By Ray Jerram Dr Nathan Hodson
Miscarriage and mental illness are common but often hidden life experiences. Emerging evidence reveals the toxic symbiotic relationship between these two stigmatized parts of life. To some extent their connection may be unsurprising, considering how we increasingly recognise the pervasiveness of psychiatric issues, as well as the trauma of miscarriage, but it is worth taking a closer look at the bidirectional relationship in this understudied and misunderstood area.
A Norwegian study by Maria C. Magnus et al. investigated the relationship between pre-existing anxiety, depression and other mental disorders in relation to the risk of miscarriage. The authors used prospective data collection on cohorts of women interacting with the Norwegian healthcare system over a 7-year period, finding that the risk of miscarriage was elevated in most of the studied disorders. These interactions include visits to medical specialists and hospitals over three national health registries. Miscarriage was defined in this study as ‘a foetal death before 20 gestational weeks, with a birth weight <500g’. Miscarriage risk over this period was estimated to be 17.2%, but in women with psychiatric disorders the risk increased to 22%. The increase was particularly pronounced in bipolar affective disorder at 1.35 (95% CI 1.26–1.44), ADHD at 1.27 (95% CI 1.21–1.33) and depressive disorders at 1.25 (95% CI 1.23–1.27). Risk increased further when the number of co-morbid psychiatric diagnoses increased, for example a co-occurrence of depression and anxiety resulted in an odds ratio of 1.45 (95% CI 1.40–1.51) (the most common two conditions by far, co-occurring in 2% of all pregnancies).
These results raise questions about the mechanism behind the associations. It is possible that there is a direct effect of psychiatric illnesses on the risk of miscarriage. For example, the authors suggested that women with psychiatric conditions may have an ‘increased risk of adverse obstetric outcomes through changes in neurotrophic factors in the brain’. However, indirect factors also play a part in explaining the findings. Socio-economic conditions strongly relate to risk of psychiatric disorders; challenging living conditions often contribute to stressful experiences. Furthermore, smoking and higher BMI are associated with psychiatric disorders, for example psychotic illnesses are associated with higher levels of smoking and antipsychotic drugs, particularly newer atypical drugs, are associated with weight gain. A third explanation is that the medications used to treat psychiatric disorders have an adverse effect on the risk of miscarriage. Ultimately, this important study highlights the need for greater awareness and outreach for women susceptible to risks presented by psychiatric difficulties, but leaves open questions about the causal chain so targeted intervention remains difficult.
‘Miscarriage matters: the epidemiological, physical, psychological, and economic costs of early pregnancy loss’ was a paper published in the Lancet in early 2021. The authors review the epidemiological, physical, psychological and economic costs of early pregnancy loss. They conclude that 15.3% of all recognised pregnancies end in miscarriage. They also find that the risk of miscarriage compounds with age and number of previous miscarriages, steeply increasing to 65% in women of 45 years of age, or 42% in women with three or more previous miscarriages.
The review goes on to consider the ramifications of early pregnancy loss. This review found that many psychiatric disorders such as anxiety and depression appear to arise following miscarriage, with 18% of women categorised as having markers of post-traumatic stress and a further 17% with anxiety in a multicentre, prospective cohort study on 537 women following miscarriage. Physical health problems can also increase, such as risks of cardiovascular disease and UTIs. Meanwhile, the social impact of miscarriage is difficult to make sense of as cases vary so widely. One measure is economic: the authors’ economic review was limited by the few studies conducted, but they found the mean value of work absences to be £431, as a consequence of loss of productivity following miscarriage.
Both these papers demonstrate clear links between mental health and miscarriage but point to complex webs of causality. These papers show that effective strategies to improve miscarriage care and reduce recurrent miscarriage could have mental health benefits on a population level. Similarly, it is plausible that effective mental health care could reduce the miscarriage rate. Both papers also concede that research into the overlap of these topics remains sparse. Altogether, joined up working between mental health teams and reproductive health teams is called for to improve outcomes for women.
Authors: Ray Jerram, King’s College London, and Dr Nathan Hodson, University of Warwick