Mammographic density and markers of socioeconomic status: a cross-sectional study

BMC Cancer

Table 1 Baseline characteristics of the participants and their association with mammographic percent density

*Participant baseline characteristics*	n	Mean	SD
Age at mammography (yrs)	487	48.6	1.6
Weight (kg)	487	67.6	12.9
Age at menarche (yrs)	194	13.1	1.5
		n	%	Median PD (25 ^th , 75 ^th ) ¹
Smoking	487
Never		273	56	26.7 (13.7, 43.5)
Ex smoker		152	31	29.5 (14.1, 46.7)
Current		62	13	27.2 (10.5, 42.7)
Height (m)	487
<1.60		158	32	24.9 (13.3, 43.8)
1.60-1.64		137	28	26.9 (12.3, 43.5)
1.65-1.69		110	23	28.6 (15.4, 43.4)
≥ 1.7		82	17	31.1 (18.2, 43.0)
BMI (kg/m²)	487
<22		115	24	46.0 (32.1, 61.6)
22-24.9		145	30	31.5 (19.5, 43.1)
25-27.9		115	24	22.1 (11.6, 37.4)
≥ 28		112	23	9.5 (4.0, 21.6)
Number of full-term pregnancies	487
0		63	13	32.9 (10.4, 53.6)
1-2		297	61	28.7 (14.2, 45.6)
3+		127	26	23.5 (13.8, 39.0)
Age at first full-term pregnancy²	424
<24 years		140	33	22.7 (12.0, 37.8)
24-28.9 years		160	38	26.3 (14.6, 42.4)
≥ 29 years		124	29	31.6 (16.1, 49.7)
Family history of breast cancer	487
Yes		53	11	28.6 (15.8, 46.5)
No		434	89	27.5 (13.7, 43.4)
Lifetime breast feeding^2,3	326
Never		55	17	21.6 (9.4, 37.9)
1-6 months		90	28	28.4 (13.3, 39.7)
7-12 months		60	18	30.0 (15.5, 52.6)
≥ 13 months		121	37	32.1 (16.4, 47.2)

¹ Median percent mammographic density (%) with 25^th and 75^th percentiles
² Among parous women only
³ Available only for the 369 women who completed the follow-up questionnaire, 326 of whom were parous

ISSN: 1471-2407