The main issue involved here in my mind is the reason behind the ongoing breast growth. You didn't mention the age of the person in question, so if it's someone who is still maturing, and the breast growth is a natural part of her puberty/maturation process and just not complete, I would not want to perform breast augmentation until this is complete. This is for a couple of reasons. First, breast augmentation is a commitment to permanently alter one's anatomy, and these decisions should not be taken lightly. Young ladies who are not yet physically mature, may also not be emotionally mature enough to take on this decision. While some are, I think the default position is to err on the side of safety and wait until physical and emotional maturity are assured. Furthermore, we can't predict what effects, if any, breast augmentation may have on breasts that are still developing. While the implants themselves are unlikely to cause any harm, say chemically, the stress and pressure that the surgery or the implants will place on the tissues may have an adverse effect. In addition, doing anything to alter the size of a body part that is in a state of flux and still changing in size on its own is like shooting at a moving target. In my opinion this compromises accuracy and puts you at risk for unsatisfactory results. Again, I would delay surgery until things were stable and we could make a more reliable plan to enlarge the breasts with predictable long term results. Lastly, in the event that the person in question is beyond the age that we would normally expect breast maturation to be complete, we have to ask why then the breasts are growing? Is there some type of hormonal change, including pregnancy, that may be involved and need to be addressed in some way, or is the person gaining or losing weight, which secondarily affects the breasts? The bottom line is that most surgeons would likely agree that doing anything like augmenting the breasts is something that we only want to do when we have a reasonable shot at accuracy and long term stable results, and if we have what is essentially an unstable situation we ought not to contemplate this type of surgery.