Age at first birth and the risk of breast cancer in BRCA1 and BRCA2 mutation carriers

Abstract An early age at first full-term birth is associated with a reduction in the subsequent devel-opment of breast cancer among women in the gen-eral population. A similar effect has not yet been reported among women who carry an inherited BRCA1 or BRCA2 mutation. We conducted a mat-ched case–control study on 1816 pairs of women with a BRCA1 (n = 1405) or BRCA2 (n = 411) mutation in an attempt to elucidate the relationship between age at first full-term pregnancy and the risk of developing breast cancer. Information about the age at first childbirth and other pregnancy-related vari-ables was derived from a questionnaire administered to women during the course of genetic counselling. There was no difference in the mean age at first full