Table 1 Baseline characteristics of cohort participants
From: Timing of pubertal stages and breast cancer risk: the Breakthrough Generations Study
Variable | Mean [SD] or N (%) |
|---|---|
Age at recruitment, years | 46.7 [13.4] |
Average person-time, years | 4.1 [1.7] |
Adult height, cm | 164.3 [6.6] |
Menopausal status | |
Postmenopausal | 44,373 (42.3) |
Premenopausal | 60,534 (57.7) |
Never periods | 24 (0.0) |
Family history of breast cancer | |
No | 89,069 (84.9) |
Yes | 15,862 (15.1) |
Age at first full-term pregnancy, years | |
≤24 | 25,700 (24.5) |
25 to 29 | 31,104 (29.6) |
≥30 | 19,285 (18.4) |
Parous; age not reported | 166 (0.2) |
Nulliparous | 28,513 (27.2) |
Parity missing | 163 (0.2) |
Ethnicity | |
White | 103,655 (98.8) |
Mixed white/non-white | 585 (0.5) |
Non-white | 611 (0.6) |
Missing | 80 (0.1) |
Socio-economic statusa | |
1 (Highest) | 47,952 (45.7) |
2 | 12,001 (11.4) |
3 | 29,886 (28.5) |
4 | 8,449 (8.0) |
5 (Lowest) | 6,042 (5.8) |
Channel islands/isle of manb | 497 (0.5) |
Unclassified | 104 (0.1) |
Total | 104,931 (100.0) |