From: Pubertal timing and breast density in young women: a prospective cohort study
 | Number | Mean | SD | Percentage |
---|---|---|---|---|
Child characteristics | ||||
 Race/ethnicity | ||||
  White | 164 |  |  | 90 |
  Other | 18 |  |  | 10 |
 Age at baseline, years | 182 | 9.13 | 0.59 |  |
 BMI z-score at baseline | 182 | 0.23 | 0.90 |  |
 Age at thelarche, years | 170 | 10.59 | 1.09 |  |
 Age at pubarche, years | 173 | 10.97 | 1.19 |  |
 Age at menarche, years | 182 | 12.90 | 1.26 |  |
Adult characteristics | ||||
 Age at follow-up, years | 182 | 27.17 | 1.02 |  |
 BMI, kg/m2 | 182 | 25.39 | 5.36 |  |
 DXA % body fat, % | 176 | 35.41 | 8.82 |  |
 Exogenous hormone use | ||||
  Never | 11 |  |  | 6 |
  Former | 66 |  |  | 36 |
  Current | 105 |  |  | 58 |
 Duration of hormone use, years | 171 | 5.6 | 3.5 |  |
 Parous (vs nulliparous) | 53/182 |  |  | 29 |
 Education |  |  |  |  |
  Graduate degree | 25 |  |  | 14 |
  Bachelor’s degree | 95 |  |  | 52 |
  Some college or less | 62 |  |  | 34 |
 Ever smokers (vs never-smokers) | 82/182 |  |  | 45 |
 Breast density measures | ||||
  Percent dense breast volume (%) | 182 | 27.6 | 20.5 |  |
  Absolute dense breast volume (cm3) | 182 | 104.2 | 70.6 |  |
  Absolute non-dense breast volume (cm3) | 182 | 413.3 | 364.3 |  |