pollution and fetal growth

Adverse associations of pre-pregnancy exposure to PM2.5 and its components with fetal growth alleviated by residential greenness: a prospective cohort study

Maternal exposure to fine particulate matter (PM2.5) and residential greenness both influence fetal growth. No previous studies have examined their sex-specific and interaction effects. We aim to evaluate the sex-specific effects in these associations and exposure interactions. This study involved 1,275 mother-child pairs enrolled in the Ma'anshan birth cohort in China. Pre-pregnancy exposure to PM2.5 and its components was assessed using a spatiotemporal model based on maternal addresses, while residential greenness was estimated through the normalized difference vegetation index (NDVI) based on satellite data. Fetal parameters-including biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), and estimated fetal weight (EFW)-were measured during pregnancy via ultrasound. To examine associations between these exposures and both continuous and categorical outcomes, generalized estimating equations (GEE) and generalized linear regression were applied. Subgroup analyses were conducted to evaluate sex-specific effects. Pre-pregnancy exposure to PM2.5, OM, BC, SO42-, NH4+, and NO3- was correlated with decreased Z-scores of fetal parameters (BPD, FL, EFW, AC) during the second trimester, particularly in male fetuses. In the third trimester, we found that the Z-scores of AC (0.081, 95% CI: 0.001, 0.160) and EFW (0.097, 95% CI: 0.008, 0.185) increased with each interquartile range (IQR) increase in residential greenness. We observed the effect modification of PM2.5 and its components on the relationship between residential greenness and fetal growth in utero. Residential greenness can mitigate the adverse effects of PM2.5 and its components prior to pregnancy on fetal growth. Our findings suggest that increased residential greenness during pregnancy preparation may help alleviate air pollution's detrimental effects on fetal growth.

Sex-specific associations between maternal exposure to metal mixtures and fetal growth trajectories: A prospective birth cohort study

BACKGROUND

The associations of prenatal metals exposure with birth outcomes have been widely assessed. However, evidence on the associations between metal mixtures and fetal intrauterine growth trajectories is scarce.

OBJECTIVES

This study aimed to explore the associations of metal mixtures with fetal intrauterine growth trajectories overall and by sex.

METHODS

We analyzed data from the Ma'anshan birth cohort, which included a total of 1041 pregnant woman. The concentrations of 12 metals in maternal blood were measured during early pregnancy, and fetal intrauterine growth indicators were standardized and assessed at 16, 23, 30, 34, and 38 weeks of gestation. We used generalized linear regression and linear mixed models to identify the key fetal growth indicator (biparietal diameter (BPD)), and applied GBTM to characterize BPD SD-scores trajectories. To further assess the individual and combined effects of metals, we conducted multivariable logistic regression and repeated holdouts weighted quantile sum (WQS) regression analyses, respectively. Finally, we performed a sex-stratified analysis to explore sex-specific associations.

RESULTS

The sex-stratified multivariable logistic regression analysis indicated that in male fetal, cobalt (Co) (OR: 0.60, 95 % CI: 0.38, 0.92) was negatively associated with the high-growth BPD-SD scores trajectory. In contrast, Co (OR: 2.39, 95 % CI: 1.40, 4.45) showed a positive association in female fetal. Results from the WQS showed that early pregnancy metal mixture exposure was associated with BPD-SD scores at 16, 34, and 38 weeks in female fetal. The results highlighted Zn and Co as key metals associated with high-growth BPD SD-scores trajectory. We also identified a significant interaction between early pregnancy metal mixtures and sex on high-growth BPD SD-scores trajectories. The WQS*sex interaction term had a mean odds ratio of 1.271 (95 % CI: 1.027, 1.619).

CONCLUSION

This study suggests that exposure to prenatal metal mixtures affects fetal intrauterine growth trajectories with sexual dimorphism.

Association between prenatal air pollutant exposure and autism spectrum disorders in young children: A matched case-control study in Canada

The direction and magnitude of association between maternal exposure to ambient air pollutants across gestational windows and offspring risk of autism spectrum disorders (ASD) remains unclear. We sought to evaluate the time-varying effects of prenatal air pollutant exposure on ASD. We conducted a matched case-control study of singleton term children born in Ontario, Canada from 1-Apr-2012 to 31-Dec-2016. Provincial birth registry data were linked with applied behavioural analysis services and ambient air pollutant datasets to ascertain prenatal exposure to nitrogen dioxide (NO2), ground-level ozone (O3), fine particulate matter (PM2.5), and ASD diagnoses. Covariate balance between cases and controls was established using coarsened exact matching. Conditional logistic regression was used to assess the association between prenatal air pollutant exposure and ASD. Distributed lag non-linear models (DLNM) were used to examine the effects of single-pollutant exposure by prenatal week. Sensitivity analyses were conducted to assess the impact of exposure period on the observed findings. The final sample included 1589 ASD cases and 7563 controls. Compared to controls, cases were more likely to be born to mothers living in urban areas, delivered by Caesarean section, and assigned male sex at birth. NO2 was a consistent and significant contributor to ASD risk after accounting for co-exposure to O3, PM2.5 and covariates. The odds ratio per interquartile range increase was 2.1 (95%CI 1.8-2.3) pre-conception, 2.2 (2.0-2.5) for the 1st trimester, 2.2 (1.9-2.5) for the 2nd trimester, and 2.1 (1.9-2.4) for the 3rd trimester. In contrast, findings for O3 and PM2.5 with ASD were inconsistent. Findings from DLNM and sensitivity analyses were similar. Exposure to NO2 before and during pregnancy was significantly associated with ASD in offspring. The relationship between prenatal O3 and PM2.5 exposure and ASD remains unclear. Further investigation into the combined effects of multi-pollutant exposure on child neurodevelopment is warranted.

Health benefits of air pollution reduction: Evidence from economic slowdown in India

This paper evaluates health benefits associated with the impact of air pollution reduction on infant mortality in India. Leveraging plausibly exogenous geographic variation in air pollution due to the post-2010 economic slowdown-a period largely overlooked in the literature-I find that improvements in air quality resulted in a significant decline in infant mortality, particularly through respiratory diseases and biological pathways such as in utero and post-birth exposure. The associated health benefits correspond to 1338 saved infant lives, translating to monetary gains of $312.5 million. The paper advances our understanding of the link between air pollution and human health in settings with elevated air pollution and suboptimal regulatory frameworks.

Prenatal exposure to environmental phenols and fetal growth across pregnancy in the LIFECODES fetal growth study

INTRODUCTION

Environmental phenols are endocrine disrupting chemicals hypothesized to affect early life development. Previous research examining the effects of phenols on fetal growth has focused primarily on associations with measures of size at delivery. Few have included ultrasound measures to examine growth across pregnancy.

OBJECTIVE

Investigate associations between prenatal exposure to phenols and ultrasound and delivery measures of fetal growth.

METHODS

Using the LIFECODES Fetal Growth Study (n = 900), a case-cohort including 248 small-for-gestational-age, 240 large-for-gestational age, and 412 appropriate-for-gestational-age births, we estimated prenatal exposure to 12 phenols using three urine samples collected during pregnancy (median 10, 24, and 35 weeks gestation). We abstracted ultrasound and delivery measures of fetal growth from medical records. We estimated associations between pregnancy-average phenol biomarker concentrations and repeated ultrasound measures of fetal growth using linear mixed effects models and associations with birthweight using linear regression models. We also used logistic regression models to estimate associations with having a small- or large-for-gestational birth.

