Kathleen As far as I know, Fibrocystic 'disease' of the breast does not affect the ability to breastfeed. During lactation, some symptoms of fibrocystic disease may lessen due to relatively low oestrogen levels in mother. Some studies have found a relationship between blocked ducts and pre-existing breast cysts from fibrocystic disease, but I don't know how common that is. The hormonal relationship to breast symptoms is still under debate, and other factors such as caffeine intake, fats in the diet etc are important as well. Hope this helps Fiona Coombes MBBS IBCLC Perth Western Australia gradually cooling down at last.