Cohort profile: the ECHO prenatal and early childhood pathways to health consortium (ECHO-PATHWAYS)

Prenatal exposure to ambient fine particulate matter and child lung function in the CANDLE cohort

BACKGROUND

Ambient fine particulate matter (PM2.5) exposure adversely impacts child airway health; however, research on prenatal PM2.5 exposure, and child lung function is limited. We investigated these associations in the ECHO-PATHWAYS Consortium, focusing on the role of exposure timing during different phases of fetal lung development.

METHODS

We included 675 children in the CANDLE cohort born between 2007 and 2011 in Memphis, TN, USA. Prenatal exposure to ambient PM2.5 was estimated using a spatiotemporal model based on maternal residential history and averaged over established prenatal periods of lung development. Forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) were measured by spirometry at age 8-9 years. We used linear regression and Bayesian Distributed Lag Interaction Models (BDLIM) to estimate associations between exposure and lung function z-scores, adjusting for maternal/child characteristics, prenatal/postnatal tobacco exposure, and birth year/season, and evaluating effect modification by child sex and allergic sensitization.

RESULTS

The average ambient concentration of PM2.5 during pregnancy was 11.1 µg/m3 (standard deviation:1.0 µg/m3). In the adjusted linear regression and BDLIM models, adverse, but not statistically significant, associations were observed between exposure during the pseudoglandular (5-16 weeks of gestation) and saccular (24-36 weeks) phases of lung development and FEV1 and FVC. The strongest association was between a 2 μg/m3 higher concentration of PM2.5 during the saccular phase and FEV1 z-score (-0.176, 95% Confidence Interval [CI]: -0.361, 0.010). The FEV1/FVC ratio was not associated with PM2.5 in any exposure window. No effect modification by child sex or allergic sensitization was observed.

CONCLUSIONS

We did not find strong evidence of associations between prenatal ambient PM2.5 exposure and child lung function in a large, well-characterized study sample. However, there was a suggested adverse association between FEV1 and exposure during late pregnancy. The saccular phase of lung development might be an important window for exposure to PM2.5.

A longitudinal path model examining the transactional nature of parenting and child externalizing behaviors in a large, sociodemographically diverse sample

Children's externalizing behaviors are associated with impairments across the lifespan. Developmental psychopathology theories propose transactional (bidirectional) associations between child externalizing behaviors and parenting during childhood and adolescence. Yet, these foundational relations in early childhood are not well-studied. Utilizing a large, mixed-sex sample, we examined the reciprocal nature of parenting and child externalizing behaviors across early childhood using robust repeated-measures models. Repeated measures data were drawn from a socioeconomically diverse, longitudinal pregnancy cohort of 1287 (64% Black, 31% White) mother-child dyads at four time points (ages one to six). Three variables were included in cross-lagged panel models: observed parenting quality, child externalizing symptoms, and a maternal risk composite. In covariate-adjusted models, higher parenting quality at Wave 1 predicted lower child externalizing symptoms at Wave 2. Higher externalizing symptoms at Wave 1 and Wave 2 predicted lower parenting quality at Wave 2 and Wave 3, respectively. Maternal risk and parenting quality were not significantly associated. Findings showed both parent-driven and child-driven effects across early childhood that did not vary by child sex. The transactional nature of the parent-child relationship begins in infancy, underscoring the importance of early screening and provision of supports for families to minimize and prevent the development of serious psychopathology.

Assessment of adverse childhood experiences in adolescents from a rural agricultural community: Associations with depressive symptoms and psychosocial problems

The main goal of this study was to determine the prevalence of adverse childhood experiences (ACEs) among Latino adolescents from an agricultural community and to examine how it may impact their neuropsychiatric functioning. This research particularly assessed the association between ACEs and depression, as well as ACEs and psychosocial problems. The study sample consisted of 852 adolescents treated at a rural primary care clinic with a comprehensive ACE screening protocol that assesses for ACEs, depressed mood, and psychosocial functioning during every annual Well-Child Visit. Study results showed that ACEs were relatively common among participants with 64 % endorsing having experienced at least one ACE. Approximately 23 % of participants screened positive for depressed mood and 11 % for psychosocial problems. ACEs were found to have significant associations with both depression symptoms and with psychosocial problems. Males were found to have less depression symptoms than females among subjects with exposure to most ACE types, and older age was associated with lower psychosocial impairment. Study participants live in an agricultural community and are likely exposed to both chemical and non-chemical stressors. The exposure to ACEs and chemical environmental stressors may interact with pathological synergy to alter their biobehavioral development. Further research is needed to understand the "rules" for which stressors at what dose and at what stage of development place youth at greatest risk.

RNAseqCovarImpute: a multiple imputation procedure that outperforms complete case and single imputation differential expression analysis

Missing covariate data is a common problem that has not been addressed in observational studies of gene expression. Here, we present a multiple imputation method that accommodates high dimensional gene expression data by incorporating principal component analysis of the transcriptome into the multiple imputation prediction models to avoid bias. Simulation studies using three datasets show that this method outperforms complete case and single imputation analyses at uncovering true positive differentially expressed genes, limiting false discovery rates, and minimizing bias. This method is easily implemented via an R Bioconductor package, RNAseqCovarImpute that integrates with the limma-voom pipeline for differential expression analysis.

Ambient Air Pollution Exposures and Child Executive Function: A US Multicohort Study

BACKGROUND

Executive function, which develops rapidly in childhood, enables problem-solving, focused attention, and planning. Animal models describe executive function decrements associated with ambient air pollution exposure, but epidemiologic studies are limited.

METHODS

We examined associations between early childhood air pollution exposure and school-aged executive function in 1235 children from three US pregnancy cohorts in the ECHO-PATHWAYS Consortium. We derived point-based residential exposures to ambient particulate matter ≤2.5 µm in aerodynamic diameter (PM 2.5 ), nitrogen dioxide (NO 2 ), and ozone (O 3 ) at ages 0-4 years from spatiotemporal models with a 2-week resolution. We assessed executive function across three domains, cognitive flexibility, working memory, and inhibitory control, using performance-based measures and calculated a composite score quantifying overall performance. We fitted linear regressions to assess air pollution and child executive function associations, adjusting for sociodemographic characteristics, maternal mental health, and health behaviors, and examined modification by child sex, maternal education, and neighborhood educational opportunity.

RESULTS

In the overall sample, we found hypothesized inverse associations in crude but not adjusted models. Modified associations between NO 2 exposure and working memory by neighborhood education opportunity were present ( Pinteraction = 0.05), with inverse associations more pronounced in the "high" and "very high" categories. Associations of interest did not differ by child sex or maternal education.

CONCLUSION

This work contributes to the evolving science regarding early-life environmental exposures and child development. There remains a need for continued exploration in future research endeavors, to elucidate the complex interplay between natural environment and social determinants influencing child neurodevelopment.

