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.