RESULTS

We observed positive associations between 2,4-dichlorophenol, benzophenone-3, and triclosan (TCS) and multiple ultrasound measures of fetal growth. For example, TCS was associated with a 0.09 (95 % CI: 0.01, 0.18) higher estimated fetal weight z-score longitudinally across pregnancy. This effect size corresponds to a 21 g increase in estimated fetal weight at 30 weeks gestation. Associations with delivery measures of growth were attenuated, but TCS remained positively associated with birthweight z-scores (mean difference: 0.13, 95 % CI: 0.02, 0.25). Conversely, methylparaben was associated with higher odds of a small-for-gestational age birth (odds ratio: 1.45, 95 % CI: 1.06, 1.98).

DISCUSSION

We observed associations between some biomarkers of phenol exposure and ultrasound measures of fetal growth, though associations at the time of delivery were attenuated. These findings are consistent with hypotheses that phenols have the potential to affect growth during the prenatal period.

The adverse impact of maternal ozone exposure on fetal growth in utero and the interaction with residential greenness

This study aimed to investigate the effect of maternal ozone exposure on fetal growth during pregnancy, as well as the combined effect and interaction of ozone and residential greenness. We included a total of 14990 singleton pregnancies from the Fujian Birth Cohort Study. During pregnancy, fetal growth parameters including estimated fetal weight (EFW), femur length (FL), head circumference (HC), and abdominal circumference (AC). To investigate the associations between ozone exposure and the above-mentioned outcomes, generalized estimating equation approach and generalized linear regression were used, as appropriate. In the adjusted models, we observed that the Z scores of EFW (-0.031 (-0.048, -0.014)), FL (-0.021 (-0.038, -0.004)), and AC (-0.025 (-0.042, -0.007)) decreased with per interquartile range (IQR) increase of ozone concentration. Compared to participants with low ozone exposure and high NDVI, those with high ozone exposure and low NDVI experienced the largest decrease in Z scores for EFW (-0.049 (-0.079, -0.02)), FL (-0.034 (-0.063, -0.004)), HC (-0.034 (-0.065, -0.004)), and AC (-0.041 (-0.072, -0.01)), respectively. Interestingly, we discovered the effect modification of NDVI on the relationship between ozone exposure and fetal growth restriction (P for interaction < 0.05). This study established a negative relationship of maternal ozone exposure and fetal growth. Of importance, this study discovered the joint effect and interaction between ozone and residential greenness exposure.

Weekly prenatal PM2.5 and NO2 exposures in preterm, early term, and full term infants: Decrements in birth weight and critical windows of susceptibility

BACKGROUND

Previous studies have observed associations between birth weight and prenatal air pollution exposure, but there is not consensus on timing of critical windows of susceptibility.

OBJECTIVE

We estimated the difference in birth weight among preterm, early term and full term births associated with weekly exposure to PM2.5 and NO2 throughout gestation.

METHODS

We included all singleton live births in the Lower Peninsula of Michigan (United States) between 2007 and 2012 occurring at or after 32 weeks gestational age (n = 497,897). Weekly ambient PM2.5 and NO2 concentrations were estimated at maternal residences using 1-km gridded data from ensemble-based models. We utilized a distributed lag nonlinear model to estimate the difference in birth weight associated with weekly exposures from the last menstrual period (week 0) through 31 weeks gestation for preterm births; through 36 weeks gestation for early term births; and through 38 weeks gestation for full term births.

RESULTS

In single-pollutant models, a 5 μg/m3 increase in PM2.5 exposure was associated with a reduction in birth weight among preterm births (-37.1 g [95% confidence interval [CI]: 60.8 g, -13.5 g]); early term births (-13.5 g [95% CI: 26.2 g, -0.67 g]); and full term births (-8.23 g [95% CI: 15.8 g, -0.68 g])]. In single-pollutant models, a 10 ppb increase in NO2 exposure was associated with a -11.7 g (95% CI: 14.46 g, -8.92 g) decrement in birth weight among full term births only. In models co-adjusted for PM2.5 and NO2, PM2.5 exposure was associated with reduced birth weight among preterm births (-36.9 g [95% CI: 61.9 g, -11.8 g]) and NO2 exposure was associated with reduced birth weight among full term births (-11.8 g [95% CI: 14.7 g, -8.94 g]). The largest decrements in birth weight were associated with PM2.5 exposure between approximately 10 and 26 weeks of pregnancy; for NO2 exposure, the largest decrements in birth weight in full term births were associated with exposure between weeks 6-18.

CONCLUSION

We observed the largest and most persistent adverse associations between PM2.5 exposure and birth weight in preterm infants, and between NO2 exposure and birth weight in full term infants. Exposure during the first half of pregnancy had a greater impact on birthweight.

The pregnancy research on inflammation, nutrition, & city environment: systematic analyses study (PRINCESA) cohort, 2009-2015

The Pregnancy Research on Inflammation, Nutrition, & City Environment: Systematic Analyses Study (PRINCESA) cohort was set up to evaluate associations between air pollution and birth outcomes among pregnant persons in Mexico City. Specifically, the study was designed to improve air pollution exposure assessment and elucidate biological mechanisms underlying associations between maternal exposures and adverse pregnancy outcomes. Pregnant persons (all women) (N = 935) between ages 18-45 who lived and/or worked in metropolitan Mexico City, Mexico, from 2009 to 2015 and liveborn singleton infants (N = 815) of participants who completed follow-up were enrolled in the cohort. We followed participants monthly from enrollment to delivery and the following categories of data were obtained: demographic, medical and obstetric history, geo-referenced data, repeated measures on daily activity patterns, reported food intake, anthropometric, clinical and obstetric data, 20 serum and 20 cervicovaginal cytokines, and lower reproductive tract infection. Repeated ultrasound measures of fetal parameters and infant birth data are also included in the study's database. In addition, PRINCESA investigators calculated air pollution exposure measures for six pollutants measured by the Mexico City Atmospheric Monitoring System (SIMAT). These estimates utilize participants' addresses to account for spatial variation in exposure (nearest monitor, inverse distance weighting, and kriging) and are available daily during pregnancy for participants. To date, associations between environmental and nutritional impacts on maternal and child health outcomes have been evaluated. PRINCESA has a comprehensive database of maternal and infant data and biological samples and offers collaboration opportunities to study associations between environmental and other factors, including nutrition and pregnancy outcomes.

Susceptible windows of exposure to fine particulate matter and fetal growth trajectories in the Spanish INMA (INfancia y Medio Ambiente) birth cohort

While prior studies report associations between fine particulate matter (PM2.5) exposure and fetal growth, few have explored temporally refined susceptible windows of exposure. We included 2328 women from the Spanish INMA Project from 2003 to 2008. Longitudinal growth curves were constructed for each fetus using ultrasounds from 12, 20, and 34 gestational weeks. Z-scores representing growth trajectories of biparietal diameter, femur length, abdominal circumference (AC), and estimated fetal weight (EFW) during early (0-12 weeks), mid- (12-20 weeks), and late (20-34 weeks) pregnancy were calculated. A spatio-temporal random forest model with back-extrapolation provided weekly PM2.5 exposure estimates for each woman during her pregnancy. Distributed lag non-linear models were implemented within the Bayesian hierarchical framework to identify susceptible windows of exposure for each outcome and cumulative effects [βcum, 95% credible interval (CrI)] were aggregated across adjacent weeks. For comparison, general linear models evaluated associations between PM2.5 averaged across multi-week periods (i.e., weeks 1-11, 12-19, and 20-33) and fetal growth, mutually adjusted for exposure during each period. Results are presented as %change in z-scores per 5 μg/m3 in PM2.5, adjusted for covariates. Weeks 1-6 [βcum = -0.77%, 95%CrI (-1.07%, -0.47%)] were identified as a susceptible window of exposure for reduced late pregnancy EFW while weeks 29-33 were positively associated with this outcome [βcum = 0.42%, 95%CrI (0.20%, 0.64%)]. A similar pattern was observed for AC in late pregnancy. In linear regression models, PM2.5 exposure averaged across weeks 1-11 was associated with reduced late pregnancy EFW and AC; but, positive associations between PM2.5 and EFW or AC trajectories in late pregnancy were not observed. PM2.5 exposures during specific weeks may affect fetal growth differentially across pregnancy and such associations may be missed by averaging exposure across multi-week periods, highlighting the importance of temporally refined exposure estimates when studying the associations of air pollution with fetal growth.

