Table 2.

Crude and multivariable adjusted percent mammographic breast density, dense breast area, and total breast area and 95% CI in luteal compared with follicular phase of the menstrual cycle for 204 premenopausal women

Mean percent density (95% CI)Mean dense breast area (95% CI), cm2Mean total breast area (95% CI), cm2
Follicular phase*36 (33-39)312 (283-341)940 (895-985)
Luteal phase37 (34-40)324 (296-351)958 (913-1002)
Mean difference: luteal-follicular (95% CI)Mean difference: luteal-follicular (95% CI)Mean difference: luteal-follicular (95% CI)
Crude difference0.9 (−0.4 to 2.1)11.5 (−1.9 to 24.9)17.4 (−2.0 to 36.9)
P0.1790.0930.079
Adjusted difference1.1 (−0.2 to 2.3)13.1 (0.1-26.1)16.7 (−2.8 to 36.2)
P0.0890.0480.092
  • * Days 7 to 15 or week 2 of cycle.

  • Days 21 to 35 or week 4 of cycle.

  • Adjusted for weight change and time between exams.