High blood pressure during pregnancy can feel like a complication confined to those nine months. But a nationwide study suggests it may also reveal something about a woman’s health years later, including her long-term vulnerability to vascular disease and possibly dementia.
Researchers followed more than 1.37 million women for about two decades after delivery. Women who had experienced hypertensive disorders of pregnancy initially showed a higher risk of developing dementia later in life.
But the relationship changed once researchers accounted for health problems that developed after pregnancy, including hypertension, diabetes, heart attack and stroke. That shift suggests the pregnancy complication may be acting more like an early warning sign of long-term vascular vulnerability than a direct cause of dementia.
Researchers followed more than 1.3 million women for two decades
The study used nationwide health data from 1,370,485 women who delivered between 2002 and 2005. Researchers then followed them through the end of 2024 to see who later developed dementia.
The JAMA Network Open study included 28,747 women who experienced hypertensive disorders of pregnancy, a category that included gestational hypertension, preeclampsia, HELLP syndrome and eclampsia.
The median follow-up was about 21 years. By the end of that period, dementia had been diagnosed in 18 women who had experienced hypertensive disorders of pregnancy and 297 women who had not.
The overall numbers were small, especially among women with pregnancy-related hypertension, but the long follow-up allowed researchers to examine a question that cannot be answered during pregnancy itself: does this complication signal risk that persists into midlife?
Takeaway: A pregnancy complication that may seem temporary was associated with health differences that remained visible many years later.
Dementia risk initially appeared almost twice as high
After accounting for maternal age, socioeconomic factors and obstetric differences, women with hypertensive disorders of pregnancy had about a 96% higher risk of later dementia than women without those complications.
The cumulative incidence remained low in both groups, but it was higher among women with hypertensive disorders of pregnancy: about 7.2 cases per 10,000 women compared with 2.8 per 10,000 among women without them.
At first glance, that could suggest pregnancy-related hypertension itself is directly responsible for the higher dementia risk.
The next stage of the analysis told a more complicated story.
Researchers adjusted for health problems that developed after delivery, including chronic hypertension, diabetes, myocardial infarction and stroke. Once those conditions were included, the association weakened substantially and was no longer statistically significant.
Takeaway: The initial link with dementia became much weaker after researchers accounted for later cardiovascular and metabolic disease.
The strongest clue may be what happened after pregnancy
Women who experienced hypertensive disorders during pregnancy were much more likely to develop several cardiovascular and metabolic conditions during follow-up. Half later developed hypertension, compared with about one in five women who had not experienced a hypertensive pregnancy disorder.
Diabetes was also more common, affecting 28.5% of women with hypertensive pregnancy disorders compared with 15.2% of the comparison group. Cerebrovascular and cardiovascular disease were also diagnosed more often.
Those later health problems may help explain why dementia initially appeared more common.
Stroke stood out in particular. In the fully adjusted model, it had a much stronger association with later dementia than hypertension, diabetes or heart attack.
That fits with the broader idea that damage to blood vessels and the brain’s circulation can influence cognitive health many years later.
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Takeaway: The long-term health effects seen after pregnancy may be more important to dementia risk than the pregnancy complication itself.
Pregnancy may act like a stress test for future vascular health
Researchers describe hypertensive disorders of pregnancy as a possible early marker of neurovascular vulnerability. In other words, pregnancy may reveal an underlying tendency toward blood-vessel and metabolic problems that becomes more obvious later in life.
Pregnancy places major demands on the cardiovascular system. Blood volume rises, the heart works harder and the body undergoes large metabolic and hormonal changes.
For some women, those demands may expose vulnerabilities that were not obvious beforehand.
That helps explain why pregnancy complications are increasingly viewed as relevant to lifelong health rather than isolated obstetric events. A history of preeclampsia or gestational hypertension may provide doctors with useful information about future cardiovascular risk.
The new study suggests brain health could eventually become part of that conversation too, though the findings do not prove that hypertensive pregnancy disorders directly cause dementia.
Takeaway: A difficult pregnancy may reveal underlying vascular risk years before other health problems become obvious.
The dementia numbers were small, so the results need caution
Despite the enormous study population, relatively few women developed dementia during the follow-up period. Only 18 dementia cases occurred among women with hypertensive disorders of pregnancy, which limits how precisely researchers can estimate the true level of risk.
That matters because the women were still relatively young by the end of follow-up. Their average age at delivery was around 29, so many participants had only reached their late 40s or early 50s by the time the study ended.
Most dementia cases occur later in life.
Longer follow-up could reveal stronger, weaker or different patterns as more participants age into the years when dementia becomes more common.
The researchers also could not reliably compare different forms of dementia or individual pregnancy disorders because the number of cases was too small.
Takeaway: The study identifies an important long-term signal, but more years of follow-up are needed before the size of the dementia risk becomes clear.
Pregnancy history may deserve a bigger role in lifelong care
The most useful message from this study may not be that pregnancy-related hypertension causes dementia. It is that a complication decades earlier may help identify women who could benefit from closer attention to cardiovascular and metabolic health later on.
Blood pressure, blood sugar, stroke prevention and other vascular risks are already important for healthy aging.
A history of gestational hypertension, preeclampsia or related complications could provide another reason to take those factors seriously long after pregnancy ends.
That shifts the focus away from fear and toward prevention. If pregnancy reveals an early vulnerability, the years afterward may offer time to address the conditions that appear to drive much of the later risk.
Question for you. Do you think pregnancy complications should remain part of a woman’s health record and routine care decades after childbirth?
