Birth outcomes in relation to neighborhood food access and individual food insecurity during pregnancy in the Environmental Influences on Child Health Outcomes (ECHO)-wide cohort study.

BACKGROUND: Limited access to healthy foods, resulting from residence in neighborhoods with low-food access or from household food insecurity, is a public health concern. Contributions of these measures during pregnancy to birth outcomes remain understudied. OBJECTIVES: We examined associations between neighborhood food access and individual food insecurity during pregnancy with birth outcomes. METHODS: We used data from 53 cohorts participating in the nationwide Environmental Influences on Child Health Outcomes-Wide Cohort Study. Participant inclusion required a geocoded residential address or response to a food insecurity question during pregnancy and information on birth outcomes. Exposures include low-income-low-food-access (LILA, where the nearest supermarket is >0.5 miles for urban or >10 miles for rural areas) or low-income-low-vehicle-access (LILV, where few households have a vehicle and >0.5 miles from the nearest supermarket) neighborhoods and individual food insecurity. Mixed-effects models estimated associations with birth outcomes, adjusting for socioeconomic and pregnancy characteristics. RESULTS: Among 22,206 pregnant participants (mean age 30.4 y) with neighborhood food access data, 24.1% resided in LILA neighborhoods and 13.6% in LILV neighborhoods. Of 1630 pregnant participants with individual-level food insecurity data (mean age 29.7 y), 8.0% experienced food insecurity. Residence in LILA (compared with non-LILA) neighborhoods was associated with lower birth weight [ß -44.3 g; 95% confidence interval (CI): -62.9, -25.6], lower birth weight-for-gestational-age z-score (-0.09 SD units; -0.12, -0.05), higher odds of small-for-gestational-age [odds ratio (OR) 1.15; 95% CI: 1.00, 1.33], and lower odds of large-for-gestational-age (0.85; 95% CI: 0.77, 0.94). Similar findings were observed for residence in LILV neighborhoods. No associations of individual food insecurity with birth outcomes were observed. CONCLUSIONS: Residence in LILA or LILV neighborhoods during pregnancy is associated with adverse birth outcomes. These findings highlight the need for future studies examining whether investing in neighborhood resources to improve food access during pregnancy would promote equitable birth outcomes.

Ultra-processed and fast food consumption, exposure to phthalates during pregnancy, and socioeconomic disparities in phthalate exposures.

BACKGROUND: Consuming ultra-processed foods may increase exposure to phthalates, a group of endocrine disruptors prevalent in food contact materials. OBJECTIVES: Investigate associations between ultra-processed food intake and urinary phthalates during pregnancy, and evaluate whether ultra-processed foods mediate socioeconomic disparities in phthalate exposures. METHODS: In a socioeconomically diverse sample of 1031 pregnant women from the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) Study in the urban South, the Block Food Frequency Questionnaire was administered and urinary phthalate metabolites were measured in the second trimester. Linear regressions modeled associations between phthalates and overall ultra-processed food consumption, individual ultra-processed foods, and exploratory factor analysis dietary patterns. Causal mediation analyses examined whether ultra-processed food intake mediates relationships between socioeconomic disparities and phthalate exposures. RESULTS: Ultra-processed foods constituted 9.8-59.0 % (mean = 38.6 %) of participants' diets. 10 % higher dietary proportion of ultra-processed foods was associated with 13.1 % (95 %CI: 3.4 %-22.9 %) higher molar sum concentrations of di(2-ethylhexyl) phthalate metabolites (ΣDEHP). 10 % higher consumption of minimally-processed foods was associated with lower ΣDEHP (10.8 %: 3.4 %-22.9 %). Ultra- and minimally-processed food consumption were not associated with non-DEHP metabolites. Standard deviation higher consumptions of hamburger/cheeseburger, French fries, soda, and cake were associated with 10.5 % (4.2 %-17.1 %), 9.2 % (2.6 %-16.2 %), 7.4 % (1.4 %-13.6 %), and 6.0 % (0.0 %-12.4 %), respectively, higher ΣDEHP. Exploratory factor analysis corroborated positive associations of processed food with ΣDEHP, and uncovered a healthy dietary pattern associated with lower urinary ΣDEHP, mono(2-ethyl-5-hydroxyhexyl) (MEHHP), mono(2-ethyl-5-carboxypentyl) (MECPP), mono(2-carboxymethylhexyl) (MCMHP), and mono-isononyl (MINP) phthalates. Significant indirect effects indicated that lower income and education levels were associated with 1.9 % (0.2 %-4.2 %) and 1.4 % (0.1 %-3.3 %) higher ΣDEHP, respectively, mediated via increased ultra-processed food consumption. CONCLUSIONS: Consumption of ultra-processed foods may increase exposure to phthalates. Policies to reduce dietary phthalate exposures from food packaging and processing are needed, as socioeconomic barriers can preclude dietary recommendations as a sole means to reduce phthalate exposures.

