Table 1 Baseline characteristics of study participants in the UK Biobank
From: Healthy lifestyles, systemic inflammation and breast cancer risk: a mediation analysis
|  | Overall (N = 259,435) |
|---|---|
Age at recruitment (years) | 57 (8.01) |
Menopausal status at recruitment | Â |
 Premenopausal | 77,777 (29.98%) |
 Postmenopausal | 181,658 (70.02%) |
Body mass index (kg/m2) | Â |
 < 18.5 | 1957 (0.75%) |
 18.5–25.0 | 101,021 (38.94%) |
 25.0–30.0 | 94,871 (36.57%) |
 ≥ 30.0 | 60,662 (23.38%) |
Number of births | Â |
 0 | 48,304 (18.62%) |
 1 | 34,532 (13.31%) |
 2 | 113,359 (43.69%) |
 ≥ 3 | 62,625 (24.14%) |
Family history of breast cancer | Â |
 No | 213,775 (82.4%) |
 Yes | 26,774 (10.32%) |
Age at menarche (years) | Â |
 < 13 | 97,778 (37.69%) |
 13–15 | 138,665 (53.45%) |
 ≥ 15 | 14,778 (5.7%) |
Oral contraceptive use | Â |
 No | 48,521 (18.7%) |
 Yes | 209,742 (80.85%) |
Hormone replacement therapy | Â |
 No | 159,779 (61.59%) |
 Yes | 98,337 (37.9%) |
Smoking | Â |
 Never | 154,097 (59.4%) |
 Former | 80,999 (31.22%) |
 Current | 23,057 (8.89%) |