Pregnancy as a Cardiovascular Stress Test

Pregnancy as a Cardiovascular Stress Test

---

Medical Disclaimer: This content is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Information is based on current medical literature and clinical guidelines but may not apply to your specific situation. Individual responses vary based on personal medical history and concurrent conditions. Always consult qualified healthcare providers for medical decisions. Never delay seeking medical care based on content you’ve read. If experiencing a medical emergency, seek immediate medical attention.

These articles provide education to enhance your healthcare partnership. All treatment decisions should involve your healthcare team. Use this knowledge to have informed discussions, not replace medical care.

---

In Brief

The events of pregnancy carry cardiovascular information that no other window in a woman’s life provides as clearly. A pregnancy complication that resolved at delivery is not just an obstetric event in her past. It is an early reading from a cardiovascular stress test.

The evidence is no longer in dispute. Preeclampsia approximately doubles long-term risk of ischemic heart disease and stroke and quadruples the risk of heart failure. (1,2) Gestational diabetes doubles cardiovascular risk in the first decade postpartum, independent of whether type 2 diabetes develops. (3) Preterm delivery increases coronary heart disease risk by approximately 50 percent and doubles the risk of dying from it. (4) Stillbirth carries cardiovascular implications comparable to the hypertensive disorders. The 2021 American Heart Association scientific statement and the 2019 ACC/AHA primary prevention guideline formally incorporate adverse pregnancy outcomes as risk-enhancing factors for cardiovascular care. (6,7) This article maps each adverse pregnancy outcome, the specific cardiovascular implications it carries, and what belongs in your medical record and your visits — whether your pregnancy was last year or thirty years ago.

The Stress Test Concept

A cardiac stress test in routine clinical practice loads the heart — with exercise, with pharmacologic stimulation, or with both — and watches for abnormalities that emerge under load but would not be visible at rest. The principle is that latent vascular disease often becomes detectable only when the system is asked to perform.

Pregnancy is a sustained cardiovascular stress test. Maternal physiology adapts to support fetal development through changes that, in their magnitude, exceed what is typically asked of the cardiovascular system across the rest of life. (6) Plasma volume expands by approximately 40 to 50 percent. Resting heart rate rises. Cardiac output increases by 30 to 50 percent by mid-pregnancy. The maternal vasculature dilates substantially under estrogen and relaxin influence. The kidneys filter approximately 50 percent more blood per minute. The clotting system shifts toward a hypercoagulable state.

When these adaptations proceed smoothly, the pregnancy progresses to term with mother and infant well. When the cardiovascular and metabolic systems cannot accommodate the load, the failures of adaptation are diagnosable and often dramatic: hypertension that did not exist before, glucose intolerance that resolves after delivery, placental insufficiency producing growth restriction or preterm delivery, and in the most severe cases, preeclampsia or eclampsia.

The 2021 American Heart Association scientific statement makes the framing explicit in its opening: pregnancy complications are not simply obstetric events that resolve at delivery. They are early manifestations of vascular and metabolic vulnerability that predict disease decades later. (6)

The clinical consequence is direct. A woman who has had an adverse pregnancy outcome has, in effect, completed a cardiovascular stress test. The result is part of her medical record. The conversation it should produce — about cardiovascular risk, screening, and prevention — has historically not happened, because the connection between obstetric history and cardiovascular care has been poorly integrated.

What Counts as an Adverse Pregnancy Outcome

The 2021 American Heart Association scientific statement identifies the following adverse pregnancy outcomes as cardiovascular risk markers. Each is defined in standard obstetric terms; specific diagnostic criteria are not the focus of this article. (6)

Hypertensive disorders of pregnancy. A spectrum including gestational hypertension (new-onset hypertension after 20 weeks without other features), preeclampsia (hypertension with proteinuria or other end-organ involvement), eclampsia (preeclampsia with seizures), and superimposed preeclampsia in women with chronic hypertension. Affects approximately 5 to 10 percent of pregnancies in the United States.

Gestational diabetes mellitus. Glucose intolerance first identified in pregnancy. Affects approximately 7 to 14 percent of pregnancies depending on diagnostic criteria, with rising prevalence.

