Pregnancy complications and chronic stress combine to raise blood pressure years later

Virginia Nuckols was 25 years old, on average, when the women in her study began showing the first signs that a difficult pregnancy might follow them for years. Not in the form of another complication, but as a quiet, persistent rise in blood pressure, detectable 2 to 7 years after delivery and tied to something that is easy to overlook in a postpartum follow-up: stress.

Nuckols, a postdoctoral fellow at the University of Delaware, is the lead author of a new study published in Hypertension, an American Heart Association journal. Her team analyzed data from 3,322 first-time mothers enrolled in the Nulliparous Pregnancy Outcomes Study, a racially, ethnically, and geographically diverse cohort drawn from 17 medical centers across eight U.S. states.

The stress-blood pressure connection, but only for some

The study tracked perceived stress at three time points: during the first trimester, the third trimester, and 2 to 7 years after delivery. Blood pressure was measured at the same intervals. The researchers then separated the women into two groups: those who had experienced adverse pregnancy outcomes (preeclampsia, preterm birth, small-for-gestational-age birthweight, or stillbirth) and those who had not.

The finding was specific. Among women who had experienced pregnancy complications, persistently higher stress levels were associated with blood pressure that was 2 mm Hg higher than that of women in the low-stress group during the follow-up period. Among women without complications, the same stress levels were not associated with higher blood pressure.

Two millimeters of mercury may sound trivial. It is not. Small, sustained increases in blood pressure accumulate over decades and are associated with meaningful increases in cardiovascular risk, particularly when they begin in young adulthood. These women were, on average, between 25 and 27 years old.

A vulnerability that persists

The implication is that pregnancy complications may create a lasting physiological vulnerability to the cardiovascular effects of stress. The mechanism is not yet clear. It could involve vascular changes initiated during a complicated pregnancy that make blood vessels more reactive to stress hormones. It could involve inflammatory pathways activated during preeclampsia that persist at low levels for years. Or it could reflect the compounding effects of the psychological burden of a difficult pregnancy on a cardiovascular system already under strain.

The researchers cannot yet distinguish between these possibilities. What they can say is that the combination of adverse pregnancy outcomes and chronic stress appears to matter more than either factor alone.

Who was most affected

Women reporting moderate to high stress levels tended to be younger, had higher body mass index, and had lower educational attainment. The cohort was 66% white, 14% Hispanic, and 11% Black, reflecting the broader demographic composition of the study sites. The study did not have sufficient statistical power to examine whether the stress-blood pressure interaction varied by race or ethnicity, a question the authors flag for future work.

Clinical implications: monitoring stress, not just blood pressure

Current American Heart Association guidelines already emphasize blood pressure monitoring after adverse pregnancy events. This study suggests that stress assessment may deserve a place alongside blood pressure checks in postpartum and long-term follow-up care.

Laxmi Mehta, chair of the AHA's Council on Clinical Cardiology (not involved in the study), noted that the findings reinforce the need to proactively assess and address stress as part of comprehensive cardiovascular care, particularly for women with complicated pregnancy histories.

What remains unknown

The study measured perceived stress through self-report questionnaires, which capture a real but subjective dimension of the stress experience. Objective stress biomarkers such as cortisol levels or heart rate variability were not included. The second trimester was not assessed, leaving a gap in the stress trajectory. And the analysis pooled all adverse pregnancy outcomes together rather than examining whether specific complications (such as preeclampsia versus preterm birth) carry different risk profiles.

The study also included only first pregnancies. Whether the findings extend to women with subsequent pregnancies, and whether additional complications compound the risk, remains to be tested.

The central question the authors want answered next is whether stress reduction interventions, delivered to women with complicated pregnancies, can actually lower cardiovascular risk. The association is now established. The intervention trial is the logical next step.