Environmental exposure to melamine and its derivatives and kidney outcomes in children

Melamine caused acute nephrotoxicity in a past food adulteration incident, but it is unclear whether and how widespread ambient exposure to melamine and related compounds might affect pediatric kidney health. We assessed cross-sectional associations between childhood exposure to melamine and its derivatives and biomarkers of kidney injury and health and explored potential heterogeneity by sex suggested by sex-dependent differences in renal physiology. We measured melamine and its derivatives ammeline, ammelide, and cyanuric acid (CYA) in spot urine samples collected from 192 children from an urban site (Seattle, WA) and 187 children from a rural site (Yakima, WA) aged 4-8 years in the Global Alliance to Prevent Prematurity and Stillbirth (GAPPS) Study. In addition, biomarkers of kidney injury were measured in the same urine samples, including albumin, total protein, KIM-1, NAG, NGAL, and EGF. We utilized linear regressions to examine associations between individual chemical exposures and kidney biomarkers. Interaction terms examined association modification by sex, as well as potential interactions between melamine and CYA. Despite comparable exposures, girls had higher levels of many kidney injury biomarkers compared to boys. A ten-fold higher melamine concentration was associated with a 18% (95% CI: 5.6%, 31%) higher EGF in the full sample, while ten-fold higher melamine was associated with a 76% (14.1%, 173%) higher KIM-1 in boys but not in girls (-10.1% (-40.6%, 36.1%), interaction p = 0.026). Melamine exhibited significant negative interactions with CYA in association with total protein and NAG that appeared to be specific to girls. Our results suggest possible associations between melamine exposure and markers of kidney injury that may be more pronounced in boys. These findings provide novel insights into melamine and related derivative compound health effects at low levels of exposure in children and emphasize the role of sex in mediating the relationship between nephrotoxicant exposure and kidney injury.

Prenatal exposure to polycyclic aromatic hydrocarbons and executive functions at school age: Results from a combined cohort study

BACKGROUND

Executive functions develop rapidly in childhood, enabling problem-solving, focused attention, and planning. Exposures to environmental toxicants in pregnancy may impair healthy executive function development in children. There is increasing concern regarding polycyclic aromatic hydrocarbons (PAHs) given their ability to transfer across the placenta and the fetal blood-brain barrier, yet evidence from epidemiological studies is limited.

METHODS

We examined associations between prenatal PAH exposure and executive functions in 814 children of non-smoking mothers from two U.S. cohorts in the ECHO-PATHWAYS Consortium. Seven mono-hydroxylated PAH metabolites were measured in mid-pregnancy urine and analyzed individually and as mixtures. Three executive function domains were measured at age 8-9: cognitive flexibility, working memory, and inhibitory control. A composite score quantifying overall performance was further calculated. We fitted linear regressions adjusted for socio-demographics, maternal health behaviors, and psychological measures, and examined modification by child sex and stressful life events in pregnancy. Bayesian kernel machine regression was performed to estimate the interactive and overall effects of the PAH mixture.

RESULTS

The results from primary analysis of linear regressions were generally null, and no modification by child sex or maternal stress was indicated. Mixture analyses suggested several pairwise interactions between individual PAH metabolites in varied directions on working memory, particularly interactions between 2/3/9-FLUO and other PAH metabolites, but no overall or individual effects were evident.

CONCLUSION

We conducted a novel exploration of PAH-executive functions association in a large, combined sample from two cohorts. Although findings were predominantly null, the study carries important implications for future research and contributes to evolving science regarding developmental origins of diseases.

A genome scale transcriptional regulatory model of the human placenta

Gene regulation is essential to placental function and fetal development. We built a genome-scale transcriptional regulatory network (TRN) of the human placenta using digital genomic footprinting and transcriptomic data. We integrated 475 transcriptomes and 12 DNase hypersensitivity datasets from placental samples to globally and quantitatively map transcription factor (TF)-target gene interactions. In an independent dataset, the TRN model predicted target gene expression with an out-of-sample R2 greater than 0.25 for 73% of target genes. We performed siRNA knockdowns of four TFs and achieved concordance between the predicted gene targets in our TRN and differences in expression of knockdowns with an accuracy of >0.7 for three of the four TFs. Our final model contained 113,158 interactions across 391 TFs and 7712 target genes and is publicly available. We identified 29 TFs which were significantly enriched as regulators for genes previously associated with preterm birth, and eight of these TFs were decreased in preterm placentas.

Transcriptomic comparison of in vitro models of the human placenta

Studying the human placenta through in vitro cell culture methods is necessary due to limited access and amenability of human placental tissue to certain experimental methods as well as distinct anatomical and physiological differences between animal and human placentas. Selecting an in vitro culture model of the human placenta is challenging due to representation of different trophoblast cell types with distinct biological roles and limited comparative studies that define key characteristics of these models. Therefore, the aim of this research was to create a comprehensive transcriptomic comparison of common in vitro models of the human placenta compared to bulk placental tissue from the CANDLE and GAPPS cohorts (N=1083). We performed differential gene expression analysis on publicly available RNA sequencing data from 6 common in vitro models of the human placenta (HTR-8/SVneo, BeWo, JEG-3, JAR, Primary Trophoblasts, and Villous Explants) and compared to CANDLE and GAPPS bulk placental tissue or cytotrophoblast, syncytiotrophoblast, and extravillous trophoblast cell types derived from bulk placental tissue. All in vitro placental models had a substantial number of differentially expressed genes (DEGs, FDR<0.01) compared to the CANDLE and GAPPS placentas (Average DEGs=10,873), and the individual trophoblast cell types (Average DEGs=5,346), indicating that there are vast differences in gene expression compared to bulk and cell-type specific human placental tissue. Hierarchical clustering identified 53 gene clusters with distinct expression profiles across placental models, with 22 clusters enriched for specific KEGG pathways, 7 clusters enriched for high-expression placental genes, and 7 clusters enriched for absorption, distribution, metabolism, and excretion genes. In vitro placental models were classified by fetal sex based on expression of Y-chromosome genes that identified HTR-8/SVneo cells as being of female origin, while JEG-3, JAR, and BeWo cells are of male origin. Overall, none of the models were a close approximation of the transcriptome of bulk human placental tissue, highlighting the challenges with model selection. To enable researchers to select appropriate models, we have compiled data on differential gene expression, clustering, and fetal sex into an accessible web application: "Comparative Transcriptomic Placental Model Atlas (CTPMA)" which can be utilized by researchers to make informed decisions about their selection of in vitro placental models.

Maternal stressful life events during pregnancy and childhood asthma and wheeze

BACKGROUND

Studies have linked prenatal maternal psychosocial stress to childhood wheeze/asthma but have rarely investigated factors that may mitigate risks.

