Table 2.

Association of prenatal factors with percent density for all women and by menopausal status at time of mammography, Minnesota Breast Cancer Family Study

Prenatal factorAll women
Premenopausal
Postmenopausal
Full model
Full model
Full model
nAdj mean*Adj mean (95% CI)nAdj mean*Adj mean (95% CI)nAdj mean*Adj mean (95% CI)
Maternal age
    <199619.620.8 (19.1-22.5)2633.232.5 (28.8-36.2)7018.518.9 (17.1-20.6)
    20-2438119.820.6 (19.8-21.4)8232.231.8 (30.1-33.4)29919.019.0 (18.0-19.9)
    25-2937121.522.2 (21.4-23.1)9634.833.6 (32.0-35.3)27520.620.5 (19.5-21.5)
    30-3435019.920.7 (19.8-21.6)8533.231.9 (29.9-33.8)26518.919.0 (18.0-19.9)
    35+35220.921.6 (20.7-22.5)9934.533.8 (32.0-35.5)25319.719.7 (18.7-20.7)
    P trend0.240.420.490.650.370.49
    Don't know8719.220.7 (18.8-22.6)825.926.2 (18.7-33.8)7918.819.4 (17.4-21.4)
    Missing13019.820.5 (19.1-21.9)2632.631.8 (29.3-34.3)10419.118.9 (17.3-20.5)
Birth order
    1st child43020.221.1 (20.3-21.9)9633.032.5 (30.8-34.2)33419.419.3 (18.4-20.2)
    2nd child33620.821.3 (20.4-22.3)9336.535.8 (34.1-37.5)24318.818.7 (17.6-19.7)
    3rd child26420.821.5 (20.4-22.5)6534.133.3 (31.4-35.2)19919.819.8 (18.6-21.0)
    4th child19721.022.0 (20.9-23.1)5032.432.4 (30.1-34.8)14720.620.6 (19.4-21.9)
    5th+ child40919.820.7 (19.9-21.6)9031.832.3 (30.5-34.2)31919.119.2 (18.3-20.1)
    P trend0.800.910.200.390.540.39
    Don't know13119.720.7 (19.2-22.1)2831.430.9 (27.8-34.1)10319.419.4 (17.7-21.0)
Mother smoked during pregnancy
    No1,37620.521.3 (20.8-21.7)27933.332.6 (31.6-33.6)1,09719.619.5 (19.1-20.0)
    Yes15720.020.9 (19.4-22.3)8033.933.2 (31.4-35.0)7717.817.6 (15.5-19.8)
    P0.670.740.640.680.260.23
    Don't know10719.420.3 (18.4-22.2)3534.032.4 (28.5-36.4)7218.118.2 (16.1-20.3)
    Missing12719.920.7 (19.3-22.2)2832.731.7 (29.4-34.0)9919.319.2 (17.6-20.8)
Mother drank alcohol during pregnancy
    No1,22320.421.2 (20.7-21.6)23933.032.6 (31.6-33.6)98419.519.4 (18.9-19.9)
    Yes10820.721.4 (19.7-23.2)5733.633.1 (30.9-35.2)5120.020.0 (17.4-22.6)
    P0.971.00.890.850.720.68
    Don't know31220.321.1 (20.1-22.1)9934.733.5 (31.5-35.5)21318.818.5 (17.3-19.7)
    Missing12419.920.7 (19.2-22.2)2732.731.8 (29.4-34.3)9719.419.1 (17.4-20.7)
  • * Means adjusted for age at mammography, weight at follow-up 1, HRT use, and menopausal status.

  • Means and 95% CIs, additionally adjusted for education, age at menarche, parity and age at first birth, oral contraceptive use, alcohol use, current smoking status, and smoking history.