Validation of the Children's Eating Behaviour Questionnaire in a low-income preschool-aged sample in the United States

The Children's Eating Behaviour Questionnaire (CEBQ; Wardle, Guthrie, Sanderson, & Rapoport, 2001) is a widely used measure of child eating behaviors. Yet, only one study has examined the factor structure of the CEBQ among low-income children. In the current study, we examined the internal consistency, factor structure, and validity of the CEBQ among 1002 low-income preschool-age children recruited from Head Start locations in the United States. Confirmatory Factor Analysis indicated the CEBQ evidenced a reasonable fit to the data. Results also indicate that CEBQ subscales demonstrate good internal reliability (α's ≥ .70) and validity, with 7 of the 8 subscales associated with children's BMI z-scores in the expected directions. Equivalent factor loadings and indicator means across White and Black non-Hispanic participants were found, supporting measurement invariance between these two groups. In sum, our study supports the factor structure of the CEBQ among low-income preschool-aged children in the United States.

Prenatal Iron Supplementation Reduces Maternal Anemia, Iron Deficiency, and Iron Deficiency Anemia in a Randomized Clinical Trial in Rural China, but Iron Deficiency Remains Widespread in Mothers and Neonates

BACKGROUND

Previous trials of prenatal iron supplementation had limited measures of maternal or neonatal iron status.

OBJECTIVE

The purpose was to assess effects of prenatal iron-folate supplementation on maternal and neonatal iron status.

METHODS

Enrollment occurred June 2009 through December 2011 in Hebei, China. Women with uncomplicated singleton pregnancies at ≤20 wk gestation, aged ≥18 y, and with hemoglobin ≥100 g/L were randomly assigned 1:1 to receive daily iron (300 mg ferrous sulfate) or placebo + 0.40 mg folate from enrollment to birth. Iron status was assessed in maternal venous blood (at enrollment and at or near term) and cord blood. Primary outcomes were as follows: 1) maternal iron deficiency (ID) defined in 2 ways as serum ferritin (SF) <15 μg/L and body iron (BI) <0 mg/kg; 2) maternal ID anemia [ID + anemia (IDA); hemoglobin <110 g/L]; and 3) neonatal ID (cord blood ferritin <75 μg/L or zinc protoporphyrin/heme >118 μmol/mol).

RESULTS

A total of 2371 women were randomly assigned, with outcomes for 1632 women or neonates (809 placebo/folate, 823 iron/folate; 1579 mother-newborn pairs, 37 mothers, 16 neonates). Most infants (97%) were born at term. At or near term, maternal hemoglobin was significantly higher (+5.56 g/L) for iron vs. placebo groups. Anemia risk was reduced (RR: 0.53; 95% CI: 0.43, 0.66), as were risks of ID (RR: 0.74; 95% CI: 0.69, 0.79 by SF; RR: 0.65; 95% CI: 0.59, 0.71 by BI) and IDA (RR: 0.49; 95% CI: 0.38, 0.62 by SF; RR: 0.51; 95% CI: 0.40, 0.65 by BI). Most women still had ID (66.8% by SF, 54.7% by BI). Adverse effects, all minor, were similar by group. There were no differences in cord blood iron measures; >45% of neonates in each group had ID. However, dose-response analyses showed higher cord SF with more maternal iron capsules reported being consumed (β per 10 capsules = 2.60, P < 0.05).

CONCLUSIONS

Prenatal iron supplementation reduced anemia, ID, and IDA in pregnant women in rural China, but most women and >45% of neonates had ID, regardless of supplementation. This trial was registered at clinicaltrials.gov as NCT02221752.

Mealtime behavior among siblings and body mass index of 4-8 year olds: a videotaped observational study

Background

Being a last-born child and having a sister have been associated with higher body mass index (BMI). Encouragement to eat that overrides children’s self-regulation has been reported to increase the risk of obesogenic eating behaviors. This study sought to test the hypothesis that encouragement to eat during mealtime from older siblings and sisters mediates associations of being last-born or having a sister with higher BMI.

Methods

Children aged 4–8 years (n = 75) were videotaped while eating a routine evening meal at home with one sibling present. Encouragement to eat (defined as direct prompts to eat or general positive statements about food) delivered to the index child (IC) from the sibling was coded from the videotape. Path analysis was used to examine associations between IC’s birth order, sibling’s sex, encouragement counts, and IC’s measured BMI z-score (BMIz).

