Factors associated with age at natural menopause in a multiethnic sample of midlife women

An unprecedented number of women will experience menopause in the next deca de. Although the timing of menopause affects long-term disease risk, little is known about factors that affect this timing. In the present 1995-1997 c ross-sectional study, the Study of Women's Health Across the Nation, the re lation of demographic and lifestyle factors to age at natural menopause was examined in seven US centers and five racial/ethnic groups. All characteri stics were self-reported by women aged 40-55 years (n = 14,620). Cox propor tional hazards models were used to estimate the probability of menopause by age. Overall, median age at natural menopause was 51.4 years, after adjust ment for smoking, education, marital status, history of heart disease, pari ty, race/ethnicity, employment, and prior use of oral contraceptives. Curre nt smoking, lower educational attainment, being separated/widowed/divorced, nonemployment, and history of heart disease were all independently associa ted with earlier natural menopause, while parity, prior use of oral contrac eptives, and Japanese race/ethnicity were associated with later age at natu ral menopause. This sample is one of the largest and most diverse ever stud ied, and comprehensive statistical methods were used to assess factors asso ciated with age at natural menopause, Thus, this study provides important i nsights into this determinant of long-term disease risk in women.