Spinal Inhibitory Interneuron Diversity Delineates Variant Motor Microcircuits.

Animals generate movement by engaging spinal circuits that direct precise sequences of muscle contraction, but the identity and organizational logic of local interneurons that lie at the core of these circuits remain unresolved. Here, we show that V1 interneurons, a major inhibitory population that controls motor output, fractionate into highly diverse subsets on the basis of the expression of 19 transcription factors. Transcriptionally defined V1 subsets exhibit distinct physiological signatures and highly structured spatial distributions with mediolateral and dorsoventral positional biases. These positional distinctions constrain patterns of input from sensory and motor neurons and, as such, suggest that interneuron position is a determinant of microcircuit organization. Moreover, V1 diversity indicates that different inhibitory microcircuits exist for motor pools controlling hip, ankle, and foot muscles, revealing a variable circuit architecture for interneurons that control limb movement.

From infancy to eight: How early maternal mental health, emotion reminiscing, and language shape children's mental health.

To test the transmission of mental health difficulties from mother to child, we examined mediation through emotion reminiscing conversations and child language. Maternal depression symptoms were measured at 9 months post-partum, and child mental health outcomes were measured at age 8 years. Emotion reminiscing conversations between 1,234 mother-child pairs (624 boys, 610 girls) were recorded as part of a large, diverse, longitudinal cohort Growing Up in New Zealand. The 1,234 reminiscing conversations were transcribed and coded for maternal elaboration and emotion resolution quality (mother and child). The coded reminiscing variables did not mediate the pathway from maternal depression to child mental health outcomes; however, each maternal reminiscing variable together with child language skill serially mediated the relationship from maternal depression symptoms to child-reported anxiety and depression symptoms, and parent-reported child externalizing symptoms. Language as a skill and it's use as a tool for making shared meaning from past events are highlighted as possible mechanisms for the intergenerational transmission of mental health difficulties. These findings point to potential opportunities for early interventions, including prevention of and support for postnatal depression, family intervention in reminiscing training, and supporting child language development.

Prevalence and maternal determinants of early and late introduction of complementary foods: results from the Growing Up in New Zealand cohort study.

A nationally generalisable cohort (n 5770) was used to determine the prevalence of non-timely (early/late) introduction of complementary food and core food groups and associations with maternal sociodemographic and health behaviours in New Zealand (NZ). Variables describing maternal characteristics and infant food introduction were sourced, respectively, from interviews completed antenatally and during late infancy. The NZ Infant Feeding Guidelines were used to define early (≤ 4 months) and late (≥ 7 months) introduction. Associations were examined using multivariable multinomial regression, presented as adjusted relative risk ratios and 95 % confidence intervals (RRR; 95% CI). Complementary food introduction was early for 40·2 % and late for 3·2 %. The prevalence of early food group introduction were fruit/vegetables (23·8 %), breads/cereals (36·3 %), iron-rich foods (34·1 %) and of late were meat/meat alternatives (45·9 %), dairy products (46·2 %) and fruits/vegetables (9·9 %). Compared with infants with timely food introduction, risk of early food introduction was increased for infants: breastfed < 6months (2·52; 2·19-2·90), whose mothers were < 30 years old (1·69; 1·46-1·94), had a diploma/trade certificate v. tertiary education (1·39; 1·1-1·70), of Maori v. European ethnicity (1·40; 1·12-1·75) or smoked during pregnancy (1·88; 1·44-2·46). Risk of late food introduction decreased for infants breastfed < 6 months (0·47; 0.27-0·80) and increased for infants whose mothers had secondary v. tertiary education (2·04; 1·16-3·60) were of Asian v. European ethnicity (2·22; 1·35, 3·63) or did not attend childbirth preparation classes (2·23; 1·24-4·01). Non-timely food introduction, specifically early food introduction, is prevalent in NZ. Interventions to improve food introduction timeliness should be ethnic-specific and support longer breast-feeding.

Comparing primary caregivers' reported injury data with routinely recorded injury data to assess predictors of childhood injury.

