Increased Risk of Preterm Birth in Veterans with PTSD

Posttraumatic stress disorder (PTSD) is relatively common among women, with a lifetime prevalence of PTSD estimated to be about 10%. While PTSD occurs in all age groups, it is most prevalent among women of childbearing age, and PTSD symptoms are common during pregnancy and the postpartum period.  

Previous studies have indicated that women with a diagnosis of PTSD have an increased risk of preterm birth. In one study, it was observed that the risk was particularly high in women with diagnoses of both PTSD and major depression; these women had a 4-fold increased risk of preterm birth.  

PTSD and Preterm Birth in US Veterans

In 2014, Shaw and colleagues examined the relationship between PTSD and risk of preterm birth in a group of women followed by the Veterans Health Administration. In this retrospective study of 16,334 deliveries between 2000 and 2012, the researchers identified women with PTSD. They compared outcomes in women with a diagnosis of PTSD present during the year prior to delivery (active PTSD) to outcomes in women with earlier diagnosis of PTSD (historical PTSD) or no PTSD. In the Veterans Health Administration system, mandatory PTSD screening using a validated instrument is built into the electronic medical record.

This study demonstrated that spontaneous preterm delivery was more common in women with active PTSD (9.2%) than in women with historical PTSD (8.0%) or no PTSD (7.4%). After adjusting for possible confounding factors, the association between PTSD and preterm birth persisted only in those with active PTSD (adjusted OR 1.35, 95% CI 1.14-1.61). 

Other Factors Associated with preterm Birth in Veterans with PTSD

In a recent publication, researchers from the Veterans Administration take a closer look at this population to better define factors associated with spontaneous preterm birth among pregnant veterans with active PTSD. This analysis included 3,242 births to veterans with active PTSD between 2005 and 2015.

In this cohort, 249 (7.7%) of the women had spontaneous preterm births. Veterans who gave birth preterm were older and had more frequently diagnosed with a substance use disorder (37.0% vs. 29.5%; P =.01). Among the pregnant veterans with active PTSD, the majority (79.1%) received some type of mental health treatment. Comorbid depression was prevalent (61.4%).  

Preterm birth in women with active PTSD was associated with preeclampsia/eclampsia (adjusted odds ratio, 3.30; 95% CI, 1.67–6.54) and six or more dispensations of an antidepressant medication (aOR 1.89; 95% CI, 1.29–2.77). The findings were similar when they considered the risk of preterm birth in women with and without a diagnosis of major depressive disorder.

While this study and others indicate an association between PTSD and spontaneous preterm birth, it is difficult to determine which veterans with active PTSD are at risk for this adverse outcome. Although use of antidepressants was associated with an increase in risk of preterm birth in veterans with PTSD, the authors speculate that use of antidepressants is not a significant risk factor but rather a proxy for more severe illness or comorbidity.

Women with PTSD at Risk for Preterm Birth, Worse Pregnancy Outcomes 

These studies demonstrate a statistically significant risk of preterm birth among women with active PTSD. This 35% increase in risk is similar in magnitude to what is observed with other risk factors, such as advanced maternal age. These are the largest studies to date exploring the link between PTSD and risk for preterm birth.

Although the nature of trauma in veterans is distinct from the trauma experienced by women in the general population, the findings of these studies are consistent with smaller studies in non-military populations. In the first study from Shaw et al (2014), nearly one third of the deliveries were to women with recent deployment (Afghanistan or Iraq); however, 23% of the deliveries were to women reporting a history of sexual trauma. The authors note that while the population studied here is distinct from women in the general population, military women experience a diverse set of traumas; yet, the most common antecedent of PTSD in military women is sexual trauma, which is exactly what is observed women in the general population.

While we don’t know exactly how trauma may increase risk for preterm birth, it has been hypothesized that activation of the hypothalamic-pituitary-adrenal (HPA) axis plays an important role. In response to stress, individuals with PTSD have elevated levels of corticotropin-releasing hormone (CRH). Throughout the course of a normal pregnancy, the levels of CRH gradually increase and determine the timing of childbirth. Thus, abnormally elevated levels of CRH may result in preterm birth. Activation of the HPA axis may also contribute to other adverse outcomes, including hypertension, pre-eclampsis/eclampsia, fetal growth restriction, and altered HPA axis functioning in offspring. 

Ruta Nonacs, MD PhD

Panelli DM, Chan CS, Shaw JG, et al. An exploratory analysis of factors associated with spontaneous preterm birth among pregnant veterans with post-traumatic stress disorder. Womens Health Issues. Published online October 28, 2022. doi:10.1016/j.whi.2022.09.005

Shaw JG, Asch SM, Kimerling R, et al.  Posttraumatic Stress Disorder and Risk of Spontaneous Preterm Birth.  Obstet Gynecol 2014.

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