Results

Being the younger sibling in the sibling dyad was associated with the IC receiving more encouragements to eat from the sibling (β: 0.93, 95 % confidence interval (CI): 0.59, 1.26, p < 0.0001). The IC having a sister compared with a brother was not associated with the IC receiving more encouragements to eat from the sibling (β: 0.18, 95 % CI: −0.09, 0.47, p = 0.20). The IC receiving more encouragements to eat from the sibling was associated with lower IC BMIz (β: −0.06, 95 % CI: −0.12, 0.00, p = 0.05).

Conclusions

Children were more likely to receive encouragements to eat from older siblings than younger siblings. Being the recipient of encouragements to eat from a sibling was associated with lower, not higher, child BMIz, which may reflect sibling modeling of maternal behavior. Future longitudinal studies are needed to examine whether encouragements to eat from siblings lead to increase in BMI over time. Encouragements from siblings may be a novel intervention target for obesity prevention.

Maternal Feeding Goals Described by Low-Income Mothers

OBJECTIVE

To identify maternal feeding goals and examine associations of number and type of goals with mother and child characteristics.

DESIGN

Qualitative interviews about child feeding and quantitative assessment of goal prevalence and associations with mother and child characteristics.

SETTING

Southeastern Michigan.

PARTICIPANTS

A total of 287 low-income mothers (31% Hispanic or non-white) and their children ages 4 to 8 years.

MAIN OUTCOME MEASURE

Maternal feeding goals.

ANALYSIS

Themes were generated using the constant comparative method, individual interviews were coded, and the prevalence of feeding goals was determined. Regression analyses examined associations of mother and child characteristics with the number and type of feeding goals.

RESULTS

Thirteen maternal feeding goals were identified. The most prevalent were to restrict less nutrient-dense food (60%), promote autonomy around eating (54%), prevent obesity (53%), and promote fruits or vegetables (52%). A child who was female and heavier with an older, non-Hispanic white, more educated mother with less chaos in the home predicted more maternal feeding goals (all P < .05). Specific maternal and child characteristics were associated with individual feeding goals.

CONCLUSIONS AND IMPLICATIONS

Depending on their current goals for child feeding, some mothers may benefit from interventions focused on goal development, whereas other mothers may benefit from interventions designed to facilitate goal implementation.

Permutation Testing for Treatment-Covariate Interactions and Subgroup Identification

We consider the problem of using permutation-based methods to test for treatment-covariate interactions from randomized clinical trial data. Testing for interactions is common in the field of personalized medicine, as subgroups with enhanced treatment effects arise when treatment-by-covariate interactions exist. Asymptotic tests can often be performed for simple models, but in many cases, more complex methods are used to identify subgroups, and non-standard test statistics proposed, and asymptotic results may be difficult to obtain. In such cases, it is natural to consider permutation-based tests, which shuffle selected parts of the data in order to remove one or more associations of interest; however, in the case of interactions, it is generally not possible to remove only the associations of interest by simple permutations of the data. We propose a number of alternative permutation-based methods, designed to remove only the associations of interest, but preserving other associations. These methods estimate the interaction term in a model, then create data that "looks like" the original data except that the interaction term has been permuted. The proposed methods are shown to outperform traditional permutation methods in a simulation study. In addition, the proposed methods are illustrated using data from a randomized clinical trial of patients with hypertension.

Exploration of the composition and sources of urban fine particulate matter associated with same-day cardiovascular health effects in Dearborn, Michigan

The objective was to explore associations of chemical components and source factors of ambient fine particulate matter (aerodynamic diameter ≤ 2.5 μm; PM2.5) with cardiovascular (CV) changes following same-day exposure to ambient PM2.5. Twenty-five healthy adults living in rural Michigan were exposed to ambient air in an urban/industrial community for 4 to 5 h daily for five consecutive days. CV health outcomes were measured 1-2 h post exposure. Contributing emission sources were identified via positive matrix factorization. We examined associations between PM2.5 mass, composition and source factors, and same-day changes in CV outcomes using mixed-model analyses. PM2.5 mass (10.8 ± 6.8 μg/m(3)), even at low ambient levels, was significantly associated with increased heart rate (HR). Trace elements as well as secondary aerosol, diesel/urban dust and iron/steel manufacturing factors potentially explained the HR changes. However, trace element analysis demonstrated additional associations with other CV responses including changes in blood pressure (BP), arterial compliance, autonomic balance and trends toward reductions in endothelial function. Two factors were related to BP changes (diesel/urban dust, motor vehicle) and trends toward impaired endothelial function (diesel/urban dust). This study indicates composition of PM2.5 and its sources may contribute to CV health effects independently of PM2.5 mass.