BACKGROUND: Linking self-reported data collected from longitudinal studies with administrative health records is timely and cost-effective, provides the opportunity to augment information contained in each and can offset some of the limitations of both data sources. The aim of this study was to compare maternal-reported child injury data with administrative injury records and assess the level of agreement. METHODS: A deterministic linkage was undertaken to link injury-related data from the Growing up in New Zealand (GUiNZ) study to routinely collected injury records from New Zealand's Accident Compensation Corporation (ACC) for preschool children. The analyses compared: (i) the characteristics of mothers with linked data vs. those without, (ii) injury incidences from maternal recall with those recorded in ACC injury claims, and (iii) the demographic characteristics of concordant and discordant injury reports, including the validity and reliability of injury records from both data sources. RESULTS: Of all mothers who responded to the injury questions in the GUiNZ study (n = 5836), more than 95% (n = 5637) agreed to have their child's record linked to routine administrative health records. The overall discordance in injury reports showed an increasing trend as children grew older (9% at 9 M to 29% at 54 M). The mothers of children with discordance between maternal injury reports and ACC records were more likely to be younger, of Pacific ethnicity, with lower educational attainment, and live in areas of high deprivation (p < 0.001). The level of agreement between maternal injury recall and ACC injury record decreased (κ = 0.83 to κ = 0.42) as the cohort moved through their preschool years. CONCLUSIONS: In general, the findings of this study identified that there was underreporting and discordance of the maternal injury recall, which varied by the demographic characteristics of mothers and their child's age. Therefore, linking the routinely gathered injury data with maternal self-report child injury data has the potential to augment longitudinal birth cohort study data to investigate risk or protective factors associated with childhood injury.

Maternal depressive symptoms and child language development: Exploring potential pathways through observed and self-reported mother-child verbal interactions.

Maternal depressive symptoms (MDS) in the postnatal period may impact children's later development through poorer quality parent-child interactions. The current study tested a specific pathway from MDS (child age 9 months) to child receptive vocabulary (4 ½ years) through both self-reported and observed parent-child verbal interactions (at both 2 and 4 ½ years). Participants (n = 4,432) were part of a large, diverse, contemporary pre-birth national cohort study: Growing Up in New Zealand. Results indicated a direct association between greater MDS at 9 months and poorer receptive vocabulary at age 4 ½ years. There was support for an indirect pathway through self-reported parent-child verbal interactions at 2 years and through observed parent-child verbal interactions at 4 ½ years. A moderated mediation effect was also found: the indirect effect of MDS on child vocabulary through observed verbal interaction was supported for families living in areas of greater socioeconomic deprivation. Overall, findings support the potential role of parent-child verbal interactions as a mechanism for the influence of MDS on later child language development. This pathway may be particularly important for families experiencing socioeconomic adversity, suggesting that effective and appropriate supportive parenting interventions be preferentially targeted to reduce inequities in child language outcomes.

Antenatal and early childhood exposures associated with non-fatal infant injury: evidence from a longitudinal birth cohort in New Zealand.

OBJECTIVE: To identify antenatal and early childhood exposures of unintentional injury among infants in New Zealand (NZ). METHOD: The theoretical life-course framework of child injury prevention domains was utilised to analyse data from a prospective longitudinal NZ birth cohort (Growing Up in NZ). Risk and protective factors for injury were identified using Robust Poisson regression models. RESULT: Among children included for the analysis(n=6304), 52% were male, 55% were born to European mothers, and 37% lived in a household with high levels of deprivation. Mothers reported that 6% of infants (n=406) had sustained at least one injury by 9 months. Multivariate analysis showed injury risk among single mothers with antenatal depression were more than twice that (IRR=2.20) of children of mothers with partners and without depression. CONCLUSION: Understanding antenatal risk and protective factors for infant injury will assist in implementing injury prevention programmes or modifying the existing policies that affect these vulnerable age groups.

Manifold child, family and social variables are associated with injury among New Zealand preschool children.

