Your Birth Weight May Play A Role In Your Stroke Risk Than Your Current Adult Weight, Says New Study

Your birth weight may be more important than your current adult weight when it comes to your risk of stroke later in life. A new study hints that people who were born with a low birthweight may face a higher risk of stroke in young adulthood, even if they are not overweight or underweight as adults. This suggests that what happens in the womb and during early birth can leave a long-term mark on the brain's blood-supply system, which may show up as higher stroke risk several years later. The study is set to be presented at this year's European Congress on Obesity (ECO2026) in Istanbul, Turkey (12-15 May). Dr Lina Lilja and Dr Maria Bygdell of the University of Gothenburg, Gothenburg, Sweden, who are study authors and colleagues say that low birthweight can be included in stroke risk assessment for adults.

For the study, the researchers looked at almost 8,00,000 people over several decades and found that those whose birth weight was below the average (about 3.5 kg or 7.7 pounds) had a higher risk of stroke, compared with those born heavier. This risk was present even after the researchers adjusted for how heavy the person was as a young adult, and also after accounting for whether they were born full-term or preterm.

What The Study Found?

The study, conducted by researchers at the University of Gothenburg in Sweden, followed individuals from birth into early and middle adulthood, tracking who later had a stroke. Across the entire group, people whose birth weight was below the median of 3.5 kg had about a 21% higher risk of all stroke events combined, including both ischaemic (blocked vessel) strokes and intracerebral haemorrhagic (bleeding) strokes. Women with low-birthweight showed an 18% higher stroke risk, while men with low-birthweight had a 23% higher risk.

The increased risk was seen regardless of how much the person weighed as a young adult. This means that even people who grew up to have a normal or low BMI were still at higher risk if they started life with a low birth weight. The authors suggest that low birthweight could be added to standard stroke-risk checklists that doctors use, so that a person's early growth history is considered alongside blood pressure, cholesterol, smoking, and body weight.

Why Birth Weight Might Matter?

Scientists think low birthweight often reflects slower or disturbed growth in the womb, which can affect how the heart, blood vessels, and brain develop. This may lead to subtle changes in blood-vessel structure or blood pressure control that persist into adulthood, making the brain more vulnerable to stroke even if the person does not have the other classic risk factors like obesity or high cholesterol. Some genetic and metabolic links between low birthweight and stroke have also been identified in earlier studies.

Interestingly, the Swedish data show that the risk pattern is similar for both men and women, and for both main types of stroke; ischaemic and haemorrhagic.

How Will This Changes The Way We Think About Stroke Risk?

For years, doctors have focused strongly on adult risk factors such as high blood pressure, smoking, diabetes, and being overweight. The new study adds an extra layer; your weight at birth might also be a useful marker. If someone had a low birthweight, doctors may want to be more aggressive about checking blood pressure, cholesterol, and lifestyle habits, even if the person looks healthy and is not obese.

This does not mean that everyone who was a small baby will have a stroke. It also doesn't mean that being overweight in adulthood is unimportant. Rather, it suggests that stroke risk is built over a lifetime, starting before birth. Paying attention to birth history, combined with healthy habits, such as regular exercise, a balanced diet, not smoking, and controlled blood pressure, can provide a more complete picture of how to protect the brain as you age.

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