Genetic screening for postnatal depression

Issues for consideration by Rose Coates, PhD student, University of Sussex

I am doing research on conceptualising and screening for postnatal mental health problems and am writing in response to the recent publication of research by Engineer and colleagues identifying possible genetic markers for postnatal depression.  A lot of media reports interpreted this as leading to genetic screening for postnatal depression (e.g. Sky News) and I was contemplating what this means for mothers experiencing any kind of postnatal distress. On the one hand, any research into postnatal depression is welcome and raises awareness of how prevalent and debilitating it is. We also need to understand physiological vulnerability as well as psychological and social vulnerabilities. On the other hand, I have a number of concerns about the focus on genetic screening for postnatal depression.

My first concern is that not all women who screen positive will go on to develop postnatal depression. The potential value of genetic screening therefore needs to be balanced against the potential impact on women of being told they might get postnatal depression. Screening positive could increase stress and anxiety during pregnancy, which studies have shown is associated with preterm labour and poor infant outcomes (e.g. Schuurmans & Karrasch, 2013, Dunkel Schetter & Tanner. 2012). After birth, women might persistently worry about any feelings of distress and quick to pathologise symptoms that may be a normal part of the transition to motherhood.

My second concern is that some women who screen negative will go on to develop postnatal depression. In these circumstances, will women feel that their experience is less valid because the test gave them the all-clear? Will it be clear to women that the test is screening for only one marker of elevated risk for postnatal depression and not the many other forms of distress that women can and do experience e.g. anxiety, PTSD, bonding and adjustment disorders? Given the lack of knowledge and information about other forms of postnatal distress in the public sphere this seems unlikely. Beyond mothers, will midwives and health visitors be given enough training and time to fully understand and communicate these issues of the tests sensitivity and specificity?

My third concern and perhaps the most worrying aspect to me are reports in the media that the screen could be a time- and money-saving method of detecting mothers at risk of depression. The implication is that midwives and health visitors could use this test with new mothers in their care instead of asking about wellbeing and women disclosing feelings of distress. Many studies show that what mothers want, and what helps them through distress, is talking to someone supportive (e.g. Cuijpers et al., 2008). Of course there will always be some mothers who do not want to disclose their feelings but it is not certain that screening for increased genetic risk of depression will lead to improved help and support for this group anyway.

In my view, more research and consideration of the impact of screening on women is needed. As Engineer and colleagues take pains to acknowledge, their results are based on a small convenience sample and they assessed postnatal depression using a score of 10 or more on the Edinburgh Postnatal Depression Scale (EPDS).  Irrespective of the utility of using the EPDS to detect postnatal depression, the usual cut-off score is 13 or more, which likely accounts for their high prevalence of probable depression (24%). The EPDS was also given only once postpartum (4-6 weeks) so it is possible a number of women who screened positive may simply be experiencing transient distress. Matthey (2010) argues that two high scores on the EPDS, separated by two weeks, and combined with a clinical interview provide a more accurate assessment for ongoing depression. It is therefore important that we consider the impact of screening on women and the best way in which to do this.

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How do we measure perinatal PTSD?

The saying “rubbish in, rubbish out” emphasizes the importance of accurate measurement in research. Simply put, if our measures aren’t right our results are not valid. Most studies of perinatal PTSD use self-report questionnaires because we need to screen a lot of women in order to identify the small proportion of women who need help. However, if our questionnaires are not accurate it undermines the results of our research.

At the risk of stating the obvious, how we measure PTSD is therefore critical. Clinical interviews are proposed to be the ‘gold standard’ of measurement and some questionnaires have been validated against interviews to determine how sensitivity and specific they are in terms of identifying women with PTSD. However, there are a number of perennial issues we need to consider. These issues include whether to use general PTSD measures or birth-specific measures. Studies suggest that postnatal women might over-report symptoms of hyperarousal and under-report symptoms of avoidance, so birth-specific measures may be more appropriate. Another issue is whether to take a diagnostic approach to PTSD as a ‘disorder’ or a continuum approach focusing on PTSD symptoms. It is clear that some women who do not fulfill diagnostic criteria for PTSD still want and need help. However, there is currently no agreement over what constitutes significant subclinical symptoms. Similarly, different questionnaires focus on a variety of symptoms or diagnostic criteria so we need to be clear about which approach we are taking before we choose our measures. A recent issue is that diagnostic criteria for PTSD changed with the publication of DSM-V but, as yet, questionnaires have not been updated to account for these changes.