OBJECTIVE

To investigate associations between prenatal stress and childhood wheeze/asthma, evaluating factors that may modify stress effects.

METHODS

Participants included 2056 mother-child dyads from Environmental influences on Child Health Outcomes (ECHO)-PATHWAYS, a consortium of 3 prospective pregnancy cohorts (the Conditions Affecting Neurocognitive Development and Learning in Early Childhood study, The Infant Development and Environment Study, and a subset of the Global Alliance to Prevent Prematurity and Stillbirth study) from 6 cities. Maternal stressful life events experienced during pregnancy (PSLEs) were reported using the Pregnancy Risk Assessment Monitoring System Stressful Life Events questionnaire. Parents reported child wheeze/asthma outcomes at age 4 to 6 years using standardized questionnaires. We defined outcomes as ever asthma, current wheeze, current asthma, and strict asthma. We used modified Poisson regression with robust standard errors (SEs) to estimate risk ratios (RRs) and 95% CI per 1-unit increase in PSLE, adjusting for confounders. We evaluated effect modification by child sex, maternal history of asthma, maternal childhood traumatic life events, neighborhood-level resources, and breastfeeding.

RESULTS

Overall, we observed significantly elevated risk for current wheeze with increasing PSLE (RR, 1.09 [95% CI, 1.03-1.14]), but not for other outcomes. We observed significant effect modification by child sex for strict asthma (P interaction = .03), in which risks were elevated in boys (RR, 1.10 [95% CI, 1.02-1.19]) but not in girls. For all other outcomes, risks were significantly elevated in boys and not in girls, although there was no statistically significant evidence of effect modification. We observed no evidence of effect modification by other factors (P interactions > .05).

CONCLUSION

Risk of adverse childhood respiratory outcomes is higher with increasing maternal PSLEs, particularly in boys.

Associations of prenatal ambient air pollution exposures with asthma in middle childhood

We examined associations between prenatal fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) exposures and child respiratory outcomes through age 8-9 years in 1279 ECHO-PATHWAYS Consortium mother-child dyads. We averaged spatiotemporally modeled air pollutant exposures during four fetal lung development phases: pseudoglandular (5-16 weeks), canalicular (16-24 weeks), saccular (24-36 weeks), and alveolar (36+ weeks). We estimated adjusted relative risks (RR) for current asthma at age 8-9 and asthma with recent exacerbation or atopic disease, and odds ratios (OR) for wheezing trajectories using modified Poisson and multinomial logistic regression, respectively. Effect modification by child sex, maternal asthma, and prenatal environmental tobacco smoke was explored. Across all outcomes, 95% confidence intervals (CI) included the null for all estimates of associations between prenatal air pollution exposures and respiratory outcomes. Pseudoglandular PM2.5 exposure modestly increased risk of current asthma (RRadj = 1.15, 95% CI: 0.88-1.51); canalicular PM2.5 exposure modestly increased risk of asthma with recent exacerbation (RRadj = 1.26, 95% CI: 0.86-1.86) and persistent wheezing (ORadj = 1.28, 95% CI: 0.86-1.89). Similar findings were observed for O3, but not NO2, and associations were strengthened among mothers without asthma. While not statistically distinguishable from the null, trends in effect estimates suggest some adverse associations of early pregnancy air pollution exposures with child respiratory conditions, warranting confirmation in larger samples.

Sex-specific associations between placental corticotropin releasing hormone and problem behaviors in childhood

Placental corticotropin-releasing hormone (pCRH) is a neuroactive peptide produced in high concentrations in mid-late pregnancy, during key periods of fetal brain development. Some evidence suggests that higher pCRH exposure during gestation is associated with adverse neurodevelopment, particularly in female offspring. In 858 mother-child dyads from the sociodemographically diverse CANDLE cohort (Memphis, TN), we examined: (1) the slope of pCRH rise in mid-late pregnancy and (2) estimated pCRH at delivery as a measure of cumulative prenatal exposure. When children were 4 years-old, mothers reported on problem behaviors using the Child Behavior Checklist (CBCL) and cognitive performance was assessed by trained psychologists using the Stanford-Binet Intelligence Scales. We fitted linear regression models examining pCRH in relation to behavioral and cognitive performance measures, adjusting for covariates. Using interaction models, we evaluated whether associations differed by fetal sex, breastfeeding, and postnatal neighborhood opportunity. In the full cohort, log-transformed pCRH measures were not associated with outcomes; however, we observed sex differences in some models (interaction p-values≤0.01). In male offspring, an interquartile (IQR) increase in pCRH slope (but not estimated pCRH at delivery), was positively associated with raw Total (β=3.06, 95%CI: 0.40, 5.72), Internalizing (β=0.89, 95%CI: 0.03, 1.76), and Externalizing (β=1.25, 95%CI: 0.27, 2.22) Problem scores, whereas, in females, all associations were negative (Total Problems: β=-1.99, 95%CI: -3.89, -0.09; Internalizing: β=-0.82, 95%CI: -1.42, -0.23; Externalizing: β=-0.56, 95%CI: -1.34, 0.22). No associations with cognitive performance were observed nor did we observe moderation by breastfeeding or postnatal neighborhood opportunity. Our results provide further evidence that prenatal pCRH exposure may impact subsequent child behavior in sex-specific ways, however in contrast to prior studies suggesting adverse impacts in females, steeper mid-gestation pCRH rise was associated with more problem behaviors in males, but fewer in females.

Individual and Neighborhood Level Predictors of Children's Exposure to Residential Greenspace

Inequities in urban greenspace have been identified, though patterns by race and socioeconomic status vary across US settings. We estimated the magnitude of the relationship between a broad mixture of neighborhood-level factors and residential greenspace using weighted quantile sum (WQS) regression, and compared predictive models of greenspace using only neighborhood-level, only individual-level, or multi-level predictors. Greenspace measures included the Normalized Difference Vegetation Index (NDVI), tree canopy, and proximity of the nearest park, for residential locations in Shelby County, Tennessee of children in the CANDLE cohort. Neighborhood measures include socioeconomic and education resources, as well as racial composition and racial residential segregation. In this sample of 1012 mother-child dyads, neighborhood factors were associated with higher NDVI and tree canopy (0.021 unit higher NDVI [95% CI: 0.014, 0.028] per quintile increase in WQS index); homeownership rate, proximity of and enrollment at early childhood education centers, and racial composition, were highly weighted in the WQS index. In models constrained in the opposite direction (0.028 unit lower NDVI [95% CI: - 0.036, - 0.020]), high school graduation rate and teacher experience were highly weighted. In prediction models, adding individual-level predictors to the suite of neighborhood characteristics did not meaningfully improve prediction accuracy for greenspace measures. Our findings highlight disparities in greenspace for families by neighborhood socioeconomic and early education factors, and by race, suggesting several neighborhood indicators for consideration both as potential confounders in studies of greenspace and pediatric health as well as in the development of policies and programs to improve equity in greenspace access.

