Affective disorders following childbirth range from 'maternity blues' to postpartum psychosis, a serious condition requiring hospitalisation . Along this spectrum postnatal depression (PND) is classified in DSM-IV as 'a depressive condition that often exhibits the disabling symptoms of dysphoria, emotional lability, insomnia, confusion, anxiety, guilt and suicidal ideation' . A meta-analysis of 59 longitudinal and epidemiological studies showed a prevalence of PND in the region of 13%, ranging from 3 to 25% of women in the year following childbirth . PND has been shown to affect both the mother and her baby, leading to mother-infant relationship difficulties  and long-term child behavioural [5–9], cognitive [10, 11], and intellectual problems ; particularly for boys from disadvantaged backgrounds . The treatment of PND is a public health priority, and recent UK National Institute for Health and Clinical Excellence guidance recommends that all women be screened for PND during the first eight weeks postnatally using the three Whooley questions to identify women experiencing difficulties . It also suggests that women experiencing such problems should be offered support from health care professionals and voluntary organisations.
The aetiology of PND suggests the importance of a multitude of contributing factors such as life stresses, difficult infant behaviour, marital conflict, low maternal self-esteem and lack of social support [14, 15]. Research has shown that factors such as the need to talk to someone who has experienced similar problems, lack of an intimate friend or confidante, the need for support without having to ask for it, and social isolation are all significant in the aetiology of PND (ibid). The use of 8 'listening visits' by specially trained health visitors has been identified as effective in supporting women experiencing PND . However, the prevalence of PND is high and there is much unmet need, particularly for women who feel unable to admit to experiencing problems due to fears about being perceived as inadequate or the possibility of their baby being removed from the family. In addition, some women are not perceived to be experiencing sufficiently severe problems to justify additional support. This points to the potential value of developing peer-supporters. The NHS Expert Patient Report  recommends the development of lay-led self-management training programmes in order to make use of the knowledge and experience held by patients, and the White Paper "Our Health, Our Care, Our Say" underlined the importance of assistive technology, with a strong emphasis on patient education and empowerment.
A review of non-biological interventions for the treatment of PND identified four evaluations of the effectiveness of peer-support interventions . The first three studies comprised evaluations of a post-partum support group targeting both depressed and non-depressed Canadian women , a Chinese evaluation of weekly support group meetings for depressed women only , and an Australian study of group-based support for postnatally 'distressed' women and their partners . The studies suffered from serious theoretical limitations (such as the inclusion of both depressed and non-depressed women) and methodological weaknesses, rendering the results equivocal. The fourth study, however, comprised a Canadian telephone-based peer-support pilot RCT with women identified as being at high-risk of depression . The findings showed significant group differences in depressive symptomatology at the 12-week assessment and support the provision of peer-support to women experiencing PND.
Peer support has been defined as "the giving of assistance and encouragement by an individual considered equal" . Another definition states "that people who have like experiences can better relate and can consequently offer more authentic empathy and validation". Individuals who have similar lived experiences can often offer practical advice and coping strategies of which health professionals may be unaware, and it is suggested that this non- professional approach is vital in helping people to re-connect with their community . The most comprehensive definition of peer support within a healthcare concept is "the provision of emotional, appraisal and informational assistance by a created social network member who possesses experiential knowledge of a specific behaviour or stressor and similar characteristics as the target population" .
Research to identify the 'critical ingredients' of peer-support has identified three distinct factors: structure (program structure and environment), values (belief systems) and processes (peer-support, education/advocacy) . The structural category defines how the support is constructed and its basic rules i.e. non-coerced, lay-led, safe, flexible informal setting, non-medical approach with no hierarchies. The value category refers to a set of belief systems, which include "the peer principle" (building an equal relationship with someone who has similar life experiences), "the helper principle" (the idea that helping someone else can be self-healing) and "empowerment" (discovering hope and the belief that recovery is possible, enabling someone to take personal responsibility for achieving their full potential). 'Process' refers to the way in which peer-support is delivered, such that it enables choice, encourages decision-making opportunities, and develops skills through knowledge and education, reciprocity, supportive mutual relationships, developing awareness, and a sense of community [25, 26]. The underlying principle in terms of incorporating peer-support into health care is that new knowledge may be understood more effectively when it is communicated by a peer who has shared a common experience .
Development of Mums4Mums: telephone peer-support for mums experiencing PND
The current proposal has adapted for use in the UK a telephone-based peer-support intervention shown to be effective in Canada , to pilot its use, and provide preliminary data on its effectiveness in reducing depressive symptoms amongst women experiencing PND.
The proposal builds on an exploratory study that examined a range of stakeholder's views about the need for, and potential acceptability of, a telephone-based peer-support intervention, their views about the potential impact of the intervention, and how it would fit into current practice. General Practitioners (GPs) (n = 6), health visitors (n = 7) and mothers who had recovered from PND (n = 10) were interviewed and the results indicated that stakeholders perceived a need for a telephone-based peer-support intervention for women currently experiencing PND in the UK. It was suggested that this would represent an additional resource for mothers, and that a telephone-based intervention would be acceptable due to its flexibility and use of non face-to-face contact.
The Mums4Mums telephone support intervention was piloted with women currently living with PND (n = 8). The pilot study was conducted to explore key elements of the telephone based peer-support intervention such as training, acceptability, and recruitment. In-depth interviews were again conducted, and the initial findings suggested that the Mums4Mums intervention was acceptable and potentially beneficial in supporting women with PND.
Mums4Mums Feasibility Trial
The current study aims to test the feasibility of conducting a large-scale randomised controlled trial of a telephone based peer-support intervention to reduce depressive symptomology in women with PND.
The objectives of the feasibility study are to:
ascertain the acceptability of a randomised control trial for women with PND;
explore effective methods of recruitment;
explore the participants' and health professionals' views about the intervention;
ascertain the acceptability of the outcome measures;
identify a cost-effectiveness measure;
provide an estimate of the size of change that might be expected with such an intervention to inform the power calculation for the larger RCT;
build a working alliance with health care professionals for the larger clinical trial;
make any necessary adaptations to the intervention and develop a full proposal for a main RCT to be submitted to the MRC in 2012.