Sociodemographic differences in 24-hour time-use behaviours in New Zealand children.

BACKGROUND: The time that children spend in physical activity, sedentary behaviour, and sleep each day (i.e., 24-h time-use behaviours), is related to physical and mental health outcomes. Currently, there is no comprehensive evidence on New Zealand school-aged children's 24-h time-use behaviours, adherence to the New Zealand 24-h Movement Guidelines, and how these vary among different sociodemographic groups. METHODS: This study utilises data from the 8-year wave of the Growing Up in New Zealand longitudinal study. Using two Axivity AX3 accelerometers, children's 24-h time-use behaviours were described from two perspectives: activity intensity and activity type. Compositional data analysis techniques were used to explore the differences in 24-h time-use compositions across various sociodemographic groups. RESULTS: Children spent on average, 31.1%, 22.3%, 6.8%, and 39.8% of their time in sedentary, light physical activity, moderate-to-vigorous physical activity, and sleep, respectively. However, the daily distribution of time in different activity types was 33.2% sitting, 10.8% standing, 7.3% walking, 0.4% running, and 48.2% lying. Both the activity intensity and activity type compositions varied across groups of child ethnicity, gender, and household income or deprivation. The proportion of children meeting each of the guidelines was 90% for physical activity, 62.5% for sleep, 16% for screen time, and 10.6% for the combined guidelines. Both gender and residence location (i.e., urban vs. rural) were associated with meeting the physical activity guideline, whereas child ethnicity, mother's education and residence location were associated with meeting the screen time guideline. Child ethnicity and mother's education were also significantly associated with the adherence to the combined 24-h Movement Guidelines. CONCLUSIONS: This study provided comprehensive evidence on how New Zealand children engage in 24-h time-use behaviours, adherence to the New Zealand 24-h Movement Guidelines, and how these behaviours differ across key sociodemographic groups. These findings should be considered in designing future interventions for promoting healthy time-use patterns in New Zealand children.

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.

Staphylococcus aureus colonisation and its relationship with skin and soft tissue infection in New Zealand children.

New Zealand children suffer from high rates of skin and soft tissue infection (SSTI). Staphylococcus aureus colonisation is known to increase the risk of nosocomial infection. We aimed to determine whether S. aureus colonisation also increased the risk of community-onset SSTI. This study, performed within the Growing Up in New Zealand cohort, used interview and administrative data, and bacterial culture results from the nose, throat, and skin swabs collected at 4½ years of age. Multivariable log-binomial regression was used to derive adjusted risk ratios. S. aureus was isolated from 2225/5126 (43.4%) children. SSTI affected 1509/5126 (29.4%) children before age five. S. aureus colonisation at any site was associated with SSTI (aRR = 1.09, 95%CI 1.01-1.19), particularly in the year prior to swab collection (aRR = 1.18, 95%CI 1.02-1.37). The strongest association was between skin colonisation and SSTI within the year prior to swab collection (aRR = 1.47, 95%CI 1.14-1.84). Socioeconomic and ethnic variables remained independent determinants of SSTI. S. aureus colonisation was associated with an increased risk of community-onset SSTI. Socioeconomic and ethnic factors and eczema had independent effects on SSTI risk. Interventions which reduce the prevalence of S. aureus colonisation may be expected to reduce the incidence of community-onset SSTI.

Association between maternal depression symptoms and child telomere length.

The biological mechanisms that explain how adverse early life events influence adult disease risk are poorly understood. One proposed mechanism is via the induction of accelerated biological aging, for which telomere length is considered a biomarker. We aimed to determine if maternal depression pre- and post-partum was associated with telomere length in children at 4 years of age (n = 4299). Mothers completed structured questionnaires assessing depression during pregnancy (Edinburgh Depression Scale), at 9 months (Edinburgh Depression Scale), and at 54 months postpartum (Patient Health Questionnaire 9). Regression methods were used to investigate the relationship between telomere length (DNA from saliva) and maternal depression score recorded at each stage. Significant covariates included in the final model were: maternal age at pregnancy; child sex; child ethnicity; gestational age group, and rurality group. Child telomere length was found to be longer if their mother had a higher depression score at both postpartum time points tested (9 months of age; coefficient 0.003, SE = 0.001, P = 0.01, 54 months of age; coefficient 0.003, SE = 0.002, P = 0.02). Although these findings seem paradoxical, increased telomere length may be an adaptive response to early life stressors. We propose several testable hypotheses for these results and to determine if the positive association between depression and telomere length is a developmental adaptation or an indirect consequence of environmental factors.

