Table 3.

Percentage difference in percent dense breast volume (%DBV) and absolute dense breast volume (ADBV) associated with a one standard deviation difference in adolescent and young adulthood leisure-time physical activity in current non-oral contraceptive users only.

	MODEL 1 Unadjusteda					MODEL 2 Adjustedb					MODEL 3 Also adjusted for childhood and young adult BMIc
Percent Dense Breast Volume (%DBV)
Leisure time Physical Activity Estimate, MET·hr·wk−1	n	% Diff	95% CI	p	R2d	n	% Diff	95% CI	p	R2d	n	% Diff	95% CI	p	R2d
High School (14–17 years)	76	3.2	−17.9, 29.6	0.79	0.02	74	−3.8	−23.1, 20.4	0.73	0.19	74	2.9	−13.1, 21.9	0.74	0.55
Post High School (18–21 years)	77	15.9	−10.2, 49.6	0.25	0.01	75	5.8	−18.3, 37.1	0.66	0.13	75	−1.4	−18.5, 19.4	0.89	0.55
Past Year	77	51.7	15.4, 99.4	0.003	0.11	75	43.0	2.9, 98.7	0.03	0.20	75	13.6	−12.5, 47.4	0.33	0.55
Principal Component Scoree	76	9.8	−13.0, 38.6	0.43	0.03	74	0.4	−20.3, 26.4	0.97	0.19	74	2.2	−14.1, 21.6	0.80	0.55
Absolute Dense Breast Volume (ADBV)
High School (14–17 years)	76	3.2	−13.0, 22.3	0.71	0.00	74	−0.2	−15.2, 17.4	0.98	0.16	74	−0.3	−15.1, 17.2	0.98	0.18
Post High School (18–21 years)	77	3.5	−14.3, 25.2	0.72	0.00	75	−2.4	−19.0, 17.6	0.80	0.14	75	−3.5	−19.6, 15.9	0.70	0.18
Past Year	77	10.9	−10.3, 37.1	0.33	0.00	75	8.3	−15.6, 39.0	0.52	0.14	75	2.6	−20.2, 31.9	0.84	0.17
Principal Component Scoree	76	4.0	−12.6, 23.8	0.65	0.00	74	−0.5	−16.0, 17.7	0.95	0.16	74	−1.1	−16.3, 16.9	0.90	0.18

^aEstimates from four linear mixed effects models for each outcome (%DBV and ADBV) including clinic site as a random effect and leisure time physical activity estimates as fixed effects. Adolescent and young adulthood leisure time physical activity estimates are modeled separately without mutual adjustment.

^bEstimates from four linear mixed effects models as described above under ‘a’ plus including treatment group, race [white (0) or. non-white (1)], education [did not attend (0) or. attended (1) 4 year college], smoking status [former/never (0) or current (1)], days until next menses (cubic spline), duration of oral contraceptive use, and parity [none (0) or ≥1 (1)] as fixed effects.

^cEstimates from four linear mixed effects models as described above under ‘b’ plus including BMI z-score at 8–10 years old and adult BMI.

^dProportion of variance explained by model.

^ePrincipal component score includes high school, post high school, and past year leisure time physical activity estimates.