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Table 1 Basic characteristics of the study population (n = 775)

From: No relationship between circulating levels of sex steroids and mammographic breast density: the Prospect-EPIC cohort

Age (years) 60.2 (5.4)
Height (cm) 163.7 (6.1)
Weight (kg) 69.7 (11.7)
Body mass index (kg/m2) 26.0 (4.1)
Waist–hip ratio 0.79 (0.06)
Family history of breast cancer (mother and/or sister with history of breast cancer) 106 (13.7)a
Reproductive factors  
   Age at menarche (years) 13.5 (1.7)
   Nulliparous 99 (12.8)a
   Age at first child birth(years) (among parous women only) 25.4 (4.0)
   Number of children (average) (among parous women only) 2.6 (0.9)
   Ever breast feeding(among parous women only) 558 (82.5)a
   Age at menopause (years) 48.8 (4.9)
   Time since menopause (years) 11.2 (6.8)
Lifestyle factors  
   Ever used oral contraceptives 416 (53.7)a
   Ever used hormone therapy 112 (14.4)a
   Time since stopped hormone therapy use (years) (among former hormone therapy users only) 7.1 (6.4)
   Current smoking 171 (22.1)a
   Ever smoked 421 (54.3)a
   Alcohol intake (g/day) 8.1 (11.2)
Sex steroids and sex hormone binding globulin  
   Oestrone (pg/ml) 15.26 (4.38–53.16)b
   Oestradiol (pg/ml) 8.22 (2.92–23.17)b
   Free oestradiol (pg/ml) 0.24 (0.09–0.73)b
   Dehydroepiandrosterone sulfate (ng/ml) 446.7 (102.3–1,949.8)b
   Androstenedione (ng/ml) 0.46 (0.10–2.11)b
   Testosterone (ng/ml) 0.25 (0.09–0.72)b
   Free testosterone (pg/ml) 5.30 (1.46–19.23)b
   Sex hormone binding globulin (nmol/l) 19.63 (5.21–73.96)b
Breast measures  
   Percentage breast density 21.7 (14.9–30.8)c
   Dense area 25.3 (18.4–35.5)c
   Nondense area 95.1 (70.1–121.9)c
  1. Data presented as the mean (standard deviation), unless stated otherwise: a n (%), bgeometric mean (± 2 standard deviations), cmedian (interquartile range).