Developing a National-Scale Exposure Index for Combined Environmental Hazards and Social Stressors and Applications to the Environmental Influences on Child Health Outcomes (ECHO) Cohort.

Tools for assessing multiple exposures across several domains (e.g., physical, chemical, and social) are of growing importance in social and environmental epidemiology because of their value in uncovering disparities and their impact on health outcomes. Here we describe work done within the Environmental influences on Child Health Outcomes (ECHO)-wide Cohort Study to build a combined exposure index. Our index considered both environmental hazards and social stressors simultaneously with national coverage for a 10-year period. Our goal was to build this index and demonstrate its utility for assessing differences in exposure for pregnancies enrolled in the ECHO-wide Cohort Study. Our unitless combined exposure index, which collapses census-tract level data into a single relative measure of exposure ranging from 0-1 (where higher values indicate higher exposure to hazards), includes indicators for major air pollutants and air toxics, features of the built environment, traffic exposures, and social determinants of health (e.g., lower educational attainment) drawn from existing data sources. We observed temporal and geographic variations in index values, with exposures being highest among participants living in the West and Northeast regions. Pregnant people who identified as Black or Hispanic (of any race) were at higher risk of living in a "high" exposure census tract (defined as an index value above 0.5) relative to those who identified as White or non-Hispanic. Index values were also higher for pregnant people with lower educational attainment. Several recommendations follow from our work, including that environmental and social stressor datasets with higher spatial and temporal resolutions are needed to ensure index-based tools fully capture the total environmental context.

The role of prenatal violence exposure in the development of disparities in children's adiposity from birth to middle childhood.

OBJECTIVE: This study examined whether women's exposure to multiple types of violence during childhood and pregnancy was associated with children's BMI trajectories and whether parenting quality moderated those associations. METHODS: A cohort of 1288 women who gave birth between 2006 and 2011 self-reported their exposure to childhood traumatic events, intimate partner violence (IPV), and residential address (linked to geocoded index of violent crime) during pregnancy. Children's length/height and weight at birth and at age 1, 2, 3, 4 to 6, and 8 years were converted to BMI z scores. Observed mother-child interactions were behaviorally coded during a dyadic teaching task. RESULTS: Covariate-adjusted growth mixture models identified three trajectories of children's BMI from birth to 8 years old: Low-Stable (17%), Moderate-Stable (59%), and High-Rising (22%). Children whose mothers experienced more types of IPV during pregnancy were more likely to be in the High-Rising than the Low-Stable (odds ratio [OR] = 2.62; 95% CI: 1.27-5.41) trajectory. Children whose mothers lived in higher crime neighborhoods were more likely to be in the High-Rising than the Low-Stable (OR = 1.11; 95% CI:1.03-1.17) or Moderate-Stable trajectories (OR = 1.08; CI: 1.03-1.13). Main effects of childhood traumatic events and moderation by parenting were not detected. CONCLUSIONS: Maternal experiences of violence during pregnancy increase children's risk for developing overweight, highlighting intergenerational transmission of social adversity in children's health.