Maternal racism experience and cultural identity in relation to offspring telomere length.

Racism is a determinant of individual and offspring health. Accelerated telomere shortening, an indicator of cellular aging, is a potential mechanism through which parental experience of racism could affect offspring. Here we longitudinally evaluated the relationship between maternal lifetime experience of an ethnically-motivated verbal or physical attack, as reported in pregnancy, with offspring telomere length in 4.5-year-old children. We also explored the potential association between positive feelings about one's culture and offspring telomere length. Data come from a nationally representative, multi-ethnic birth cohort in Aotearoa New Zealand (NZ) (Maori N = 417, Pacific N = 364, Asian N = 381). In models adjusting for covariates, including socioeconomic status and health status, Maori mothers who experienced an ethnically-motivated physical attack had children with significantly shorter telomere length than children of Maori mothers who did not report an attack (B = - 0.20, p = 0.01). Conversely, Maori mothers who had positive feelings about their culture had offspring with significantly longer telomeres (B = 0.25, p = 0.02). Our results suggest that ethnicity-based health inequities are shaped by racism, with impacts for clinical care and policy. Future research should also evaluate the potential protective effects of positive cultural identity.

Effects of heavy rainfall on waterborne disease hospitalizations among young children in wet and dry areas of New Zealand.

Heavy rainfall is associated with increased risk of waterborne disease. However, it is not known whether the risk increment differs between wet and dry regions. We examined this question in New Zealand, which has a wide geographical variation of annual rainfall totals (10th-90th percentile difference ≥3000 mm). We conducted a nested case-crossover study within a prospective child cohort (born in 2009-2010) for assessing transient health effects when modified by longitudinal exposures to rainfall. Short-term heavy rainfall effects on hospitalizations due to enteric bacterial and viral infectious causes at lag of 0-14 days were assessed using a Cox regression model adjusted for daily temperature, relative humidity and evapotranspiration. We derived quantiles of time-weighted long-term rainfall levels at the children's homes and these were added as an interaction term to the short-term effect model. Hospitalization risks were higher two days after heavy rainfall days (hazard ratio [95% confidence interval]: 1.73 [1.10-2.70]). The lowest-observable-adverse-effect-level was detected at the 94th percentile of daily rainfall total. Hospital admissions 1-2 days after heavy rainfall increased most in locations with the lowest and highest long-term rainfall. An interaction of this kind between short-term weather and long-term climate has not been reported previously. It is relevant to climate change risk assessments given global projections of increasing intensity of precipitation, against a background of more severe, and possibly more frequent, droughts and flooding.

Telomere length in early childhood is associated with sex and ethnicity.

Telomeres are repetitive DNA sequences at the end of chromosomes that function to protect chromosomes from degradation. Throughout the life course, telomere length decreases with age and is influenced by environmental factors and health conditions. This study aimed to determine the relative telomere lengths in a diverse cohort of about 4000 four-year-old children in New Zealand. Linear regression was used to investigate the relationship between telomere length, child gender, ethnicity, paternal age and deprivation. We observed substantial variation in telomere length according to sex and self-identified ethnicity. Telomere length was longer in females compared to males (coefficient of 0.042, 95% confidence interval (CI) 0.024-0.060). European children had shorter telomere than both the indigenous Maori (coefficient of 0.03, CI 0.007-0.055) and Pacific children (coefficient of 0.15, CI 0.12-0.18). The data suggest that telomere lengths are highly variable and variability between individuals arise from early age, influenced partly by sex and ethnicity. Longer telomeres in indigenous Maori and Pacific children may reflect the heritability of telomere length in genetically less complex populations. This study increases our understanding of telomere dynamics in young children since the majority of telomere studies are conducted in adults.