Placental transcriptomic signatures of prenatal and preconceptional maternal stress

Prenatal exposure to maternal psychological stress is associated with increased risk for adverse birth and child health outcomes. Accumulating evidence suggests that preconceptional maternal stress may also be transmitted intergenerationally to negatively impact offspring. However, understanding of mechanisms linking these exposures to offspring outcomes, particularly those related to placenta, is limited. Using RNA sequencing, we identified placental transcriptomic signatures associated with maternal prenatal stressful life events (SLEs) and childhood traumatic events (CTEs) in 1 029 mother-child pairs in two birth cohorts from Washington state and Memphis, Tennessee. We evaluated individual gene-SLE/CTE associations and performed an ensemble of gene set enrichment analyses combing across 11 popular enrichment methods. Higher number of prenatal SLEs was significantly (FDR < 0.05) associated with increased expression of ADGRG6, a placental tissue-specific gene critical in placental remodeling, and decreased expression of RAB11FIP3, an endocytosis and endocytic recycling gene, and SMYD5, a histone methyltransferase. Prenatal SLEs and maternal CTEs were associated with gene sets related to several biological pathways, including upregulation of protein processing in the endoplasmic reticulum, protein secretion, and ubiquitin mediated proteolysis, and down regulation of ribosome, epithelial mesenchymal transition, DNA repair, MYC targets, and amino acid-related pathways. The directional associations in these pathways corroborate prior non-transcriptomic mechanistic studies of psychological stress and mental health disorders, and have previously been implicated in pregnancy complications and adverse birth outcomes. Accordingly, our findings suggest that maternal exposure to psychosocial stressors during pregnancy as well as the mother's childhood may disrupt placental function, which may ultimately contribute to adverse pregnancy, birth, and child health outcomes.

Prenatal polycyclic aromatic hydrocarbon exposure and asthma at age 8-9 years in a multi-site longitudinal study

BACKGROUND AND AIM

Studies suggest prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) may influence wheezing or asthma in preschool-aged children. However, the impact of prenatal PAH exposure on asthma and wheeze in middle childhood remain unclear. We investigated these associations in socio-demographically diverse participants from the ECHO PATHWAYS multi-cohort consortium.

METHODS

We included 1,081 birth parent-child dyads across five U.S. cities. Maternal urinary mono-hydroxylated PAH metabolite concentrations (OH-PAH) were measured during mid-pregnancy. Asthma at age 8-9 years and wheezing trajectory across childhood were characterized by caregiver reported asthma diagnosis and asthma/wheeze symptoms. We used logistic and multinomial regression to estimate odds ratios of asthma and childhood wheezing trajectories associated with five individual OH-PAHs, adjusting for urine specific gravity, various maternal and child characteristics, study site, prenatal and postnatal smoke exposure, and birth year and season in single metabolite and mutually adjusted models. We used multiplicative interaction terms to evaluate effect modification by child sex and explored OH-PAH mixture effects through Weighted Quantile Sum regression.

RESULTS

The prevalence of asthma in the study population was 10%. We found limited evidence of adverse associations between pregnancy OH-PAH concentrations and asthma or wheezing trajectories. We observed adverse associations between 1/9-hydroxyphenanthrene and asthma and persistent wheeze among girls, and evidence of inverse associations with asthma for 1-hydroxynathpthalene, which was stronger among boys, though tests for effect modification by child sex were not statistically significant.

CONCLUSIONS

In a large, multi-site cohort, we did not find strong evidence of an association between prenatal exposure to PAHs and child asthma at age 8-9 years, though some adverse associations were observed among girls.

Subpopulations of children with multiple chronic health outcomes in relation to chemical exposures in the ECHO-PATHWAYS consortium

A multimorbidity-focused approach may reflect common etiologic mechanisms and lead to better targeting of etiologic agents for broadly impactful public health interventions. Our aim was to identify clusters of chronic obesity-related, neurodevelopmental, and respiratory outcomes in children, and to examine associations between cluster membership and widely prevalent chemical exposures to demonstrate our epidemiologic approach. Early to middle childhood outcome data collected 2011-2022 for 1092 children were harmonized across the ECHO-PATHWAYS consortium of 3 prospective pregnancy cohorts in six U.S. cities. 15 outcomes included age 4-9 BMI, cognitive and behavioral assessment scores, speech problems, and learning disabilities, asthma, wheeze, and rhinitis. To form generalizable clusters across study sites, we performed k-means clustering on scaled residuals of each variable regressed on study site. Outcomes and demographic variables were summarized between resulting clusters. Logistic weighted quantile sum regressions with permutation test p-values associated odds of cluster membership with a mixture of 15 prenatal urinary phthalate metabolites in full-sample and sex-stratified models. Three clusters emerged, including a healthier Cluster 1 (n = 734) with low morbidity across outcomes; Cluster 2 (n = 192) with low IQ and higher levels of all outcomes, especially 0.4-1.8-standard deviation higher mean neurobehavioral outcomes; and Cluster 3 (n = 179) with the highest asthma (92 %), wheeze (53 %), and rhinitis (57 %) frequencies. We observed a significant positive, male-specific stratified association (odds ratio = 1.6; p = 0.01) between a phthalate mixture with high weights for MEP and MHPP and odds of membership in Cluster 3 versus Cluster 1. These results identified subpopulations of children with co-occurring elevated levels of BMI, neurodevelopmental, and respiratory outcomes that may reflect shared etiologic pathways. The observed association between phthalates and respiratory outcome cluster membership could inform policy efforts towards children with respiratory disease. Similar cluster-based epidemiology may identify environmental factors that impact multi-outcome prevalence and efficiently direct public policy efforts.

Long-term ozone exposure and lung function in middle childhood

BACKGROUND

Ozone (O3) exposure interrupts normal lung development in animal models. Epidemiologic evidence further suggests impairment with higher long-term O3 exposure across early and middle childhood, although study findings to date are mixed and few have investigated vulnerable subgroups.

METHODS

Participants from the CANDLE study, a pregnancy cohort in Shelby County, TN, in the ECHO-PATHWAYS Consortium, were included if children were born at gestational age >32 weeks, completed a spirometry exam at age 8-9, and had a valid residential history from birth to age 8. We estimated lifetime average ambient O3 exposure based on each child's residential history from birth to age 8, using a validated fine-resolution spatiotemporal model. Spirometry was performed at the age 8-9 year study visit to assess Forced Expiratory Volume in the first second (FEV1) and Forced Vital Capacity (FVC) as primary outcomes; z-scores were calculated using sex-and-age-specific reference equations. Linear regression with robust variance estimators was used to examine associations between O3 exposure and continuous lung function z-scores, adjusted for child, sociodemographic, and home environmental factors. Potential susceptible subgroups were explored using a product term in the regression model to assess effect modification by child sex, history of bronchiolitis in infancy, and allergic sensitization.