Associations between social, biologic, and behavioral factors and biomarkers of oxidative stress during pregnancy: Findings from four ECHO cohorts.

BACKGROUND: Lower socioeconomic status (SES) and elevated psychosocial stress are known contributors to adverse pregnancy outcomes; however, biological mechanisms linking these factors to adverse pregnancy outcomes are not well-characterized. Oxidative stress may be an important, yet understudied mechanistic pathway. We used a pooled study design to examine biological, behavioral, and social factors as predictors of prenatal oxidative stress biomarkers. METHODS: Leveraging four pregnancy cohorts from the Environmental influences on Child Health Outcomes (ECHO) Program spanning multiple geographic regions across the United States (U.S.) (N = 2082), we measured biomarkers of oxidative stress in urine samples at up to three time points during pregnancy, including 8-isoprostane-prostaglandin F2α (8-isoPGF2α), its major metabolite, 2,3-dinor-5,6-dihydro-15-F2t-isoprostane, and prostaglandin F2α (PGF2α). Maternal age, pre-pregnancy body mass index, marital/partnered status, parity, and smoking status were included as biological and behavioral factors while race/ethnicity, maternal education, and stressful life events were considered social factors. We examined associations between each individual biological, behavioral, and social factor with oxidative stress biomarkers using multivariable-adjusted linear mixed models. RESULTS: Numerous biological, behavioral, and social factors were associated with elevated levels of 8-isoPGF2α, its major metabolite, and PGF2α. Pregnant people who were current smokers relative to non-smokers or had less than a high school education relative to a college degree had 11.04% (95% confidence interval [CI] = -1.97%, 25.77%) and 9.13% (95% CI = -1.02%, 20.32%) higher levels of 8-isoPGF2α, respectively. CONCLUSIONS: Oxidative stress biomarkers are elevated among pregnant people with higher socioeconomic disadvantage and may represent one pathway linking biological, behavioral, and social factors to adverse pregnancy and child health outcomes, which should be explored in future work.

A Comprehensive Assessment of Associations between Prenatal Phthalate Exposure and the Placental Transcriptomic Landscape.

BACKGROUND: Phthalates are commonly used endocrine-disrupting chemicals that are ubiquitous in the general population. Prenatal phthalate exposure may alter placental physiology and fetal development, leading to adverse perinatal and childhood health outcomes. OBJECTIVE: We examined associations between prenatal phthalate exposure in the second and third trimesters and the placental transcriptome at birth, including genes and long noncoding RNAs (lncRNAs), to gain insight into potential mechanisms of action during fetal development. METHODS: The ECHO PATHWAYs consortium quantified 21 urinary phthalate metabolites from 760 women enrolled in the CANDLE study (Shelby County, TN) using high-performance liquid chromatography-tandem mass spectrometry. Placental transcriptomic data were obtained using paired-end RNA sequencing. Linear models were fitted to estimate separate associations between maternal urinary phthalate metabolite concentration during the second and third trimester and placental gene expression at birth, adjusted for confounding variables. Genes were considered differentially expressed at a Benjamini-Hochberg false discovery rate (FDR) p<0.05. Associations between phthalate metabolites and biological pathways were identified using self-contained gene set testing and considered significantly altered with an FDR-adjusted p<0.2. RESULTS: We observed significant associations between second-trimester phthalate metabolites mono (carboxyisooctyl) phthalate (MCIOP), mono-2-ethyl-5-carboxypentyl phthalate, and mono-2-ethyl-5-oxohexyl phthalate and 18 genes in total, including four lncRNAs. Specifically, placental expression of NEAT1 was associated with multiple phthalate metabolites. Third-trimester MCIOP and mono-isobutyl phthalate concentrations were significantly associated with placental expression of 18 genes and two genes, respectively. Expression of genes within 27 biological pathways was associated with mono-methyl phthalate, MCIOP, and monoethyl phthalate concentrations. DISCUSSION: To our knowledge, this is the first genome-wide assessment of the relationship between the placental transcriptome at birth and prenatal phthalate exposure in a large and diverse birth cohort. We identified numerous genes and lncRNAs associated with prenatal phthalate exposure. These associations mirror findings from other epidemiological and in vitro analyses and may provide insight into biological pathways affected in utero by phthalate exposure. https://doi.org/10.1289/EHP8973.