AIM: Approaches to understanding child injury tend to focus on short-term proximal influences. Previous analyses have found higher rates of injury among Maori and Pacific children in Aotearoa New Zealand (NZ). This study aimed to investigate how combinations of situations and multiple events act across the life-course to either protect preschool children from, or place them at risk of, repeated injuries requiring medical attention. METHODS: Longitudinal data were used to identify parent-reported injuries requiring medical attention among 6114 preschool NZ children. The environments experienced by children with multiple and/or severe injury were explored using multivariable analyses. RESULTS: Eight percent of children (n=505) experienced 1-3 injuries with at least one hospitalisation or ≥4 injuries (high injury group) from birth to 4.5 years of age. After accounting for antenatal, sociodemographic and psychosocial variables, children of Maori mothers (OR=0.7, 95% CI 0.5 to 0.97) and children of Asian mothers (OR=0.5, 95% CI 0.3 to 0.7) were less likely to be in the high injury group than children of European mothers. After adjusting for maternal ethnicity and child variables (gender, temperament, level of activity and behaviour difficulties), cumulative exposure to factors in four domains was associated with injury category: maternal, family, social and service use. CONCLUSION: This study identified social and economic opportunities to lower rates of injury among preschool children, that might reduce associated direct and indirect costs. Our findings in relation to ethnicity go against the standard public rhetoric and provide support for shifting the apportioning of blame for child injury from individuals to wider environmental exposures for which public health and societal solutions are required.

Proximal Processes and Contextual Factors Associated with Early Socio-emotional Competence Development.

There is growing interest in child socio-emotional competence from parents, educators, employers and policy makers, with emphasis on developing it as early as possible. The aim of the present study was to examine contextual and proximal factors that influence socio-emotional competence development across the first five years of a child's life. We used data from 3200 mothers and their children drawn mostly from four major data collection waves (antenatal, 9 months, 2 years and 4.5 years) of the population-based longitudinal study, Growing Up in New Zealand. Regression analyses were carried out to identify the predictors of socio-emotional competence after controlling for demographics and prior score(s) of socio-emotional competence. We found that specific maternal behaviours, such as playing games and playing with toys with children, singing songs or telling stories to them, reading books with them, having rules around viewing TV, DVDs and videos, and praising children have a positive effect on socio-emotional competence. Parental relationship warmth and less family stress at 9 months also made positive contributions to socio-emotional competence at 9 months and 2 years. In contrast, attending childcare and having more siblings at home negatively predicted socio-emotional competence at 9 months. Mother's unemployment, living in neighbourhoods perceived as negative and being in contact with family and social services were negatively associated with concurrent socio-emotional competence at 2 years. Overall, more and/or stronger contemporaneous effects were found suggesting that negative effects of contextual factors may not have lasting impact on socio-emotional competence. In addition, the results showed that maternal behaviours need to be practised regularly to have positive impact on child's socio-emotional development.

An index measuring adherence to New Zealand Infant Feeding Guidelines has convergent validity with maternal socio-demographic and health behaviours and with children's body size.

Using data from a nationally generalisable birth cohort, we aimed to: (i) describe the cohort's adherence to national evidence-based dietary guidelines using an Infant Feeding Index (IFI) and (ii) assess the IFI's convergent construct validity, by exploring associations with antenatal maternal socio-demographic and health behaviours and with child overweight/obesity and central adiposity at age 54 months. Data were from the Growing Up in New Zealand cohort (n 6343). The IFI scores ranged from zero to twelve points, with twelve representing full adherence to the guidelines. Overweight/obesity was defined by BMI-for-age (based on the WHO Growth Standards). Central adiposity was defined as waist-to-height ratio > 90th percentile. Associations were tested using multiple linear regression and Poisson regression with robust variance (risk ratios, 95 % CI). Mean IFI score was 8·2 (sd 2·1). Maternal characteristics explained 29·1 % of variation in the IFI score. Maternal age, education and smoking had the strongest independent relationships with IFI scores. Compared with children in the highest IFI tertile, girls in the lowest and middle tertiles were more likely to be overweight/obese (1·46, 1·03, 2·06 and 1·56, 1·09, 2·23, respectively) and boys in the lowest tertile were more likely to have central adiposity (1·53, 1·02, 2·30) at age 54 months. Most infants fell short of meeting national Infant Feeding Guidelines. The associations between IFI score and maternal characteristics, and children's overweight/obesity/central adiposity, were in the expected directions and confirm the IFI's convergent construct validity.

