Table 2.
Associations of breastfeeding duration with mammographic breast density measures a
| Volumetric Percent Density | Dense Volume (cm3) | Non-dense Volume (cm3) | ||
|---|---|---|---|---|
| Breastfeeding Duration | N | 10^β (95%CI) | 10^β (95%CI) | 10^β (95%CI) |
|
| ||||
| All women | 964 | |||
| Nulliparous | 228 | Reference | Reference | Reference |
| Parous never breastfed | 289 | 0.88 (0.81, 0.96) | 0.93 (0.83, 1.04) | 1.07 (0.95, 1.20) |
| 0–6 months | 115 | 0.88 (0.79, 0.98) | 0.91 (0.79, 1.05) | 1.07 (0.93, 1.24) |
| 7–12 months | 91 | 1.00 (0.89, 1.13) | 0.94 (0.81, 1.10) | 0.96 (0.82, 1.11) |
| >12 months | 241 | 0.95 (0.87, 1.04) | 0.87 (0.78, 0.98) | 0.94 (0.84, 1.05) |
| P trend | 0.92 | 0.03 | 0.10 | |
|
| ||||
| Parous women | 736 | |||
| Parous never breastfed | 289 | Reference | Reference | Reference |
| 0–6 months | 115 | 0.99 (0.89, 1.09) | 0.98 (0.86, 1.12) | 1.01 (0.89, 1.16) |
| 7–12 months | 91 | 1.12 (1.00, 1.25) | 1.02 (0.88, 1.18) | 0.91 (0.78, 1.06) |
| >12 months | 241 | 1.06 (0.98, 1.16) | 0.94 (0.84, 1.06) | 0.90 (0.80, 1.01) |
| P trend | 0.07 | 0.38 | 0.04 | |
a.
Models were adjusted for age (continuous), age at menarche (continuous), BMI (continuous), race (non-Hispanic white, non-Hispanic black, other), and family history of breast cancer (yes, no). Mammographic breast density measures were log10 transformed due to the skewed distribution. Coefficients were back-transformed for easy interpretation. CI = confidence intervals, MBD= mammographic breast density. Bold indicates statistical significance (p<0.05).