The Revised WIC Food Package and Child Development: A Quasi-Experimental Study.

BACKGROUND AND OBJECTIVES: The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), one of the largest US safety net programs, was revised in 2009 to be more congruent with dietary guidelines. We hypothesize that this revision led to improvements in child development. METHODS: Data were drawn from a cohort of women and children enrolled in the Conditions Affecting Neurocognitive Development and Learning in Early Childhood study from 2006 to 2011 (Shelby County, TN; N = 1222). Using quasi-experimental difference-in-differences analysis, we compared measures of growth, cognitive, and socioemotional development between WIC recipients and nonrecipients before and after the policy revision. RESULTS: The revised WIC food package led to increased length-for-age z scores at 12 months among infants whose mothers received the revised food package during pregnancy (ß = .33, 95% confidence interval: 0.05 to 0.61) and improved Bayley Scales of Infant Development cognitive composite scores at 24 months (ß = 4.34, 95% confidence interval: 1.11 to 7.57). We observed no effects on growth at age 24 months or age 4 to 6 years or cognitive development at age 4 to 6 years. CONCLUSIONS: This study provides some of the first evidence that children of mothers who received the revised WIC food package during pregnancy had improved developmental outcomes in the first 2 years of life. These findings highlight the value of WIC in improving early developmental outcomes among vulnerable children. The need to implement and expand policies supporting the health of marginalized groups has never been more salient, particularly given the nation's rising economic and social disparities.

Identification of Modifiable Social and Behavioral Factors Associated With Childhood Cognitive Performance.

Importance: Inequities in social environments are likely associated with a large portion of racial disparities in childhood cognitive performance. Identification of the specific exposures associated with cognitive development is needed to inform prevention efforts. Objective: To identify modifiable factors associated with childhood cognitive performance. Design, Setting, and Participants: This longitudinal pregnancy cohort study included 1503 mother-child dyads who were enrolled in the University of Tennessee Health Science Center-Conditions Affecting Neurodevelopment and Learning in Early Life study between December 1, 2006, and July 31, 2011, and assessed annually until the children were aged 4 to 6 years. The analytic sample comprised 1055 mother-child dyads. A total of 155 prenatal, perinatal, and postnatal exposures were included to evaluate environment-wide associations. Participants comprised a community-based sample of pregnant women who were recruited between 16 weeks and 28 weeks of gestation from 4 hospitals in Shelby County, Tennessee. Women with high-risk pregnancies were excluded. Data were analyzed from June 1, 2018, to April 15, 2019. Exposures: Individual and neighborhood socioeconomic position, family structure, maternal mental health, nutrition, delivery complications, birth outcomes, and parenting behaviors. Main Outcomes and Measures: Child's full-scale IQ measured by the Stanford-Binet Intelligence Scales, Fifth Edition, at age 4 to 6 years. Results: Of 1055 children included in the analytic sample, 532 (50.4%) were female. Among mothers, the mean (SD) age was 26.0 (5.6) years; 676 mothers (64.1%) were Black, and 623 mothers (59.0%) had an educational level of high school or less. Twenty-four factors were retained in the least absolute shrinkage and selection operator regression analysis and full models adjusted for potential confounding. Associations were noted between child cognitive performance and parental education and breastfeeding; for each increase of 1.0 SD in exposure, positive associations were found with cognitive growth fostering from observed parent-child interactions (ß = 1.12; 95% CI, 0.24-2.00) and maternal reading ability (ß = 1.42; 95% CI, 0.16-2.68), and negative associations were found with parenting stress (ß = -1.04; 95% CI, -1.86 to -0.21). A moderate increase in these beneficial exposures was associated with a notable improvement in estimated cognitive test scores using marginal means (0.5% of an SD). Black children experienced fewer beneficial cognitive performance exposures; in a model including all 24 exposures and covariates, no racial disparity was observed in cognitive performance (95% CIs for race included the null). Conclusions and Relevance: The prospective analysis identified multiple beneficial and modifiable cognitive performance exposures that were associated with mean differences in cognitive performance by race. The findings from this observational study may help guide experimental studies focused on reducing racial disparities in childhood cognitive performance.

