Having a baby is a significant transitional life event, especially for women having their first child. It involves changes in relationships between couples and within families, and is commonly a cause of additional financial stress, even among households with relatively high incomes [1]. The impact of stressful life events and social health issues on maternal psychological morbidity, such as depression, has been identified in several studies. O'Hara [2] noted that stressful life events experienced in pregnancy or early postpartum was a strong predictor of postnatal depressive symptoms. A Swedish study identified that one of the factors associated with depressive symptoms in a large national sample was two or more stressful life events in the year prior to pregnancy [3]. Studies from Australia [4] and the USA [5] have also found associations between experiencing stressful life events and maternal depression.

Internationally there is increasing recognition that maternal depression is a major public health issue, with potential long term consequences for women's health and the health of her infant and other family members [6, 7]. Concern about under-detection and poor management of maternal depression has led to development of guidelines for assessment and screening of pregnant and postnatal women in many Western countries. Other psychosocial morbidity, including anxiety, has generally been overlooked in these national responses. This is despite evidence that symptoms of depression and anxiety commonly co-occur [8, 9] and that this co morbidity may be an indicator of severity of psychological ill-health [10]. Antenatal anxiety has been shown to be associated with preterm birth [11] and predict postnatal depressive disorders [8]. Studies examining outcomes associated with maternal postnatal anxiety suggest exposure is related to adverse psychological problems in children [12].

Previous research have used socio-demographic determinants (i.e. income, educational attainment) to describe social disparities in maternal emotional wellbeing [13, 14]. The few studies examining perinatal stressful life events and psychological morbidity have focussed on maternal depression alone [2–5, 15, 16]. This study addresses limitations of previous research, drawing on data from a large Australian population based survey of recent mothers to examine anxiety, depression and co-morbid symptoms at six months postpartum, together with women's experiences of stressful life events and social health issues. The primary aims of analyses presented in the paper are to: (i) determine the prevalence of maternal anxiety and depressive symptoms, and co-morbid symptoms, at six months postpartum; (ii) investigate the association between postpartum anxiety and depression and stressful life events and social health issues experienced in the six months following birth.

This study is the first to assess depression, anxiety and co-morbid anxiety and depression in a large population-based sample. Results show a concerning level of psychological morbidity with 17% experiencing depression and 13% experiencing anxiety at six months postpartum. Of particular concern is the identified level of co-morbidity with nearly one in ten women reporting both anxiety and depressive symptoms.

The high level of maternal anxiety and co-morbid anxiety and depression is generally not recognised in the perinatal depression literature [8, 25]. Several exceptions to this come from Australia, including a small study using the DASS 21 which identified that 7% of women had symptoms of anxiety and depression at six weeks to six months postpartum [26]. A recent cohort study using the Edinburgh Postnatal Depression Scale (EPDS) [27] in combination with an interval symptom question and clinical interview identified that 8% had primary anxiety and 12% mixed depression and anxiety in the 6-8 month postnatal period [9].

The literature on life events draws attention to the significant impact of events such as moving house, the death of a family member and starting a new job. All of the women in this study were in the midst of managing one major life event: the birth of a baby and first few months after the birth. Many also experienced a range of stressful life events, such as the serious illness or death of a family member or friend, moving house or having a major illness themselves. In addition, some women experienced social health issues including serious family conflict, not having enough money to buy food, having a lot of bills they couldn't pay, or trouble associated with illicit drugs, alcohol or gambling. Data from 19 states participating in the USA PRAMS echoes these findings with 41% of women reporting at least one of several hardships (i.e. many bills that couldn't be paid, loss of job, separation or divorce) [1].

This study provides the first Australian population-based data on stressful life events and social health issues experienced by women in the six months following birth, and identifies a significant association with psychological morbidity. Australian and international studies [3, 5, 28, 29] have also identified similar association between stressful life events and psychological ill-health, however are confined to perinatal depression as the outcome of interest. While it is not possible to determine causal pathways in an observational study such as this population-based survey, it is unlikely that such large effect sizes are explained by unmeasured confounders. The findings draw attention to social circumstances in women's lives that may place them at higher risk of poor mental health outcomes.

