I prefer to put the majority of my patients' breast implants subpectoral, which is "under the muscle" to most of us. They are actually done with the "dual plane" technique (which most of us were doing before someone named it that). So they are under the pectoralis muscle for their upper 1/2 or so, and under breast tissue for the lower 1/2 or so. This is, IMHO, not as reproducibly done using the "armpit" (I say transaxillary) approach, so I don't usually do it that way. Why under the muscle? Pros: Possibly less chance of interfering with mammograms and possibly lower chance of hardening of the implant capsules, more natural upper breast slope and less visible upper breast rippling. Also, in thin women, less "fake" look. Cons: positional distortion possibly (when the woman puts her hands on her hips and squeezes her "pecs" the implants may ride up). Most women accept this as a trade-off for the above "pros". Best of luck to you.