Table 2.

ORs and 95% CIs associated with hormonal and reproductive characteristics in relation to ER status among African American women in the WCHS

ControlsER+ERER vs. ER+
N (%)N (%)OR (95% CI)aN (%)OR (95% CI)aOR (95% CI)a
Age at menarche
 <12278 (27.4)174 (29.9)1.0 (ref.)66 (28.3)1.0 (ref.)1.0 (ref.)
 12–13471 (46.4)264 (45.4)0.83 (0.64–1.08)113 (48.5)0.92 (0.64–1.31)1.13 (0.78–1.65)
 ≥14265 (26.1)143 (24.6)0.70 (0.51–0.95)54 (23.2)0.57 (0.37–0.88)0.82 (0.51–1.29)
Age at FLB, y
 <18176 (20.8)97 (20.1)1.0 (ref.)38 (18.7)1.0 (ref.)1.0 (ref.)
 18–24408 (48.2)234 (48.4)1.03 (0.74–1.43)113 (55.7)1.33 (0.86–2.07)1.35 (0.84–2.18)
 25–29126 (14.9)82 (17.0)1.37 (0.90–2.09)31 (15.3)1.46 (0.82–2.61)1.12 (0.60–2.07)
 ≥30136 (16.1)70 (14.5)1.02 (0.66–1.58)21 (10.3)0.91 (0.48–1.74)0.93 (0.46–1.88)
Interval between menarche and first birth, y
 <5167 (19.8)85 (17.6)1.0 (ref.)31 (15.3)1.0 (ref.)1.0 (ref.)
 5–9313 (37.0)185 (38.3)1.29 (0.90–1.83)90 (44.3)2.03 (1.23–3.36)1.58 (0.92–2.71)
 10–14182 (21.5)104 (21.5)1.36 (0.91–2.03)50 (24.6)2.26 (1.29–3.95)1.68 (0.93–3.04)
 15–1993 (11.0)61 (12.6)1.73 (1.07–2.78)18 (8.9)1.73 (0.86–3.50)1.04 (0.49–2.20)
 ≥2090 (10.7)48 (9.9)1.35 (0.82–2.24)14 (6.9)1.42 (0.66–3.08)1.02 (0.44–2.36)
  • aAdjusted for age, country of origin, reference year, state, education, family history of breast cancer, history of BBD, menopausal status/age at menopause, and BMI at the age of 20 years.