High blood pressure is a risk factor for heart disease and stroke in later life.
Girls in the study had three times the risk of higher blood pressure. Some doctors suggest the significant difference between boys and girls could be explained by exercise levels.
Researchers say the obese teen girls tended to be less active. And researchers from the University of California worry the link may counteract the known protective effect of estrogen on the heart.
The study was presented during an American Physiological Society conference.