The role of cortisol in the association between prenatal air pollution and fetal growth: A prospective cohort study

Prenatal air pollutant exposure has been linked to impaired fetal growth. However, its special vulnerability windows and biological mechanisms remain unclear. A prospective birth cohort study including 7419 mother-newborn pairs was conducted from 2015 to 2020 to determine critical exposure windows and examine whether cortisol mediates the relationship between air pollutant exposure and fetal growth. Air pollutant data for PM_2.5, PM₁₀, SO₂, and CO were obtained from the Hefei City Ecology and Environment Bureau. Data on fetal ultrasound measurements and birth size were collected. Maternal and cord blood samples were used for measuring cortisol. Prenatal air pollutant (PM_2.5, PM₁₀, SO₂, and CO) exposure, particularly in the first trimester, was associated with reduced fetal size from later pregnancy to birth. An IQR increase in PM_2.5 (β = 0.082, 95%CI: 0.029, 0.135), PM₁₀ (β = 0.086, 95%CI: 0.036, 0.136), SO₂ (β = 0.086, 95%CI: 0.028, 0.144), and CO (β = 0.063, 95%CI: 0.017, 0.109) exposure in the first trimester was associated with higher cord blood cortisol levels. Significant relationships were observed between air pollutant exposure in the first trimester and increased ratio of cord to maternal blood cortisol levels. Exposure to high levels of cord blood cortisol significantly reduced the Z scores of birth weight (β = -0.17, 95%CI: -0.23, -0.10), length (β = -0.09, 95%CI: -0.16, -0.03), and head circumference (β = -0.33, 95%CI: -0.42, -0.25). Mediation analysis showed that the association of air pollutant exposure in the first trimester with neonatal parameters mediated by cord blood cortisol was 20.62%. These results indicated that air pollutant exposure during pregnancy could reduce fetal growth by the increased fetal cortisol levels due to placental barrier impairment, with the critical window of exposure occurring in the first trimester.

Birth weight following pregnancy wildfire smoke exposure in more than 1.5 million newborns in Brazil: A nationwide case-control study

Background

Air pollution exposure has been associated with critical neonatal morbidities, including low birth weight (LBW). However, little is known on short-term exposure to wildfire smoke and LBW. In this study, we estimated the association between birth weight following pregnancy and wildfire smoke exposure in more than 1.5 million newborns in Brazil (considered as a very fire-prone region worldwide).

Methods

We applied a logistic regression model to estimate the percent variation in newborns with low birth weight when exposed to wildfire in different trimesters of the pregnancy.

Findings

After adjusting the model with relevant covariates, we found that an increase of 100 wildfire records in Brazil was associated with an increase in low birth weight in the Midwest region [0.98% (95%CI:0.34; 1.63)] and in the South region [18.55% (95%CI:13.66; 23.65)] when the exposure occurred in the first trimester of pregnancy.

Interpretation

Wildfires were associated with LBW and this should be of public health concern for policymakers.

Funding

Brazilian Agencies National Council for Scientific and Technological Development (CNPq); Ministry of Science, Technology and Innovation in Brazil (MCTI); and Novo Nordisk Foundation Challenge Programme.

Identifying Sensitive Windows of Exposure to NO2 and Fetal Growth Trajectories in a Spanish Birth Cohort

BACKGROUND

We previously identified associations between trimester-specific NO2 exposures and reduced fetal growth in the Spanish INfancia y Medio Ambiente (INMA) project. Here, we use temporally refined exposure estimates to explore the impact of narrow (weekly) windows of exposure on fetal growth.

METHODS

We included 1,685 women from INMA with serial ultrasounds at 12, 20, and 34 gestational weeks. We measured biparietal diameter (BPD), femur length, and abdominal circumference (AC) and from them calculated estimated fetal weight (EFW). We calculated z-scores describing trajectories of each parameter during early (0-12 weeks), mid (12-20 weeks), and late (20-34 weeks) pregnancy, based on longitudinal growth curves from mixed-effects models. We estimated weekly NO2 exposures at each woman's residence using land-use regression models. We applied distributed lag nonlinear models to identify sensitive windows of exposure. We present effect estimates as the percentage change in fetal growth per 10 μg/m3 increase in NO2 exposure, and we calculated cumulative effect estimates by aggregating estimates across adjacent lags.

RESULTS

We identified weeks 5-12 as a sensitive window for NO2 exposure on late EFW (cumulative β = -3.0%; 95% CI = -4.1%, -1.9%). We identified weeks 6-19 as a sensitive window for late growth in BPD (cumulative β = -2.0%; 95% CI = -2.7%, -1.4%) and weeks 8-13 for AC (cumulative β = -0.68%; 95% CI = -0.97%, -0.40%). We found suggestive evidence that third trimester NO2 exposure is associated with increased AC, BPD, and EFW growth in late pregnancy.

CONCLUSIONS

Our findings are consistent with the hypothesis that NO2 exposure is associated with alterations in growth of EFW, BPD, and AC dependent on the specific timing of exposure during gestation.

Critical Time Windows for Air Pollution Exposure and Birth Weight in a Multicity Canadian Pregnancy Cohort

BACKGROUND

Maternal prenatal exposure to air pollution has been associated with adverse birth outcomes. However, previous studies focused on a priori time intervals such as trimesters reported inconsistent associations.

OBJECTIVES

We investigated time-varying vulnerability of birth weight to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) using flexible time intervals.

METHODS

We analyzed 1,300 live, full-term births from Maternal-Infant Research on Environmental Chemicals, a Canadian prospective pregnancy cohort spanning 10 cities (2008-2011). Daily PM2.5 and NO2 concentrations were estimated from ground-level monitoring, satellite models, and land-use regression, and assigned to participants from pre-pregnancy through delivery. We developed a flexible two-stage modeling method-using a Bayesian Metropolis-Hastings algorithm and empirical density threshold-to identify time-dependent vulnerability to air pollution without specifying exposure periods a priori. This approach identified critical windows with varying lengths (2-363 days) and critical windows that fell within, or straddled, predetermined time periods (i.e., trimesters). We adjusted the models for detailed infant and maternal covariates.

RESULTS

Critical windows associated with reduced birth weight were identified during mid- to late-pregnancy for both PM2.5 and NO2: -6 g (95% credible interval: -11, -1 g) and -5 g (-10, -0.1 g) per µg/m3 PM2.5 during gestational days 91-139 and 249-272, respectively; and -3 g (-5, -1 g) per ppb NO2 during days 55-145.