The consequence of all of these issues is that it might be difficult at the current time to recommend a measure of PTSD for use with perinatal women and this probably needs to be decided according to the aims of the research. In the meantime, a compromise could be to use multiple measures and, wherever possible, to use clinical interviews. However, it is clear that we desperately need research evaluating different measures and adapting measures to conform to DSM-V diagnostic criteria.

All change… what does DSM-5 mean for perinatal PTSD?

By Susan Ayers, Centre for Maternal and Child Health, City University London

In May this year the American Psychiatric Association released version 5 of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) to some controversy and criticism, including from Allen Frances, the chair of the previous DSM task force (Psychology Today, 2012). The British Psychological Society also expressed concerns about aspects of DSM-5, and the Division of Clinical Psychology published a detailed statement in response to DSM-5. So what are the implications of DSM-5 for perinatal PTSD?

Key changes in DSM-5 criteria for PTSD are outlined in an APA factsheet. Frustratingly, getting access to the complete diagnostic criteria seems to be difficult unless you purchase the manual. Nonetheless, the key changes outlined by the APA factsheet and gleaned from a few other sources are as follows:

  • PTSD is now classified as a ‘trauma and stressor-related disorder’ rather than an anxiety disorder.
  • Event criteria have changed so the person has to directly experience or witness “actual or threatened death, serious injury or sexual violation”. Previous criterion A2 about individuals responding to this event with intense fear, helplessness or horror has been removed. In addition, certain events are excluded from qualifying as a traumatic event, including the unexpected death of a family member by natural causes. 
  • There are now four symptom clusters of PTSD instead of three: (1) intrusions, (2) avoidance, (3) arousal and (4) negative cognitions and mood. The new category of ‘negative cognitions and mood’ includes some symptoms of numbing that were previously included with avoidance symptoms, in addition to new symptoms such as persistent blame of self or others.
  • Arousal symptoms now include more aggressive or self-destructive behaviours.
  • Two subtypes have been added of PTSD in children and PTSD with dissociative symptoms.

For perinatal PTSD the changes to event criteria are critical. Traumatic births still fit criteria because women can directly experience the threat of death or injury. Similarly, fathers and birth partners may fit criteria by witnessing such events. However, the exclusion of death of a family member by natural causes could (arguably) exclude death of the infant before, during or after birth, depending on how ‘natural causes’ is defined. This raises the question of whether psychological problems arising from perinatal infant death are more appropriately conceptualised as PTSD or complicated grief.

This tightening of event criteria to potentially exclude infant deaths, coupled with the necessity for parents to have four types of symptoms rather than three, means prevalence rates of postpartum PTSD could reduce. On the other hand, the removal of criterion A2 where the person has to respond to the event with intense fear, helplessness or horror could increase prevalence rates of postpartum PTSD. The rationale behind this change is that people respond to traumatic events in different ways (e.g. anger, shame, guilt) and that inclusion of A2 “proved to have no utility in predicting the onset of PTSD” (see APA factsheet).

Postpartum PTSD research certainly supports the notion that women respond to traumatic birth with a wide range of negative emotions (e.g. Ayers, 2007).  However two large studies carried out in the UK and Australia suggest the removal of A2 is likely to inflate prevalence rates of postpartum PTSD because many women perceive a threat of injury or death during birth. In the UK, Ayers et al (2009) looked at prevalence of postpartum PTSD in 502 women in community studies and found 35% of women reported perceived threat of injury or death. Similarly, 35% of women reported feeling intense fear or horror at some point during birth. However, only 19.7% of women reported both perceived threat of death or injury and feeling intense fear, helplessness or horror. This was also the case in an Australian study where Boorman et al (2013) looked at criteria for a traumatic birth in 890 women and found that prevalence of traumatic birth doubled from 14.3% to 29.4% when women’s emotional responses (criterion A2) were removed.

It is therefore not clear whether changes to PTSD diagnostic criteria in DSM-5 will reduce or increase prevalence rates of postpartum PTSD. In other populations the indications are that DSM-5 criteria result in lower prevalence rates (Miller et al, 2012). Research is needed to examine whether this is also the case in perinatal samples. However, before we do this we need to consider how best to measure perinatal PTSD, given the changes introduced by DSM-5. Finally, these diagnostic changes also have implications for screening and access to treatment that we haven’t considered here.

If you have any comments on this article or related issues, such as the measurement of perinatal PTSD, please let us know or leave a reply below. We are keen to publish blog posts or articles from any of our members – just get in touch with Ellinor ( or Susan (