Paediatrics (RCH) - Theses
Permanent URI for this collection
Search Results
1 - 2 of 2
-
ItemHair cortisol as a measure of stress and social adversity in early childhood( 2019)Background: Children raised in families experiencing adversity (e.g. unemployment, financial hardship, family violence, parent mental health difficulties) are at greater risk of poor health outcomes. Physiological stress is one mechanism thought to explain the effects of early adversity on children's health. Understanding this role of physiological stress and how best to measure it, particularly in population cohorts of young children, is limited. My PhD used child hair cortisol as a measure of physiological stress to address this evidence gap by examining associations between adversity, physiological stress and health in a community-based cohort of young children experiencing adversity. Aims: To investigate 1) whether indicators of adversity are associated with children's physiological stress at 2 years; 2) the role that maternal physiological stress and parenting behaviours play in explaining children's physiological stress response to adversity at 2 years; and 3) whether social adversity is associated with children's health at 3 years, and whether physiological stress is a mechanism which mediates these effects. Methods: This was a prospective longitudinal cohort study nested within the ‘right@home’ randomised controlled trial of nurse home visiting, comprising 722 Australian women recruited for their experience of adversity while pregnant and their subsequent children. Child hair cortisol was collected at ages 2 and 3 years. Social adversity was measured as maternal reported indicators of adversity according to sociodemographic and psychosocial characteristics, collected at pregnancy and child ages 1, 2 and 3 years. Maternal physiological stress (hair cortisol) and parenting were measured at 2 years. At 3 years, child health outcomes of mental health, wellbeing and weight status were assessed. Analyses for Aims 1 and 3 used linear regression models; for Aim 2 used structural equation modelling. Results: Hair cortisol data were available for 319/603 (53%) participating children at 2 years and 297/500 (59%) at 3 years. Aim 1 showed limited evidence of associations between 18 indicators of adversity and child hair cortisol at 2 years across different types, timing and persistence of adversity. Aim 2 showed that maternal and child hair cortisol were associated with one another at 2 years. There was no evidence that adversity or maternal parenting were associated with child hair cortisol; as such there were no pathways by which maternal stress or parenting explained effects of adversity on children’s physiological stress. Aim 3 showed children experiencing greater adversity had higher externalising behaviour problems and poorer physical wellbeing at 3 years, and higher hair cortisol was associated with higher externalising problems; however, there was no evidence that hair cortisol mediated any effects of adversity on health. Conclusions: At ages 2 and 3 years, social adversity was not consistently associated with children’s physiological stress, measured using hair cortisol, nor was there any evidence that physiological stress mediated the effects of adversity on young children’s health. These findings suggest that hair cortisol may be limited as a measure of stress in young children or that measuring one aspect of the physiological stress pathway at the population level provides limited insight into the complex mechanisms underlying children’s health inequalities.
-
ItemThe ‘Kids Sleep Study': effects of an infant sleep intervention at 6 years of age: follow-up of a randomised controlled trial( 2011)BACKGROUND: Behavioural sleep problems in infancy are highly prevalent. They increase the risk of maternal depression symptoms and predict later child sleep problems, which in turn are associated with adverse mental and general health outcomes for children and parents. Controlled trials demonstrate that behavioural sleep techniques effectively reduce infant sleep problems and associated maternal depression symptoms in the short- to medium-term. However, theoretical concerns remain that these techniques harm child-parent attachment and lead to later child emotional and behaviour problems. Although they are yet to be empirically tested, these concerns are potentially causing harm, as are some practitioners who hold these concerns, by discouraging the use of effective behavioural management strategies. The capacity for behavioural techniques to have long-lasting benefits on child, child-parent and maternal outcomes to school-entry age is also unknown, because studies are yet to examine whether early child sleep problems predict these later outcomes. AIMS: Part 1 aimed to determine whether an infant behavioural sleep program caused lasting harms or benefits at child age 6 years (school-entry) to: (1) attachment-related, (2) sleep and (3) maternal mental health outcomes. Part 2 aimed to determine whether early child sleep problems (4, 12 and 24 months) predicted (4) child sleep, and (5) secondary child, child-parent, and maternal outcomes at child age 6 years, after accounting for concurrent child sleep problems. METHODS: This study drew on a pre-existing population-based cluster controlled trial of a behavioural sleep intervention (n=328, ISRCTN48752250), which recruited infants with parent-reported sleep problems at 7 months from six socioeconomically diverse Melbourne (Australia) local government areas. The original study compared an intervention comprising behavioural sleep strategies delivered by well-child nurses at 1-3 individual consultations at child age 8-10 months, with usual care. The current study revisited children and their mothers at child age 6 years with a parent questionnaire and direct assessment in the family home. Part 1 analysed data as a randomised controlled trial follow-up. Based on the results of Part 1, Part 2 pooled trial arms to analyse data as an epidemiological cohort. Aims were analysed using unadjusted and adjusted regression modelling (linear for continuous outcomes, logistic for binary outcomes) controlling for known confounders selected a priori, where possible. RESULTS: Families retained at 6 years (n=225, 69%) were more likely to speak English than those lost to follow-up (84% versus 74%, p=0.03). There was no evidence of attrition bias between groups. Part 1: There was no evidence of a difference between groups for any attachment-related, sleep or maternal mental health outcome. Although power was limited to detect effect sizes ≥0.4 standard deviations between groups, 95% confidence intervals tended to centre on equivalence and there was no pattern of effect across the sample estimates toward harms or benefits. Part 2: Early sleep problems at individual time points (4, 12, 24 months) rarely predicted outcomes at 6 years, but, when measured as an ordinal persistent count (1, 2, 3 or 4 sleep problems at these ages, taking a single sleep problem at 7 months as the reference category), demonstrated an increasing dose-response relationship with later child, child-parent and maternal outcomes, with evidence strongest for child outcomes. CONCLUSION: This brief behavioural sleep intervention was effective in the short- to medium-term and safe to use in the long-term, at least to five years post-intervention. Parents and health professionals can feel confident using and offering behavioural strategies to manage infant sleep in the second six months of life. In a sample selected for infant sleep problems at 7 months, recurring or persistent early child sleep problems predisposed children and their mothers to poorer outcomes at 6 years. Health professionals need to offer, and parents need to be able to access, strategies that adapt to the changing nature of child sleep problems as the child develops.