African-American women are more likely than other racial groups to suffer frequent hot flashes and night sweats throughout the years leading to menopause, new research suggests.

The study, which followed nearly 3,200 U.S. women for seven years, found that black women had the highest rates of so-called vasomotor symptoms - hot flashes, night sweats and cold sweats - while women of Asian descent had the lowest rates.

The racial differences persisted throughout perimenopause, the years during which a woman’s menstrual periods gradually diminish before stopping completely.

However, women of all races did show some similarities. In general, hot flashes and other vasomotor symptoms were most common in the late perimenopause stage, regardless of a woman’s race, said lead study author Dr. Ellen B. Gold of the University of California, Davis.

Late perimenopause is the point soon before menopause, when a woman goes several months between periods. In this study, the percentage of women reporting frequent vasomotor symptoms jumped during the transition from early to late perimenopause, with the same pattern seen in black, white, Hispanic and Asian women.

The findings are published in the July issue of the American Journal of Public Health.

The study included 3,198 U.S. women ages 42 to 52 who were followed from 1996 through 2002. During that time, the percentage of women reporting frequent hot flashes and sweats climbed from 11 percent to 21 percent - “frequent” being defined as six or more days in the past two weeks.

Compared with white women, black women were 63 percent more likely to have frequent symptoms, whereas the risk was lower among women of Chinese, Japanese or Hispanic descent.

The reasons for these racial differences are still unknown, Gold told Reuters Health, and ongoing research is aimed at answering the question.

But the current study also found some other risk factors that, unlike race and stage of menopause, can be changed. In general, women who were overweight were at greater risk of frequent vasomotor symptoms, as were smokers.

The implication, Gold said, is that maintaining a healthy weight and not smoking could help prevent symptoms. “These are two things women can do something about on their own,” she said.

“There are lots of good reasons not to smoke,” Gold added, “and this could be another one.”

SOURCE: American Journal of Public Health, July 2006.