Table 1 Participant characteristics (N = 177)
From: Adolescent endogenous sex hormones and breast density in early adulthood
Characteristics | N | Mean (SD) |
|---|---|---|
Age at blood collection during adolescence (yrs) | Â | |
 at ≤1 year visit | 115 | 10.2 (0.6) |
 at year 3 visit | 167 | 12.1 (0.60) |
 at year 5 visit | 143 | 14.2 (0.63) |
 at last visita | 143 | 16.6 (0.88) |
Age at breast MRI (yrs) | 177 | 27.1 (1.01) |
BMI at breast MRI (kg/m2) | 177 | 25.4 (5.38) |
Duration of hormonal contraceptive use (yrs) | 177 | 5.2 (3.68) |
Age at menarche (yrs) | 177 | 12.9 (1.26) |
| Â | N | Percentage |
Race | Â | Â |
 White | 162 | 91.5 % |
 Nonwhite | 15 | 8.5 % |
Education | Â | Â |
 Bachelor's degree | 93 | 52.5 % |
 Graduate degree | 24 | 33.9 % |
 Other | 60 | 13.6 % |
Number of pregnancies | Â | Â |
 0 | 126 | 71.2 % |
 ≥1 | 51 | 28.8 % |
Family history of breast cancer | Â | Â |
 No | 167 | 96.5 % |
 Yes | 6 | 3.5 % |
Hormonal contraceptive use | Â | Â |
 Never | 11 | 6.2 % |
 Former | 65 | 36.7 % |
 Current | 101 | 57.1 % |
Breast density measures | N | Median (IQR) |
 Percent dense breast volume (%) | 177 | 24.3 (9.7-41.2) |
 Absolute dense breast volume (cm3) | 177 | 50.0 (93.3-140.3) |
 Absolute nondense breast volume (cm3) | 177 | 299.2 (157.8-484.9) |