Patterns of Exposure to Cumulative Risk Through Age 2 and Associations with Problem Behaviors at Age 4.5: Evidence from Growing Up in New Zealand.

Exposure to cumulative risk (CR) has important implications for child development, yet little is known about how frequency, persistence, and timing of CR exposure during early childhood predict behavioral problems already before school start. We examine prospective longitudinal associations between patterns of CR exposure from third trimester through 2 years and subsequent behavior problems at 4.5 years. In 6156 diverse children in the Growing Up in New Zealand longitudinal study, the presence of 12 risk factors, spanning maternal health, social status, and home and neighborhood environment, defined CR and were assessed at last trimester and 9 months and 2 years of age. At child age 4.5 years, mothers completed the Strengths and Difficulties Questionnaire, where a score ≥ 16 indicated an abnormal level of problem behaviors (ALPB). Children exposed to a CR ≥ 1 at least once in early development, compared to those with consistent CR = 0, showed a significantly higher likelihood of ALPB at 4.5 years. Consistent high exposure to CR ≥ 4 across all three assessments had the highest prevalence (44%) of ALPB at age 4.5. Children with high CR exposure on two of three, compared to on all three, time points in early development did not evidence a significantly reduced prevalence (32%-41%) of ALPB. The common co-occurrence of risk factors and their significant developmental impact when accumulated early in life underscore the need for systematic multisector intervention and policy implementation during pregnancy and shortly after birth to improve outcomes for vulnerable children.

Agreement between Future Parents on Infant Feeding Intentions and Its Association with Breastfeeding Duration: Results from the Growing Up in New Zealand Cohort Study.

Maternal intentions are believed to have the strongest influence on infant feeding. However, what has rarely been studied, are the associations of maternal and partner intentions, and the influence these factors have on infant feeding. Our objective was to describe breastfeeding intentions of pregnant women and their partners, agreement about these intentions, and whether this agreement is associated with breastfeeding initiation and duration. This study was completed within the Growing Up in New Zealand study. Agreement between mothers and partners on intended initial infant feeding method was fair (κ = 0.21, 95% confidence interval (CI) 0.17⁻0.25) as was intended breastfeeding duration (κ = 0.25, 95% CI 0.22⁻0.28). Infants whose parents agreed antenatally on breastfeeding only were more likely to have been breastfed for >6 months, after adjustment for maternal (odds ratio (OR) = 6.3, 95% CI 3.9⁻10.2) and partner demographics (OR = 5.7, 95% CI 3.6⁻9.2). Likewise, infants whose parents agreed antenatally to breastfeed for >6 months were more likely to have been breastfed for >6 months, after adjustment for maternal (OR = 4.9, 95% CI 3.9⁻6.2) and partner demographics (OR = 5.0, 95% CI 4.0⁻6.3). Interventions that promote breastfeeding to both mothers and partners which enable parents to reach agreement about intended feeding methods have the potential to increase both breastfeeding initiation and duration.

Breastfeeding indicators among a nationally representative multi-ethnic sample of New Zealand children.

AIMS: To describe breastfeeding initiation and duration, and demographic associations with breastfeeding duration within a representative sample of New Zealand infants. METHODS: In 6,685 singletons enrolled in the Growing Up in New Zealand cohort we described breastfeeding initiation (96%), any (94%) and exclusive (93%) breastfeeding (EBF) duration. We used adjusted relative risk (RR) and 95% confidence intervals (CI) to describe associations with breastfeeding duration. RESULTS: Breastfeeding initiation occurred for 97%. Sixteen percent were EBF to age six months and 13% were breastfed to age 24 months. Exclusive breastfeeding for ≥4 months was less likely for children of mothers of Maori (RR=0.80, 95% CI 0.73-0.87), Pacific (0.90, 95% CI 0.83-0.98) or Asian (0.80, 95% CI 0.74-0.86) ethnicity. Children of mothers aged 20-29 years (1.24, 95% CI 1.04-1.49); ≥30 years (1.36, 95% CI 1.14-1); with a tertiary education (1.14, 95% CI 1.08-1.21); or planned pregnancy (1.14, 95% CI 1.08-1.21); and children with older siblings (RR=1.31, 95% CI 1.17-1.47) were more likely to be exclusively breastfed for ≥4 months. Children were more likely to be breastfed ≥6 months if their mother was aged 20-29 (1.26, 95% CI 1.10-1.45) or ≥30 years (1.40, 95% CI 1.22-1.61), had a tertiary education (1.11, 95% CI 1.06-1.59) or planned pregnancy (1.11, 95% CI 1.06-1.15), or if they had older siblings (1.04, 95% CI 1.00-1.08). CONCLUSION: In New Zealand, most children are initially breastfed, however a large proportion did not receive the recommended duration of any or exclusive breastfeeding. Maternal age, education, parity and pregnancy planning identify children at risk of shorter duration of breastfeeding and EBF, and maternal ethnicity identifies children at risk of shorter EBF duration.

