The assessment of postnatal depression, anxiety and stress using a cognitive vulnerability-stress model: a role for perceived control and individual characteristics

In comparison to the vast literature on postnatal depression, there exists a paucity of studies that examine anxiety and stress in postnatal populations. This thesis drew from the cognitive vulnerability-stress theories of depression, anxiety, and stress to form its theoretical basis. The underlying premise was that stressful life events have the potential to interact with cognitive vulnerability or characteristic ways of thinking to result in distress for some individuals. New motherhood was therefore conceptualized as a life event that can trigger not only depression, but anxiety and stress in vulnerable women. A major aim of this thesis was to assess the prevalence of postnatal distress using the Edinburgh Postnatal Depression Scale (EPDS) and the Depression Anxiety Stress Scales (DASS-21). The sample comprised 325 primiparous mothers who ranged in age from 18 to 44 years (M=32 years), whose babies were aged between 6 weeks and 6 months. Women were recruited through mother's groups and health centres in Melbourne. Results revealed that over and above the 61 women (19%) who were classified by the DASS-21 as depressed, a further 33 women (10%) showed symptoms of anxiety or stress without depression. This finding supports the assertions that postnatal women need to be assessed for broader indicators of psychological morbidity than that of depression alone. Moreover, 7% of the sample were both anxious and depressed, and had significantly higher mean scores on the EPDS and DASS-depression scales than their depressed-only counterparts. This sub-group also had significantly lower levels of maternal role satisfaction and general life satisfaction than depressed-only women. Other significant findings in relation to the anxious-depressed sub-group, point to the importance of assessing the comorbidity of anxious and depressive symtomatology, and of recognizing the extent to which these women may be at heightened risk compared to depressed-only women. This thesis adapted the biopsychosocial model of postnatal depression proposed by Milgrom, Martin, and Negri (1999) as a research framework for examining a number of unique predictors of postnatal distress. Drawing from an extensive literature on control, two control-related scales were developed (the Perception of Control and Order Scale, and the General Desire for Control and Order Scale). These scales, along with several other cognitive measures, were found to significantly differ in ratings between distressed and non-distressed women. The findings substantiated a role for both controlIII related perceptions (perceptions of control and order, self-efficacy, and perceived control of internal states) and individual characteristics (perfectionism and fear of negative evaluation) in the postpartum. In a final analysis of the cognitive vulnerability-stress model, factors that remained significant that made a unique contribution to the postnatal literature were perceptions of control and order, perceived control of internal states, fear of negative evaluation, and perceived criticism/judgement from women's mothers.