Table 2.

Relationship between reproductive factors and age at maximum height and risk of invasive ductal, lobular, and ductal-lobular breast carcinoma

Control (n = 469)
Ductal (n = 524)
Lobular (n = 324)
Ductal-lobular (n = 196)
n (%)n (%)OR* (95% CI)n (%)OR* (95% CI)n (%)OR* (95% CI)
Age at menarche (y)
    ≥14106 (22.6)108 (20.6)1.0 (Reference)79 (24.4)1.0 (Reference)31 (15.9)1.0 (Reference)
    12-13260 (55.4)309 (59.0)1.2 (0.8-1.6)177 (54.6)0.9 (0.6-1.3)112 (57.4)1.5 (0.9-2.3)
    8-11103 (22.0)107 (20.4)1.1 (0.7-1.5)68 (21.0)0.9 (0.6-1.4)52 (26.7)1.7 (1.0-3.0)
Ptrend0.800.600.04
Age at maximum height (y)§
    ≥17164 (35.3)146 (28.3)1.0 (Reference)102 (31.8)1.0 (Reference)54 (28.0)1.0 (Reference)
    15-16164 (35.3)206 (40.0)1.4 (1.0-1.9)120 (37.4)1.2 (0.9-1.7)68 (35.2)1.3 (0.8-1.9)
    ≤14137 (29.5)163 (31.7)1.3 (1.0-1.8)99 (30.8)1.2 (0.8-1.7)71 (36.8)1.6 (1.0-2.4)
Ptrend0.100.430.04
Parity
    Nulliparous36 (7.7)68 (13.0)1.0 (Reference)47 (14.5)1.0 (Reference)28 (14.3)1.0 (Reference)
    Parous433 (92.3)456 (87.0)0.5 (0.3-0.8)277 (85.5)0.5 (0.3-0.7)168 (85.7)0.5 (0.3-0.8)
  • * OR comparing cases with controls using polytomous logistic regression.

  • Adjusted for reference age and reference year. Excludes 1 woman with an unknown age at menarche.

  • Two-sided P < 0.05.

  • § Adjusted for reference age and reference year. Excludes 19 women with an unknown age at maximum height.

  • Adjusted for reference age and reference year. Among parous women, 5 women had only stillbirths.