Pregnant women with a recent diagnosis of post-traumatic stress disorder were 35 percent more likely to deliver a premature baby than other pregnant women, a study of more than 16,000 births found.
A new study from the Stanford University School of Medicine and the U.S. Department of Veterans Affairs reports that pregnant women with post-traumatic stress disorder (PTSD) face a higher risk of premature delivery. The research analyzed more than 16,000 births to female veterans and is the largest study to date evaluating links between PTSD and preterm birth.
The investigators found that women diagnosed with PTSD in the year before delivery—what the team describes as “active” PTSD—had a 35 percent greater chance of spontaneous preterm delivery compared with women without PTSD. The study’s results were published on November 6, 2014 in the journal Obstetrics & Gynecology.
Lead senior author Ciaran Phibbs, PhD, associate professor of pediatrics and investigator at the March of Dimes Prematurity Research Center at Stanford, emphasized the clinical implications: “This study gives us a convincing epidemiological basis to say that, yes, PTSD is a risk factor for preterm delivery. Mothers with PTSD should be treated as having high-risk pregnancies.”
A piece of the prematurity puzzle
Spontaneous preterm births—cases in which labor begins and delivery occurs more than three weeks before the expected date—occur at a rate of roughly six per 100 pregnancies in the general population. Because of the 35 percent increase associated with active PTSD, the researchers estimate this risk translates into about two additional premature deliveries per 100 births among women with active PTSD. Overall, approximately 12 out of every 100 babies are born prematurely; some of those are delivered early for medical reasons affecting the mother or baby rather than as a result of spontaneous labor.
“Spontaneous preterm labor has been an intractable problem,” Phibbs said, noting that rates of spontaneous early labor have changed little over the past five decades. “Before we can come up with ways to prevent it, we need to understand the causes better. This study provides one important piece of that puzzle.”
Preventing prematurity is a major clinical priority because of the significant short- and long-term consequences for infants. Premature newborns often require prolonged hospital stays, have a higher risk of infant mortality, and are more likely than full-term infants to experience developmental delays or chronic problems with vision, hearing, breathing, or digestion.
Phibbs and colleagues examined all deliveries covered by the Veterans Health Administration from 2000 through 2012, totaling 16,344 births. Among those births, 3,049 infants were born to women who had ever received a PTSD diagnosis. Of that group, 1,921 deliveries were to women with active PTSD—diagnosed within the year before delivery—a period the researchers considered plausibly influential on pregnancy outcomes.
The analysis accounted for a wide range of potential confounding factors. Consistent with prior work, older maternal age, African-American race, and twin pregnancy were associated with higher prematurity risk. The investigators also evaluated maternal chronic conditions (hypertension, diabetes, asthma), possible sources of trauma (military deployment and military sexual trauma), coexisting mental health disorders, substance use disorders, and tobacco dependence. These factors had limited impact on the link between PTSD and spontaneous preterm birth in the adjusted models.
The effect of stress
In short, while women with PTSD may have other health challenges or risk behaviors, the data point to PTSD itself as the key factor associated with earlier labor. “The mechanism is biologic,” Phibbs said. “Stress is setting off biologic pathways that are inducing preterm labor. It’s not the other psychiatric conditions or risky behaviors that are driving it.”
Importantly, women with a past diagnosis of PTSD who had not had an active diagnosis during the year prior to delivery did not show an increased risk of preterm birth compared with women without PTSD. That finding suggests that treating active PTSD during pregnancy could reduce stress levels and potentially lower the risk of premature delivery—an idea the authors say should be tested in future clinical research.
Although PTSD is more common among military veterans, Phibbs noted that many civilian women also experience PTSD. In this study, about half of the women diagnosed with PTSD had not been deployed to a combat zone. “This is not unique to the VA or combat; the findings are relevant across obstetrics,” he said.
Following these results, the VA has moved to incorporate the findings into clinical practice by designating pregnancies among women with recent PTSD as high-risk at its medical centers. Phibbs and his team are continuing to investigate whether PTSD may also increase the likelihood that a mother or fetus will develop medical conditions that prompt clinicians to recommend medically indicated early delivery.
The study’s lead author is Jonathan Shaw, MD, instructor in medicine at Stanford. Co-authors include Steven Asch, MD; Rachel Kimerling, PhD; Susan Frayne, MD; and Kate Shaw, MD, representing Stanford and the VA Palo Alto Health Care System. The research received support from the VA Office of Academic Affairs and Health Services Research & Development, VA Women’s Health Services, and Stanford’s Department of Pediatrics.
Contact: Erin Digitale – Stanford
Source: Stanford press release
Image Source: The image is credited to mijoko and is in the public domain
Original Research: The study appeared in Obstetrics & Gynecology on November 6, 2014.