DISCUSSION

We used a novel, flexible selection method to identify critical windows when maternal exposures to air pollution were associated with decrements in birth weight. Our results suggest that air pollution impacts on fetal development may not be adequately captured by trimester-based analyses.

Per- and polyfluoroalkyl substance (PFAS) exposure, maternal metabolomic perturbation, and fetal growth in African American women: A meet-in-the-middle approach

BACKGROUND

Prenatal exposures to per- and polyfluoroalkyl substances (PFAS) have been linked to reduced fetal growth. However, the detailed molecular mechanisms remain largely unknown. This study aims to investigate biological pathways and intermediate biomarkers underlying the association between serum PFAS and fetal growth using high-resolution metabolomics in a cohort of pregnant African American women in the Atlanta area, Georgia.

METHODS

Serum perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) measurements and untargeted serum metabolomics profiling were conducted in 313 pregnant African American women at 8-14 weeks gestation. Multiple linear regression models were applied to assess the associations of PFAS with birth weight and small-for-gestational age (SGA) birth. A high-resolution metabolomics workflow including metabolome-wide association study, pathway enrichment analysis, and chemical annotation and confirmation with a meet-in-the-middle approach was performed to characterize the biological pathways and intermediate biomarkers of the PFAS-fetal growth relationship.

RESULTS

Each log2-unit increase in serum PFNA concentration was significantly associated with higher odds of SGA birth (OR = 1.32, 95% CI 1.07, 1.63); similar but borderline significant associations were found in PFOA (OR = 1.20, 95% CI 0.94, 1.49) with SGA. Among 25,516 metabolic features extracted from the serum samples, we successfully annotated and confirmed 10 overlapping metabolites associated with both PFAS and fetal growth endpoints, including glycine, taurine, uric acid, ferulic acid, 2-hexyl-3-phenyl-2-propenal, unsaturated fatty acid C18:1, androgenic hormone conjugate, parent bile acid, and bile acid-glycine conjugate. Also, we identified 21 overlapping metabolic pathways from pathway enrichment analyses. These overlapping metabolites and pathways were closely related to amino acid, lipid and fatty acid, bile acid, and androgenic hormone metabolism perturbations.

CONCLUSION

In this cohort of pregnant African American women, higher serum concentrations of PFOA and PFNA were associated with reduced fetal growth. Perturbations of biological pathways involved in amino acid, lipid and fatty acid, bile acid, and androgenic hormone metabolism were associated with PFAS exposures and reduced fetal growth, and uric acid was shown to be a potential intermediate biomarker. Our results provide opportunities for future studies to develop early detection and intervention for PFAS-induced fetal growth restriction.

Household air pollution, ultrasound measurement, fetal biometric parameters and intrauterine growth restriction

BACKGROUND

Low birthweight, intrauterine growth restriction (IUGR) and perinatal mortality have been associated with air pollution. However, intervention studies that use ultrasound measurements to assess the effects of household air pollution (HAP) on fetal biometric parameters (FBP) are rare. We investigated the effect of a cookstove intervention on FBP and IUGR in a randomized controlled trial (RCT) cohort of HAP-exposed pregnant Nigerian women.

METHODS

We recruited 324 women early in the second trimester of pregnancy. Between 16 and 18 weeks, we randomized them to either continue cooking with firewood/kerosene (control group) or receive a CleanCook stove and ethanol fuel (intervention group). We measured fetal biparietal diameter (BPD), head circumference (HC), femur length (FL), abdominal circumference (AC) and ultrasound-estimated fetal weight (U-EFW) in the second and third trimesters. The women were clinically followed up at six regular time points during their pregnancies. Once during the women's second trimester and once during the third, we made 72-h continuous measurements of their personal exposures to particulate matter having aerodynamic diameter < 2.5 μm (PM_2.5). We adopted a modified intent-to-treat approach for the analysis. Differences between the intervention and control groups on impact of HAP on fetal growth trajectories were analyzed using mixed effects regression models.

RESULTS

There were no significant differences in fetal growth trajectories between the intervention and control groups.

CONCLUSIONS

Larger studies in a setting of low ambient air pollution are required to further investigate the effect of transitioning to a cleaner fuel such as ethanol on intrauterine growth.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02394574 ; September 2012.

Developing Brain Glucose Transporters, Serotonin, Serotonin Transporter, and Oxytocin Receptor Expression in Response to Early-Life Hypocaloric and Hypercaloric Dietary, and Air Pollutant Exposures

Perturbed maternal diet and prenatal exposure to air pollution (AP) affect the fetal brain, predisposing to postnatal neurobehavioral disorders. Glucose transporters (GLUTs) are key in fueling neurotransmission; deficiency of the neuronal isoform GLUT3 culminates in autism spectrum disorders. Along with the different neurotransmitters, serotonin (5-HT) and oxytocin (OXT) are critical for the development of neural connectivity. Serotonin transporter (SERT) modulates synaptic 5-HT levels, while the OXT receptor (OXTR) mediates OXT action. We hypothesized that perturbed brain GLUT1/GLUT3 regulated 5-HT-SERT imbalance, which serves as a contributing factor to postnatal neuropsychiatric phenotypes, with OXT/OXTR providing a counterbalance. Employing maternal diet restriction (intrauterine growth restriction [IUGR]), high-fat (HF) dietary modifications, and prenatal exposure to simulated AP, fetal (E19) murine brain 5-HT was assessed by ELISA with SERT and OXTR being localized by immunohistochemistry and measured by quantitative Western blot analysis. IUGR with lower head weights led to a 48% reduction in male and female fetal brain GLUT3 with no change in GLUT1, when compared to age- and sex-matched controls, with no significant change in OXTR. In addition, a ∼50% (p = 0.005) decrease in 5-HT and SERT concentrations was displayed in fetal IUGR brains. In contrast, despite emergence of microcephaly, exposure to a maternal HF diet or AP caused no significant changes. We conclude that in the IUGR during fetal brain development, reduced GLUT3 is associated with an imbalanced 5-HT-SERT axis. We speculate that these early changes may set the stage for altering the 5HT-SERT neural axis with postnatal emergence of associated neurodevelopmental disorders.

Prenatal exposure to airborne particulate matter of 1 μm or less and fetal growth: A birth cohort study in Beijing, China

BACKGROUND

The association of airborne particulate matter of 1 μm or less (PM₁) with fetal growth hasn't been studied. We aimed to investigate the association of PM₁ with fetal growth parameters measured via ultrasonography and birth weight.

METHODS

The birth cohort included 18,669 pregnant women who were pregnant between 2014 and 2017 in Tongzhou Maternal and Child Health Hospital of Beijing, China. The predicted PM₁ concentration was matched with the residential addresses of each woman. The fetal abdominal circumference (AC), head circumference (HC), femur length (FL) and estimated fetal weight (EFW) were evaluated via ultrasonography, while birth weight was measured at birth. The fetal parameters and birth weight were standardized as gestational-age- and gender-adjusted Z-score. We defined undergrowth of fetal parameters, low birth weight (LBW) and small-for-gestational-age (SGA) as categorized outcomes. Generalized estimating equations and generalized linear regression were used to examine the associations of PM₁ with quantitative and categorized outcomes, respectively.

RESULTS

A 10 μg/m³ increase in PM₁ was associated with decrement in the Z-scores of AC [-0.027, 95% confidence intervals (CI): -0.047~ -0.07]EFW (-0.055, 95%CI: -0.075~-0.035). These results remained robust after adjusting nitrogen dioxide and sulphur dioxide. We didn't observe significant results regarding the analyses of undergrowth of all fetal parameters and the analyses of birth weight outcomes.

