Second, in Pike's Breast Tissue Age model, a one-time rapid increase in breast tissue age and therefore breast can- cer risk is included immediately following the first full- term pregnancy [138]. The extension of Pike's model includes multiple births by incorporating smaller increases in risk at each additional full-term pregnancy [139]. This pattern of increased risk for breast cancer immediately following full-term pregnancies is well-doc- umented [140-142]. E2 concentrations increase steadily during pregnancy, peaking at about 100 times normal cycling levels [3]. In the days around parturition, these concentrations drop precipitously to levels below those of normal cycling females, where they are maintained for at least a month and potentially much longer (depending.
