Women who experience pregnancy complications face a higher risk of stroke in the decades after giving birth, new research shows.
The study, which tracked more than two million women over 40 years, found greater stroke risk among those who had high blood pressure or diabetes during pregnancy, a preterm birth, or a baby with low birth weight.
Researchers say these complications may act as early warnings for cardiovascular disease, giving clinicians the chance to offer support long before problems arise.
The study was led by professor Casey Crump from the Department of Family and Community Medicine at UTHealth Houston in the US.
Crump said: “We know that pregnancy is a ‘natural stress test’ that may reveal higher cardiovascular disease risks long before cardiovascular disease actually develops.
“Up to one-third of all pregnancies are affected by one of these complications.
“However, the long-term cardiovascular risks for these women remain poorly understood and so are often not considered in their routine clinical care.”
The team analysed data from a national Swedish cohort of 2,201,393 singleton pregnancies between 1973 and 2015.
Around 30 per cent of women—667,774 in total—had at least one complication, including preterm delivery (under 37 weeks), a baby born small for gestational age (in the smallest 10 per cent for their stage of pregnancy), high blood pressure in pregnancy (including preeclampsia), or pregnancy diabetes (raised blood sugar).
The researchers then tracked stroke outcomes up to 2018, comparing rates among women with pregnancy complications to those without.
They found that the risk of stroke was almost doubled for women who had raised blood pressure (excluding preeclampsia) or blood sugar during pregnancy.
The risk was about 40 per cent higher after preterm birth, 36 per cent higher with preeclampsia, and 26 per cent higher in women whose babies were small for gestational age.
Risk increased further in those who experienced more than one complication.
The highest risks were seen in the first 10 years after birth but persisted up to 46 years later. Among women with pregnancy diabetes, the stroke risk became greater over time.
To test whether genetic or environmental background could explain the findings, the researchers also compared stroke risk between sisters in the cohort.
The association remained, suggesting that shared familial factors were not the primary cause.
Crump said: “To our knowledge, this study is the largest ever to examine multiple pregnancy complications in relation to long-term stroke risks in the same cohort of women.
“Also, it is the first to assess whether families might share factors that predispose both to adverse pregnancy outcomes and stroke, but shared familial factors did not appear to explain our findings.”
He added that many of the complications involved problems such as placental abnormalities and inflammation, which may affect the structure or function of small blood vessels and contribute to long-term stroke risk.
Crump said: “Both women and their doctors should now recognise that pregnancy complications are an early signal for future stroke risk.
“This can help us identify high-risk women long before they suffer a stroke or other cardiovascular disease.
“Women who experience these complications need support to reduce other cardiovascular risk factors, including obesity, physical inactivity, unhealthy diet, smoking, high blood pressure, diabetes, and high cholesterol.
“These interventions should be implemented as early as possible, followed by long-term monitoring to reduce their stroke risk across the life course.”
