Women want good sized, round and firm breasts to enhance their beauty. But some women have oversize breasts and it looks ugly on their body, some health factors also could be generate like rashes under the breasts, back pain, neck pain, tenderness, arthritis and shortness of breath High estrogen level is main cause of over shaped breasts size and some other factors also include such as genetics, obesity, breastfeeding, pregnancy, use of certain drugs and hormonal changes in the body.