Table 1.
Descriptive characteristics of study participants (Mean ± Standard Deviation): WEB Study, 1996–2001.
| Premenopausal | Postmenopausal | |||
| Case (n = 325) | Control (n = 610) | Case (n = 841) | Control (n = 1495) | |
| Age (years) | 44.9 ± 4.6 | 44.1 ± 4.6 | 63.0 ± 8.5 | 63.4 ± 8.9 |
| Education (years) | 14.0 ± 2.3 | 14.2 ± 2.2 | 13.3 ± 2.6 | 13.0 ± 2.3 |
| Parity | 1.9 ± 1.3 | 2.0 ± 1.3 | 3.0 ± 1.9 | 2.5 ± 1.8 |
| Age at menarche (years) | 12.5 ± 1.6 | 12.6 ± 1.6 | 12.6 ± 1.6 | 12.8 ± 1.7 |
| Age at first birth (years) | 25.0 ± 5.1 | 25.8 ± 4.8 | 23.8 ± 4.7 | 23.5 ± 4.3 |
| Recent BMI (kg/m2) | 26.7 ± 6.6 | 27.2 ± 6.8 | 28.9 ± 6.1 | 28.4 ± 6.4 |
| Benign breast disease (yes) | 37% | 21% | 33% | 22% |
| Relative with breast cancer (yes) | 21% | 10% | 20% | 14% |