Table 3.

Differences in mammographic density by selected risk factors among postmenopausal women (MTC, 2006)

	Percent density^a	Ln dense area (cm²) ^a,^b	Ln non-dense area (cm²) ^a,^c

Age (years)	−0.25 (−0.48,−0.02)	−0.001 (−0.013,0.011)	0.010 (0.004,0.016)
BMI (kg/m2)	−0.43 (−0.65,−0.21)	0.017 (0.004,0.030)	0.042 (0.036,0.048)
BMI at age 18 (kg/m2)^{^}^∨	−0.47 (−0.85,−0.09)	0.020 (−0.001,0.041)	0.050 (0.040,0.060)
Weight change since age 18 (lbs)^{^}	−0.17 (−0.27,−0.08)	0.007 (0.002,0.013)	0.017 (0.015,0.020)
Nulliparity	0.39 (−2.77,3.56)	−0.016 (−0.177,0.144)	−0.012 (−0.095,0.070)
Parity^*	−0.02 (−1.13,1.10)	−0.007 (−0.063,0.049)	−0.006 (−0.035,0.024)
Family history of breast cancer	2.07 (−2.06,6.20)	0.229 (0.018,0.441)	0.075 (−0.034,0.183)
History of BBD	3.68 (0.38,6.98)	0.223 (0.055,0.392)	0.024 (−0.063,0.111)
Indigenous language/dialect	−6.41 (−11.79,−1.02)	−0.279 (−0.554,−0.005)	0.050 (−0.093,0.192)
Age at menarche
<12	Ref	Ref	Ref
12	−1.28 (−4.25,1.68)	−0.052 (−0.203,0.100)	0.022 (−0.056,0.099)
13	1.11 (−2.17,4.39)	0.078 (−0.09,0.245)	0.034 (−0.052,0.120)
14+	0.89 (−2.04,3.82)	0.079 (−0.070,0.229)	0.045 (−0.031,0.122)
Age at first pregnancy^*
<25	Ref	Ref	Ref
25+	−0.16 (−2.59,2.27)	−0.016 (−0.138,0.105)	−0.011 (−0.076,0.054)
Breastfeeding^*
Never	Ref	Ref	Ref
<12 months	−0.77 (−4.16,2.62)	−0.047 (−0.216,0.123)	−0.004 (−0.094,0.086)
12+ months	−1.22 (−4.81,2.37)	−0.023 (−0.203,0.157)	0.040 (−0.056,0.135)
Hormonal contraceptives
Never	Ref	Ref	Ref
Past	−1.91 (−4.17,0.36)	−0.114 (−0.230,0.002)	0.001 (−0.059,0.060)
Alcohol use
No	Ref	Ref	Ref
Yes	−0.16 (−2.53,2.21)	−0.020 (−0.140,0.101)	−0.027 (−0.090,0.035)
Age at natural menopause
<45	Ref	Ref	Ref
45–49	3.38 (0.57,6.19)	0.172 (0.032,0.312)	−0.027 (−0.100,0.045)
50+	3.45 (0.06,6.85)	0.183 (0.014,0.352)	−0.002 (−0.090,0.086)
HT Use
Never	Ref	Ref	Ref
Past	0.44 (−2.41,3.29)	0.051 (−0.093,0.194)	0.024 (−0.051,0.099)
Current	−0.73 (−5.01,3.54)	−0.139 (−0.354,0.076)	−0.010 (−0.122,0.102)

Adjusted for age (continuous), state (Jalisco, Veracruz), BMI (continuous), BMI at age 18 (continuous), parity (continuous), family history of breast cancer (yes, no), history of BBD (yes, no), other dialect (yes, no), nulliparity (yes, no), age at menarche (<12, 12, 13, 14+, unknown), age at first pregnancy(<25, 25+, unknown), breastfeeding (<12 months, 12+ months, unknown), hormonal contraceptives (never, ever, unknown), alcohol (none, any), HT use (never, past, current, ever – current status unknown, unknown), and age at natural menopause (<45, 45–49, 50+, unknown).

Further adjusted for non-dense area

Further adjusted for dense area

among parous

^{^}

not adjusted for current BMI