Changes in body mass index associated with head start participation

OBJECTIVES

The goal of this study was to determine if Head Start participation is associated with healthy changes in BMI.

METHODS

The sample included children participating in Head Start between 2005 and 2013 and children from 2 comparison groups drawn from a Michigan primary care health system: 5405 receiving Medicaid and 19,320 not receiving Medicaid. Change in BMI z score from the beginning to the end of each of 2 academic years and the intervening summer was compared between groups by using piecewise linear mixed models adjusted for age, gender, and race/ethnicity.

RESULTS

The total sample included 43,748 children providing 83,239 anthropometric measures. The Head Start sample was 64.9% white, 10.8% black, and 14.4% Hispanic; 16.8% of the children were obese and 16.6% were overweight at the initial observation. Children who entered Head Start as obese exhibited a greater decline in the BMI z score during the first academic year versus the comparison groups (β = -0.70 [SE: 0.05] vs -0.07 [0.08] in the Medicaid group [P < .001] and -0.15 [SE: 0.05] in the Not Medicaid group [P < .001]); patterns were similar for overweight children. Head Start participants were less obese, less overweight, and less underweight at follow-up than children in the comparison groups.

CONCLUSIONS

Preschool-aged children with an unhealthy weight status who participated in Head Start had a significantly healthier BMI by kindergarten entry age than comparison children in a primary care health system (both those receiving and those not receiving Medicaid).

Missing not at random models for masked clinical trials with dropouts

Background

Missing data are an unavoidable problem in clinical trials. Most existing missing data approaches assume the missing data are missing at random. However, the missing at random assumption is often questionable when the real causes of missing data are not well known and cannot be tested from observed data.

Methods

We propose a specific missing not at random assumption, which we call masked missing not at random, which may be more plausible than missing at random for masked clinical trials. We formulate models for categorical and continuous outcomes under this assumption. Simulations are conducted to examine the finite sample performance of our methods and compare them with other methods. R code for the proposed methods is provided in supplementary materials.

Results

Simulation studies confirm that maximum likelihood methods assuming masked missing not at random outperform complete case analysis and maximum likelihood assuming missing at random when masked missing not at random is true. For the particular missing at random model where both of missing at random and masked missing not at random are satisfied, theory suggests that maximum likelihood assuming missing at random is at least as efficient as maximum likelihood assuming masked missing not at random. However, maximum likelihood assuming masked missing not at random is nearly as efficient as maximum likelihood assuming missing at random in our simulated settings. We also applied our methods to the TRial Of Preventing HYpertension study. The missing at random estimated treatment effect and its 95% confidence interval are robust to deviations from missing at random of the form implied by masked missing not at random.

Conclusion

Methods based on the masked missing not at random assumption are useful for masked clinical trials, either in their own right or to provide a form of sensitivity analysis for deviations from missing at random. Missing at random analysis might be favored on grounds of efficiency if the estimates based on masked missing not at random and missing at random are similar, but if the estimates are substantially different, the masked missing not at random estimates might be preferred because the mechanism is more plausible.

Rationale and design of the Feeding Dynamic Intervention (FDI) study for self-regulation of energy intake in preschoolers

In 2011, the Institute of Medicine Early Childhood Prevention Policies Report identified feeding dynamics as an important focus area for childhood obesity prevention and treatment. Feeding dynamics includes two central components: (1) caregiver feeding practices (i.e., determining how, when, where, and what they feed their children) and (2) child eating behaviors (i.e., determining how much and what to eat from what food caregivers have provided). Although there has been great interest in overweight and obesity prevention and treatment in young children, they have not focused comprehensively on feeding dynamics. Interventions on feeding dynamics that reduce caregivers' excessive controlling and restrictive feeding practices and encourage the development of children's self-regulation of energy intake may hold promise for tackling childhood obesity especially in the young child but currently lack an evidence base. This manuscript describes the rationale and design for a randomized controlled trial designed to compare a group of mothers and their 3-to 5-year old children who received an intervention focused primarily on feeding dynamics called the Feeding Dynamic Intervention (FDI) with a Wait-list Control Group (WLC). The primary aim of the study will be to investigate the efficacy of the FDI for decreasing Eating in the Absence of Hunger (EAH) and improving energy compensation (COMPX). The secondary aim will be to examine the effect of the FDI in comparison to the WLC on maternal self-reported feeding practices and child satiety responsiveness.

