The survey, conducted by researchers at Group Health (a large healthcare system in the Pacific Northwest) and Fred Hutchinson Cancer Research Center in Seattle, Washington, consisted of a diverse group of women, including whites, blacks, Hawaiian/Pacific Islanders, women of mixed ethnicity, Vietnamese, Filipinos, Japanese, East Indians, Chinese, and other Asians. The women were 45 to 56 years old, had regular cycles, had no skipped periods, and were not taking hormones.

A surprising 55% of them reported having hot flashes or night sweats. (Previous studies pegged the highest rates at below 50%.) The groups with the highest proportions reporting hot flashes or night sweats were Native Americans (67%) and black (61%) women, but the differences between these groups and white women weren't statistically significant. Fifty-eight percent of white women, the largest ethnic group, reported having hot flashes or night sweats.

Compared with them, Asian and Hispanic women were significantly less likely to have these symptoms. Among Asian women, 31% of Filipino, 26% of Japanese, 25% of East Indian, 23% of "other Asian," and 18% of Chinese women reported having hot flashes or night sweats. Twenty-six percent of Hispanic women reported these symptoms.

Interestingly, white women who had symptoms were more likely to include soy in their diet, and white women who never had symptoms were more likely to have no soy in their diet.

This study should help ease a worry for women who have been surprised by hot flashes and night sweats while they are still having regular cycles. It doesn't necessarily mean they are in menopause yet, and it's perfectly normal. "Some women even have a hot flash the first couple of nights after childbirth," said Dr. Margery Gass, NAMS Executive Director.