| Characteristics† | Cohort | Cases | Age-adjusted | Multivariate-adjusted* |
| Person-years (%) | No. (%) | HR (95% CI) | HR (95% CI) | |
| Age of menarche | ||||
| Continuous | 0.98 (0.90 to 1.08) | 0.96 (0.87 to 1.05) | ||
| <14 | 93 007 (22.2) | 30 (19.6) | 1.01 (0.67 to 1.53) | 1.09 (0.71 to 1.65) |
| 14 to 16 | 252 018 (60.1) | 93 (60.8) | 1.00 (Ref) | 1.00 (Ref) |
| >16 | 74 074 (17.7) | 30 (19.6) | 0.84 (0.55 to 1.27) | 0.78 (0.51 to 1.19) |
| p Value for trend | 0.466 | 0.213 | ||
| Menstrual status | ||||
| Currently menstruating | 213 976 (51.2) | 33 (21.6) | 1.00 (Ref) | 1.00 (Ref) |
| Natural menopause | 183 612 (43.9) | 104 (68.0) | 1.22 (0.61 to 2.46) | 1.22 (0.60 to 2.45) |
| Surgically induced menopause | 20 404 (4.9) | 16 (10.5) | 2.33 (1.09 to 4.95) | 2.37 (1.11 to 5.05) |
| Hysterectomy | ||||
| No | 397 924 (94.9) | 137 (89.0) | 1.00 (Ref) | 1.00 (Ref) |
| Yes | 21 336 (5.1) | 17 (11.0) | 1.96 (1.18 to 3.25) | 2.03 (1.22 to 3.37) |
| Ovariectomy | ||||
| No | 402 768 (96.1) | 141 (91.6) | 1.00 (Ref) | 1.00 (Ref) |
| Yes | 16 492 (3.9) | 13 (8.4) | 2.19 (1.24 to 3.87) | 2.28 (1.29 to 4.03) |
| Age at menopause‡ | ||||
| Continuous variable/5 years | 0.79 (0.65 to 0.95) | 0.80 (0.66 to 0.97) | ||
| <46 | 44 713 (21.8) | 37 (30.8) | 1.88 (1.25 to 2.83) | 1.88 (1.25 to 2.82) |
| 46 to 51 | 122 102 (59.5) | 64 (53.3) | 1.00 (Ref) | 1.00 (Ref) |
| >51 | 38 309 (18.7) | 19 (15.8) | 0.94 (0.56 to 1.58) | 0.97 (0.58 to 1.64) |
| p Value for trend | 0.007 | 0.01 | ||
| Years of fertility‡ | ||||
| Continuous variable/5 years | 0.83 (0.69 to 0.99) | 0.85 (0.70 to 1.02) | ||
| <30 | 38 684 (18.9) | 34 (28.3) | 1.96 (1.29 to 2.98) | 1.90 (1.25 to 2.90) |
| 30 to 36 | 123 356 (60.1) | 63 (52.5) | 1.00 (Ref) | 1.00 (Ref) |
| >36 | 43 084 (21.0) | 23 (19.2) | 1.08 (0.67 to 1.75) | 1.14 (0.70 to 1.86) |
| p Value for trend | 0.022 | 0.044 | ||
| Years since menopause‡ | ||||
| Continuous variable/5 years | 1.27 (1.05 to 1.54) | 1.26 (1.03 to 1.53) | ||
| <5 | 43 982 (21.4) | 11 (9.2) | 0.46 (0.21 to 1.00) | 0.47 (0.22 to 1.01) |
| 5 to 17 | 117 788 (57.4) | 67 (55.8) | 1.00 (Ref) | 1.00 (Ref) |
| >17 | 43 354 (21.1) | 42 (35.0) | 1.36 (0.84 to 2.19) | 1.34 (0.83 to 2.16) |
| p Value for trend | 0.033 | 0.039 | ||
| HRT | ||||
| None | 404 432 (96.5) | 150 (98.0) | 1.00 (Ref) | 1.00 (Ref) |
| Post-menopausal HRT | 8618 (2.1) | 3 (2.0) | 0.94 (0.30 to 2.96) | 1.05 (0.33 to 3.36) |
| Peri-menopausal HRT§ | 6050 (1.4) | 0 (0.0) |
HR, hazard ratio; HRT, hormone replacement therapy; Ref, reference.
*Adjusted for age, body mass index, education, income, cigarette smoking status (ever, never), and smoking dose (packs/day).
†Categories may not add up to 419 260 person-years or 154 cases as a result of missing data.
‡Restricted to post-menopausal women.
§Zero cases in this category.