Yes, placing breast implants under the chest muscle (submuscular placement) can make the implants appear slightly smaller compared to placing them above the muscle (subglandular placement). This is because when the implant is placed under the muscle, there is an additional layer of tissue (the muscle) covering the implant which can compress and slightly flatten the implant, leading to a slightly smaller appearance. This effect can be more pronounced in certain positions or when the chest muscles are flexed. However, the overall size of the implant will not change, and the difference in size between submuscular and subglandular placement is typically only a matter of a few millimeters. The decision of whether to place the implant above or below the muscle will depend on several factors, including the patient's anatomy, the type of implant being used, and the goals of the procedure. It's important to discuss the pros and cons of each approach with your plastic surgeon to determine which option is best for you. Best of luck !