Prenatal air pollution and childhood IQ: Preliminary evidence of effect modification by folate.

OBJECTIVES: Animal studies suggest that air pollution is neurotoxic to a developing fetus, but evidence in humans is limited. We tested the hypothesis that higher air pollution is associated with lower child IQ and that effects vary by maternal and child characteristics, including prenatal nutrition. METHODS: We used prospective data collected from the Conditions Affecting Neurocognitive Development and Learning in Early Childhood study. Outdoor pollutant exposure during pregnancy was predicted at geocoded home addresses using a validated national universal kriging model that combines ground-based monitoring data with an extensive database of land-use covariates. Distance to nearest major roadway was also used as a proxy for traffic-related pollution. Our primary outcome was full-scale IQ measured at age 4-6. In regression models, we adjusted for multiple determinants of child neurodevelopment and assessed interactions between air pollutants and child sex, race, socioeconomic status, reported nutrition, and maternal plasma folate in second trimester. RESULTS: In our analytic sample (N = 1005) full-scale IQ averaged 2.5 points (95% CI: 0.1, 4.8) lower per 5 µg/m3 higher prenatal PM10, while no associations with nitrogen dioxide or road proximity were observed. Associations between PM10 and IQ were modified by maternal plasma folate (pinteraction = 0.07). In the lowest folate quartile, IQ decreased 6.8 points (95% CI: 1.4, 12.3) per 5-unit increase in PM10; no associations were observed in higher quartiles. CONCLUSIONS: Our findings strengthen evidence that air pollution impairs fetal neurodevelopment and suggest a potentially important role of maternal folate in modifying these effects.

The Impact of the Revised WIC Food Package on Maternal Nutrition During Pregnancy and Postpartum.

The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) provides nutritional support for pregnant and postpartum women and young children. The typical food package provided to recipient families was revised in October 2009 to include more whole grains, fruits, vegetables, and low-fat milk. Little is known about whether these revisions improved nutrition among women during this critical period of the life course. We conducted a quasiexperimental difference-in-differences analysis, comparing WIC recipients ("treatment" group) before and after the WIC policy change, while accounting for temporal trends among nonrecipients ("control" group). We examined nutritional outcomes among a cohort of 1,454 women recruited during pregnancy in 2006-2011 in Memphis and surrounding Shelby County, Tennessee. We found improvements in several measures of dietary quality and nutrient intake during pregnancy, although these did not persist into the postpartum period. Results were robust to numerous sensitivity analyses. At a time when federal WIC funding is threatened, this study provides some of the first evidence of the benefits of recent WIC revisions among low-income women.

The biological embedding of early-life socioeconomic status and family adversity in children's genome-wide DNA methylation.

AIM: To examine variation in child DNA methylation to assess its potential as a pathway for effects of childhood social adversity on health across the life course. MATERIALS & METHODS: In a diverse, prospective community sample of 178 kindergarten children, associations between three types of social experience and DNA methylation within buccal epithelial cells later in childhood were examined. RESULTS: Family income, parental education and family psychosocial adversity each associated with increased or decreased DNA methylation (488, 354 and 102 sites, respectively) within a unique set of genomic CpG sites. Gene ontology analyses pointed to genes serving immune and developmental regulation functions. CONCLUSION: Findings provided support for DNA methylation as a biomarker linking early-life social experiences with later life health in humans.

