Table 1 Baseline characteristics of the participants and their association with mammographic percent density
From: Mammographic density and markers of socioeconomic status: a cross-sectional study
| Participant baseline characteristics | n | Mean | SD | |
|---|---|---|---|---|
| Age at mammography (yrs) | 487 | 48.6 | 1.6 | |
| Weight (kg) | 487 | 67.6 | 12.9 | |
| Age at menarche (yrs) | 194 | 13.1 | 1.5 | |
| n | % | Median PD (25 th , 75 th ) 1 | ||
| Smoking | 487 | |||
| Never | 273 | 56 | 26.7 (13.7, 43.5) | |
| Ex smoker | 152 | 31 | 29.5 (14.1, 46.7) | |
| Current | 62 | 13 | 27.2 (10.5, 42.7) | |
| Height (m) | 487 | |||
| <1.60 | 158 | 32 | 24.9 (13.3, 43.8) | |
| 1.60-1.64 | 137 | 28 | 26.9 (12.3, 43.5) | |
| 1.65-1.69 | 110 | 23 | 28.6 (15.4, 43.4) | |
| ≥ 1.7 | 82 | 17 | 31.1 (18.2, 43.0) | |
| BMI (kg/m2) | 487 | |||
| <22 | 115 | 24 | 46.0 (32.1, 61.6) | |
| 22-24.9 | 145 | 30 | 31.5 (19.5, 43.1) | |
| 25-27.9 | 115 | 24 | 22.1 (11.6, 37.4) | |
| ≥ 28 | 112 | 23 | 9.5 (4.0, 21.6) | |
| Number of full-term pregnancies | 487 | |||
| 0 | 63 | 13 | 32.9 (10.4, 53.6) | |
| 1-2 | 297 | 61 | 28.7 (14.2, 45.6) | |
| 3+ | 127 | 26 | 23.5 (13.8, 39.0) | |
| Age at first full-term pregnancy2 | 424 | |||
| <24 years | 140 | 33 | 22.7 (12.0, 37.8) | |
| 24-28.9 years | 160 | 38 | 26.3 (14.6, 42.4) | |
| ≥ 29 years | 124 | 29 | 31.6 (16.1, 49.7) | |
| Family history of breast cancer | 487 | |||
| Yes | 53 | 11 | 28.6 (15.8, 46.5) | |
| No | 434 | 89 | 27.5 (13.7, 43.4) | |
| Lifetime breast feeding2,3 | 326 | |||
| Never | 55 | 17 | 21.6 (9.4, 37.9) | |
| 1-6 months | 90 | 28 | 28.4 (13.3, 39.7) | |
| 7-12 months | 60 | 18 | 30.0 (15.5, 52.6) | |
| ≥ 13 months | 121 | 37 | 32.1 (16.4, 47.2) |