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Table 2 Association of stage of breast cancer diagnosis and reproductive and family history variables

From: Effect of reproductive factors on stage, grade and hormone receptor status in early-onset breast cancer

Reproductive and family history characteristics Localized (n = 131) Nonlocalized (n = 116) ORa 95% CI P
Age at menarche (years)b
   <12 26 (19.8) 29 (25.4) 1.0 (ref)   
   ≥ 12 105 (80.2) 85 (74.6) 0.8 0.4–1.4 0.35
Age at first full-term pregnancy (years)
   No full-term pregnancies 48 (36.6) 29 (25.0) 1.0 (ref)   
   <20 12 (9.2) 19 (16.4) 3.0 1.2–7.4 0.02
   20–24 31 (23.7) 35 (30.2) 2.1 1.0–4.3 0.04
   25–29 25 (19.1) 24 (20.7) 1.7 0.8–3.6 0.15
   30–34 15 (11.4) 9 (7.8) 1.1 0.4–2.9 0.86
   Trend      <0.01
Total live births
   0 48 (36.6) 29 (25.0) 1.0 (ref)   
   1–2 71 (54.2) 67 (57.8) 1.7 0.9–3.1 0.07
   3 or more 12 (9.2) 20 (17.2) 3.1 1.3–7.7 0.01
   Trend      0.01
Total miscarriages (gravid women)
   0 69 (74.2) 67 (72.0) 1.0 (ref)   
   1 or more 24 (25.8) 26 (28.0) 1.2 0.6–2.3 0.59
Total induced abortions (gravid women)
   0 65 (69.9) 59 (63.4) 1.0 (ref)   
   1 or more 28 (30.1) 34 (36.6) 1.2 0.7–2.3 0.51
Breastfeeding (parous women)
   Never 25 (30.1) 26 (29.9) 1.0 (ref)   
   Ever 58 (69.9) 61 (70.1) 1.1 0.5–2.2 0.80
Months between last full-term pregnancy and diagnosis
   No full-term pregnancy 48 (36.6) 29 (25.0) 1.0 (ref)   
   0–23 23 (17.6) 26 (22.4) 1.9 0.9–3.9 0.09
   24 or more 60 (45.8) 61 (52.6) 1.9 1.0–3.5 0.05
   Trend      0.06
Oral contraceptive use
   Never 19 (14.5) 21 (18.1) 1.0 (ref)   
   Ever 112 (85.5) 95 (81.9) 0.8 0.4–1.5 0.43
Total months of oral contraceptive usec
   None 19 (14.6) 21 (18.9) 1.0 (ref)   
   1–35 35 (26.9) 29 (26.1) 0.6 0.3–1.3 0.22
   36–83 33 (25.4) 29 (26.1) 0.7 0.3–1.4 0.30
   84 or more 43 (33.1) 32 (28.8) 0.6 0.3–1.2 0.17
   Trend      0.46
Family history of breast or ovarian cancerd
   No family history 109 (83.8) 95 (82.6) 1.0 (ref)   
   Mother or sister 21 (16.2) 20 (17.4) 1.2 0.6–2.3 0.67
  1. aAnalyses adjusted for age at diagnosis and education (higher of self or spouse). bTwo records missing age at menarche. cSix records missing total months of oral contraceptive use. dTwo records were excluded because proband reported being adopted. CI, confidence interval; OR, odds ratio.