Antenatal immunisation intentions of expectant parents: Relationship to immunisation timeliness during infancy.

BACKGROUND: Most women decide about infant immunisation during pregnancy. However, we have limited knowledge of the immunisation intentions of their partners. We aimed to describe what pregnant women and their partners intended for their future child's immunisations, and to identify associations between parental intentions and the subsequent timeliness of infant immunisation. METHODS: We recruited a cohort of pregnant New Zealand (NZ) women expecting to deliver between April 2009 and March 2010. The cohort included 11% of births in NZ during the recruitment period and was generalisable to the national birth cohort. We completed antenatal interviews independently with mothers and partners. We determined immunisation receipt from the National Immunisation Register and defined timely immunisation as receiving all vaccines (scheduled at 6-weeks, 3- and 5-months) within 30 days of their due date. We described independent associations of immunisation intentions with timeliness using adjusted odds ratios (OR) and 95% confidence intervals (CI). RESULTS: Of 6172 women, 5014 (81%) intended full immunisation, 245 (4%) partial immunisation, 140 (2%) no immunisation and 773 (13%) were undecided. Of 4152 partners, 2942 (71%) intended full immunisation, 208 (5%) partial immunisation, 83 (2%) no immunisation and 921 (22%) were undecided. Agreement between mothers and partners was moderate (Kappa=0.42). Timely immunisation occurred in 70% of infants. Independent of their partner's intentions, infants of pregnant women who decided upon full immunisation were more likely to be immunised on time (OR=7.65, 95% CI: 4.87-12.18). Independent of the future mother's intentions, infants of partners who had decided upon full immunisations were more likely to be immunised on time (OR=3.33, 95% CI: 2.29-4.84). CONCLUSIONS: During pregnancy, most future parents intend to fully immunise their child; however, more partners than mothers remain undecided about immunisation. Both future mothers' and future fathers' intentions are independently associated with the timeliness of their infant's immunisations.

Colonisation with Staphylococcus aureus and Streptococcus pyogenes in New Zealand preschool children.

AIM: To describe colonisation patterns of Staphylococcus aureus (S. aureus) and Streptococcus pyogenes (S. pyogenes) among pre-school children in New Zealand. METHOD: Anterior nasal, oropharyngeal, and antecubital fossa swabs were collected from a diverse sample of 139 New Zealand children aged 4 years. Swabs were cultured for S. aureus and S. pyogenes. S. aureus isolates were tested for antibiotic susceptibility. RESULTS: S. aureus colonisation was more prevalent than S. pyogenes colonisation; 54% of the children were colonised with S. aureus whereas only 16% were colonised with S. pyogenes, at one or more sampling sites (P<0.0001). S. aureus was present in a larger proportion of swabs obtained from the anterior nasal (39%, P<0.0001) or oropharynx (32%, P=0.0002) than from the antecubital fossa (14%). S. pyogenes was present in a larger proportion of swabs obtained from the oropharynx (16%) than either the anterior nasal (4%, P=0.001) or the antecubital fossa (2%, P<0.0001). CONCLUSION: S. aureus and S. pyogenes are prevalent at superficial sites in preschool children in NZ, with S. aureus colonisation more prevalent than S. pyogenes colonisation. Colonisation frequency varies by site for both pathogens; S. aureus is more prevalent in the anterior nares and oropharynx while S. pyogenes is more prevalent in the oropharynx.