Prospective longitudinal study investigating predictors of childhood injuries from Growing Up in New Zealand cohort: study protocol.

BACKGROUND: Injury is one of the leading causes of mortality and morbidity worldwide and yet preventable and predictable. In New Zealand (NZ), unintentional injury is the leading cause of emergency department visits, hospitalisations and death among children, making it a significant public health concern. OBJECTIVE: To identify the factors that place young children in NZ at an increased risk of unintentional injury. METHODS: This study will investigate injuries among children from the prospective Growing Up in NZ birth cohort of 6853 children and their families. The primary outcome of interest is injury events where medical treatment was sought. The data sources include parental reports of child injury and Accident Compensation Corporation-NZ's no-fault injury compensation system-injury claims. The linked datasets will be utilised to examine the distribution of life course exposures and outcome data using descriptive statistics. A temporal multilevel model will then be developed to examine relationships between neighbourhood, child and family characteristics and injury from birth to 5 years of age for all children for whom parental consent to link data were obtained. DISCUSSION: The findings of this research will help to identify how the multiplicity of influences between children, family and their broader societal context acting across time affect their risk of experiencing a preschool injury. This information will provide an evidence base to inform context-relevant strategies to reduce and prevent childhood injuries.

Fostering Resilience Among Mothers Early (FRAME): using growth mixture modeling to identify resources that mitigate perinatal depression.

The primary objective of this study was to delineate classes of individuals based on depression trajectories from the antenatal period through 54-month postpartum and internal and external resources that are associated with low depression risk. Participants came from the Growing Up in New Zealand (GUiNZ) study (n = 5664), which is a pregnancy cohort study and is nationally representative of the ethnic and socioeconomic diversity of contemporary New Zealand births. Growth curve mixture modeling was used to identify distinct subgroups based on depression scores from the antenatal period through 54-month postpartum. Logistic regression models were run to investigate socioeconomic factors and internal and external resources that were associated with depression class membership. A two-class model, "low risk" and "high risk," resulted in the best model fit. Most of the sample (n = 5110, 90%) fell into the "low-risk" class defined by no-to-mild depression symptoms during pregnancy and decreasing depressive symptoms over time (bintercept = - .05, bslope = - .05). Approximately 10% of the sample fell into the "high-risk" class (n = 554, 10%) defined by mild-to-moderate depressive symptoms during pregnancy and increasing depressive symptomology over time (bintercept = .39, bslope = .57). More positive parenting-related attitudes, better pre-pregnancy self-reported health, informal social supports, and community belonging were significantly associated with greater odds of being in the "low-risk" class, after controlling for socioeconomic factors. These findings suggest that targeting internal and external resources for individuals across the perinatal and early childhood periods is important to mitigating maternal depression.

Prevalence of antidepressant use and unmedicated depression in pregnant New Zealand women.

BACKGROUND: Throughout pregnancy, women are at an increased risk of depression, with prevalence estimates between 6.5% and 18%. Global prevalence of antenatal antidepressant use is considerably lower at 3%. OBJECTIVE: The present study determined the proportion of women taking antidepressants across pregnancy in New Zealand. We investigated whether variation exists across age bands, area-level deprivation and ethnicities, and identified how many women experienced unmedicated depression. METHOD: Antenatal data (n = 6822) consisted of primarily third-trimester interviews conducted with mothers participating in Growing Up in New Zealand, a longitudinal study investigating child development. Women were asked about their antidepressant intake during pregnancy and assessed on antenatal depression symptoms using the Edinburgh Postnatal Depression Scale. Antidepressant use data were also compared to population-level data from Statistics New Zealand's Integrated Data Infrastructure. RESULTS: Antidepressant prevalence across pregnancy was 3.2%, with a 2.7% prevalence in trimester one and 2.6% following the first trimester. There was no significant difference in usage within age bands and area-level deprivation quintiles. Ethnicity-specific data revealed that Pasifika and Asian ethnicities had the lowest antidepressant use, and New Zealand Europeans the highest. The rate of unmedicated depression, where women met the Edinburgh Postnatal Depression Scale criteria for significant depressive symptoms but did not receive antidepressants during pregnancy, was 11.8%, indicating that antenatal depression treatment may be inadequate. Greater rates of unmedicated depression were seen for younger women (⩽24 years), those living in high deprivation areas and mothers of Pasifika, Asian and Maori ethnicities. CONCLUSIONS: Antenatal antidepressant use in New Zealand follows global prevalence estimates and highlights possible undertreatment of antenatal depression in New Zealand. Future research including other treatment types (e.g. behavioural therapy) is needed to evaluate whether undertreatment occurs across all treatment options.

