A woman’s race and ethnicity appear to be important predictors of the age at which she will enter menopause, study findings hint.

Compared with non-Latina White women, natural menopause appears to occur at an earlier age among Latina women and a later age among Japanese-American women, Dr. Katherine DeLellis Henderson and colleagues found.

Age at natural menopause among African American and Native Hawaiian women appears similar to that of non-Latina White women.

However, these variations “translate to a difference in months rather than in years,” Henderson told Reuters Health. The largest, that for non-U.S. born Latinas versus non-Latina Whites, “translated to a difference of about 9 months,” said Henderson, of the City of Hope National Medical Center in Duarte, California.

The findings, published in the American Journal of Epidemiology, are based on 95,704 postmenopausal women enrolled in the Multiethnic Cohort Study, a population-based study of women living in the Los Angeles, California area and Hawaii.

The women were nearly 60 years old on average. About 25 percent were non-Latina White, nearly 19 percent were African-American, and almost 28 percent were Japanese-American. Another 10 percent each were Latina-U.S. born and Latina-non-U.S. born, and 7 percent were Native Hawaiian.

Further analyses that factored for smoking, age at menstruation, number of births, and body weight did not significantly alter the race/ethnicity differences in start of menopause seen in the study, the investigators note.

Nonetheless, smoking was still associated with earlier menopause, as was earlier age at menstruation, lower number of births, and lower body weight.

“These findings support the hypothesis that genetic factors are important, perhaps alone or in combination with lifestyle or reproductive factors,” Henderson surmised.

“Our results support the growing literature that age at natural menopause is a complex trait,” added Henderson.

SOURCE: American Journal of Epidemiology, June 1, 2008.