Preterm delivery. Delivery before 37 weeks gestation. Affects approximately 10 percent of pregnancies in the United States. Both spontaneous preterm labor and medically indicated preterm delivery carry cardiovascular implications.

Small-for-gestational-age birth. Infant birthweight below the 10th percentile for gestational age. Often, but not always, reflects placental insufficiency.

Pregnancy loss. Includes miscarriage (loss before 20 weeks) and stillbirth (loss at or after 20 weeks). The cardiovascular implications differ between these categories and are addressed below.

Adverse pregnancy outcomes are not rare. Preeclampsia and gestational diabetes alone affect more than one in eight pregnancies. The broader category encompassing all hypertensive disorders, gestational diabetes, preterm delivery, and small-for-gestational-age birth affects approximately one in five. (6)

For any individual woman with a pregnancy history, the practical question is straightforward: did any of these occur? If yes, the cardiovascular implications discussed below apply.

Preeclampsia

Preeclampsia is the most extensively studied adverse pregnancy outcome and provides the clearest evidence for the stress test concept. The foundational analysis is the 2007 BMJ systematic review by Bellamy and colleagues, pooling data from approximately 3.5 million women including roughly 198,000 with a history of preeclampsia. (1)

The Bellamy analysis established the pattern that subsequent research has confirmed and refined: women with a history of preeclampsia have approximately double the risk of subsequent ischemic heart disease, stroke, and venous thromboembolism, and approximately a fourfold higher risk of hypertension, compared with women without a history of preeclampsia. (1) The associations remained after adjustment for known cardiovascular risk factors, indicating that preeclampsia is not merely a marker of pre-existing risk but identifies a distinct biological phenotype.

A 2017 meta-analysis by Wu and colleagues in Circulation: Cardiovascular Quality and Outcomes pooled data from 22 studies including more than 6.4 million women, with more than 258,000 in the preeclampsia group. (2) The findings were consistent with Bellamy and extended the picture. Women with a history of preeclampsia had:

• Approximately four times the risk of incident heart failure (RR 4.19, 95% CI 2.09–8.38)
• Approximately 2.5 times the risk of coronary heart disease (RR 2.50, 95% CI 1.43–4.37)
• Approximately twice the risk of cardiovascular death (RR 2.21, 95% CI 1.83–2.66)
• Approximately 80 percent increased risk of stroke (RR 1.81, 95% CI 1.29–2.55)

The heart failure association is notable because heart failure had been less examined in earlier syntheses. The mechanism is thought to involve subclinical structural and functional changes that persist after pregnancy, with progression accelerated by the cardiovascular risk factor burden that preeclampsia identifies.

The risk emerges early. Women who had preeclampsia show measurable differences in blood pressure, lipids, glucose, and vascular function within the first decade after delivery, before the conventional cardiovascular event risk has begun to accumulate. (6) This means the cardiovascular conversation is most actionable in the years immediately following the pregnancy, not in midlife when the standard cardiovascular workup begins.

Gestational Hypertension

Gestational hypertension — new-onset hypertension after 20 weeks of pregnancy without proteinuria or other features that would qualify as preeclampsia — was historically treated as the milder cousin of preeclampsia. The data have not supported that framing.

The 2021 American Heart Association scientific statement summarizes the consistent finding across multiple cohort studies. Gestational hypertension carries an increased risk of future chronic hypertension and cardiovascular disease that approaches the risk associated with preeclampsia, though typically of lesser magnitude. (6) Approximately one in three women with gestational hypertension develops chronic hypertension within five years of the index pregnancy. Subsequent cardiovascular event rates are elevated, with risk ratios for coronary heart disease and stroke in the range of 1.5 to 2.0 in most cohort studies.

Gestational hypertension should not be filed as transient. The hypertension is transient. The underlying vascular susceptibility it reveals is not.

Gestational Diabetes

Gestational diabetes mellitus is most often discussed in terms of progression to type 2 diabetes — and that progression is substantial, with approximately half of women with gestational diabetes developing type 2 diabetes within ten years. (6) The cardiovascular implications of gestational diabetes extend beyond the diabetes pathway.