Do Patterns of Levels of Socio-emotional Competence During Early Childhood Predict Executive Function at 4.5 Years?

Socio-emotional competence and executive function both work together to meet the demands of the everyday environment. While many studies have focused on how various domains of socio-emotional competence are predicted by, or associated with executive function, the predictive influence of socio-emotional competence on executive function has largely been ignored despite strong theoretical links. In addition, contradictory information exists with regard to the divergent validity of two subtypes of executive function: cool and hot. Using data from 4839 children participating in three data collection waves (9 months, 2 years and 4.5 year) in the Growing Up in New Zealand longitudinal study, we examined how different patterns of socio-emotional competence development during the early preschool years (persistent lows, recent low, improved and no lows) related to cool and hot executive function measured at aged 4.5 using a hand clap task and a gift wrap task, respectively. Findings showed that children with persistent lows (with no improvement) in the levels of early socio-emotional competence had increased odds of having below average cool and hot executive function at 4.5 years. However, no difference was found in the influence of socio-emotional competence on cool and hot executive function. Possible explanations for these associations between socio-emotional competence and executive function are discussed.

The Association Between Persistence and Change in Behavioral Difficulties During Early to Middle Childhood and Cognitive Abilities at Age 8.

We investigated the association between persistence and change in behavioral difficulties during early to middle childhood and several cognitive outcomes. We observed 3904 8-year-olds enrolled in the longitudinal study Growing Up in New Zealand (50% male/female; 23% Maori, 9% Pacific Peoples, 13% Asian, 2% Middle Eastern/Latin American/African, 9% Other, 43% European). The NIH Toolbox Cognition Battery was used to assess cognitive functioning at 8 years and the Strengths and Difficulties Questionnaire for behavioral difficulties at 4.5 and 8 years. Multivariate logistic regression analyses were conducted, controlling for well-known sociodemographic confounders. Children with persistent or later onset of behavioral difficulties were at higher risk for poorer vocabulary, reading, inhibitory control/attention, episodic memory, working memory and processing speed at age 8 compared to children with no or improved difficulties. Our study supports the importance of addressing both cognitive and behavioral aspects when planning educational programmes and interventions in early and middle childhood.

Demographic discrepancies between administrative-prioritisation and self-prioritisation of multiple ethnic identifications.

Ethnic classification is an inherently subjective process, especially when multiple ethnic identifications are involved. There are two methods commonly used to classify multiple ethnicities into single categories: administrative-prioritisation (assignment via a predetermined hierarchy) and self-prioritisation (where individuals select their "main" ethnicity). Currently, little is known about whether the demographic composition of outputted ethnic groups differs by prioritisation method. This study utilised large-scale data of multi-ethnic children (N = 1,860), adolescents (N = 2,413), and adults (N = 1,056) from Aotearoa New Zealand to examine individual and contextual demographic characteristics associated with discrepancies between administratively-prioritised and self-prioritised ethnicity. Results showed that discrepancy rates, which exceeded 50%, were systematically associated with neighbourhood ethnic composition and socioeconomic deprivation, but largely not associated with gender, age, and birthplace. The contextual nature of self-prioritisation highlights the importance of researchers' choice of ethnic classification method. Implications are discussed in the context of increasing multi-ethnic prevalence.

Child feeding indexes measuring adherence to New Zealand nutrition guidelines: Development and assessment.

