Breast cancer is one of the most common forms of cancer in the world – about 1 in 8 American women will be diagnosed with it in their lifetimes. There's good news for moms, however – women who've had children have a decreased risk of developing the disease, especially if they gave birth early in their lives.
Women who have their first full-term pregnancy before age 20 have about half the risk of developing hormone receptor-positive breast cancer as those who have their first pregnancy after age 30, according to the National Cancer Institute. The risk of developing hormone receptive-negative breast cancer, however, is about the same between the groups. Breastfeeding for at least one year is also associated with a decrease in the risk of developing all forms of the diseases for all women.
Additionally, the more children you've had in your lifetime, the smaller your chances of developing breast cancer become, the organization says. Women who have given birth to five or more babies have half the risk of nulliparous women (those who have never born children) of developing the disease.