No Significant Difference in Age at Menarche, Menstrual Cycle Length, Age at First Full-Term Pregnancy, and Nulliparity Among BRCA1 Mutation Carriers Compared with Their Unaffected Relatives

Abstract

Early age at menarche, short menstrual cycle length, late age at first full-term pregnancy, and nulliparity are known risk factors for breast cancer (BC). These risk factors differ between BC patients with and without a family history of BC, and between BC patients and controls. Self-administered questionnaires were filled out by 95 women with a family history of known BRCA1 mutations; 39 were BRCA1 mutation carriers and 56 were not. Age at menarche did not significantly differ between BRCA1 mutation carriers and non-carriers, after adjustment for year of birth (p = 0.40). There were no significant differences between BRCA1 mutation carriers and non-carriers in: a) Menstrual cycle length (among women not using oral contraceptives) at age 30, or at the current age in younger women, after adjustment for year of birth and age at menarche (p = 0.60). b) Age at first full-term pregnancy, after adjustment for year of birth, age at menarche, and menstrual cycle length (p = 0.69). Nulliparity was not more common between BRCA1 mutation carriers compared with non-carriers, after adjustment for year of birth, age at menarche, and menstrual cycle length (p = 0.81). Our results suggest that reproductive risk factors for BC are not related to BRCA1 carrier status.