CONCLUSION

This study identified the negative associations between PM₁ and fetal parameters in utero. The findings provided robust evidence that strategies for reducing PM₁ exposure can prevent early-life health.

Prenatal fine particulate matter exposure, placental DNA methylation changes, and fetal growth

This study was designed to examine the impact of prenatal fine particulate matter (PM_2.5) exposure on fetal growth and the underlying placental epigenetic mechanism in a cohort of Chinese women. Within the prospective Shanghai Mother-Child Pairs cohort (Shanghai MCPC), 329 women carrying singleton pregnancy with a due date in 2018 were recruited between 2017 and 2018. Maternal PM_2.5 exposure levels were estimated using gestational exposure prediction model combining satellite-driven ambient concentrations and personal air sampling. Fetal growth characteristics were evaluated by prenatal ultrasound examinations and anthropometric measurements at birth. In a discovery phase, whole-genome DNA methylation analysis was performed using the Infinium 850 K array. In a validation phase, placental DNA methylation was measured using bisulfite pyrosequencing for five candidate genes that showed the most significant alterations and function relevance in our methylation array screen, including BID (BH3 interacting domain death agonist), FOXN3 (Forkhead box N3), FOXP1 (Forkhead box P1), IGF2 (Insulin-like growth factor 2) and HSD11B2 (Hydroxysteroid 11-beta dehydrogenase 2). Multivariate linear regression models were applied to examine the associations among PM_2.5 exposure, fetal growth characteristics and DNA methylation on placental candidate genes. Sobel tests were used to evaluate the mediating role of DNA methylation in multivariable models. After excluding women who withdrew or failed to provide placenta, a total of 287 pregnant women with an average age of 30 entered the final analysis. Increased PM_2.5 exposure was significantly associated with reduced biparietal diameter (BPD) (β: -0.136 mm, 95% CI: -0.228 to -0.043), head circumference (HC) (β: -0.462 mm, 95% CI: -0.782 to -0.142), femur length (FL) (β: -0.113 mm, 95% CI: -0.185 to -0.041) and abdominal circumference (AC) (β: -0.371 mm, 95% CI: -0.672 to -0.071) in the second trimester and birth length (β: -0.013 cm, 95% CI: -0.025 to -0.001). Prenatal PM_2.5 exposure could lead to aberrant changes in DNA methylation profile of placenta genome, which were mainly enriched in reproductive development, energy metabolism and immune response. DNA methylation of IGF2 and BID showed significant associations with PM_2.5 exposures during all exposure windows. In addition, BID methylation was negatively correlated with HC (β: -1.396 mm, 95% CI: -2.582 to -0.209) and BPD (β: -0.330 mm, 95% CI: -0.635 to -0.026) in the second trimester. Further mediation analysis indicated that BID methylation mediated about 30% of the effects of PM_2.5 exposure on HC. These findings collectively suggested that prenatal PM_2.5 exposure may cause adverse effects on fetal growth by modifying placental DNA methylation.

Prenatal exposure to fine particulate matter and fetal growth: a cohort study from a velocity perspective

BACKGROUND

Reduced growth velocity before birth increases the risk of adverse health outcomes in adult life. However, until recently, there has been a lack of studies demonstrating the impact of prenatal PM_2.5 exposure on fetal growth velocity.

METHODS

The current study was embedded in a previous cohort built between January 1, 2014, and April 30, 2015, in Shanghai First Maternity and Infant Hospital, China, in 6129 eligible singleton pregnancies. The PM_2.5 concentration was estimated by an inverse distance weighted method according to the residential addresses of the participants. Repeated fetal biometry measurements, including head circumference (HC), abdominal circumference (AC), femur length (FL), and biparietal diameter (BPD), were measured through ultrasound between 14 and 41 gestational weeks. A principal component analysis through conditional expectation for sparse longitudinal data was used to estimate the corresponding velocities.

RESULTS

A total of 22782 ultrasound measurements were conducted among 6129 participants with a median of 2 and a maximum of 9 measurements. With each 10 μg/m³ increase in cumulative PM_2.5 exposure, the velocity of HC, AC FL and BPD decreased by 0.12 mm/week, 0.17 mm/week, 0.02 mm/week and 0.02 mm/week, respectively, on average. The results of the Generalized Functional Concurrent Model showed that the velocity decreased significantly with PM_2.5 exposure between 22 and 32 gestational weeks, which might be the potential sensitive exposure window.

CONCLUSIONS

There are negative associations between prenatal exposure to PM_2.5 and fetal growth velocity, and the late second trimester and early third trimester might be the potential sensitive window.

Prenatal Fine Particulate Matter (PM2.5) Exposure and Pregnancy Outcomes-Analysis of Term Pregnancies in Poland

Air pollution is currently one of the greatest threats to global health. Polish cities are among the most heavily polluted in Europe. Due to air pollution 43,100 people die prematurely in Poland every year. However, these data do not take into account the health consequences of air pollution for unborn children. Thus, the aim of this study was to evaluate the effects of the fine particulate matter air pollution (less than 2.5 μm in diameter) on pregnancy outcomes. An analysis of pregnant women and their children was made using a questionnaire survey from a nationwide study conducted in 2017. Questionnaires from 1095 pregnant women and data from their medical records were collected. An analysis of air pollution in Poland was conducted using the air quality database maintained by the Chief Inspectorate for Environmental Protection in Poland. A higher concentration of PM_2.5 was associated with a decrease in birth weight and a higher risk of low birthweight (i.e., <2500 g). We also observed lower APGAR scores. Thus, all possible efforts to reduce air pollution are critically needed.

The associations of residential greenness with fetal growth in utero and birth weight: A birth cohort study in Beijing, China

BACKGROUND

Although studies have examined the association between residential greenness and birth weight, there is no evidence regarding the association between residential greenness and fetal growth in utero. We aimed to investigate the associations of residential greenness with both fetal growth in utero and birth weight.

METHODS

A birth cohort (2014-2017) with 18,665 singleton pregnancies was established in Tongzhou Maternal and Child hospital of Beijing, China. Residential greenness was matched with maternal residential address and estimated from remote satellite data using normalized difference vegetation index with 200 m and 500 m buffers (NDVI-200 and NDVI-500). Fetal parameters including estimated fetal weight (EFW), abdominal circumference (AC), head circumference (HC) and femur length (FL) were assessed by ultrasound measurements during pregnancy. Fetal parameters were standardized as gestational-age- and gender-adjusted Z-score and undergrowth was defined as Z-score < -1.88. Birth weight Z-score, low birth weight (LBW) and small for gestational age (SGA) were assessed as birth outcomes. Generalized estimating equations with the autoregressive working correlation structure and generalized linear regression were used to examine the associations of residential greenness with quantitative and categorized outcomes.

RESULTS

We found an increase Z-score of EFW [0.054, 95% confidence interval (CI): 0.020-0.087], AC (0.045, 95%CI: 0.011-0.080) and HC (0.054, 95%CI: 0.020-0.089) associated with residential greenness above NDVI-500 median compared to less than and equal to NDVI-500 median. Stratified analyses indicated that the associations might be stronger in women exposed to lower levels of particles with aerodynamic diameters ≤2.5 µm. No associations were found in the analyses of NDVI-250 with fetal growth in utero. We didn't observe significant associations of NDVI with birth weight Z-score, LBW and SGA.

CONCLUSIONS

This study identified a positive association of NDVI-500 and fetal growth in utero, but we didn't observe its association with birth weight measures. Our results suggest that building sufficient green infrastructure might potentially promote early life health.

