Table 4.

Standardized percent density and absolute density are adjusted for age at examination and BMI

		Percent density				Absolute density
		Threshold		Volumetric		Threshold, cm²		Volumetric, cm³
		β	95% CI	β	95% CI	β	95% CI	β	95% CI
Age at examination^a	Per year	−0.056	−0.077 to −0.036	−0.060	−0.082 to −0.038	−0.049	−0.071 to −0.026	−0.005	−0.027 to 0.017
BMI^b	Per 2-kg/m² increase	−0.206	−0.241 to −0.170	−0.144	−0.182 to −0.105	−0.137	−0.176 to −0.097	0.191	0.153 to 0.230
Nulliparous	Yes	0.137	−0.072 to 0.346	0.260	0.038 to 0.482	0.118	−0.112 to 0.348	0.073	−0.152 to 0.297
Postmenopausal	Yes	−0.201	−0.389 to −0.012	−0.133	−0.334 to 0.069	−0.223	−0.430 to −0.016	−0.043	−0.246 to 0.160
Age at menarche	Per year	0.045	−0.012 to 0.102	0.013	−0.049 to 0.075	0.044	−0.018 to 0.107	−0.008	−0.070 to 0.054
Age at menopause	Per year	0.016	−0.008 to 0.041	0.015	−0.010 to 0.040	0.024	0.000 to 0.048	0.029	0.005 to 0.053
Age at first delivery	Per 2 year	0.045	0.004 to 0.086	0.052	0.009 to 0.096	0.050	0.005 to 0.094	0.033	−0.011 to 0.078
Ever HT use	Yes	0.134	−0.061 to 0.329	0.193	−0.016 to 0.402	0.186	−0.029 to 0.400	0.215	0.006 to 0.424
Ever pill use	Yes	−0.095	−0.362 to 0.172	−0.221	−0.507 to 0.064	−0.106	−0.073 to 0.028	−0.068	−0.355 to 0.220
Family history	Yes	0.101	−0.132 to 0.335	0.077	−0.172 to 0.327	0.111	−0.146 to 0.367	0.052	−0.198 to 0.302

NOTE: β is the number of SD change in breast density.

↵^aβ_age is adjusted for BMI.
↵^bβ_BMI is adjusted for age.