Breast cancer risk increases post-birth - but only temporarily
Having a baby temporarily increases the risk of breast cancer by about 80% compared with women who have never given birth, researchers behind a new study have concluded.
Breast cancer risk peaks 4.6 years after a woman's most recent birth but then begins to fall, according to chief author Dr Hazel Nichols of UNC's Lineberger Comprehensive Cancer Center in North Carolina, US, and colleagues.
After another 19 years, the risk returns to the same level as a woman who has never given birth. From there, it continues to drop.
While a 45-year-old woman who had never given birth had a 0.62% chance of being diagnosed with breast cancer up to that point in her life, the odds for a woman of the same age who had given birth in the past 3-7 years were only slightly higher, at 0.66%.
Similarly, by age 50, the odds of being diagnosed with breast cancer were 1.95% for nulliparous women and 2.20% for