The associations of particulate matters with fetal growth in utero and birth weight: A birth cohort study in Beijing, China

BACKGROUND

Previous studies examined the associations of particulate matters (PM) with fetal growth in utero or birth weight with inconsistent results, and few studies investigated that whether the associations of PM with fetal growth in utero also present at birth. We aimed to investigate the associations of PM with both fetal growth in utero and birth weight.

METHODS

We established a birth cohort (2014-2017) with 18,863 singleton pregnancies in Tongzhou Maternal and Child Hospital of Beijing, China. Maternal exposure to PM with aerodynamic diameters ≤2.5 μm and ≤ 10 μm (PM2.5/PM10) during pregnancy was estimated using the inverse distance weighting method. Estimated birth weight (EFW) was assessed by ultrasound measurements and birth weight was measured at birth, which were both standardized as gestational-age- and gender-adjusted Z-score. EFW undergrowth, low birth weight (LBW) and small-for-gestational-age were defined as the categorized outcomes. Generalized estimating equations and generalized linear regression were used to examine the associations of PM with quantitative and categorized outcomes, controlling for temperature, greenspace and individual covariates.

RESULTS

A 10 μg/m3 increase in PM2.5 and PM10 were associated with lower EFW Z-score [-0.031, 95% confident interval (CI): -0.047, -0.016 and -0.030, 95% CI: -0.043, -0.017]. A 10 μg/m3 increase in PM2.5 was associated with lower birth weight Z-score (-0.035, 95% CI: -0.061, -0.010) and higher risk of LBW (OR = 1.240, 95% CI: 1.019, 1.508). These results remained robust in co-pollutant models and sensitivity analyses. We didn't find significant results in other analyses.

CONCLUSIONS

The study identified an inverse association between PM and fetal growth in utero. The association between PM2.5 and fetal growth persisted from pregnancy to birth. This study supported that further actions towards controlling air pollution are strongly recommended for promoting early-life health.

Outdoor Air Pollution and Brain Structure and Function From Across Childhood to Young Adulthood: A Methodological Review of Brain MRI Studies

Outdoor air pollution has been recognized as a novel environmental neurotoxin. Studies have begun to use brain Magnetic Resonance Imaging (MRI) to investigate how air pollution may adversely impact developing brains. A systematic review was conducted to evaluate and synthesize the reported evidence from MRI studies on how early-life exposure to outdoor air pollution affects neurodevelopment. Using PubMed and Web of Knowledge, we conducted a systematic search, followed by structural review of original articles with individual-level exposure data and that met other inclusion criteria. Six studies were identified, each sampled from 3 cohorts of children in Spain, The Netherlands, and the United States. All studies included a one-time assessment of brain MRI when children were 6–12 years old. Air pollutants from traffic and/or regional sources, including polycyclic aromatic hydrocarbons (PAHs), nitrogen dioxide, elemental carbon, particulate matter (<2.5 or <10 μm), and copper, were estimated prenatally (n = 1), during childhood (n = 3), or both (n = 2), using personal monitoring and urinary biomarkers (n = 1), air sampling at schools (n = 4), or a land-use regression (LUR) modeling based on residences (n = 2). Associations between exposure and brain were noted, including: smaller white matter surface area (n = 1) and microstructure (n = 1); region-specific patterns of cortical thinness (n = 1) and smaller volumes and/or less density within the caudate (n = 3); altered resting-state functional connectivity (n = 2) and brain activity to sensory stimuli (n = 1). Preliminary findings suggest that outdoor air pollutants may impact MRI brain structure and function, but limitations highlight that the design of future air pollution-neuroimaging studies needs to incorporate a developmental neurosciences perspective, considering the exposure timing, age of study population, and the most appropriate neurodevelopmental milestones.

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 PM_2.5 exposure (10 μg/m³) during the entire pregnancy was negatively associated with head circumference at birth (β = - 0.30 cm, 95% CI - 0.49, - 0.10), and NO₂ exposure during the entire pregnancy was significantly linked to shorter length at birth (β = - 0.03 cm, 95% CI - 0.05, - 0.02). Maternal exposure to higher NO₂ and PM_2.5 during pregnancy may impair neonatal head circumference and length development, respectively. More studies are needed to confirm the effects of NO₂ and PM_2.5 and to identify the sources and major toxic components of PMs.

Maternal exposure to ambient fine particulate matter and fetal growth in Shanghai, China

BACKGROUND

Fetal growth restriction (FGR) is not only a major determinant of perinatal morbidity and mortality but also leads to adverse health effects in later life. Over the past decade, numerous studies have indicated that maternal exposure to ambient air pollution has been a risk factor for abnormal fetal growth in developed countries where PM2.5 levels are relatively low. However, studies in highly polluted regions, such as China, and studies that rely on assessments in utero are scarce.

METHODS

A total of 7965 women were selected from 11,441 women from the Shanghai Maternity and Infant Living Environment (SMILE) cohort who were pregnant between January 1, 2014, and April 30, 2015. From January 1, 2014, to April 30, 2015, weekly average PM2.5 values from 53 monitors were calculated and the inverse distance weighted (IDW) method was used to create a Shanghai pollution surface map according to the participants residential addresses. Individual exposure was the average PM2.5 value of every gestational week between the first gestational week and one week before the ultrasound measurement date (the range of measurements per participant was 1 to 10). Repeated fetal ultrasound measurements during gestational weeks 14~40 were selected. The estimated fetal weight (EFW) was calculated by biparietal diameter (BPD), abdominal circumference (AC), and femur length (FL) formulas. In total, 29,926 ultrasound measurements were analysed. Demographic variables, other pollutants (SO2, NO2, PM10 and O3) and relative humidity and temperature were controlled for potential confounding through generalized estimating equations (GEE).

RESULTS

The full model showed that with each 10 μg/m3 increase in PM2.5 exposure, the means (mm) of AC, BPD, FL decreased by 5.48 (- 9.06, - 1.91), 5.57 (- 6.66, - 4.47), and 5.47 (- 6.39, - 4.55), respectively; the mean EFW decreased by 14.49 (- 16.05, - 13.49) grams by Hadlock's third formula and 13.56 (- 14.71, - 12.50) grams by Shepard's formula with each 10 μg/m3 increase in PM2.5 exposure.

CONCLUSIONS

A negative correlation existed between maternal PM2.5 exposure during pregnancy and fetal growth indicators, which may increase the risk of fetal growth restriction.

Autophagy is a new protective mechanism against the cytotoxicity of platinum nanoparticles in human trophoblasts

Nanoparticles are widely used in commodities, and pregnant women are inevitably exposed to these particles. The placenta protects the growing fetus from foreign or toxic materials, and provides energy and oxygen. Here we report that autophagy, a cellular mechanism to maintain homeostasis, engulfs platinum nanoparticles (nPt) to reduce their cytotoxicity in trophoblasts. Autophagy was activated by nPt in extravillous trophoblast (EVT) cell lines, and EVT functions, such as invasion and vascular remodeling, and proliferation were inhibited by nPt. These inhibitory effects by nPt were augmented in autophagy-deficient cells. Regarding the dynamic state of nPt, analysis using ICP-MS demonstrated a higher accumulation of nPt in the autophagosome-rich than the cytoplasmic fraction in autophagy-normal cells. Meanwhile, there were more nPt in the nuclei of autophagy-deficient cells, resulting in greater DNA damage at a lower concentration of nPt. Thus, we found a new protective mechanism against the cytotoxicity of nPt in human trophoblasts.