Family Socioeconomic Status, Cortisol, and Physical Health in Early Childhood: The Role of Advantageous Neighborhood Characteristics.

OBJECTIVE: Children from families with lower socioeconomic status (SES) evidence greater physiological dysregulation and poorer health. Despite recognition of environmental contributors, little is known about the influence of neighborhood characteristics. The present study examined the moderating role of community-level risks and resources on the relation of family SES to children's daily cortisol output and physical health during the kindergarten year. METHODS: In fall and spring of kindergarten, children's (N = 338) daily total cortisol was measured and parents and teachers rated children's global physical health. Parents reported family SES. Neighborhood characteristics were assessed using the Child Opportunity Index, a population-level tool that evaluates the quality of multiple domains of neighborhood attributes. RESULTS: In fall, children reared in lower SES family environments had higher cortisol when residing in lower quality (lower opportunity) neighborhoods (b = -.097, p < .001), but there was no relation between family SES and children's cortisol in more advantaged (higher opportunity) neighborhoods (b = -.023, p = .36). Lower family SES was prospectively associated with poorer physical health in spring (controlling for fall health) only among children living in lower opportunity neighborhoods (b = -.250, p = .018) and was unrelated to physical health among children residing in higher opportunity neighborhoods (b = .042, p = .70). CONCLUSIONS: Higher opportunity neighborhoods may protect against the negative consequences of low family SES on children's stress physiology and physical health. Public health interventions that bolster neighborhood opportunities may benefit young children reared in socioeconomically disadvantaged family environments.

Socioeconomic Disparities in Childhood Obesity Risk: Association With an Oxytocin Receptor Polymorphism.

Importance: Pediatricians are paying increased attention to the effects of socioeconomic status (SES) on children's health. Low SES is a robust predictor of obesity across the life course and may interact with genes affecting metabolism to influence obesity risk. Recent animal literature and burgeoning human research suggest that the hormone oxytocin (OT) may be important for metabolic regulation. To date, this association has not been examined in children. Objectives: To examine whether an OT receptor polymorphism (rs53576) interacts with SES, potentially exacerbating and buffering the effects of stress, to predict anthropometry during childhood, and based on differential neurobiological susceptibility theory, to test whether carriers of the A allele of the OXTR gene, compared with GG genotyped individuals, would be most sensitive to the effects of SES on anthropometry for better or for worse. Design, Setting, and Participants: In this observational study, families were recruited from public school classrooms and enrolled in the Peers and Wellness Study (PAWS), which examined the effects of social status on health. Families were assessed during children's kindergarten year (fall semester of 2003, 2004, and 2005) and again during middle childhood (2009-2011) for a follow-up assessment that included anthropometric measures and DNA collection. The dates of the analysis were January 2015 to June 2016. Exposures: Socioeconomic disparities. Main Outcomes and Measures: Child body mass index z score (BMIz) and triceps skinfold thickness. Family SES was collected through questionnaires mailed to homes. Body measurements and DNA were collected in homes by trained research assistants. Results: From the original community sample of 338 typically developing children, participants were 186 socioeconomically and racially/ethnically diverse children (mean age, 10.3 years; age range, 9.4-11.3 years; 93 females [50%]) who had sufficient data at the follow-up assessment for inclusion in this study. Among 97 A allele carriers, a 1-SD increase in SES was associated with a decrease in BMIz of 0.28 (95% CI, -0.47 to -0.09) and a decrease in skinfold thickness of 0.95 (95% CI, -1.77 to -0.12) mm, such that they exhibited the highest BMIz and skinfold thickness in contexts of low SES but exhibited the lowest BMIz and skinfold thickness in contexts of high SES. Socioeconomic status was unrelated to BMIz (95% CI, -0.21 to 0.26) or skinfold thickness (95% CI, -0.42 to 1.45) for 89 GG genotyped children. Conclusions and Relevance: These findings advance etiologic understanding of childhood obesity, highlighting complex effects of SES on child health and adding to growing evidence that OT relates to human obesity risk. The results also support differential neurobiological susceptibility theory, suggesting that the A allele renders individuals more sensitive to both positive and negative health effects of socioecological context.

