Attachment, parenting stress and temperament across infancy in a community sample: Contributions to internalising versus externalising toddler behaviours

Mental health problems affect around one in ten infants. Little is known however of the etiology of problem behaviours in infancy. Increased knowledge would inform early prevention and intervention programs. The current longitudinal study investigated the development of two year olds' internalising and externalising problem behaviours in a middle class, low risk, community sample of 121 mothers and their infants aged from 4 to 24 months. Mothers' parenting stress was conceptualised as key organising construct. Risk factors at 4 and 12 months were hypothesised to affect both parenting stress at 12 months and toddler problem behaviours at 24 months. Mediating and/or moderating effects were expected. Determinants and sequelae of parenting stress associated with the mother's relationship with her infant (parent-child) compared with stress associated with her relationships with others (parent-other) were investigated. Mothers and infants were expected to form at least two trajectories, high and low, according to their levels of parenting stress and socioemotional difficulty respectively. Trajectory membership was expected to be associated with predictable differences in levels of toddler internalising and externalising problem behaviours. Empirical investigations supported direct effects of early maternal depression and maternal attachment anxiety on the development of parenting stress in mothers of 12 month old infants. Negative marital relations affected parenting stress indirectly via maternal depression. No protective effect of positive marital relations was observed. Infant attachment avoidance was negatively associated with parenting stress. Findings were similar for parent-child versus parent-other stress. Problem behaviours were not affected by demographic characteristics such as maternal age, education, family income or size, infant gender, or separation. Early maternal depression, infant socioemotional difficulty and difficult temperament and concurrent parenting stress predicted both toddler internalising and externalising problem behaviours. Effects of attachment anxiety and avoidance were small. Mediation and moderation by concurrent parenting stress was supported. Analyses supported functional differences amongst maternal avoidant attachment strategies of idealisation, derogation and lack of memory. At risk (<16%) infants and mothers had higher toddler problem behaviours than low risk (>80%). At risk dyads included mothers with elevated scores around the referral level, on the Parenting Stress Index and the Center for Epidemiological Studies Depression scale and/or infants with elevated Ages and Stages: Social Emotional difficulty scores. The current study demonstrated characteristics of both mother and infant were more important than relational factors in the development of toddler problem behaviours. Findings supported interactions amongst risk factors and the importance of infant and maternal attachment anxiety and avoidance for delineating specific pathways to toddlers' internalising versus externalising problem behaviours. Risk profiles for problem behaviours in two year olds were found to be established by four months of age. Implications included early mother and infant screening for mental health difficulties and targeted interventions for at-risk mother-infant dyads.