Increasing risk of congenital anomalies associated with seasonal pattern of air pollution: Differences by maternal comorbidities

To interpret the relationship of the seasonal pattern of air pollution exposure associated with increased risk of congenital anomalies (CA) and the trimester-specific effects. In this work, 55,428 hospital records with 847 doctor-diagnosed CA from July 2013 to December 2016 were collected in Hohhot, China. Maternal exposure to critical air pollutants (SO₂, CO, PM₁₀, O₃, NO₂ and PM_2.5) were estimated using an inverse distance weighted (IDW) method on the basis of the ambient air quality monitoring stations. Logistic regression analysis was employed to determine the association of CA (in terms of odds ratio (OR) and 95% confidence interval (CI)) in three trimesters with heating/none heating season exposure. The results showed that CO exposure was found a significant association with ORs (95% CI) 1.58 (1.09, 2.27) changing from IQR2-3 and 1.40 (1.01, 1.93) changing from IQR3-IQR4 in 1st trimester and 1.51 (1.12, 2.04) changing from IQR2-3 in 2nd trimester, respectively. PM₁₀ also presented significant association with ORs (95% CI) 1.42(1.08, 1.86) changing from IQR3-4 in 2nd trimester. Exposure effects were found more obvious in heating season, i.e. CO exposure levels were associated with the risks of CA with IQR changing ORs (95% CI) of 5.21(2.02, 7.44), 2.24 (1.21, 4.15) and 1.84 (1.10, 3.11) in 1st trimester, respectively; PM_2.5 exposure levels were associated with the risks of CA with IQR changing ORs (95% CI) of 3.76 (1.48, 6.55), 2.45 (1.10, 5.44) and 3.30 (1.63, 6.67) in 2nd trimester, respectively. Our findings suggested some positive associations of pregnancy and CA with maternal exposure to ambient CO and PM_2.5 during the 1st and 2nd trimester after controlling for maternal comorbidities general covariates and other pollutants. PM₁₀ was also found significantly associated with increased risk of CA in 2_nd trimester besides seasons. There was no association found in 3rd trimester.

Effects of prenatal exposure to ambient air pollutant PM10 on ultrasound-measured fetal growth

Background

Limited epidemiological studies have investigated the relationship between prenatal exposure to ambient particulate matter and risk of abnormal fetal growth, and have reached inconclusive results. No study has been conducted in areas with very high air pollution levels. We investigated the hypothesis that exposure to high levels of particulate matter with aerodynamic diameter no larger than 10 µm (PM10) during pregnancy increases the risk of abnormal fetal growth.

Methods

A birth cohort study was performed in Lanzhou, China, 2010-12, including 8877 pregnant women with 18 583 ultrasound measurements of four fetal growth parameters during pregnancy, including biparietal diameter (BPD), femur length (FL), head circumference (HC) and abdominal circumference (AC). Mixed-effects modelling was used to examine the associations between PM10 exposure and risk of abnormal fetal growth.

Results

When average PM10 exposure from conception until the ultrasound examination exceeded 150 µg/m3, there were significant increases in standardized FL (β = 0.095, P = 0.0012) and HC (β = 0.090, P = 0.0078) measures. When average PM10 exposure was treated as continuous variable, we found a significant decrease in standardized BPD (β = -0.018, P = 0.0016) as per 10 µg/m3 increase in PM10. After examining the associations by various exposure windows, positive associations between higher levels of PM10 and fetal overgrowth were consistently seen for HC measures.

Conclusions

Our study suggested that prenatal exposure to high levels of ambient PM10 increased the risk of abnormal fetal growth. The findings from our study have important public health implications and also call for future studies to explore the underlying mechanisms and post-natal consequences of these findings.

Air pollution exposure during pregnancy and ultrasound and birth measures of fetal growth: A prospective cohort study in Korea

Few studies have examined the effects of air pollution on fetal growth based on ultrasound measures during pregnancy. More data is needed to evaluate the windows of special vulnerability. Our aim was to investigate the association of ambient air pollution during pregnancy with fetal and neonatal characteristics in a cohort of Korean women. Maternal exposure to particulate matter with an aerodynamic diameter<10μm (PM₁₀) and nitrogen dioxide (NO₂) was estimated using land-use regression models based on residential address. The biparietal diameter (BPD), abdominal circumference (AC), femur length (FL), and estimated fetal weight (EFW) were evaluated via ultrasonography, and birth weight (BW), birth length (BL), and head circumference at birth (BHC) were obtained from medical records. The multiple linear regression model was used to adjust for confounders, and the mixed-effect model was used to evaluate longitudinal effect. The negative effects for NO₂ and PM₁₀ were estimated; in the adjusted analyses the decreases of BPD were -0.26mm (95% confidence interval [CI]=-0.41 to -0.11, with a 10μg/m³ increase) in the second trimester for NO₂, and -0.30mm (95% CI=-0.59 to -0.03, with a 10μg/m³ increase) in the third trimester for PM₁₀. Both NO₂ and PM₁₀ levels (10μg/m³) during third trimester were inversely associated with BHC, and NO₂ level was inversely associated with BL in all exposure windows. No significant associations for AC, FL, and EFW were observed. The longitudinal analyses showed inverse association of NO₂ exposure with head and length growth (P<0.001). Our findings suggest that ambient air pollution is associated with impaired fetal head size from mid-gestation onwards.

The Built Environment and Child Health: An Overview of Current Evidence

Urbanization and the shaping of the built environment have provided a number of socioeconomic benefits, but they have also brought unwanted side effects on health. We aimed to review the current epidemiological evidence of the associations between the built environment, closely related exposures, and child health. We focused on growth and obesity, neuropsychological development, and respiratory and immune health. We used existing review articles and supplemented these with relevant work published and not included in existing reviews. The present review shows that there is good evidence for an association between air pollution and fetal growth restriction and respiratory health, whereas for other exposure and outcome combinations, further evidence is needed. Future studies should make efforts to integrate the different built environment features and to include the evaluation of environments other than home, as well as accessibility, qualitative and perception assessment of the built environment, and, if possible, with improved and standardized tools to facilitate comparability between studies. Efforts are also needed to conduct longitudinal and intervention studies and to understand potential mechanisms behind the associations observed. Finally, studies in low- and middle-income countries are needed.

Fetal growth and air pollution - A study on ultrasound and birth measures

Air pollution has been suggested to affect fetal growth, but more data is needed to assess the timing of exposure effects by using ultrasound measures. It is also important to study effects in low exposure areas to assess eventual thresholds of effects. The MAPSS (Maternal Air Pollution in Southern Sweden) cohort consists of linked registry data for around 48,000 pregnancies from an ultrasound database, birth registry and exposure data based on residential addresses. Measures of air pollution exposure were obtained through dispersion modelling with input data from an emissions database (NO_x) with high resolution (100-500m grids). Air pollution effects were assessed with linear regressions for the following endpoints; biparietal diameter, femur length, abdominal diameter and estimated fetal weight measured in late pregnancy and birth weight and head circumference measured at birth. We estimated negative effects for NO_x; in the adjusted analyses the decrease of abdominal diameter and femur length were -0.10 (-0.17, -0.03) and -0.13 (-0.17, -0.01)mm, respectively, per 10µg/m³ increment of NO_x. We also estimated an effect of NO_x-exposures on birth weight by reducing birth weight by 9g per 10µg/m³ increment of NO_x. We estimated small but statistically significant effects of air pollution on late fetal and birth size and reduced fetal growth late in pregnancy in a geographic area with levels below current WHO air quality guidelines.