RESULTS

In our sample (n = 648), O3 exposure averaged from birth to age 8 was modest (mean 26.6 [SD 1.1] ppb). No adverse associations between long-term postnatal O3 exposure were observed with either FEV1 (β = 0.12, 95% CI: -0.04, 0.29) or FVC (β = 0.03, 95% CI: -0.13, 0.19). No effect modification by child sex, history of bronchiolitis in infancy, or allergic sensitization was detected for associations with 8-year average O3.

CONCLUSIONS

In this sample with low O3 concentrations, we did not observe adverse associations between O3 exposures averaged from birth to age 8 and lung function in middle childhood.

Prenatal Exposure to Nonpersistent Environmental Chemicals and Postpartum Depression

Importance

Postpartum depression (PPD) affects up to 20% of childbearing individuals, and a significant limitation in reducing its morbidity is the difficulty in modifying established risk factors. Exposure to synthetic environmental chemicals found in plastics and personal care products, such as phenols, phthalates, and parabens, are potentially modifiable and plausibly linked to PPD and have yet to be explored.

Objective

To evaluate associations of prenatal exposure to phenols, phthalates, parabens, and triclocarban with PPD symptoms.

Design, Setting, and Participants

This was a prospective cohort study from 5 US sites, conducted from 2006 to 2020, and included pooled data from 5 US birth cohorts from the National Institutes of Health Environmental Influences on Child Health Outcomes (ECHO) consortium. Participants were pregnant individuals with data on urinary chemical concentrations (phenols, phthalate metabolites, parabens, or triclocarban) from at least 1 time point in pregnancy and self-reported postnatal depression screening assessment collected between 2 weeks and 12 months after delivery. Data were analyzed from February to May 2022.

Exposures

Phenols (bisphenols and triclosan), phthalate metabolites, parabens, and triclocarban measured in prenatal urine samples.

Main Outcomes and Measures

Depression symptom scores were assessed using the Edinburgh Postnatal Depression Scale (EPDS) or the Center for Epidemiologic Studies Depression Scale (CES-D), harmonized to the Patient-Reported Measurement Information System (PROMIS) Depression scale. Measures of dichotomous PPD were created using both sensitive (EPDS scores ≥10 and CES-D scores ≥16) and specific (EPDS scores ≥13 and CES-D scores ≥20) definitions.

Results

Among the 2174 pregnant individuals eligible for analysis, nearly all (>99%) had detectable levels of several phthalate metabolites and parabens. PPD was assessed a mean (SD) of 3 (2.5) months after delivery, with 349 individuals (16.1%) and 170 individuals (7.8%) screening positive for PPD using the sensitive and specific definitions, respectively. Linear regression results of continuous PROMIS depression T scores showed no statistically significant associations with any chemical exposures. Models examining LMW and HMW phthalates and di (2-ethylhexyl) phthalate had estimates in the positive direction whereas all others were negative. A 1-unit increase in log-transformed LMW phthalates was associated with a 0.26-unit increase in the PROMIS depression T score (95% CI, -0.01 to 0.53; P = .06). This corresponded to an odds ratio (OR) of 1.08 (95% CI, 0.98-1.19) when modeling PPD as a dichotomous outcome and using the sensitive PPD definition. HMW phthalates were associated with increased odds of PPD (OR, 1.11; 95% CI, 1.00-1.23 and OR, 1.10; 95% CI, 0.96-1.27) for the sensitive and specific PPD definitions, respectively. Sensitivity analyses produced stronger results.

Conclusions and Relevance

Phthalates, ubiquitous chemicals in the environment, may be associated with PPD and could serve as important modifiable targets for preventive interventions. Future studies are needed to confirm these observations.

Prenatal exposures to phthalates and life events stressors in relation to child behavior at age 4-6: A combined cohort analysis

Prenatal exposures to chemical and psychosocial stressors can impact the developing brain, but few studies have examined their joint effects. We examined associations between prenatal phthalate exposures and child behavior, hypothesizing that prenatal stressful life events (PSLEs) may exacerbate risks. To do so, we harmonized data from three U.S. pregnancy cohorts comprising the ECHO-PATHWAYS consortium. Phthalate metabolites were measured in single mid-pregnancy urine samples. When children were ages 4-6 years, mothers completed the Child Behavior Checklist (CBCL), from which a Total Problems score was calculated. Mothers additionally provided recall on their exposure to 14 PSLEs during pregnancy. Primary models examined problem behaviors in relation to: (1) phthalate mixtures calculated through weighted quantile sums regression with permutation test-derived p-values; and (2) joint exposure to phthalate mixtures and PSLEs (counts) using interaction terms. We subsequently refitted models stratified by child sex. Secondarily, we fit linear and logistic regression models examining individual phthalate metabolites. In our main, fully adjusted models (n = 1536 mother-child dyads), we observed some evidence of weak main effects of phthalate mixtures on problem behaviors in the full cohort and stratified by child sex. Interaction models revealed unexpected relationships whereby greater gestational exposure to PSLEs predicted reduced associations between some phthalates (e.g., the metabolites of di-2-ethylhexyl phthalate, di-n-octyl phthalate, di-iso-nonyl phthalate) and problem behaviors, particularly in males. Few associations were observed in females. Additional research is needed to replicate results and examine potential mechanisms.

Parental sensitivity modifies the associations between maternal prenatal stress exposure, autonomic nervous system functioning and infant temperament in a diverse, low-income sample

Evidence suggests that adversity experienced during fetal development may shape infant physiologic functioning and temperament. Parental sensitivity is associated with child stress regulation and may act as a buffer against risk for intergenerational health effects of pre- or postnatal adversity. Building upon prior evidence in a racially and ethnically diverse sample of infants (M infant age = 6.5 months) and women of low socioeconomic status, this study examined whether coded parenting sensitivity moderated the association between an objective measure of prenatal stress exposures (Stressful Life Events (SLE)) and infant parasympathetic (respiratory sinus arrhythmia; RSA) or sympathetic (pre-ejection period; PEP) nervous system functioning assessed during administration of the Still-Face-Paradigm (SFP) (n = 66), as well as maternal report of temperament (n = 154). Results showed that parental sensitivity moderated the associations between prenatal stress exposures and infant RSA reactivity, RSA recovery, PEP recovery, and temperamental negativity. Findings indicate that greater parental sensitivity is associated with lower infant autonomic nervous system reactivity and greater recovery from challenge. Results support the hypothesis that parental sensitivity buffers infants from the risk of prenatal stress exposure associations with offspring cross-system physiologic reactivity and regulation, potentially shaping trajectories of health and development and promoting resilience.

