The size of the breasts depends on the amount of fatty tissue they contain. The more frequently the mother nurses, the more milk is produced. Milk is produced in the glands in the back of breast and is then carried to the nipple by the milk ducts. This breastfeeding tissue develops early during pregnancy in every woman. Breast size increases during pregnancy and while nursing.
Breasts return to their pre-pregnancy state after weaning.
Breasts may become less firm after pregnancy but this is a result of pregnancy, not breastfeeding. Breastfeeding has an extra advantage to help nursing mothers get back to their non-pregnancy figures. The hormones produced during breastfeeding cause the uterus to contract and return to its pre-pregnancy state. When breastfeeding is initiated immediately after delivery, bleeding is less since the uterus is already beginning to contract and reduce in size. Most breastfeeding mothers lose the weight gained during pregnancy more quickly than non-nursing mothers.