Maternal mobile device use during a structured parent-child interaction task

OBJECTIVE

To examine associations of maternal mobile device use with the frequency of mother-child interactions during a structured laboratory task.

METHODS

Participants included 225 low-income mother-child pairs. When children were ∼6 years old, dyads were videotaped during a standardized protocol in order to characterize how mothers and children interacted when asked to try familiar and unfamiliar foods. From videotapes, we dichotomized mothers on the basis of whether or not they spontaneously used a mobile device, and we counted maternal verbal and nonverbal prompts toward the child. We used multivariate Poisson regression to study associations of device use with eating prompt frequency for different foods.

RESULTS

Mothers were an average of 31.3 (SD 7.1) years old, and 28.0% were of Hispanic/nonwhite race/ethnicity. During the protocol, 23.1% of mothers spontaneously used a mobile device. Device use was not associated with any maternal characteristics, including age, race/ethnicity, education, depressive symptoms, or parenting style. Mothers with device use initiated fewer verbal (relative rate 0.80; 95% confidence interval 0.63, 1.03) and nonverbal (0.61; 0.39, 0.96) interactions with their children than mothers who did not use a device, when averaged across all foods. This association was strongest during introduction of halva, the most unfamiliar food (0.67; 0.48, 0.93 for verbal and 0.42; 0.20, 0.89 for nonverbal interactions).

CONCLUSIONS

Mobile device use was common and associated with fewer interactions with children during a structured interaction task, particularly nonverbal interactions and during introduction of an unfamiliar food. More research is needed to understand how device use affects parent-child engagement in naturalistic contexts.

Simple subgroup approximations to optimal treatment regimes from randomized clinical trial data

We consider the use of randomized clinical trial (RCT) data to identify simple treatment regimes based on some subset of the covariate space, A. The optimal subset, A, is selected by maximizing the expected outcome under a treat-if-in-A regime, and is restricted to be a simple, as it is desirable that treatment decisions be made with only a limited amount of patient information required. We consider a two-stage procedure. In stage 1, non-parametric regression is used to estimate treatment effects for each subject, and in stage 2 these treatment effect estimates are used to systematically evaluate many subgroups of a simple, prespecified form to identify A. The proposed methods were found to perform favorably compared with two existing methods in simulations, and were applied to prehypertension data from an RCT.

Heart disease management by women: does intervention format matter?

A randomized controlled trial of two formats of a program (Women Take PRIDE) to enhance management of heart disease by patients was conducted. Older women (N = 575) were randomly assigned to a group or self-directed format or to a control group. Data regarding symptoms, functional health status, and weight were collected at baseline and at 4, 12, and 18 months. The formats produced different outcomes. At 18 months, the self-directed format was better than the control in reducing the number (p ≤ .02), frequency (p ≤ .03), and bothersomeness (p ≤ .02) of cardiac symptoms. The self-directed format was also better than the group format in reducing symptom frequency of all types (p ≤ .04). The group format improved ambulation at 12 months (p ≤ .04) and weight loss at 18 months (p ≤ .03), and group participants were more likely to complete the program (p ≤ .05). The availability of different learning formats could enhance management of cardiovascular disease by patients.

Associations between maternal depressive symptoms and child feeding practices in a cross-sectional study of low-income mothers and their young children

Background

Maternal depression may influence feeding practices important in determining child eating behaviors and weight. However, the association between maternal depressive symptoms and feeding practices has been inconsistent, and most prior studies used self-report questionnaires alone to characterize feeding. The purpose of this study was to identify feeding practices associated with maternal depressive symptoms using multiple methodologies, and to test the hypothesis that maternal depressive symptoms are associated with less responsive feeding practices.