Prenatal exposure to polycyclic aromatic hydrocarbons and cognition in early childhood

BACKGROUND

Epidemiological evidence for gestational polycyclic aromatic hydrocarbon (PAH) exposure and adverse child cognitive outcomes is mixed; little is known about critical windows of exposure.

OBJECTIVE

We investigated associations between prenatal PAH exposure and child cognition in a large, multi-site study.

METHODS

We included mother-child dyads from two pooled prospective pregnancy cohorts (CANDLE and TIDES, N = 1,223) in the ECHO-PATHWAYS Consortium. Seven urinary mono-hydroxylated PAH metabolites were measured in mid-pregnancy in both cohorts as well as early and late pregnancy in TIDES. Child intelligence quotient (IQ) was assessed between ages 4-6. Associations between individual PAH metabolites and IQ were estimated with multivariable linear regression. Interaction terms were used to examine effect modification by child sex and maternal obesity. We explored associations of PAH metabolite mixtures with IQ using weighted quantile sum regression. In TIDES, we averaged PAH metabolites over three periods of pregnancy and by pregnancy period to investigate associations between PAH metabolites and IQ.

RESULTS

In the combined sample, PAH metabolites were not associated with IQ after full adjustment, nor did we observe associations with PAH mixtures. Tests of effect modification were null except for the association between 2-hydroxynaphthalene and IQ, which was negative in males (βmales = -0.67 [95%CI:-1.47,0.13]) and positive in females (βfemales = 0.31 [95%CI:-0.52,1.13])(pinteraction = 0.04). In analyses across pregnancy (TIDES-only), inverse associations with IQ were observed for 2-hydroxyphenanthrene averaged across pregnancy (β = -1.28 [95%CI:-2.53,-0.03]) and in early pregnancy (β = -1.14 [95%CI:-2.00,-0.28]).

SIGNIFICANCE

In this multi-cohort analysis, we observed limited evidence of adverse associations of early pregnancy PAHs with child IQ. Analyses in the pooled cohorts were null. However, results also indicated that utilizing more than one exposure measures across pregnancy could improve the ability to detect associations by identifying sensitive windows and improving the reliability of exposure measurement. More research with multiple timepoints of PAH assessment is warranted.

Characterization of Xenobiotic and Steroid Disposition Potential of Human Placental Tissue and Cell Lines (BeWo, JEG-3, JAR, and HTR-8/SVneo) by Quantitative Proteomics

The placenta is a fetal organ that performs critical functions to maintain pregnancy and support fetal development, including metabolism and transport of xenobiotics and steroids between the maternal-fetal unit. In vitro placenta models are used to study xenobiotic and steroid disposition, but how well these models recapitulate the human placenta is not well understood. We first characterized the abundance of proteins involved in xenobiotic and steroid disposition in human placental tissue. In pooled human placenta, the following xenobiotic and steroid disposition proteins were detected (highest to lowest), 1) enzymes: glutathione S-transferase P, carbonyl reductase 1, aldo-keto reductase 1B1, hydroxysteroid dehydrogenases (HSD3B1 and HSD11B1), aromatase, epoxide hydrolase 1 (EPHX1) and steryl-sulfatase, and 2) transporters: monocarboxylate transporters (MCT1 and 4), organic anion transporting polypeptide 2B1, organic anion transporter 4, and breast cancer resistance protein (BCRP). Then, the tissue proteomics data were compared with four placental cell lines (BeWo, JEG-3, JAR, and HTR-8/SVneo). The differential global proteomics analysis revealed that the tissue and cell lines shared 1420 cytosolic and 1186 membrane proteins. Although extravillous trophoblast and cytotrophoblast marker proteins were detected in all cell lines, only BeWo and JEG-3 cells expressed the syncytiotrophoblast marker, chorionic somatomammotropin hormone 1. BeWo and JEG-3 cells expressed most target proteins including aromatase, HSDs, EPHX1, MCT1, and BCRP. JEG-3 cells treated with commonly detected phthalates in human biofluids showed dysregulation of steroid pathways. The data presented here show that BeWo and JEG-3 cells are closer to the placental tissue for studying xenobiotic and steroid disposition. SIGNIFICANCE STATEMENT: This is the first study to compare proteomics data of human placental tissue and cell lines (BeWo, JAR, JEG-3, and HTR-8/SVneo). The placental cell line and tissue proteomes are vastly different, but BeWo and JEG-3 cells showed greater resemblance to the tissue in the expression of xenobiotic and steroid disposition proteins. These data will assist researchers to select an optimum cell model for mechanistic investigations on xenobiotic and steroid disposition in the placenta.

Prenatal polycyclic aromatic hydrocarbon exposure and asthma at age 8-9 years in a multi-site longitudinal study

Background and aim

Studies suggest prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) may influence wheezing or asthma in preschool-aged children. However, the impact of prenatal PAH exposure on asthma and wheeze in middle childhood remain unclear. We investigated these associations in diverse participants from the ECHO PATHWAYS multi-cohort consortium.

Methods

We included 1,081 birth parent-child dyads across five U.S. cities. Maternal urinary mono-hydroxylated PAH metabolite concentrations (OH-PAH) were measured during mid-pregnancy. Asthma at age 8-9 years and wheezing trajectory across childhood were characterized by caregiver reported asthma diagnosis and asthma/wheeze symptoms. We used logistic and multinomial regression to estimate odds ratios of asthma and childhood wheezing trajectories associated with five individual OH-PAHs, adjusting for urine specific gravity, various maternal and child characteristics, study site, prenatal and postnatal smoke exposure, and birth year and season in single metabolite and mutually adjusted models. We used multiplicative interaction terms to evaluate effect modification by child sex and explored OH-PAH mixture effects through Weighted Quantile Sum regression.

Results

The prevalence of asthma in the study population was 10%. We found limited evidence of adverse associations between pregnancy OH-PAH concentrations and asthma or wheezing trajectories. We observed adverse associations between 1/9-hydroxyphenanthrene and asthma and persistent wheeze among girls, and evidence of inverse associations with asthma for 1-hydroxynathpthalene, which was stronger among boys, though tests for effect modification by child sex were not statistically.

Conclusions

In a large, multi-site cohort, we did not find strong evidence of an association between prenatal exposure to PAHs and child asthma at age 8-9 years, though some adverse associations were observed among girls.

Associations of prenatal exposure to NO2 and near roadway residence with placental gene expression

INTRODUCTION

Traffic-related air pollution (TRAP), a common exposure, potentially impacts pregnancy through altered placental function. We investigated associations between prenatal TRAP exposure and placental gene expression.

