Complexities of Trauma Exposure Over the Life Course and Hypertensive Disorders in Pregnancy

Hypertensive disorders in pregnancy (HDP), defined by the Centers for Disease Control and Prevention (CDC) as chronic or pregnancy-associated hypertension (i.e., gestational hypertension, preeclampsia/eclampsia), pose significant threats to the health and well-being of pregnant individuals and their infants [1, 2]. In the United States, HDP affects an estimated 16% of pregnancies, and the prevalence has been rising over time [1]. Further, Black individuals bear a disproportionate burden of HDP, with an estimated prevalence of 21% [1] and an HDP-related maternal mortality rate almost four-fold higher than White individuals [2]. These disparities extend across the life course—with hypertension prevalence being approximately 45% in women who are Black compared with approximately 30% in women who are Asian, Hispanic, or White [3]. Given these highly concerning trends and disparities, we must gain a better understanding of potential causes so that effective prevention and treatment strategies can be developed and implemented. In addition to conventional risk factors such as maternal age, family history and body mass index, mental health conditions, and past traumatic experiences have also been implicated in hypertensive disorders. However, screening for and defining trauma exposure remains complex and variable. When examined through the framework of adverse childhood experiences, more extensive trauma histories have been associated with increases in complications such as preterm birth and HDP [4, 5]. One proposed mechanism underlying the relationship between trauma history and pregnancy complications involves the pro-inflammatory effects of chronic stress, which may vary depending on the timing of the stressor(s) relative to the index pregnancy, as well as on individual coping mechanisms that may confer physiological resilience. These findings underscore the importance of addressing trauma histories in perinatal care as a potential way to mitigate the risk of adverse pregnancy outcomes. However, more research is needed to develop effective interventions. In this issue of Paediatric and Perinatal Epidemiology, Stanhope and colleagues [6] share findings that strengthen our understanding of the trauma experiences of pregnant individuals and how those experiences relate to HDP. They collected data from pregnant and breastfeeding persons at a safety-net hospital in Atlanta, Georgia, from 2017 to 2022. They found that lifetime exposure to trauma was widespread (94%) and most often first occurred as a young child (less than 10 years old). The researchers also found that 31% of individuals who experienced trauma had a probable depression diagnosis, compared with 2% of those who had not. Contrary to their hypothesis, however, no increased risk of HDP was observed with exposure to trauma. The prevalence of HDP was 40.4% in individuals exposed to trauma and 41.9% in individuals without exposure to trauma, and this similarity was robust in multivariable analyses. Although not the primary aim of this study, the findings underscore the high burdens of trauma and mental and physical health conditions in a safety-net hospital population of pregnant and postpartum individuals. The CDC estimates that two-thirds (64%) of adults in the United States have experienced an adverse childhood experience [7], and 16% of pregnant individuals have a diagnosis of HDP [1]. In this study, nearly everyone had a traumatic experience, primarily in childhood, and almost half had an HDP. The authors justifiably posit that the exceptionally high burden of trauma and HDP in the study population could explain why no association was observed, in contrast to similar studies in other populations [5]. We believe that readers should not take away from this study that lifetime trauma does not affect the blood pressure of pregnant individuals; instead, they should be prompted to consider the complexity of causal pathways of cumulative exposures across the life course. This is particularly important for individuals who are most at risk of HDP due to their social environments and lived experiences of systemic racism and discrimination over their life course. A notable strength of the study by Stanhope et al. [6] is that the researchers could use detailed, reliable data on trauma exposure and HDP. This increased the internal validity of the research and enabled the consideration of different types of trauma and the timing of initial trauma. In particular, they were able to observe a considerably higher prevalence of depression and post-traumatic stress disorder among individuals who experienced or witnessed violence before age 10, but more consistent associations across age groups for experience of interpersonal trauma and sexual trauma. The study team also employed analytical techniques to consider potential biases, such as selection bias from the hospital population. Such techniques are valuable for paediatric and perinatal epidemiology researchers and are worth considering for similar studies. Finally, as mentioned, the study was conducted in a population most in need of public health efforts to prevent and treat HDP—the outcome of interest. Readers should bear in mind the study limitations. The study was conducted at a single safety-net hospital, and its generalisability to other populations remains uncertain, which the authors note. In addition, the exceptionally high prevalence of the exposure (94%; 661 out of 704 individuals) affects the ability to evaluate how variation in the exposure may be related to the risk of the outcome and could affect identifiability conditions, particularly positivity. That is, causal inference from this observational study would require that individuals could be in either exposure group for every level of each covariate. Finally, data on treatments, such as the use of antidepressant medications or the use of low-dose aspirin, was not ascertained and could play a role in a causal pathway between trauma exposure in early life and later HDP. As we advance, this study raises several important questions for researchers. Stanhope et al. [6] identified a dichotomous exposure of any versus no lifetime trauma experience, but it has long been recognised that accumulated lifetime trauma experience—both in the number and type of traumatic events—likely leads to an increasing risk of mental health conditions [8]. It would be worthwhile for future studies to assess cumulative trauma effects on HDP as well as to replicate the current research in other populations and identify any differences in results. Finally, awareness is needed that trauma is prevalent, and our understanding of its effects over the life course—including pregnancy and childhood—and how interventions may mitigate such effects is still limited. S.A.L. and D.M.P. wrote the manuscript. The authors declare no conflicts of interest. The authors have nothing to report.