Mechanisms Underlying the Association Between Early-Life Adversity and Physical Health: Charting a Course for the Future.

Early-life adversities (ELA) are associated with subsequent pervasive alterations across a wide range of neurobiological systems and psychosocial factors that contribute to accelerated onset of health problems and diseases. In this article, we provide an integrated perspective on recent developments in research on ELA, based on the articles published in this Special Issue of Psychosomatic Medicine. We focus on the following: 1) the distinction between specific versus general aspects of ELA with regard to the nature of exposure (e.g., physical and sexual abuse, emotional abuse or neglect, relative socioeconomic deprivation), biological and behavioral correlates of ELA, and differences across diseases; 2) the importance of timing in the critical phases of exposure to ELA; and 3) adaptive versus dysfunctional responses to ELA and their consequences for biological and behavioral risk factors for adverse health outcomes. This article concludes with outlining important new targets for research in this area, including the neurobiology of affect as a mechanism linking ELA to adverse health outcomes, and the need for large-scale longitudinal investigations of multisystem processes relevant to ELA in diverse samples, starting prenatally, continuing to late adolescence, and with long-term follow-up assessments that enable evaluation of incident disease outcomes.

Socioeconomic Adversity, Negativity in the Parent Child-Relationship, and Physiological Reactivity: An Examination of Pathways and Interactive Processes Affecting Young Children's Physical Health.

OBJECTIVE: We tested the hypothesis that socioeconomic status (SES) would predict children's physical health problems at the end of kindergarten among children whose parent reported greater parent-child relationship (PCR) negativity and/or who exhibited greater parasympathetic (RSA) reactivity. We also tested whether RSA and PCR negativity mediated the SES-health association. METHODS: Data were collected from 338 children (mean [SD] age, 5.32 [.32] years) and their primary caregivers (87% biological mothers) during the fall and subsequent spring of kindergarten. In the fall, parents reported income and education level (SES) and PCR negativity, and RSA reactivity was assessed via a standardized challenge protocol for young children. In the fall and then spring, parents reported children's chronic medical conditions and physical health impairments. Multivariate regression was conducted within a structural equation-modeling framework to test hypotheses. RESULTS: Significant interactions were found between SES and PCR negativity (b = -0.074, p = .035) and between SES and RSA reactivity (b = 0.169, p = .019) as predicts children's spring health impairment, adjusting for health in the preceding fall. Lower SES was associated with greater health impairment among children whose parents reported more PCR negativity (b = -0.110, p = .024) and children who showed greater RSA reactivity (b = -0.106, p = .011). Socioeconomic status was unrelated to physical health at low PCR negativity or RSA reactivity. Mediation models were not supported. CONCLUSION: Parent-child relationship quality and individual differences in stress reactivity may modulate the influence of SES on physical health in childhood.

Social stratification, classroom climate, and the behavioral adaptation of kindergarten children.