METHODS

Whole transcriptome sequencing was performed on placental samples from CANDLE (Memphis, TN) (n = 776) and GAPPS (Seattle and Yakima, WA) (n = 205), cohorts of the ECHO-PATHWAYS Consortium. Residential NO2 exposures were computed via spatiotemporal models for full-pregnancy, each trimester, and the first/last months of pregnancy. Individual cohort-specific, covariate-adjusted linear models were fit for 10,855 genes and respective exposures (NO2 or roadway proximity [≤150 m]). Infant-sex/exposure interactions on placental gene expression were tested with interaction terms in separate models. Significance was based on false discovery rate (FDR<0.10).

RESULTS

In GAPPS, final-month NO2 exposure was positively associated with MAP1LC3C expression (FDR p-value = 0.094). Infant-sex interacted with second-trimester NO2 on STRIP2 expression (FDR interaction p-value = 0.011, inverse and positive associations among male and female infants, respectively) and roadway proximity on CEBPA expression (FDR interaction p-value = 0.045, inverse among females). In CANDLE, infant-sex interacted with first-trimester and full-pregnancy NO2 on RASSF7 expression (FDR interaction p-values = 0.067 and 0.013, respectively, positive among male infants and inverse among female infants).

DISCUSSION

Overall, pregnancy NO2 exposure and placental gene expression associations were primarily null, with exception of final month NO2 exposure and placental MAP1LC3C association. We found several interactions of infant sex and TRAP exposures on placental expression of STRIP2, CEBPA, and RASSF7. These highlighted genes suggest influence of TRAP on placental cell proliferation, autophagy, and growth, though additional replication and functional studies are required for validation.

Role of Air Pollution in the Development of Asthma Among Children with a History of Bronchiolitis in Infancy

BACKGROUND

Infants experiencing bronchiolitis are at increased risk for asthma, but few studies have identified modifiable risk factors. We assessed whether early life air pollution influenced child asthma and wheeze at age 4-6 years among children with a history of bronchiolitis in the first postnatal year.

METHODS

Children with caregiver-reported physician-diagnosed bronchiolitis were drawn from ECHO-PATHWAYS, a pooled longitudinal cohort from six US cities. We estimated their air pollution exposure from age 1 to 3 years from validated spatiotemporal models of fine particulate matter (PM 2.5 ), nitrogen dioxide (NO 2 ), and ozone (O 3 ). Caregivers reported children's current wheeze and asthma at age 4-6 years. We used modified Poisson regression to estimate relative risks (RR) and 95% confidence intervals (CI), adjusting for child, maternal, and home environmental factors. We assessed effect modification by child sex and maternal history of asthma with interaction models.

RESULTS

A total of 224 children had caregiver-reported bronchiolitis. Median (interquartile range) 2-year pollutant concentrations were 9.3 (7.8-9.9) µg/m 3 PM 2.5 , 8.5 (6.4-9.9) ppb NO 2 , and 26.6 (25.6-27.7) ppb O 3 . RRs (CI) for current wheeze per 2-ppb higher O 3 were 1.3 (1.0-1.7) and 1.4 (1.1-1.8) for asthma. NO 2 was inversely associated with wheeze and asthma whereas associations with PM 2.5 were null. We observed interactions between NO 2 and PM 2.5 and maternal history of asthma, with lower risks observed among children with a maternal history of asthma.

CONCLUSION

Our results are consistent with the hypothesis that exposure to modest postnatal O 3 concentrations increases the risk of asthma and wheeze among the vulnerable subpopulation of infants experiencing bronchiolitis.

Association between maternal occupational exposure to cleaning chemicals during pregnancy and childhood wheeze and asthma

Background

Asthma is a leading cause of childhood morbidity in the U.S. and a significant public health concern. The prenatal period is a critical window during which environmental influences, including maternal occupational exposures, can shape child respiratory health. Cleaning chemicals are commonly encountered in occupational settings, yet few studies have examined the potential link between prenatal occupational exposures to cleaning chemicals and risk of childhood wheeze and asthma.

Methods

We evaluated the potential influence of maternal occupational exposure to cleaning chemicals during pregnancy on pediatric asthma and wheeze at child age 4-6 years in 453 mother-child pairs from two longitudinal pregnancy cohorts, TIDES and GAPPS, part of the ECHO prenatal and early childhood pathways to health (ECHO-PATHWAYS) consortium. Maternal occupational exposure to cleaning chemicals was defined based on reported occupation and frequency of occupational use of chemicals during pregnancy. Child current wheeze and asthma outcomes were defined by parental responses to a widely-used, standardized respiratory outcomes questionnaire administered at child age 4-6 years. Multivariable Poisson regression with robust standard errors was used to estimate relative risk (RR) of asthma in models adjusted for confounding. Effect modification by child sex was assessed using product interaction terms.

Results

Overall, 116 mothers (25.6%) reported occupational exposure to cleaning chemicals during pregnancy, 11.7% of children had current wheeze, and 10.2% had current asthma. We did not identify associations between prenatal exposure to cleaning chemicals and current wheeze [RRadjusted 1.03, 95% confidence interval (CI): 0.56, 1.90] or current asthma (RRadjusted 0.89, CI: 0.46, 1.74) in the overall sample. Analyses of effect modification suggested an adverse association among females for current wheeze (RR 1.82, CI: 0.76, 4.37), compared to males (RR 0.68, CI: 0.29, 1.58), though the interaction p-value was >0.05.

Conclusion

We did not observe evidence of associations between maternal prenatal occupational exposure to cleaning chemicals and childhood wheeze or asthma in the multi-site ECHO-PATHWAYS consortium. We leveraged longitudinal U.S. pregnancy cohorts with rich data characterization to expand on limited and mixed literature. Ongoing research is needed to more precisely characterize maternal occupational chemical exposures and impacts on child health in larger studies.

A Multi-Cohort Examination of the Independent Contributions of Maternal Childhood Adversity and Pregnancy Stressors to the Prediction of Children's Anxiety and Depression

Women's social experiences can have long-term implications for their offspring's health, but little is known about the potential independent contributions of multiple periods of stress exposures over time. This study examined associations of maternal exposure to adversity in childhood and pregnancy with children's anxiety and depression symptoms in a large, sociodemographically diverse sample. Participants were 1389 mother-child dyads (child age M = 8.83 years; SD = 0.66; 42% Black, 42% White; 6% Hispanic) in the ECHO-PATHWAYS Consortium's three U.S. pregnancy cohorts. Women reported their exposure to childhood traumatic events (CTE) and pregnancy stressful life events (PSLE). Children self-reported on their symptoms of anxiety and depression at age 8-9 years. Regression analyses estimated associations between maternal stressors and children's internalizing problems, adjusting for confounders, and examined child sex as a modifier. Exploratory interaction analyses examined whether geospatially-linked postnatal neighborhood quality buffered effects. In adjusted models, PSLE counts positively predicted levels of children's anxiety and depression symptoms ([ßAnxiety=0.08, 95%CI [0.02, 0.13]; ßDepression=0.09, 95%CI [0.03, 0.14]); no significant associations were observed with CTE. Each additional PSLE increased odds of clinically significant anxiety symptoms by 9% (95%CI [0.02, 0.17]). Neither sex nor neighborhood quality moderated relations. Maternal stressors during pregnancy appear to have associations with middle childhood anxiety and depression across diverse sociodemographic contexts, whereas maternal history of childhood adversity may not. Effects appear comparable for boys and girls. Policies and programs addressing prevention of childhood internalizing symptoms may benefit from considering prenatal origins and the potential two-generation impact of pregnancy stress prevention and intervention.

