Being born especially tiny might confer a long-term rise in risk for stroke at a relatively young age, new data suggests.

The Swedish study couldn't prove cause-and-effect, but the association suggests that doctors might want to consider birth weight as a factor when assessing stroke risk in young adults, researchers said.

"Lower birthweight is associated with an increased risk of early adult stroke," wrote a team led by Lina Lilja and Maria Bygdell of the University of Gothenburg.

"There is similar increased risk for both men and women and for both the major types of stroke, ischemic and hemorrhagic," they added.

The findings are slated to be presented next month at the European Congress on Obesity in Istanbul, Turkey.

The study tracked the birth weights and later-life stroke incidence of everyone born in Sweden between 1973 and 1982 — almost 800,000 people. 

Researchers looked at both types of stroke: ischemic, caused by blockages in vessels, and the less-common hemorrhagic stroke, caused by a brain bleed.

In total, 2,252 people went on to experience a stroke while relatively young (average age: 36), the data showed. 

Compared to those who weighed more, people with a birth weight below the median 7.7 pounds had 21% higher odds of having a stroke while young, the team found. (Median means half weighed more, half weighed less.)

The rise in risk was higher (27%) for hemorrhagic stroke, they noted. 

The effect seemed stronger for men versus women. However, length of time spent in the womb didn't seem to matter, nor did the person's body weight at the time they had the stroke. 

The bottom line, according to the researchers: "These findings suggest that low birth weight may be included in assessments of stroke risk in adults."

Because these findings are being presented at a medical meeting, they should be considered preliminary until published in a peer-reviewed journal.