Socioeconomic status (SES) is the single most potent determinant of health within human populations, from infancy through old age. Although the social stratification of health is nearly universal, there is persistent uncertainty regarding the dimensions of SES that effect such inequalities and thus little clarity about the principles of intervention by which inequalities might be abated. Guided by animal models of hierarchical organization and the health correlates of subordination, this prospective study examined the partitioning of children's adaptive behavioral development by their positions within kindergarten classroom hierarchies. A sample of 338 5-y-old children was recruited from 29 Berkeley, California public school classrooms. A naturalistic observational measure of social position, parent-reported family SES, and child-reported classroom climate were used in estimating multilevel, random-effects models of children's adaptive behavior at the end of the kindergarten year. Children occupying subordinate positions had significantly more maladaptive behavioral outcomes than their dominant peers. Further, interaction terms revealed that low family SES and female sex magnified, and teachers' child-centered pedagogical practices diminished, the adverse influences of social subordination. Taken together, results suggest that, even within early childhood groups, social stratification is associated with a partitioning of adaptive behavioral outcomes and that the character of larger societal and school structures in which such groups are nested can moderate rank-behavior associations.

Rigor, vigor, and the study of health disparities.

Health disparities research spans multiple fields and methods and documents strong links between social disadvantage and poor health. Associations between socioeconomic status (SES) and health are often taken as evidence for the causal impact of SES on health, but alternative explanations, including the impact of health on SES, are plausible. Studies showing the influence of parents' SES on their children's health provide evidence for a causal pathway from SES to health, but have limitations. Health disparities researchers face tradeoffs between "rigor" and "vigor" in designing studies that demonstrate how social disadvantage becomes biologically embedded and results in poorer health. Rigorous designs aim to maximize precision in the measurement of SES and health outcomes through methods that provide the greatest control over temporal ordering and causal direction. To achieve precision, many studies use a single SES predictor and single disease. However, doing so oversimplifies the multifaceted, entwined nature of social disadvantage and may overestimate the impact of that one variable and underestimate the true impact of social disadvantage on health. In addition, SES effects on overall health and functioning are likely to be greater than effects on any one disease. Vigorous designs aim to capture this complexity and maximize ecological validity through more complete assessment of social disadvantage and health status, but may provide less-compelling evidence of causality. Newer approaches to both measurement and analysis may enable enhanced vigor as well as rigor. Incorporating both rigor and vigor into studies will provide a fuller understanding of the causes of health disparities.

Kindergarten stressors and cumulative adrenocortical activation: the "first straws" of allostatic load?

Using an ethnically diverse longitudinal sample of 338 kindergarten children, this study examined the effects of cumulative contextual stressors on children's developing hypothalamic-pituitary-adrenocortical (HPA) axis regulation as an early life indicator of allostatic load. Chronic HPA axis regulation was assessed using cumulative, multiday measures of cortisol in both the fall and spring seasons of the kindergarten year. Hierarchical linear regression analyses revealed that contextual stressors related to ethnic minority status, socioeconomic status, and family adversity each uniquely predicted children's daily HPA activity and that some of those associations were curvilinear in conformation. Results showed that the quadratic, U-shaped influences of family socioeconomic status and family adversity operate in different directions to predict children's HPA axis regulation. Results further suggested that these associations differ for White and ethnic minority children. In total, this study revealed that early childhood experiences contribute to shifts in one of the principal neurobiological systems thought to generate allostatic load, confirming the importance of early prevention and intervention efforts. Moreover, findings suggested that analyses of allostatic load and developmental theories accounting for its accrual would benefit from an inclusion of curvilinear associations in tested predictive models.

Temperament variation in sensitivity to parenting: predicting changes in depression and anxiety.

Temperament was examined as a moderator of maternal parenting behaviors, including warmth, negativity, autonomy granting, and guidance. Observations of parenting and questionnaire measures of temperament and adjustment were obtained from a community sample (N = 214; ages 8-12). Trajectories of depression and anxiety were assessed across 3 years. The pattern of parenting as a predictor of internalizing symptoms depended on temperament. Maternal negativity predicted increases in depression for children low in fear. Effortful control moderated sensitivity to maternal negativity, autonomy granting, and guidance. Children low in effortful control reported more symptoms in the presence of negative or poor-fitting parenting. The results support differential responding, but also suggest that temperament may render children vulnerable for the development of problems regardless of parenting.