The older you are, the greater your chance of developing this frightening disease. Breast cancer rarely occurs before the age of 20. The odds of developing it increase sharply with age until menopause. After that, the chances of developing breast cancer continue to rise with age, but not as rapidly. The longer a woman remains fertile, the greater her chances of developing breast cancer.
Pregnancy seems to short-circuit the process under certain circumstances.
The earlier a woman completes her first full-term pregnancy, the less likelihood she has of contracting the disease. For example, a woman's lifetime risk of developing breast cancer drops by as much as 70 percent when she has a baby before her eighteenth birthday. This beneficial effect steadily tapers off during her 20s and seems to vanish entirely by the time she reaches the age of 30. Women who have their first baby after the age of 35 are twice as likely to develop breast cancer as those who give birth while still in their teens. Abortion does not appear to increase your risk of breast cancer, though this issue is not definitively settled.