Premature birth may create a risk for high blood pressure, a study by scientists based on tests of Swedish men showed on Monday.The study, to be presented in the Wednesday edition of the Journal of the American Heart Association, involved 329,495 Swedish men born between 1973 and 1981 and drafted for military service between 1993 and 2001, who had blood pressure tests.It found that men born extremely pre-term, at less than 29 weeks, had almost twice the risk of high blood pressure, which raises the chances of heart attacks, strokes and other illnesses.Men born very pre-term, at 29-32 weeks, had a 45 percent increased risk, while those born moderately pre-term, at 33 to 36 weeks, had a 24 percent increased risk.