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Table 1 Baseline characteristics of the analytic cohort

From: Lifetime body size and estrogen-receptor-positive breast cancer risk in the California Teachers Study cohort

  Premenopausal Postmenopausal, current HT use Postmenopausal, not using HT
(N = 46,822) (N = 36,977) (N = 21,788)
Number % Median IQR Number % Median IQR Number % Median IQR
Age (years)    41 34–46    57 52–65    64 55–72
Age at menarche (years)    12 12–13    12 12–13    13 12–13
Parous 30,580 65.3%    28,793 77.9%    16,440 75.5%   
Age at first full-term pregnancy (among parous)    28 25–30    25 22–28    25 23–29
History of benign breast biopsy 4491 9.6%    7726 20.9%    3776 17.3%   
Mother or sister with breast cancer 4482 9.6%    4503 12.2%    3241 14.9%   
Consumption of a plant-based diet (factor score)    -0.35 -0.86 -0.33    -0.07 -0.65 -0.65    0.01 -0.60 -0.76
Alcohol consumption (g/day)
 none 15,215 32.5%    10,463 28.3%    7810 35.8%   
 <20 26,397 56.4%    21,315 57.6%    10,803 49.6%   
 ≥20 2692 5.7%    3575 9.7%    1918 8.8%   
Socioeconomic status (deciles)
 1–2 (low) 1820 3.9%    1053 2.8%    968 4.4%   
 3–4 5858 12.5%    3676 9.9%    2833 13.0%   
 5–6 8656 18.5%    5552 15.0%    3683 16.9%   
 7–8 14,884 31.8%    10,673 28.9%    6224 28.6%   
 9–10 (high) 15,041 32.1%    15,559 42.1%    7777 35.7%   
  1. Percent of missing data: age 0%; age at menarche 1%; parous 2%; age at first full-term pregnancy (n = 2); history of benign breast biopsy 0.4%; mother or sister with breast cancer 3% (includes women who were adopted); dietary factor score 9%; alcohol consumption 5%; and socioeconomic status 1%. HT hormone therapy