New Zealand (NZ) lacks nationally representative or generalisable information on the dietary intakes of pre-schoolers. We used Growing Up in New Zealand cohort data to i) develop child feeding indexes (CFIs) based on National Food and Nutrition Guidelines for 2- and 4.5-year-olds; ii) describe the cohort adherence to the guidelines at 2 (n = 6046) and 4.5 years (n = 5889) and; iii) assess the CFIs' convergent construct validity, by exploring associations with maternal sociodemographic and health behaviours and with child body mass index for age (BMI/age) and the waist-to-height ratio at 4.5 years. The CFIs scores ranged from 0 to 11, with 11 representing full adherence to the guidelines. Associations were tested using multiple linear regressions and Poisson regressions with robust variance (risk ratios [RR], 95% confidence intervals, 95% CI). The CFIs mean scores (SD) at 2 and 4.5 years were, respectively, 6.13 (1.21) and 6.22 (1.26) points. Maternal characteristics explained, respectively, 27.2% and 31.9% of the variation in the CFIs scores at 2 and 4.5 years. In the adjusted model at the 4.5-year interview, in relation to girls ranked in the 5th quintile, those in the 2nd (RR, 95% CI: 1.48; 1.03; 1.24) and 4th (1.53; 1.05; 2.23) quintiles of the CFI were more likely to have BMI/age > +2z (World Health Organization growth standards) at 4.5 years. At 2 and 4.5 years, most children fell short of meeting national guidelines. The associations between the CFIs scores at both time points with maternal characteristics and with children's body size at 4.5 years were in the expected directions, confirming the CFIs' convergent construct validity among NZ pre-schoolers.

Exploring the Factor Structure of the NIH Toolbox Cognition Battery in a Large Sample of 8-Year-Old Children in Aotearoa New Zealand.

OBJECTIVE: The objective of this study was to derive a factor structure of the measures of the National Institutes of Health (NIH) Toolbox Cognition Battery (CB) that is representative of cognitive abilities in a large ethnically diverse cohort of 8-year-old children in Aotearoa New Zealand. METHODS: Our sample comprised of 4298 8-year-old children from the Growing Up in New Zealand study. We conducted exploratory and confirmatory factor analysis for the NIH Toolbox CB measures to discover the best-fitting factor structure in our sample. Measurement invariance of the identified model was tested across child's gender, socio-economic status (SES), and ethnicity. RESULTS: A three-dimensional factor structure was identified, with one factor of Crystallised Cognition (Reading and Vocabulary), and two distinguished factors of fluid cognition: Fluid Cognition I (Attention/Inhibitory Control, Processing Speed, and Cognitive Flexibility) and Fluid Cognition II (Working Memory, Episodic Memory). The results demonstrate excellent model fit, but reliability of the factors was low. Measurement invariance was confirmed for child's gender. We found configural, but neither metric nor scalar, invariance across SES and the four major ethnic groups: European, Maori, Pacific Peoples, and Asian. CONCLUSION: Our findings show that, at the age of 8 years, fluid abilities are more strongly associated with one another than with crystallised abilities and that fluid abilities need to be further differentiated. This dimensional structure allows for comparisons across child's gender, but evaluations across SES and ethnicity within the Aotearoa New Zealand context must be conducted with caution. We recommend using raw scores of the individual NIH Toolbox CB measures in future research.

Vitamin D status at birth and acute respiratory infection hospitalisation during infancy.

BACKGROUND: Hospital admission for acute respiratory infections (ARIs) during early childhood is a global public health concern. Vitamin D deficiency is prevalent during pregnancy and infancy. Evidence indicates that vitamin D supplementation prevents ARIs. OBJECTIVES: To determine whether vitamin D deficiency at birth is associated with ARI hospitalisations during infancy. METHODS: We performed a nested case-control study in children aged 0-12 months. Cases had ≥1 ARI hospitalisation and 4 controls were individually matched to each case. Newborn 25(OH)D concentration was measured on dried blood spots using two-dimensional liquid chromatography-tandem mass spectrometry. Hospital admissions were measured using health care records. Median serum 25(OH)D concentration in cases and controls was compared, and covariates of ARI hospitalisation during infancy were assessed using conditional logistic regression analysis. RESULTS: Six per cent of the cohort (n = 384) had an ARI hospitalisation during infancy, and 1536 controls were matched to cases. Median DBS [25(OH)D] was lower among ARI cases than controls (46 nmol/l vs. 61 nmol/L). Median 25(OH)D levels were lower for those hospitalised ≥2 times (47, IQR 36, 58) vs. those hospitalised once (52, IQR 42, 62) vs. the controls and also lower for those who stayed in the hospital for ≥3 days (45, IQR 36, 54) vs 1-2 days (48, IQR 38, 59) compared to the controls. After adjustment for season of birth and covariates describing demographic, antenatal, perinatal, and infant characteristics, DBS 25(OH)D concentration (<50 nmol/L) at birth was associated with increased odds of ARI hospitalisation during infancy (odds ratio 2.20, 95% confidence interval 1.48, 2.91). CONCLUSIONS: Vitamin D deficiency at birth is associated with increased odds of ARI hospitalisations in infants. The findings have implications for a developed country like New Zealand where vitamin D supplementation is not routinely recommended and the burden of ARI hospitalisation in young children is high.