A 2019 meta-analysis by Kramer and colleagues in Diabetologia pooled data from observational studies and found that women with a history of gestational diabetes have a twofold higher risk of cardiovascular events in the first decade postpartum compared with women without a history of gestational diabetes (relative risk 2.31, 95% confidence interval 1.57 to 3.39). (3) The analysis then asked whether this elevated risk was driven entirely by progression to type 2 diabetes. It was not. When restricted to women who did not develop type 2 diabetes, gestational diabetes was still associated with a 56 percent higher risk of future cardiovascular events (relative risk 1.56, 95% confidence interval 1.04 to 2.32). (3)

The Kramer finding reframed the clinical conversation about gestational diabetes. The condition is not only a herald of diabetes risk. It is an independent marker of cardiovascular vulnerability. Even women who escape progression to type 2 diabetes — through weight loss, lifestyle change, or favorable physiology — carry an elevated cardiovascular risk profile that warrants attention.

Preterm Delivery

Preterm delivery predicts maternal cardiovascular risk in a pattern that has emerged consistently across multiple cohorts and was synthesized in a 2018 meta-analysis by Wu and colleagues in the Journal of the American Heart Association. (4) The analysis included 21 studies covering more than 5.8 million women, including over 338,000 with a history of preterm delivery.

The pooled findings:

• Composite cardiovascular disease: relative risk 1.43 (95% CI 1.18 to 1.72)
• Coronary heart disease: relative risk 1.49 (95% CI 1.38 to 1.60)
• Coronary heart disease death: relative risk 2.10 (95% CI 1.87 to 2.36)
• Stroke: relative risk 1.65 (95% CI 1.51 to 1.79)
• Cardiovascular disease death: relative risk 1.78 (95% CI 1.42 to 2.21)

These are relative risks across pooled cohort follow-up. The absolute increase for any individual woman depends on her age, baseline cardiovascular risk factor profile, and the years over which the risk is being measured. A 49 percent relative increase in coronary heart disease risk applied to a baseline that is itself modest produces a real but moderate absolute increase, and the increment is concentrated in women whose underlying risk profile is already elevated.

The risks were highest for women whose preterm delivery occurred before 32 weeks gestation and for those whose preterm delivery was medically indicated rather than spontaneous. (4) Medically indicated preterm delivery is most often driven by preeclampsia or growth restriction — placental and maternal vascular pathology — which is consistent with the broader stress test framing.

Spontaneous preterm labor had historically been viewed as an obstetric event without obvious cardiovascular implications. The Wu meta-analysis and the cohort studies it synthesized changed that view. Even spontaneous preterm delivery is associated with elevated cardiovascular risk, though the mechanisms are less well understood than for the preeclampsia pathway.

Pregnancy Loss

The cardiovascular implications of pregnancy loss have been the most contested area within the adverse pregnancy outcome literature, and the picture has evolved with the most recent evidence.

A 2013 meta-analysis by Oliver-Williams and colleagues in Heart found that a history of miscarriage was associated with an approximately 45 percent higher odds of subsequent coronary heart disease, and a history of recurrent miscarriage was associated with an approximately doubled odds of coronary heart disease. (8) The analysis included 10 studies and over 500,000 women.

A more recent 2024 meta-analysis by Vlachou and colleagues in PLOS Medicine included 56 observational studies covering more than 1.1 million women with pregnancy loss. (5) Vlachou reached a more nuanced conclusion. Stillbirth was clearly associated with future cardiovascular disease — relative risk approximately 1.56 for ischemic heart disease, 1.71 for cerebrovascular disease, and 1.86 for any cardiovascular disease — along with increased risks of type 2 diabetes and renal disease. (5) Miscarriage, however, single or recurrent, did not show a statistically significant association with future cardiovascular disease in this larger, more recent synthesis. (5)

The discrepancy between the 2013 and 2024 meta-analyses likely reflects better confounder adjustment in newer cohort studies, larger sample sizes that allow more precise estimates, and refined definitions of pregnancy loss. The 2024 analysis does not definitively rule out a small cardiovascular signal from miscarriage, but it argues against the larger associations suggested by older analyses. (5)

For women: the evidence for a cardiovascular signal from stillbirth is now reasonably strong. The evidence for a cardiovascular signal from miscarriage is mixed and may have been overstated in earlier literature. Recurrent pregnancy loss, particularly with documented placental pathology, may carry implications that single early miscarriage does not.