Methods

In this cross-sectional, observational study, participants (n = 295) included low-income mothers and their 4- to 8-year-old children. Maternal feeding practices were assessed via interviewer-administered questionnaires, semi-structured narrative interviews, and videotaped observations in home and laboratory settings. Maternal depressive symptoms were measured using the Center for Epidemiologic Studies-Depression scale (CES-D). Regression analyses examined associations between elevated depressive symptoms (CES-D score ≥16) and measures of maternal feeding practices, adjusting for: child sex, food fussiness, number of older siblings; and maternal age, body mass index (BMI), education, race/ethnicity, single parent status, perceived child weight, and concern about child weight.

Results

Thirty-one percent of mothers reported depressive symptoms above the screening cutoff. Mothers with elevated depressive symptoms reported more pressuring of children to eat (β = 0.29; 95% Confidence Interval (CI): 0.03, 0.54) and more overall demandingness (β = 0.16; 95% CI: 0.03, 0.29), and expressed lower authority in child feeding during semi-structured narrative interview (Odds Ratio (OR) for low authority: 2.82; 95% CI: 1.55, 5.12). In homes of mothers with elevated depressive symptoms, the television was more likely audible during meals (OR: 1.91; 95% CI: 1.05, 3.48) and mothers were less likely to eat with children (OR: 0.48; 95% CI: 0.27, 0.85). There were no associations between maternal depressive symptoms and encouragement or discouragement of food in laboratory eating interactions.

Conclusions

Mothers with elevated depressive symptoms demonstrated less responsive feeding practices than mothers with lower levels of depressive symptoms. These results suggest that screening for maternal depressive symptoms may be useful when counseling on healthy child feeding practices. Given inconsistencies across methodologies, future research should include multiple methods of characterizing feeding practices and direct comparisons of different methodologies.

Diurnal cortisol pattern, eating behaviors and overweight in low-income preschool-aged children

This study examined, among children, the associations among chaos in the home, diurnal cortisol patterns, eating behaviors and being overweight. Participants included 331 low-income children aged 3-4years. Mean salivary cortisol-intercept (representing morning peak, 60min since waking) and cortisol-slope (representing diurnal decline after peak) were calculated using mixed models from samples obtained across 3days. Parents reported chaos in the home by questionnaire and responded to the Children's Eating Behavior Questionnaire, generating subscales Food Responsiveness (FR), Emotional Overeating (EO), Enjoyment of Food (EF), and Satiety Responsiveness (SR). Body mass index was categorized as overweight vs. not. Path analysis evaluated associations among chaos, cortisol patterns, eating behaviors, and weight status. Children living in more chaotic homes had lower morning cortisol levels, consistent with "hypocortisolism" reported among individuals who have experienced significant allostatic load as a result of substantial early life chronic stress. Among girls, the hypocortisolism pattern predicted a higher likelihood of being overweight both directly and mediated through reduced Satiety Responsiveness; in boys, the association of the hypocortisolism pattern with being overweight was mediated entirely through Emotional Overeating. In summary, our results provide support for the conceptual model that psychosocial stress contributes to hypocortisolism, which contributes directly to a higher likelihood of being overweight in girls, and indirectly through reduced Satiety Responsiveness in girls and through increased Emotional Overeating in boys.

Motor activity and intra-individual variability according to sleep-wake states in preschool-aged children with iron-deficiency anemia in infancy

BACKGROUND

A chronic or acute insult may affect the regulatory processes that guide motor and behavioral performance, leading to increased intra-individual variability (IIV). Increased variability is often interpreted as an indication of regulatory dysfunction. Iron plays an important role in the regulatory processes of the nervous system and affects motor activity. To our knowledge, no study has examined the long-lasting patterns and IIV of motor activity following iron-deficiency anemia in human infants.

AIMS

This study compared 48-h motor activity and variability in preschool-aged children with or without iron-deficiency anemia (IDA) in infancy.

METHODS

Motor activity was recorded through actigraphs during two week-days in 47 4-year-old Chilean children (23 former IDA and 24 non-anemic in infancy). All were given oral iron as infants. Sleep-wake states were identified by means of automated software. The frequency of movement units per minute was determined for each waking/sleep state during the individual day and night periods; data were examined in blocks of 15 min. Analyses of mean frequency and duration and intra-individual variability were conducted using multivariate mixed models.

