Stress May Augment Impact of Adverse Pregnancy Outcomes on CV Health

Women who have an adverse pregnancy outcome (APO) appear to be more adversely affected by feeling stressed, with higher blood pressure as a result, than their peers whose pregnancies don’t involve such complications, according to an analysis of prospectively collected data.

In this study, women who reported increased psychosocial stress during and after a complicated pregnancy involving hypertensive disorders of pregnancy, a small-for-gestational-age baby, stillbirth, or preterm birth had significantly higher diastolic blood pressure 2 to 7 years following delivery.

Researchers say this may help explain, at least in part, why APOs are associated with worse CV health not just in the short term, but also in the long term. They note that the most recent US hypertension guidelines “emphasize blood pressure monitoring and management after APOs, but psychosocial stress represents an emerging cardiovascular risk factor and potential therapeutic target.”

Virginia R. Nuckols, PhD (University of Delaware, Newark), lead author of the new report, told TCTMD that her team wanted to look at the interplay not just as a snapshot, but also over time. To do this, they analyzed women’s own perceived stress levels during and after pregnancy—and importantly, years later.

“There is some data that has come out in the last few years that linked a history of adverse pregnancy outcomes to stress in women, and we know that stress is also related to cardiovascular risk. So we wanted to see if stress experienced during and after pregnancy was a factor in cardiovascular risk in women,” particularly in relation to APOs, Nuckols noted, adding that “this is the first study to put those pieces together.”

The connections between pregnancy and cardiovascular health have historically been underappreciated, she pointed out. Now, the interdisciplinary specialty of cardio-obstetrics is “seeking to bridge this gap between pregnancy care and postpartum continuity of care for women who [after an APO] have an elevated cardiovascular risk but are no longer in that fourth-trimester time period,” said Nuckols.

Perceived Stress at Three Time Points

For the study, which was published earlier this month in Hypertension, Nuckols and colleagues did a secondary analysis of data on 3,322 women from the prospective nuMoM2b-HHS cohort. On average, participants were in their late 20s and all were in the first trimester of their first pregnancy at the time of enrollment.

Maternal stress was assessed using the 10-item Perceived Stress Scale at three time points: in the first trimester, in the third trimester, and at the final follow-up visit. The tool captures the degree to which life events are felt to be uncontrollable, unpredictable, or overwhelming.

Women tended to fall into three trajectories, wherein they had persistent stress levels deemed low (n = 785), moderate (n = 1,593), or high (n =  944) across each assessment. Individuals with moderate or high stress, compared to those with low stress, were younger on average and more likely to be Black or Hispanic and to have a history of tobacco use. They tended to have higher body mass index and less education and were less likely to have partners.

Hypertensive disorders of pregnancy, small-for-gestational-age babies, and stillbirth were equally prevalent across the stress groups; however, preterm birth was more common among those with high versus moderate or low stress (10% vs 7%; P < 0.05).

Stress is a really dynamic process. Virginia R. Nuckols

Stress levels did not, in and of themselves, appear to influence blood pressure or incident hypertension at 2 to 7 years. For example, a woman reporting high stress was no more vulnerable to these conditions than a woman reporting low stress.

Yet among women who’d experienced an APO, stress had a disproportionate effect on diastolic blood pressure (P for interaction = 0.04), with a trend toward greater impact on systolic blood pressure (P for interaction = 0.06). Stress was tied to higher diastolic blood pressure among those with an APO, increasing it by a mean of 1.991 mm Hg (P = 0.02), but not among those without an APO (P = 0.93).

Nuckols said that the next step will be determining how it’s possible to reduce stress among pregnant women and whether those actions then improve cardiovascular health. Given what’s known in the general population, “it certainly doesn’t hurt” for clinicians to consider ways their pregnant and postpartum patients can reduce stress, Nuckols commented. That said, she added, “are we at the point where we feel we know it would make a difference in outcomes? I think the short answer is no.”

Approaches to stress must be tailored to this specific context, Nuckols advised, noting that some stressors may be beyond an individual patient’s control.

Researchers at her center plan to pursue physiological studies that are aiming to answer why, at a vascular level, for instance, women who’ve had an APO have a stronger association between stress and blood pressure than women who’ve had an uncomplicated pregnancy. They also want to delve into the types of stressors pregnant patients are facing and the qualities of physical or mental symptoms that occur in response to those stressors.

The Perceived Stress Scale used in the nuMoM2b-HHS cohort “gives us one piece of the puzzle,” Nuckols said, “but stress is a really dynamic process and there’s more to understand about that process.”