A number of studies have identified socio-demographic associations with postpartum depression, including factors associated with financial hardship [29], not being married [30] and migration of the mother from a country where English is not the primary community language [14, 29]. At a univariate level this study supports these associations however only the maternal country of birth (non-English speaking background) remained statistically significant at the multivariate level. For the first time in a population-based sample we have identified that maternal country of birth is also associated with postpartum anxiety and co-morbid symptoms of depression and anxiety. In this study women with three or more stressful life events or social health issues were four to five times more likely to score above the cut-off scores on the DASS 21 for anxiety and depression, and almost six times more likely to have scores indicating co-morbid symptoms than women who did not report any stressful life events or social health issues in the months following birth. The strong relationship with postpartum emotional health is striking and illustrates the extent to which mental health in the postnatal period is related to exogenous factors over and beyond the immediate stresses associated with recovery after birth, and the physical and emotional demands of parenting.

The findings should alert health professionals engaged with women in the perinatal period to be attuned and responsive to potential stressors in women's lives. Providing perinatal care that is responsive to complexity in women's lives is challenging, especially in health systems characterised by short consultation times, limited integration between primary and specialist services, inadequate professional training in psychosocial assessment and treatment strategies, and limited availability of accessible and acceptable services for referral. The recently published NICE Guideline: Pregnancy and complex social factors A model for service provision for pregnant women with complex social factors provides a starting point for rethinking systems of care in ways that are likely to be more responsive to women experiencing major life events and social health issues in the months after childbirth [31]. Our findings suggest that the effectiveness of treatment options for depression and anxiety may be limited if the potential impact of stressful life events and social health issues is not recognised. Cognitive Behavioural Therapy and pharmacological approaches have proven effectiveness in treatment of depression, but may be less effective in resolving maternal depression and anxiety if social determinants are not addressed.

The focus of this paper has been on the postnatal period, but women are likely to experience a similar range and number of stressors during pregnancy [11] with evidence that life stressors in pregnancy are associated with depression after birth [2, 29]. We hope our findings invigorate debate about the role of antenatal care in acting early to identify and support women at risk of poor mental health outcomes; about whose responsibility it is to provide support to women experiencing social adversity during and after pregnancy; and how services can work together to provide care that addresses the social context of women's lives and impact of a range of common life events and social health issues. This will require change across a currently fragmented system of perinatal care with integration between interventions to counter the provision of distinct vertical programs [32]. Reform strategies will need to be multi-faceted; focus on a continuum of care spanning maternal, newborn and child health; and strongly grounded in an integrated approach to service delivery that addresses underlying social determinants [33].

Strengths of this study include: a population-based sample with adequate power to detect differences between sub-groups including groups of women who are less likely to participate in surveys of this kind, for example younger women; the capacity to identify the extent of selection bias by comparing study participants with women giving birth in the study period using routine data collections in both states; a largely representative sample in terms of important obstetric covariates (e.g. method of birth, parity); and use of standardised measures for anxiety and depressive symptoms. The DASS-21 was used in preference to the EPDS used in previous Victorian surveys as it includes a scale for anxiety symptoms, and because the EPDS is now in increasingly common use in clinical settings in Victoria and South Australia, which compromises its value as a research instrument. The DASS-21 has good psychometric properties and the depression scale correlates well with the EPDS. The 21 item DASS was well completed, with 2% of women unable to be categorised due to missing values. Prevalence of depressive symptoms was similar to estimates of prevalence found in other studies including the three previous Victorian surveys using the EPDS [2, 18, 34, 35].

The response fraction was similar to other recent population-based surveys [e.g. [36]]. Compared to the Victorian surveys of recent mothers of 1998, 2004 and 2000 [10–12] this study was larger and several processes differed in order to conform to ethics and privacy requirements. We are aware that several participating hospitals found managing some of the processes associated with identification of births, exclusions and mail-out procedures challenging. The quoted response fraction is conservative, and it is likely that the response from women who actually received a mailed survey was higher.

Like other postal surveys of this kind the survey under-represents women who are single, young, born overseas in a non-English speaking background country and not privately insured at the time of birth [10, 11]. These factors limit the generalisbility of the findings. It is likely that prevalence estimates for depression and anxiety underestimate the true prevalence due to the under representation of younger women and women of non-English speaking background in our sample.

Given the high prevalence of psychological morbidity and the association with social health issues experienced by women in the months following birth, it is critical that health professionals providing care to women in the perinatal period be alert to the range of social health issues. Awareness and recognition needs to be followed through with care which it is sensitive and supportive of women's individual health and social circumstances. Integrated care pathways would enable care providers to respond with a coordinated approach to on-going support and management of women at risk of poor mental health outcomes. Care that is responsive to women's social health may well lead to improvements in women's emotional wellbeing following birth.