nulliparity and age at first pregnancy
A relatively earlier age for a first birth is protective against the onset of breast carcinoma. Compared to nulliparous women, the relative risk for those having their first child before the age of 20 is 0.5. There is anecdotal evidence that a first child after the age of 35 is associated with an increased risk of breast carcinoma.
Conversely, nulliparous women have a relatively greater risk compared to parous women.
Last reviewed 01/2018