The Cardiovascular Signal at a Glance

The contemporary evidence base on adverse pregnancy outcomes and cardiovascular risk can be summarized as follows.

Adverse pregnancy outcome	Cardiovascular signal
Preeclampsia	~4× incident heart failure; ~2.5× coronary heart disease; ~2× cardiovascular death; ~1.8× stroke; ~4× future chronic hypertension (1,2)
Gestational hypertension	~1.5–2× coronary heart disease and stroke; ~1 in 3 develops chronic hypertension within 5 years; approaches preeclampsia in magnitude (6)
Gestational diabetes	~2× cardiovascular events in first decade postpartum; ~1.5× even without progression to type 2 diabetes; ~50% develop type 2 diabetes within 10 years (3,6)
Preterm delivery (any cause)	~1.5× coronary heart disease; ~2× coronary heart disease death; ~1.65× stroke; highest with delivery before 32 weeks (4)
Stillbirth	~1.6× ischemic heart disease; ~1.7× cerebrovascular disease (5)
Miscarriage (single or recurrent)	No statistically significant cardiovascular association in 2024 meta-analysis of 1.1 million women (5)

The hierarchy is meaningful for clinical conversations. Preeclampsia carries the strongest and most extensively studied signal. Gestational hypertension, gestational diabetes, and preterm delivery each carry independent signals. Stillbirth carries a signal that is distinct from miscarriage, which the most recent evidence suggests carries little or no independent signal once confounders are accounted for.

Why This Happens: Shared Mechanisms

The cardiovascular signal from adverse pregnancy outcomes is unlikely to reflect any single mechanism. Several plausible pathways operate, and they likely act in combination. (6)

Endothelial dysfunction. The vascular endothelium plays a central role in the adaptations of pregnancy. In preeclampsia and growth restriction in particular, the placenta releases factors that produce systemic endothelial activation, increased oxidative stress, and impaired nitric oxide signaling. The endothelial changes that allow these obstetric conditions to develop also predispose to the slow accumulation of vascular injury that produces cardiovascular disease decades later.

Shared upstream factors. Many of the same risk factors that predispose to adverse pregnancy outcomes also predispose to cardiovascular disease — obesity, insulin resistance, hypertension, dyslipidemia, chronic kidney disease, autoimmune conditions. Pregnancy unmasks vulnerabilities that would have produced cardiovascular disease eventually even without pregnancy.

Persistent metabolic and vascular changes. Adverse pregnancy outcomes are followed in many women by lasting changes in blood pressure regulation, glucose handling, lipid profiles, and arterial structure. These changes are themselves cardiovascular risk factors and accumulate across the years following pregnancy.

Subclinical cardiac structural changes. Cardiac imaging studies have demonstrated that women with a history of preeclampsia have measurably different ventricular geometry and diastolic function years after delivery compared with women without preeclampsia, even when blood pressure is normal. The structural changes appear to be part of the pathway from preeclampsia to subsequent heart failure.

No single mechanism explains the full pattern. The most coherent interpretation is that adverse pregnancy outcomes reveal a vascular and metabolic phenotype that, once identified, persists.

What This Means for Risk Assessment

The integration of adverse pregnancy outcomes into routine cardiovascular risk assessment has been gradual but substantial.

The 2019 American College of Cardiology and American Heart Association Guideline on the Primary Prevention of Cardiovascular Disease lists premature menopause and adverse pregnancy outcomes — specifically hypertensive disorders of pregnancy, preeclampsia, gestational diabetes, preterm delivery, and small-for-gestational-age birth — among the “risk-enhancing factors” that may modify cardiovascular risk assessment in women. (7) A woman whose calculated ten-year cardiovascular risk falls into a borderline category may be reclassified into a higher-risk category, with more intensive prevention recommended, based on her pregnancy history.

The 2021 American Heart Association scientific statement on adverse pregnancy outcomes goes further, framing the postpartum period as an opportunity for cardiovascular risk identification that the obstetric-to-primary-care transition has historically failed to capture. (6) The statement recommends that adverse pregnancy outcomes be documented in the medical record in a way that makes them retrievable for cardiovascular care, that women with adverse pregnancy outcomes receive earlier and more attentive cardiovascular risk factor screening, and that the pregnancy history be revisited at midlife when the cardiovascular implications most often become clinically actionable.

