High blood pressure during pregnancy is often treated as a concern that belongs to a specific period of a woman’s life. But new research suggests its significance may extend much further.
Researchers found that women who experienced hypertensive disorders during pregnancy initially had a higher rate of dementia later in life. However, that association became much weaker after researchers accounted for health conditions that developed after pregnancy, including high blood pressure, diabetes, heart attack and stroke.
The findings do not establish that pregnancy related high blood pressure causes dementia. Instead, researchers say these pregnancy complications may serve as an early marker of long term vascular and brain health.
The study followed women for more than 20 years
Researchers used health records from South Korea’s National Health Insurance Service. The study included 1,370,485 women who delivered between 2002 and 2005 and did not have chronic high blood pressure before pregnancy. Participants were followed through the end of 2024.
About 28,747 women, or 2.1% of the study population, experienced a hypertensive disorder of pregnancy. The category included gestational hypertension, preeclampsia, HELLP syndrome and eclampsia.
During the follow-up period, dementia was diagnosed in 18 women who had experienced one of these pregnancy complications and 297 women who had not.
Although the number of dementia cases was relatively small, the long follow up gave researchers an opportunity to examine whether differences associated with pregnancy health remained visible years later.
Dementia risk initially looked higher
After accounting for maternal, socioeconomic and pregnancy related factors, researchers found that women with hypertensive disorders of pregnancy had an adjusted dementia risk nearly twice as high as women without those complications.
The cumulative incidence was still low in both groups. By the end of follow up, dementia had occurred at a rate of 7.2 cases per 10,000 women in the hypertensive disorder group compared with 2.8 cases per 10,000 women in the comparison group.
That difference initially raised an important question: Could pregnancy related high blood pressure itself be connected to dementia decades later?
The researchers additional analysis offered a more complicated explanation.
Later health conditions changed the picture
When researchers accounted for conditions that developed after delivery, including high blood pressure, diabetes, heart attack and stroke, the association between hypertensive disorders of pregnancy and dementia was substantially reduced and was no longer statistically significant.
That distinction is important.
Rather than showing that a pregnancy complication directly leads to dementia, the findings suggest that women who experience high blood pressure during pregnancy may be more likely to develop cardiovascular and metabolic conditions later.
Those conditions could, in turn, contribute to long term brain health.
High blood pressure was much more common later
The study found notable differences in the health of participants during the years after pregnancy.
Half of the women who had experienced a hypertensive disorder during pregnancy later developed high blood pressure, compared with about 20% of women who had not experienced one. Diabetes also occurred more often, affecting 28.5% of the hypertensive pregnancy group compared with 15.2% of the comparison group.
Cerebrovascular disease and cardiovascular disease were also more common among women with a history of hypertensive pregnancy disorders.
Stroke was particularly important in the researchers analysis because of its relationship with later dementia.
Pregnancy may provide an early health warning
Pregnancy places substantial demands on the cardiovascular system. For some women, complications involving blood pressure may reveal a susceptibility to vascular or metabolic problems that becomes more apparent later.
That is why the researchers describe hypertensive disorders of pregnancy as a possible early life marker of long term neurovascular vulnerability.
In practical terms, pregnancy history may provide useful information for future health care. A history of gestational hypertension or preeclampsia can be one reason to pay close attention to blood pressure, blood sugar and cardiovascular health in the years following pregnancy.
The dementia finding needs more research
The study’s size is impressive, but the dementia results need to be interpreted cautiously.
Only 18 women with hypertensive disorders of pregnancy developed dementia during follow up. The researchers note that the relatively small number of cases limited the precision of the findings and prevented reliable analysis of individual dementia types.
The participants were also relatively young when the study ended. Their average age at delivery was 29.2, meaning many had reached only their late 40s or early 50s by the end of follow up. Since dementia becomes more common at older ages, additional years of observation could provide a clearer picture.
What the findings mean for long term health
The study does not suggest that experiencing high blood pressure during pregnancy means a woman will develop dementia.
Instead, it adds to evidence that pregnancy related blood pressure problems may be an important clue about future cardiovascular and metabolic health.
The researchers findings suggest that the conditions that develop after pregnancy may be more relevant to later dementia risk than the pregnancy complication alone.
That makes long term follow up particularly important. Pregnancy may end after delivery, but its health history can remain useful for years to come.