RESULTS

For daytime sleep, former IDA children were more active without a difference in the total duration. They also spent less time awake throughout the individual day period. Motor activity intra-individual variability was higher in former IDA children.

CONCLUSIONS

The findings suggest that IDA in infancy sets the stage for long lasting dysfunction in the neural processes regulating sleep-wake states and spontaneous motor activity patterns.

Overweight adolescents and life events in childhood

OBJECTIVES

To test the association of life events in childhood with overweight risk in adolescence; to examine the effects of chronicity, timing, intensity, valence, and type of life events; and to test potential moderators.

METHODS

Mothers of children enrolled in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Study of Early Child Care and Youth Development responded to the Life Experiences Survey at ages 4, 9, and 11 years. Using logistic regression analysis, we tested the association of experiencing many negative life events with being overweight at age 15 years, controlling for child gender, race/ethnicity, maternal education, and maternal obesity. Child gender, maternal education, maternal obesity, child's ability to delay gratification for food, and maternal sensitivity were tested as moderators.

RESULTS

Among the 848 study children (82% non-Hispanic white), experiencing many negative life events was associated with a higher risk of overweight (odds ratio: 1.47 [95% confidence interval: 1.04-2.10]). Greater chronicity and negative valence of the event were associated with greater overweight risk; timing of exposure and maternal reported impact of the event were not. The association was more robust for events related to family physical or mental health and among children of obese mothers and children who waited longer for food.

CONCLUSIONS

Children who experience many negative life events are at higher risk of being overweight by age 15 years. Future work should investigate mechanisms involved in this association, particularly those connected to appetitive drive and self-regulation; these mechanisms may hold promise for obesity prevention strategies.

Functional significance of early-life iron deficiency: outcomes at 25 years

OBJECTIVE

To evaluate adulthood function following chronic iron deficiency in infancy.

STUDY DESIGN

At 25 years, we compared 33 subjects with chronic iron deficiency in infancy to 89 who were iron-sufficient before and/or after iron therapy. Outcomes included education, employment, marital status, and physical and mental health.

RESULTS

Adjusting for sex and socioeconomic status, a higher proportion of the group with chronic iron deficiency did not complete secondary school (58.1% vs 19.8% in iron-sufficient group; Wald value = 8.74; P = .003), were not pursuing further education/training (76.1% vs 31.5%; Wald value = 3.01; P = .08; suggestive trend), and were single (83.9% vs 23.7%, Wald value = 4.49; P = .03). They reported poorer emotional health and more negative emotions and feelings of dissociation/detachment. Results were similar in secondary analyses comparing the chronic iron-deficient group with subjects in the iron-sufficient group who had been iron-deficient before treatment in infancy. Path analysis showed direct paths for chronic iron deficiency in infancy and being single and more detachment/dissociation at 25 years. There were indirect paths for chronic iron deficiency and not completing secondary school via poorer cognitive functioning in early adolescence and more negative emotions via behavior problems in adolescence, indicating a cascade of adverse outcomes.

CONCLUSION

The observational nature of this study limits our ability to draw causal inference, even when controlling for background factors. Nonetheless, our results indicate substantial loss of human potential. There may be broader societal implications, considering that many adults worldwide had chronic iron deficiency in infancy. Iron deficiency can be prevented or treated before it becomes chronic or severe.

Blunted cortisol response to stress is associated with higher body mass index in low-income preschool-aged children

No known studies have tested the hypothesis that a blunted pattern of cortisol reactivity to stress, which is often found following exposure to chronic life stressors, is associated with a higher body mass index (BMI) in very young children. Low-income children (n=218, mean age 56.6 (range: 38.1-78.5; SD 7.0) months, 49.1% male, 56.4% white, 16.1% black, 11.5% Hispanic/Latino) participated in a series of behavioral tasks designed to elicit stress. Cortisol was sampled in saliva 5 times during the protocol, and area under the curve (AUC), representing total cortisol output during stress elicitation, was calculated. Children were weighed and height measured and body mass index (BMI) z-score was calculated. Linear regression was used to evaluate the association between cortisol AUC and BMI z-score, controlling for child age, sex, and race/ethnicity (non-Hispanic white vs. not); primary caregiver weight status (overweight, defined as BMI ≥ 25 vs. not); and family income-to-needs ratio. Mean child BMI z-score was 0.88 (SD=1.03). Mean cortisol AUC was 6.11 μg/dL/min (SD=10.44). In the fully adjusted model, for each 1-standard deviation unit decrease in cortisol AUC, the child's BMI z-score increased by 0.17 (SE 0.07) standard deviation units (p<0.02). A blunted cortisol response to stress, as is often seen following chronic stress exposure, is associated with increased BMI z-score in very young children. Further work is needed to understand how associations between stress, cortisol, and elevated body mass index may develop very early in the lifespan.

