Although it seems like it would be easy to just cut the outer circumference of the areola to reduce the diameter, there are a number of things to consider regarding the outcome.
Lets say that with your diameter areola of 8 to 9cm, (this is quite large) you wanted to have a reduction to a 4cm diameter. This means that the radius of the your areola will be reduced by 2 to 2.5 cm. When this is done, the nipple will essentially be raised that much higher on your breast. This is OK if your breast are sagging but if they are not they could be sitting too high.
Another important thing to consider is that the difference in circumference between a 8cm diameter and a 4 cm is over 12 cm. This means that the big circle left on the outside of the areola which was left after cutting away the nipple border has a circumference 12cm larger than the new nipple border. If this is sutured without a permanent suture to retain the diameter, then the big outer circle will eventually stretch the smaller areolar circle back to close to it's original size. There is also a chance of puckering around the border.
An areolar reduction does not interfere with breast feeding but make sure you consider the above issues. I would recommend a compromise to my patient of maybe a diameter of 5 to 6 cm to reduce the discrepancy.