Whether these recommendations are followed in any individual woman’s care depends substantially on whether she raises the history. Pregnancy histories from decades earlier are not always part of the cardiovascular workup unless the patient mentions them. The most actionable point: the pregnancy history matters, and raising it in cardiovascular conversations is what converts the history into modified care.

The Postpartum Window

The cardiovascular risk signal from adverse pregnancy outcomes does not wait decades to emerge. It begins in the years immediately following the pregnancy.

Women with a history of preeclampsia have measurably elevated blood pressure, lipids, and inflammatory markers within five years of delivery. (6) Women with a history of gestational diabetes have measurably elevated cardiovascular event rates within the first decade postpartum, as the Kramer meta-analysis demonstrated. (3) The biological window during which a woman’s adverse pregnancy outcome carries the strongest predictive value for her future cardiovascular health is the same window during which the conventional cardiovascular conversation has typically not yet begun.

Postpartum care historically focuses on immediate physical recovery, contraception, and the infant’s wellbeing. Cardiovascular risk factor monitoring is not standardized. Earlier intervention in this window — for blood pressure control, weight, glucose tolerance, lipids, and lifestyle — has the most time to alter long-term trajectories.

Several health systems have begun establishing postpartum cardiovascular clinics specifically targeting women with adverse pregnancy outcomes. The evidence base for specific interventions is still developing. The principle is straightforward: the cardiovascular conversation that conventional risk assessment would not initiate until midlife can, and should, begin in the years following an adverse pregnancy outcome.

What Your Care Should Cover

If the events of pregnancy carry cardiovascular information — and the evidence shows they do — several things follow for how a woman engages with her own care.

Document the pregnancy history in a way that is retrievable. A preeclampsia diagnosis at 32, a gestational diabetes diagnosis at 28, a preterm delivery at 35 — these belong in the medical record in a place that subsequent clinicians will see. They are part of your cardiovascular history, not only your obstetric history.

Raise the history with primary care and cardiology. Pregnancy histories from decades earlier are not retrieved automatically. The conversation that converts the history into modified prevention often depends on the patient bringing it forward.

Use the postpartum window if you are in it. If you have had an adverse pregnancy outcome in the past few years, the cardiovascular risk factor evaluation — blood pressure, lipids, glucose, weight, lifestyle — does not need to wait until midlife. Earlier evaluation has more time to alter the trajectory.

Recognize that the risk is modifiable. Blood pressure, lipids, glucose, weight, smoking, and physical activity each respond to attention in a woman with an adverse pregnancy history the same way they do in a woman without. The history identifies a vulnerability. The standard prevention measures address it.

Connect the dots with related risk-enhancing factors. Adverse pregnancy outcomes interact with premature menopause (Article 5 of this series), autoimmune disease (Article 9), and the cardiovascular risk calculator framework (Article 10). A woman with multiple risk-enhancing factors warrants a calibrated cardiovascular conversation, not the calculator output alone.

The Bottom Line

The events of pregnancy carry cardiovascular information that no other window in a woman’s life provides as clearly. Preeclampsia approximately doubles the risk of ischemic heart disease and stroke and quadruples the risk of heart failure. Gestational hypertension carries similar though somewhat lesser implications. Gestational diabetes doubles cardiovascular risk in the first decade postpartum, with much of that risk persisting even if type 2 diabetes never develops. Preterm delivery, both spontaneous and medically indicated, increases the risk of coronary heart disease by approximately 50 percent and doubles the risk of dying from it. Stillbirth carries cardiovascular implications similar to those of the hypertensive disorders. Miscarriage, in the most recent evidence, does not appear to.

The 2019 ACC/AHA primary prevention guideline and the 2021 American Heart Association scientific statement formally incorporate adverse pregnancy outcomes as a window into long-term cardiovascular vulnerability and as an opportunity for earlier prevention. The integration into routine cardiovascular practice has been gradual. What closes the gap fastest is the woman raising the history herself — in postpartum care if she is in that window, in midlife visits if she is past it, and in every cardiovascular conversation where her risk profile is being assessed.

