Washington ? The rapid rise in obesity has stalled among women in the United States, the first sign that the epidemic may be peaking, federal health officials reported Tuesday.

After climbing continuously and quickly for decades, the number of American women who were obese held steady near 33 percent between 1999 and 2004 – marking the first time that has happened in any segment of the population, according to an analysis of the most recent national data.

Officials cautioned it was too soon to tell whether the plateau was the beginning of a trend or perhaps even a prelude to a decline. But they greeted the crest with cautious optimism.

“It looks like it’s leveling off,” said Cynthia Ogden of the National Center for Health Statistics, who reported the new data in today’s issue of the Journal of the American Medical Assn. “We’ll need more data over the next few years to know for sure, but hopefully we’ll see this continue, which would be terrific.”

Ogden emphasized that it is a major public health problem that nearly two-thirds of U.S. women are still overweight and more than one-third are obese, and that the percentage of children, adolescents and men who are overweight and obese continued to increase.

“There’s good news and bad news,” Ogden said. “We’re definitely nowhere near being out of the woods.”

But Ogden and others said the leveling of obesity among women could be a signal that the intense public health efforts to stem the epidemic in recent years may have begun to have an effect.

“There’s growing awareness that this is not a healthy condition. Women historically have been the early adopters of positive health behaviors,” said William Dietz of the federal Centers for Disease Control and Prevention in Atlanta. “This plateau may reflect an increased effort by women to control their weight.”

He speculated that the next group to show a similar trend may be children.

“Children and adolescents tend to be influenced by their mothers,” Dietz said. “So perhaps we may see something similar start to happen in those groups.”

The proportion of Americans who are overweight and obese has been rising steadily for more than 25 years, doubling among adults and tripling among children since the 1980s. Because obesity increases the risk for heart disease, cancer, diabetes and other major health problems, the rapid rise has raised alarm among health experts.

For the new study, Ogden and her colleagues analyzed the most recent data collected by the National Health and Nutrition Examination Survey, a nationally representative sample of nearly 8,400 adults and children.

Between surveys conducted in 1999-2000 and then again in 2003-2004, obesity rates worsened for most groups, increasing from about 14 percent to 18 percent in boys ages 2 to 19 and from about 14 percent to 16 percent in girls of that age. The percentage of men age 20 and older who were overweight increased from about 67 percent to 71 percent, and the proportion of those who were obese rose from about 27 percent to 31 percent. But the percentage of adult women who were overweight or obese remained steady at about 62 percent and 33 percent, respectively, the researchers found.

Several experts said women may be more responsive to anti-obesity campaigns because they tend to be more concerned about their weight, primarily for cosmetic reasons.

“We know that women in this society are very focused on their weight – somewhat for health issues and somewhat for appearance issues,” said June Stevens of the University of North Carolina at Chapel Hill. “That may make them more susceptible to the public health messages we have been sending out.”