Table 1. Characteristics of study population: Group Health, Seattle, WA – Years of recruitment 2004 - 2005 (N = 192*).
| Age, y (mean, SD) | 42.4 | (1.4) |
| Age at menarche, y (mean, SD) | 12.8 | (1.3) |
| Age at first birth§, y (mean, SD) | 29.0 | (5.8) |
| BMI, kg/m2 (mean, SD) | 25.7 | (4.6) |
| Height, m (mean, SD) | 1.65 | (0.07) |
| Weight, kg (mean, SD) | 70.1 | (13.4) |
| Waist:Hip ratio (mean, SD) | 0.79 | (0.06) |
| Parity (n, %) | ||
| Nulliparous | 55 | (28.6) |
| Had 1 or 2 children | 69 | (35.9) |
| Had 3+ children | 65 | (33.8) |
| Had a history of breast-feeding§ (n, %) | 111 | (82.2) |
| Had a history of hormone useŦ (n, %) | 137 | (71.4) |
| First degree relative with breast and/or ovarian cancer (n, %) | 24 | (12.5) |
| Smoking status (n, %) | ||
| Current | 8 | (4.2) |
| Former | 54 | (28.1) |
| Never | 128 | (66.7) |
| Race / ethnicity (n, %) | ||
| Asian | 14 | (7.3) |
| White | 166 | (86.5) |
| Other | 10 | (5.2) |
| Years of school completed (n, %) | ||
| ≤ 12 | 12 | (6.2) |
| 13 – 15 | 49 | (25.5) |
| 16 | 57 | (29.7) |
| ≥ 17 years | 72 | (37.5) |
| Income (n, %) | ||
| ≤ $49,999 | 29 | (15.1) |
| $50,000 - $75,000 | 44 | (22.9) |
| > $75,000 | 90 | (46.9) |
| Prefer not to answer | 26 | (13.5) |
§
Among parous women only (n = 135)
*
Numbers may not add up to 192 for some characteristics due to missing values
Ŧ
Use of oral contraceptives, hormone patches, hormone injections, hormone implants, or intrauterine devices containing progesterone at any time prior to the 6 month-period before the screening mammogram