A pregnancy complication that resolved at delivery is not a closed chapter. It is information. The information matters most when it makes it into the visits that determine subsequent care.

---

Next: Article 4 addresses the cardiovascular implications of hormonal contraception — what the modern evidence shows about combined oral contraceptives, who is and isn’t at meaningful cardiovascular risk, and what effective non-estrogen options exist when the cardiovascular risks are high.

---

Key Terms

Adverse pregnancy outcome (APO): An umbrella term used in the 2021 American Heart Association scientific statement covering hypertensive disorders of pregnancy, gestational diabetes, preterm delivery, small-for-gestational-age birth, and pregnancy loss. Each carries cardiovascular implications beyond the immediate pregnancy.

Eclampsia: Preeclampsia with seizures. A medical emergency requiring immediate delivery and supportive care.

Endothelial dysfunction: Impaired ability of the inner vascular lining to regulate vessel tone, blood flow, inflammation, and thrombosis. A common underlying mechanism in both adverse pregnancy outcomes and subsequent cardiovascular disease.

Gestational diabetes mellitus (GDM): Glucose intolerance first identified in pregnancy. Carries cardiovascular implications even in women who do not progress to type 2 diabetes.

Gestational hypertension: New-onset hypertension after 20 weeks of pregnancy without proteinuria or other features of preeclampsia. Approximately one in three affected women develops chronic hypertension within five years.

Preeclampsia: New-onset hypertension after 20 weeks of pregnancy with proteinuria or other end-organ involvement. The most extensively studied adverse pregnancy outcome with respect to long-term cardiovascular implications.

Preterm delivery: Delivery before 37 weeks gestation. Both spontaneous and medically indicated preterm delivery carry cardiovascular implications, with the strongest signal in deliveries before 32 weeks.

Risk-enhancing factor: A term in the 2019 American College of Cardiology and American Heart Association primary prevention guideline for factors beyond the standard risk calculator inputs that may justify reclassifying cardiovascular risk and altering prevention intensity. Includes adverse pregnancy outcomes, premature menopause, autoimmune disease, and several other conditions.

Small-for-gestational-age (SGA): Infant birthweight below the 10th percentile for gestational age. Often reflects placental insufficiency and is listed among the adverse pregnancy outcomes with cardiovascular implications.

Stillbirth: Pregnancy loss at or after 20 weeks gestation. Carries cardiovascular implications similar to those of the hypertensive disorders.

References

1. Bellamy L, Casas JP, Hingorani AD, Williams DJ. Pre-eclampsia and risk of cardiovascular disease and cancer in later life: systematic review and meta-analysis. BMJ. 2007;335(7627):974.
2. Wu P, Haththotuwa R, Kwok CS, et al. Preeclampsia and future cardiovascular health: a systematic review and meta-analysis. Circ Cardiovasc Qual Outcomes. 2017;10(2):e003497.
3. Kramer CK, Campbell S, Retnakaran R. Gestational diabetes and the risk of cardiovascular disease in women: a systematic review and meta-analysis. Diabetologia. 2019;62(6):905–914.
4. Wu P, Gulati M, Kwok CS, et al. Preterm delivery and future risk of maternal cardiovascular disease: a systematic review and meta-analysis. J Am Heart Assoc. 2018;7(2):e007809.
5. Vlachou F, Iakovou D, Daru J, Khan R, Pepas L, Quenby S, Iliodromiti S. Fetal loss and long-term maternal morbidity and mortality: a systematic review and meta-analysis. PLoS Med. 2024;21(2):e1004342.
6. Parikh NI, Gonzalez JM, Anderson CAM, et al. Adverse pregnancy outcomes and cardiovascular disease risk: unique opportunities for cardiovascular disease prevention in women: a scientific statement from the American Heart Association. Circulation. 2021;143(18):e902–e916.
7. Arnett DK, Blumenthal RS, Albert MA, et al. 2019 ACC/AHA guideline on the primary prevention of cardiovascular disease: a report of the American College of Cardiology / American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol. 2019;74(10):e177–e232.
8. Oliver-Williams CT, Heydon EE, Smith GC, Wood AM. Miscarriage and future maternal cardiovascular disease: a systematic review and meta-analysis. Heart. 2013;99(22):1636–1644.