Patterns of risk exposure in first 1,000 days of life and health, behavior, and education-related problems at age 4.5: evidence from Growing Up in New Zealand, a longitudinal cohort study.

BACKGROUND: Children who are high priority candidates for early intervention need to be identified to reduce their risk for experiencing problems in development. Those exposed to multiple risk factors are more likely to exhibit problems in development than those exposed to a single or no risk factor. We examined the longitudinal associations between persistence and timing of exposure to cumulative risk (CR) on three occasions by age 2 and problems in development at age 4.5 in health, behavior, and education-related domains. METHODS: Data are from Growing Up in New Zealand (NZ), a prospective longitudinal study of a birth cohort first assessed during their last trimester in 2009-10 and followed at ages 9 months and 2 and 4.5 years. All women with an expected delivery date in a 12-month period who resided within a defined region were invited to participate, with no additional eligibility criteria. Exposure was measured for 12 sociodemographic and maternal health risk factors at third trimester and ages 9 months and 2 years, from which developmental trajectories were constructed capturing persistence and timing of CR exposure. Ten developmental outcomes were measured at age 4.5 to classify problems in overall health status, obesity, and injuries; internalizing and externalizing behavior problems; and letter naming, counting forward and backward, and expectations for starting school and completing education. RESULTS: Analyses of data from 6156 children (49% female, 33% Non-European ethnicity) who participated in the 4.5-age assessment uniformly showed associations between exposure to more than consistently zero CR across early development and higher prevalence of being classified with problems for 9 of 10 outcomes. Persistent exposure to a CR ≥ 4 was generally associated with a higher prevalence of problems for 7 of 10 outcomes, whereas the timing of first exposure to CR ≥ 4 showed a less consistent association with problem outcomes. CONCLUSIONS: These findings are concerning because over 50% of NZ children are exposed to at least one of these risk factors at some point in early development. Routine screening of most of these risk factors during pregnancy is feasible and can identify priority candidates for intervention.

Prenatal Stress and Early Childhood Body Mass Index: A Path Analysis Approach.

OBJECTIVES: Stress experienced by mothers during the prenatal period can have negative impacts on offspring development. Elevated BMI in childhood in response to early stress experience is a particularly critical outcome of interest since high BMI in childhood is associated with diabetes, heart disease and stroke in later life. The primary objective of this study was to analyze pathways between prenatal stress and early childhood BMI at 54-months of age and to begin to explore ethnic variations in these pathways. METHODS: This study used the Growing Up in New Zealand (GUiNZ) dataset, which is a longitudinal, representative birth cohort study that began with recruiting pregnant women in 2009 and 2010 in Auckland, New Zealand. Path analysis modeling was used to explore risk and protective pathways between prenatal maternal stress and early childhood body mass index (BMI) at 54-months of age and differences by ethnicity (n = 5510). RESULTS: Prenatal stress was positively associated with early childhood BMI at 54-months and maternal nutrition behaviors and length of exclusive breastfeeding mediated this direct relationship (χ2 (1) = 0.83, p = 0.36; AIC = 50,496). Mediation and moderation paths varied by ethnicity. CONCLUSIONS FOR PRACTICE: These findings contribute to the understanding of the intergenerational transmission of stress with respect to early childhood obesity. Reducing early stress exposure and/or addressing mediating and moderating factors linking stress experience with obesity development may prove to be more effective than attempting to alter health behaviors and trajectories in adulthood.