Exposure to a natural disaster during pregnancy and young children’s behaviour: prenatal and postnatal pathways, and the role of maternal mind-mindedness

Abstract

Mothers experiencing symptoms of stress and distress are more likely to have children who exhibit behavioural problems, and there are a multitude of processes by which this vulnerability may be conferred. A number of environmental mechanisms may explain this intergenerational transmission of risk, including an impact of a mother’s emotional state on the conditions of the prenatal and postnatal environment; however, disentangling these effects from genetic heritability and residual confounding constitutes a major methodological challenge. A natural disaster represents a natural experiment, enabling the investigation of the unique effects of an independent prenatal stressor on child development, whilst minimising the likelihood of these alternative explanations. This thesis investigates the prenatal and postnatal processes associated with individual differences in young children’s behavioural problems following maternal exposure to a severe flooding event during pregnancy. Specifically, it examines the direct effects of exposure to flood-related objective hardship and maternal posttraumatic stress symptoms for infant social-emotional competence and behavioural problems at 16 months, as well as testing prenatal and postnatal pathways linking flood exposure to internalising and externalising behavioural problems at 30 months. A component of maternal caregiving, maternal mind-mindedness, is tested for its potential to moderate the direct prenatal or indirect postnatal effects of flood exposure during pregnancy on child outcomes. Finally, the predictors of individual differences in maternal mind-mindedness are investigated, including maternal stress during pregnancy, concurrent mental health, and attachment style.Mothers (N = 230) pregnant in January 2011, during the floods in Queensland, Australia, completed measures of their flood-related objective hardship and posttraumatic stress symptoms, as well as their adult attachment style. At 16 months, mothers and infants attended a laboratory visit where they engaged in a joint play interaction. Mothers completed measures of depression and anxiety symptoms and their infant’s social-emotional and behavioural problems and competence. At 30 months, mothers completed measures of their own depression symptoms and their toddlers’ internalising and externalising problems. Greater flood-related maternal PTS symptoms were associated with reduced maternally-reported infant competence at 16 months. A sex difference in mothers’ reports of infant behaviour problems emerged at higher levels of maternal objective hardship. Additionally, greater PTS was associated with more maternally-reported behaviour problems at 16 months in boys; however, attenuation by concurrent maternal depressive symptoms suggested a postnatal risk pathway through worse maternal emotional functioning postnatally. Subsequent moderated serial mediation analyses testing this postnatal risk pathway found that increased flood-related objective hardship was indirectly associated with greater maternally-reported toddler internalising problems at 30 months through increased PTS symptoms and concurrent maternal depressive symptoms. Furthermore, this postnatal risk pathway was evident only for the toddlers of mothers lower in mind-mindedness; for dyads with mothers higher in appropriate mind-mindedness, the influence of flood-related maternal distress on maternally-reported toddler internalising problems was buffered. Investigation of the maternal predictors of individual differences in appropriate mind-mindedness found that more mind-minded mothers reported lower levels of avoidant attachment, with no influence of flood-related stress or concurrent maternal depression or anxiety symptoms on this caregiving quality. Results suggest that flood exposure during pregnancy may affect maternally-reported child behaviour in infancy and early childhood through both prenatal and postnatal pathways, and this may be outcome domain-specific. There may be a unique influence of maternal flood-related PTS on infant social competence, possibly through fetal programming due to maternal stress physiology, whereas toddler internalising problems were better predicted by a mother’s enduring distress in the years following the floods. Maternal mind-mindedness emerged as a protective factor, enhancing the resilience of young children exposed to a natural disaster in utero, possibly by assisting mothers experiencing depression symptoms to remain “tuned in” to their child. This maternal quality factor was best predicted by maternal personality characteristics that may have their origins in a mother’s own early caregiving relationships, which may reflect an intergenerational protective influence on children’s behaviour after natural disaster exposure. Overall these results highlight multiple pathways by which vulnerability and resilience may be conveyed from mother to child, with implications for screening and intervention with mothers and toddlers exposed to a natural disaster during pregnancy.