Do BRCA1 mutations affect the ability to breast-feed? Significantly shorter length of breast-feeding among BRCA1 mutation carriers compared with their unaffected relatives

The difference in length of breast feeding between women with a BRCA 1 mutation and their unaffected relatives was investigated. Fifty women belonging to a family with a known BRCA1 mutation had themselves undergone testing and each had given birth to at least one child. Women with BRCA1 mutation breast-fed their first infant for a significantly shorter period (P = 0.048) and the second and third infants for a non-significantly shorter time than their unaffected relatives. Computing a mean breast-feeding time per child based on the first three infants and also taking birth year of the mother and smoking into account, having a BRCA1 mutation was associated with a significantly shorter time of breast-feeding (P = 0.034), and so was smoking (P = 0.001), but birth year of the woman did not significantly influence length of breast-feeding. Seventy-five per cent of the assessable women with a BRCA1 mutation stopped breast-feeding owing to little or no milk production compared with 36% of the non-carriers OR = 5.3 (CI 95% 1.1–22.1) and (P = 0.02). Our finding may reflect a disturbed differentiation of the breast tissue in women with BRCA1 mutations.