Figure 1. Temporal trends in age at menarche, age at menopause and the number of years between menarche and menopause among 312 656 women born in Norway, during the years 1936–1964. Flexible parametric survival models were used to estimate (A) mean age at menarche, (B) mean age at menopause and (C) mean number of years between menarche and menopause.