A new government study shows deaths from heart disease, cancer and stroke continue to drop, but it also shows that half of Americans ages 55 to 64 _ including the oldest of the baby boomers _ have high blood pressure, and two in five are obese.

This means that this large group of aging Americans is in worse shape in some respects than those born a decade earlier were when they were the same age.

Medical improvements in coming years might offset these problems before they affect life expectancy, but there are no promises, health officials said.

"The late 50s and early 60s are a crucial time to focus on disease prevention," said Dr. Julie Gerberding, director of the federal Centers for Disease Control and Prevention in Atlanta. "It's never too late to adopt a healthy lifestyle to enjoy a longer, healthier life."

The report presents the latest data collected by the National Center for Health Statistics and dozens of other health agencies and organizations.

Among the findings: Deaths from heart disease, cancer and stroke, the nation's three leading killers, all dropped in 2003. They were down between 2 percent and 5 percent.

Americans' life expectancy also increased again. According to the government's calculations, a child born in 2003 can expect to live 77.6 years on average, up from 77.3 the year before. In 1990, life expectancy was 75.4 years.

U.S. life expectancy has been rising almost without interruption since 1900, thanks to several factors, including extraordinary advances in medicine and sanitation, and declines in some types of unhealthy behavior, such as smoking.

Still, health officials are trying to draw attention to unhealthy behavior, and this year chose to break out data on people 55 to 64.

The 55-to-64 age group is expected to rise from 29 million Americans in 2004 to 40 million in 2014. That is because of the baby boom, the explosion of births during the prosperous postwar period between 1946 and 1964.

The report looked back at data on people who were in the 55-to-64 bracket around the early 1990s _ basically, people born in the 1930s. Researchers compared them to people in that age range today _ essentially people born in the 1940s.

"What happens to this group is very important because it's going to affect every other group," said Amy Bernstein of the National Center for Health Statistics, which put out the new report. Among other things, this group will be drawing on Social Security and Medicare, financed by U.S. taxpayers.

The center found that rates of hypertension and obesity were higher for the current group of 55-to-64-year-olds.

When the 1930s group was tested around 1990, 42 percent had high blood pressure. That compares with 50 percent for the 1940s group. The older group's rate of obesity was 31 percent back then, compared with 39 percent for the 1940s babies now. Because of the advent of cholesterol-lowering drugs, the prevalence of high cholesterol actually went down, from 35 percent for the 1930s group to 23 percent among the 1940s babies.

Also noted in the report:

_Infant mortality in 2003 dropped slightly to 6.9 deaths per 1,000 live births. Infant mortality has been on a general decline since 1958.

_Spending on health care rose 7.7 percent in 2003, to $1.7 trillion. Health expenditures as a percentage of gross domestic product rose to 15.3 percent in 2003, up from 14.9 percent in 2002.

_Prescription drugs were the fastest-growing expenditure. Spending on prescriptions rose 11 percent in 2003.

_Twenty-eight percent of all adults reported recent low back pain.