Placental transcriptomic signatures of prenatal exposure to Hydroxy-Polycyclic aromatic hydrocarbons

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants originating from petrogenic and pyrogenic sources. PAH compounds can cross the placenta, and prenatal PAH exposure is linked to adverse infant and childhood health outcomes.

OBJECTIVE

In this first human transcriptomic assessment of PAHs in the placenta, we examined associations between prenatal PAH exposure and placental gene expression to gain insight into mechanisms by which PAHs may disrupt placental function.

METHODS

The ECHO PATHWAYS Consortium quantified prenatal PAH exposure and the placental transcriptome from 629 pregnant participants enrolled in the CANDLE study. Concentrations of 12 monohydroxy-PAH (OH-PAH) metabolites were measured in mid-pregnancy urine using high performance liquid chromatography tandem mass spectrometry. Placental transcriptomic data were obtained using paired-end RNA sequencing. Linear models were fitted to estimate covariate-adjusted associations between maternal urinary OH-PAHs and placental gene expression. We performed sex-stratified analyses to evaluate whether associations varied by fetal sex. Selected PAH/gene expression analyses were validated by treating HTR-8/SVneo cells with phenanthrene, and quantifying expression via qPCR.

RESULTS

Urinary concentrations of 6 OH-PAHs were associated with placental expression of 8 genes. Three biological pathways were associated with 4 OH-PAHs. Placental expression of SGF29 and TRIP13 as well as the vitamin digestion and absorption pathway were positively associated with multiple metabolites. HTR-8/SVneo cells treated with phenanthrene also exhibited 23 % increased TRIP13 expression compared to vehicle controls (p = 0.04). Fetal sex may modify the relationship between prenatal OH-PAHs and placental gene expression, as more associations were identified in females than males (45 vs 28 associations).

DISCUSSION

Our study highlights novel genes whose placental expression may be disrupted by OH-PAHs. Increased expression of DNA damage repair gene TRIP13 may represent a response to double-stranded DNA breaks. Increased expression of genes involved in vitamin digestion and metabolism may reflect dietary exposures or represent a compensatory mechanism to combat damage related to OH-PAH toxicity. Further work is needed to study the role of these genes in placental function and their links to perinatal outcomes and lifelong health.

Prenatal exposure to polycyclic aromatic hydrocarbons is not associated with behavior problems in preschool and early school-aged children: A prospective multi-cohort study

BACKGROUND

Epidemiological study findings are inconsistent regarding associations between prenatal polycyclic aromatic hydrocarbon (PAH) exposures and childhood behavior. This study examined associations of prenatal PAH exposure with behavior at age 4-6 years in a large, diverse, multi-region prospective cohort. Secondary aims included examination of PAH mixtures and effect modification by child sex, breastfeeding, and child neighborhood opportunity.

METHODS

The ECHO PATHWAYS Consortium pooled 1118 mother-child dyads from three prospective pregnancy cohorts in six U.S. cities. Seven PAH metabolites were measured in prenatal urine. Child behavior was assessed at age 4-6 using the Total Problems score from the Child Behavior Checklist (CBCL). Neighborhood opportunity was assessed using the socioeconomic and educational scales of the Child Opportunity Index. Multivariable linear regression was used to estimate associations per 2-fold increase in each PAH metabolite, adjusted for demographic, prenatal, and maternal factors and using interaction terms for effect modifiers. Associations with PAH mixtures were estimated using Weighted Quantile Sum Regression (WQSR).

RESULTS

The sample was racially and sociodemographically diverse (38% Black, 49% White, 7% Other; household-adjusted income range $2651-$221,102). In fully adjusted models, each 2-fold increase in 2-hydroxynaphthalene was associated with a lower Total Problems score, contrary to hypotheses (b = -0.80, 95% CI = -1.51, -0.08). Associations were notable in boys (b = -1.10, 95% CI = -2.11, -0.08) and among children breastfed 6+ months (b = -1.31, 95% CI = -2.25, -0.37), although there was no statistically significant evidence for interaction by child sex, breastfeeding, or neighborhood child opportunity. Associations were null for other PAH metabolites; there was no evidence of associations with PAH mixtures from WQSR.

CONCLUSION

In this large, well-characterized, prospective study of mother-child pairs, prenatal PAH exposure was not associated with child behavior problems. Future studies characterizing the magnitude of prenatal PAH exposure and studies in older childhood are needed.

Associations between Phthalate Exposure and Gestational Age at Delivery in a Diverse Pregnancy Cohort

The association between prenatal phthalate exposure and late preterm birth (LPTB) is unclear. We examined singleton pregnancies (2006-2011) from a racially and socioeconomically diverse sample of women in the CANDLE cohort of the ECHO-PATHWAYS Consortium. Urine collected in the second and third trimester was analyzed for 14 phthalate metabolites. Multivariate logistic and linear regressions were performed for LPTB, defined as delivery 34-37 weeks, and gestational week, respectively. Models were controlled for socio-demographics, behavioral factors, clinical measurements, medical history, and phthalates in the other trimester. Effect modification by race and pregnancy stress, indicated by intimate partner violence (IPV), was investigated. We conducted a secondary analysis in women with spontaneous preterm labor. The rate of LPTB among 1408 women (61% Black, 32% White) was 6.7%. There was no evidence of decreased gestational age (GA) in association with any phthalate metabolite. Each two-fold increase in third trimester mono-benzyl phthalate (MBzP) was associated with 0.08 weeks longer gestational age (95% CI: 0.03, 0.12). When restricting to women with spontaneous labor, second trimester mono-n-butyl phthalate (MBP) was associated with 54% higher odds (95% CI: 2%, 132%) of LPTB. Associations were not modified by maternal race or IPV exposure. In conclusion, we observed mixed evidence concerning our hypothesis that prenatal phthalate exposure increases risk of LPTB, though secondary analyses suggest increased risk of spontaneous LPTB associated with MBP, which is consistent with a recent pooled analysis of 16 cohorts.