Urinary phthalate metabolite and bisphenol A associations with ultrasound and delivery indices of fetal growth

Growth of the fetus is highly sensitive to environmental perturbations, and disruption can lead to problems in pregnancy as well as later in life. This study investigates the relationship between maternal exposure to common plasticizers in pregnancy and fetal growth. Participants from a longitudinal birth cohort in Boston were recruited early in gestation and followed until delivery. Urine samples were collected at up to four time points and analyzed for concentrations of phthalate metabolites and bisphenol A (BPA). Ultrasound scans were performed at four time points during pregnancy for estimation of growth parameters, and birthweight was recorded at delivery. Growth measures were standardized to a larger population. For the present analysis we examined cross-sectional and repeated measures associations between exposure biomarkers and growth estimates in 482 non-anomalous singleton pregnancies. Cross-sectional associations between urinary phthalate metabolites or BPA and growth indices were imprecise. However, in repeated measures models, we observed significant inverse associations between di-2-ethylhexyl phthalate (DEHP) metabolites and estimated or actual fetal weight. An interquartile range increase in summed DEHP metabolites was associated with a 0.13 standard deviation decrease in estimated or actual fetal weight (95% confidence interval=-0.23, -0.03). Associations were consistent across different growth parameters (e.g., head circumference, femur length), and by fetal sex. No consistent associations were observed for other phthalate metabolites or BPA. Maternal exposure to DEHP during pregnancy was associated with decreased fetal growth, which could have repercussive effects.

Prenatal Exposure to NO2 and Ultrasound Measures of Fetal Growth in the Spanish INMA Cohort

BACKGROUND

Air pollution exposure during pregnancy has been associated with impaired fetal growth. However, few studies have measured fetal biometry longitudinally, remaining unclear as to whether there are windows of special vulnerability.

OBJECTIVE

The aim was to investigate the impact of nitrogen dioxide (NO2) exposure on fetal and neonatal biometry in the Spanish INMA study.

METHODS

Biparietal diameter (BPD), femur length (FL), abdominal circumference (AC), and estimated fetal weight (EFW) were evaluated for up to 2,478 fetuses in each trimester of pregnancy. Size at 12, 20, and 34 weeks of gestation and growth between these points, as well as anthropometry at birth, were assessed by SD scores derived using cohort-specific growth curves. Temporally adjusted land-use regression was used to estimate exposure to NO2 at home addresses for up to 2,415 fetuses. Associations were investigated by linear regression in each cohort and subsequent meta-analysis.

RESULTS

A 10-μg/m(3) increase in average exposure to NO2 during weeks 0-12 was associated with reduced growth at weeks 0-12 in AC (-2.1%; 95% CI: -3.7, -0.6) and EFW (-1.6%; 95% CI: -3.0, -0.3). The same exposure was inversely associated with reduced growth at weeks 20-34 in BPD (-2.6%; 95% CI: -3.9, -1.2), AC (-1.8%; 95% CI: -3.3, -0.2), and EFW (-2.1%; 95% CI: -3.7, -0.2). A less consistent pattern of association was observed for FL. The negative association of this exposure with BPD and EFW was significantly stronger in smoking versus nonsmoking mothers.

CONCLUSIONS

Maternal exposure to NO2 in early pregnancy was associated with reduced fetal growth based on ultrasound measures of growth during pregnancy and measures of size at birth.

Gestational nanomaterial exposures: microvascular implications during pregnancy, fetal development and adulthood

Air pollution particulate matter and engineered nanomaterials are encompassed in the broad definition of xenobiotic particles. While the effects of perinatal air pollution exposure have been investigated, elucidation of outcomes associated with nanomaterial exposure, the focus of this review, is still in its infancy. As the potential uses of nanomaterials, and therefore exposures, increase exponentially so does the need for thorough evaluation. Up to this point, the majority of research in the field of cardiovascular nanotoxicology has focused on the coronary and vascular reactions to pulmonary exposures in young adult, healthy, male models; however, as intentional and unintentional contacts persist, the non-pulmonary risks to under-represented populations become a critical concern. Development of the maternal-fetal circulation during successful mammalian gestation is one of the most unusual complex, dynamic, and acutely demanding physiological systems. Fetal development in a hostile gestational environment can lead to systemic alterations, which may encourage adult disease. Therefore, the purpose of this review is to highlight the few knowns associated with gestational engineered nanomaterial exposure segmented by physiological periods of development or systemic targets: preconception and maternal, gestational, fetal and progeny (Abstract figure). Overall, the limited studies currently available provide compelling evidence of maternal, fetal and offspring dysfunctions after engineered nanomaterial exposure. Understanding the mechanisms associated with these multigenerational effects may allow pregnant women to safely reap the benefits of nanotechnology-enabled products and assist in the implementation of exposure controls to protect the mother and fetus allowing for development of safety by design for engineered nanomaterials.

Characterization of early changes in fetoplacental hemodynamics in a diet-induced rabbit model of IUGR

Intrauterine growth restriction (IUGR) is associated with adverse perinatal outcomes and late-onset diseases in offspring. Eating disorders, voluntary caloric restriction and maternal undernutrition can all induce IUGR but a relevant model is required to measure all its possible consequences. In this work, pregnant rabbits were used as an IUGR model. Control females (n=4) received ad libitum diet throughout pregnancy, whereas underfed females (n=5) were restricted to 50% of their daily requirements. Offspring size was measured by ultrasonography and in vivo at birth. Hemodynamic features of the umbilical cords and middle cerebral arteries (systolic peak velocity, end diastolic velocity, pulsatility index and resistance index) were characterized by Doppler ultrasonography. At day 21, maternal underfeeding resulted in a significant reduction of fetal size (occipito-nasal length). At birth, the size of kits from the underfed group was significantly lower (lower crown-rump length, biparietal and transversal thoracic diameters) and a reduced weight with respect to the control group. Feed restriction altered blood flow perfusion compared with does fed ad libitum (significant higher systolic peak, time-averaged mean velocities and lower end diastolic velocity). Fetuses affected by IUGR presented with compensative brain-sparing effects when compared with the control group. In conclusion, the present study supports using rabbits and the underfeeding approach as a valuable model for IUGR studies. These results may help to characterize IUGR alterations due to nutrient restriction of mothers in future research.

Influence of the umbilical cord insertion site on the optimal individual birth weight achievement

Study Question. To determine whether the umbilical cord insertion site of singleton pregnancies could be linked to the newborn birth weight at term and its individual growth potential achievement. Material and Methods. A cohort study including 528 records of term neonates was performed. Each neonate was assessed for growth adjusted for gestational age according to the infant's growth potential using the AUDIPOG module. We considered two categories of umbilical cord insertions: central and peripheral. Intrauterine growth restriction was defined as birth weight below the 10th percentile. Statistical analysis was performed using Chi-square, Student's t test, Wilcoxon test, ANOVA, and logistic regression. Results. We observed a total of 343 centrally inserted cords versus 185 peripheral cords. There were twice as many smokers in the mothers of the peripheral category compared to the centrally inserted ones. More importantly, we demonstrated that only 17/343 (5.0%) of infants with central cord insertion were growth restricted, compared to 37/185 (20.0%) of the infants born with a peripheral insertion. Neonates with centrally inserted cord were significantly heavier. Conclusion. The umbilical cord insertion site of singleton pregnancies is associated with the newborn's birth weight at term and its individual growth potential achievement.