Relationships between metrics of visit-to-visit variability of blood pressure

This paper examines relationships between metrics of visit-to-visit variability (VVV) of blood pressure (BP) to determine which metrics should be calculated in studies of the association of VVV with health outcomes. We examined correlation and agreement between quintiles for standard deviation (s.d.), standard deviation independent of the mean (SDIM), coefficient of variation (CV), successive variation (SV), average real variability (ARV), range, maximum, peak size and trough size of systolic BP in the Trial of Preventing Hypertension placebo arm (n=288). The average age of participants was 48 years. Mean systolic BP was 133.5 mm Hg. VVV metrics were all significantly correlated (P<0.001). Correlations between s.d., SDIM, CV and range and between ARV and SV were ≥0.90. Kappa statistics between quintiles of SD, SDIM, CV and range and between ARV and SV were ≥0.80. In studies of the relationship of VVV with health outcomes, we recommend reporting results for one of the metrics of overall variability (s.d., SDIM, CV), one of the metrics of variability between consecutive visits (SV, ARV), and one or more of the metrics of extreme values at a single visit (maximum, peak size, trough size).

Reduced metabolic insulin sensitivity following sub-acute exposures to low levels of ambient fine particulate matter air pollution

Epidemiological studies suggest that fine particulate matter (PM2.5) may increase the risk for developing diabetes mellitus (DM). To evaluate possible mechanisms explaining these associations, we investigated if sub-acute ambient-level exposures can impair insulin sensitivity. Twenty-five healthy adults living in rural Michigan were transported to an urban location for 5 consecutive days (exposure-block) of daily 4- to 5-hour-long ambient air pollution exposures. Health outcomes, including the homeostasis model assessment of insulin resistance (HOMA-IR) the primary outcome of insulin sensitivity, were measured at 3 time points in relation to exposure-blocks: 7days prior to start; on the last exposure-day; and 7days after completion. PM2.5 was monitored at the urban exposure site and at community monitors near subjects' residences. We calculated 3 "sub-acute" exposure periods (approximately 5-days-long) starting retrospective from the time of health outcome measurements (PM2.5 ranges: 9.7±3.9 to 11.2±3.9μg·m(-3)). A 10μg·m(-3) increase in sub-acute PM2.5 exposures was associated with increased HOMA-IR (+0.7, 95% confidence interval (CI) 0.1 to 1.3; p=0.023) and reduced heart rate variability (standard deviation of normal-to-normal intervals [-13.1ms, 95%CI -25.3 to -0.9; p=0.035]). No alterations in other outcomes (inflammatory markers, vascular function) occurred in relation to PM2.5 exposures. Our findings suggest that ambient PM2.5, even at low levels, may reduce metabolic insulin sensitivity supporting the plausibility that air pollution could potentiate the development of DM.

Developmental trends in auditory processing can provide early predictions of language acquisition in young infants

Auditory processing capabilities at the subcortical level have been hypothesized to impact an individual's development of both language and reading abilities. The present study examined whether auditory processing capabilities relate to language development in healthy 9-month-old infants. Participants were 71 infants (31 boys and 40 girls) with both Auditory Brainstem Response (ABR) and language assessments. At 6 weeks and/or 9 months of age, the infants underwent ABR testing using both a standard hearing screening protocol with 30 dB clicks and a second protocol using click pairs separated by 8, 16, and 64-ms intervals presented at 80 dB. We evaluated the effects of interval duration on ABR latency and amplitude elicited by the second click. At 9 months, language development was assessed via parent report on the Chinese Communicative Development Inventory - Putonghua version (CCDI-P). Wave V latency z-scores of the 64-ms condition at 6 weeks showed strong direct relationships with Wave V latency in the same condition at 9 months. More importantly, shorter Wave V latencies at 9 months showed strong relationships with the CCDI-P composite consisting of phrases understood, gestures, and words produced. Likewise, infants who had greater decreases in Wave V latencies from 6 weeks to 9 months had higher CCDI-P composite scores. Females had higher language development scores and shorter Wave V latencies at both ages than males. Interestingly, when the ABR Wave V latencies at both ages were taken into account, the direct effects of gender on language disappeared. In conclusion, these results support the importance of low-level auditory processing capabilities for early language acquisition in a population of typically developing young infants. Moreover, the auditory brainstem response in this paradigm shows promise as an electrophysiological marker to predict individual differences in language development in young children.

