Secular trend of menopausal age and related factors among Tehrani women born from 1930 to 1960; Tehran Lipid and Glucose Study.

BACKGROUND Menopause is an important milestone of a woman's reproductive life. There is limited data on the secular trend of menopausal age. The purpose of this study is to identify the secular trend of menopausal age and its related factors among Tehrani women born during 1930 - 1960. METHODS A total number of 2266 women, born between 1930 and 1960, were recruited among TLGS participants. The World Health Organization classification was used to define menopause status. Birth cohorts were created using 10-year periods, and statistical comparisons were performed with analysis of covariance (ANCOVA). RESULTS The means for menopausal age of women born in the 1930s, 1940s and 1950s were 48.5, 49.5 and 49.9 years, respectively. After adjustment for possible confounding factors in the linear regression model, the increasing trend of menopausal age was constant (P = 0.029). CONCLUSION There is an increasing trend in menopausal age in female residents of Tehran. These findings have implications for endogenous lifetime exposure of women to gonadal steroids.