Table I. Study characteristics according to year of birth among 312 656 women in the BreastScreen Norway (2006–2014).
|
Total
N (%) |
1936–1939
N (%) |
1940–1944
N (%) |
1945–1949
N (%) |
1950–1954
N (%) |
1955–1959
N (%) |
1960–1964
N (%) |
|
|---|---|---|---|---|---|---|---|
| Number of women | 312 656 (100.0) | 17 409 (5.6) | 45 831 (14.7) | 63 716 (20.4) | 70 507 (22.6) | 72 789 (23.3) | 42 404 (13.6) |
| Natural menopause | 205 731 (65.8) | 15 442 (88.7) | 40 036 (87.4) | 55 719 (87.5) | 51 617 (73.2) | 29 729 (40.8) | 13 188 (31.1) |
| <45 years at menopausea | 19 333 (6.5) | 1456 (8.9) | 3428 (7.9) | 4427 (7.3) | 4121 (6.1) | 3865 (5.5) | 2036 (5.0) |
| <40 years at menopauseb | 4062 (1.3) | 269 (1.6) | 673 (1.5) | 905 (1.5) | 825 (1.2) | 851 (1.2) | 539 (1.3) |
| Surgery on uterus and ovaries prior to menopause | |||||||
| Hysterectomy | 19 607 (6.3) | 1097 (6.3) | 3153 (6.9) | 4012 (6.3) | 4418 (6.3) | 4452 (6.1) | 2475 (5.8) |
| Bilateral oophorectomy | 1908 (0.6) | 132 (0.8) | 358 (0.8) | 445 (0.7) | 459 (0.7) | 348 (0.5) | 166 (0.4) |
| Hysterectomy and bilateral oophorectomy | 9390 (3.0) | 694 (4.0) | 2060 (4.5) | 2716 (4.3) | 2114 (3.0) | 1276 (1.8) | 530 (1.3) |
| Oral contraceptive usec | |||||||
| Yes | 166 408 (55.0) | 3774 (22.7) | 15 610 (35.5) | 28 151 (45.9) | 37 852 (55.4) | 47 580 (67.0) | 33 441 (80.6) |
| No | 136 282 (45.0) | 12 877 (77.3) | 28 384 (64.5) | 33 150 (54.1) | 30 425 (44.6) | 23 387 (33.0) | 8059 (19.4) |
| Educational leveld | |||||||
| Less than high school | 78 707 (25.5) | 8497 (50.0) | 19 196 (42.6) | 21 364 (33.9) | 16 031 (23.0) | 10 237 (14.2) | 3382 (8.1) |
| High school | 129 694 (42.0) | 5304 (31.2) | 15 267 (33.9) | 24 657 (39.2) | 29 992 (42.9) | 34 243 (47.5) | 20 231 (48.2) |
| College/university | 100 595 (32.6) | 3198 (18.8) | 10 578 (23.5) | 16 919 (26.9) | 23 829 (42.1) | 27 690 (38.4) | 18 381 (43.8) |
a
aExclusion of women with hysterectomy and/or bilateral oophorectomy before the age of 45 (N = 15 329).
b
bExclusion of women with hysterectomy and/or bilateral oophorectomy before the age of 40 (N = 7241).
c
c N = 302 690 women due to missing information about oral contraceptives.
d
d N = 308 996 women due to missing information about educational level.