Understanding the Prevalence of Postpartum Psychosis

Postpartum psychosis (PP) is a rare and severe psychiatric disorder that is generally reported at a prevalence of 1-2 per 1000 in pregnant women. While there is a breadth of research on psychiatric disorders in pregnant women, which is a major contributor to the global burden of disease in both the general population and in pregnant women specifically, little research has been done that focuses primarily on postpartum psychosis. There is a need for more research on PP to improve understanding of the causes of the disorder, increase access to resources for survivors of PP, and gain a better sense of the burden of the disorder in terms of prevalence and morbidity. PP is a difficult disorder to study not only because of its low prevalence, but also because of the variety of methods used by researchers, making it challenging to compare results across studies and compile accurate aggregate data on the disorder.

In a recent article by VanderKruik et al., the authors perform a review of the relevant literature on postpartum psychosis with the goal of obtaining a global estimate of the prevalence of PP and to understand how the disorder is evaluated and captured across various studies. Modeling their methodology after that used by the World Health Organization (WHO) in the WHO Systematic Review of Maternal Morbidity, the authors searched across several databases to find literature that mentioned postpartum psychosis. From there, they narrowed down the 24,273 results to the six studies that fit all of their criteria. Inclusion criteria included a large sample size (n > 200), clear description of methodology, specific dates of collection period (limited to data from 1990-present), and primary data on pre-defined mental health conditions included in the study.

Of the six studies included in the systematic review, four were retrospective reviews of birth registries (Valdimarsdóttir), birth and psychiatric registries (Terp), birth and hospital discharge registries (Nager), or women’s medical records (Adefuye). The other two studies collected data from household interviews (Vesga-Lopez) and observation by community health workers (Bang et al.), respectively. The studies were conducted in a variety of settings: Sweden, Denmark, the United States, Nigeria, and India. These six studies constituted the best representation of postpartum psychosis globally according to the inclusion criteria established by the investigators of the review (VanderKruik et al.).  

The results of the included studies indicated a global incidence of PP between 0.89 and 2.6 per 1000, consistent with most commonly reported prevalence rate, 1-2 per 1000.

One challenge faced by the researchers performing the review was the variability of the definition of the postpartum period. Some studies included data from psychosis experienced during pregnancy while others extended the period of data collection to one year postpartum. The high prevalence reported by one study (Vesga-Lopez) may have been due to the extended timeframe. The study by Bang et al. reported the highest incidence out of the six studies reviewed. It also had the smallest sample size, which may have been a contributor. Due to the limited number of studies reviewed, no concrete conclusions can be made regarding the effect of methodology or sample size on reported incidence or prevalence, but the results of this review indicate that among those studies reviewed, the highest incidence was among those with the smallest sample size. There is a need for a more expansive review of the literature on postpartum psychosis to determine whether these factors do influence reported incidence.

This review confirmed the commonly reported low incidence of PP (1-2 per 1000) and highlighted some of the inconsistencies across research on the disorder including a diversity of methods and sample sizes. The fact that only six studies met the inclusion criteria for this review also points to a gap in understanding about PP. There is a critical need for more attention and resources to be directed towards perinatal mental health, and in particular postpartum psychosis. Improving the methods with which we capture data on the incidence and course of postpartum psychosis will lead to better resources for women experiencing this rare yet serious disorder.  

Research summary compiled by Nicola Roux.

Vanderkruik, R., Barreix, M., Chou, D., Allen, T., Say, L., & Cohen, L. (2017). The global prevalence of postpartum psychosis: A systematic review. BMC Psychiatry, 17(1), 1-9.