Table 3.

Odds ratio for dense breast among premenopausal women. In the multivariate analysis, adjusted by age, BMI, and alcohol status, parity still showed a significant relationship. Compared with women with more than two parity, two parity, single parity, nulliparity showed a higher risk of dense breast (OR: 1.458 (95% CI; 1.123–1.894), OR: 2.349 (95% CI; 1.801–3.064), OR: 3.222 (95% CI; 2.500–4.151), respectively)

	Univariate	p	Multivariate	p
Age	0.941 (0.933–0.949)	< 0.001	0.958 (0.949–0.967)	< 0.001
BMI	0.756 (0.742–0.770)	< 0.001	0.756 (0.742–0.771)	< 0.001
Parity
0	2.782 (2.206–3.508)	< 0.001	3.222 (2.500–4.151)	< 0.001
1	2.229 (1.747–2.844)	< 0.001	2.349 (1.801–3.064)	< 0.001
2	1.490 (1.170–1.896)	< 0.001	1.458 (1.123–1.894)	0.005
≥ 3 (ref)	–	–	–	–
Trend*	0.728 (0.693–0.764)	< 0.001	0.676 (0.640–0.714)	< 0.001
Smoking status
Never (ref)	–	–	–	–
Past	1.001 (0.877–1.142)	0.991	0.969 (0.862–1.115)	0.592
Current	0.828 (0.670–1.022)	0.079	0.699 (0.549–0.889)	0.003
Alcohol status
Non (ref)	–	–	–	–
Occasional	1.091 (0.955–1.246)	0.199	1.000 (0.862–1.160)	0.998
Regular	1.205 (1.091–1.330)	< 0.001	1.097 (0.981–1.227)	0.106
Family history of breast cancer	1.006 (0.897–1.128)	0.921	–	–
Hormonal therapy	0.925 (0.813–1.053)	0.238	0.937 (0.812–1.082)	0.378

*To calculate p for trend, variables were modeled as continuous value