Enhancing self-regulation as a strategy for obesity prevention in Head Start preschoolers: the growing healthy study

BACKGROUND

Nearly one in five 4-year-old children in the United States are obese, with low-income children almost twice as likely to be obese as their middle/upper-income peers. Few obesity prevention programs for low-income preschoolers and their parents have been rigorously tested, and effects are modest. We are testing a novel obesity prevention program for low-income preschoolers built on the premise that children who are better able to self-regulate in the face of psychosocial stressors may be less likely to eat impulsively in response to stress. Enhancing behavioral self-regulation skills in low-income children may be a unique and important intervention approach to prevent childhood obesity.

METHODS/DESIGN

The Growing Healthy study is a randomized controlled trial evaluating two obesity prevention interventions in 600 low-income preschoolers attending Head Start, a federally-funded preschool program for low-income children. Interventions are delivered by community-based, nutrition-education staff partnering with Head Start. The first intervention (n = 200), Preschool Obesity Prevention Series (POPS), addresses evidence-based obesity prevention behaviors for preschool-aged children and their parents. The second intervention (n = 200) comprises POPS in combination with the Incredible Years Series (IYS), an evidence-based approach to improving self-regulation among preschool-aged children. The comparison condition (n = 200) is Usual Head Start Exposure. We hypothesize that POPS will yield positive effects compared to Usual Head Start, and that the combined intervention (POPS + IYS) addressing behaviors well-known to be associated with obesity risk, as well as self-regulatory capacity, will be most effective in preventing excessive increases in child adiposity indices (body mass index, skinfold thickness). We will evaluate additional child outcomes using parent and teacher reports and direct assessments of food-related self-regulation. We will also gather process data on intervention implementation, including fidelity, attendance, engagement, and satisfaction.

DISCUSSION

The Growing Healthy study will shed light on associations between self-regulation skills and obesity risk in low-income preschoolers. If the project is effective in preventing obesity, results can also provide critical insights into how best to deliver obesity prevention programming to parents and children in a community-based setting like Head Start in order to promote better health among at-risk children.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov Identifier: NCT01398358.

Maternal serum ferritin concentration is positively associated with newborn iron stores in women with low ferritin status in late pregnancy

Iron deficiency (ID) is common in pregnant women and infants, particularly in developing countries. The relation between maternal and neonatal iron status remains unclear. This study considered the issue in a large sample of mother-newborn pairs in rural southeastern China. Hemoglobin (Hb) and serum ferritin (SF) were measured in 3702 pregnant women at ≥37 wk gestation and in cord blood of their infants born at term (37-42 wk gestation). Maternal anemia (Hb <110 g/L) was present in 27.5% and associated with maternal SF <20 μg/L in 86.9%. Only 5.6% of neonates were anemic (Hb <130 g/L) and 9.5% had cord-blood SF <75 μg/L. There were low-order correlations between maternal and newborn iron measures (r = 0.07-0.10 for both Hb and SF; P ≤ 0.0001 due to the large number). We excluded 430 neonates with suggestion of inflammation [cord SF >370 μg/L, n = 208 and/or C-reactive protein (CRP) >5 mg/L, n = 233]. Piecewise linear regression analyses identified a threshold for maternal SF at which cord-blood SF was affected. For maternal SF below the threshold of 13.6 μg/L (β = 2.4; P = 0.001), cord SF was 0.17 SD lower than in neonates whose mothers had SF above the threshold (167 ± 75 vs. 179 ± 80 μg/L). The study confirmed that ID anemia remains common during pregnancy in rural southeastern China. Despite widespread maternal ID, however, iron nutrition seemed to meet fetal needs except when mothers were very iron deficient. The impact of somewhat lower cord SF on iron status later in infancy warrants further study.