Why Do Some Breast Augmentation Results Appear Saggy?

The issue of sagginess has two components.
The first is related to the position of the implant on the chest wall. If the implant is placed low on the chest wall, even if it is in harmony with the skin envelope and nipple position, it will appear to hang too low, or sag.
The second has to do with the position of the nipple relative to the breast mass. If the nipple-areola complex is too low relative to the implant, the nipple appears to be pointing south.
In both cases the situation can be improved by performing a lift in combination with the breast augmentation. In my office, I stand the patient in front of the mirror and let her guide me as to where on the chest wall she wants the implant. Once I know what her ideal implant position is, then I decide whether a lift will help her.
For a link on the importance of implant position, see the link below.

The implants augment the breast shape.  If there is aging before surgery, there will be sagging after surgery.

Thank you for your question. The final breast augmentation result depends on the amount of sagginess, or ptosis, present in the breasts pre-operatively, the surgeon's placement of the implants, and other factors. If the breasts have too great of sag (ptosis) pre-operatively, it may be better to undergo an aug/pexy, which both places implants and lifts the breasts through a mastopexy.

It’s not unusual for patients who have breast hypoplasia
to also have associated breast sag. How this sag is dealt with at the time of
breast augmentation may explain why some women have persistent sag following
this procedure. When this situation arises patients are often willing to make
compromises to avoid scarring. They’re willing to trade scarring for residual
breast sag.

Under these circumstances, breast implants are
occasionally placed on top of the muscle or biplanar breast augmentations are
performed with the implants partially beneath the muscle. This avoids scars
that are associated with breast lift surgery but results in persistent breast
sag.

In other cases breast sag may develop following breast augmentation
surgery. This can occur following pregnancy, breast feeding, weight loss,
weight gain, hormonal replacement, menopause, and normal aging.

It’s important to realize that the type of procedure
performed is dependent upon the patient’s anatomic findings and aesthetic
goals. When these decisions are made a series of tradeoffs
are necessary. In many cases patients are willing to accept persistent breast
sag to avoid scarring.

If you see photos of women with saggy breasts after breast augmentation, then chances are a breast lift may have been needed prior to surgery. While some implants can help lift the breasts to a certain extent, if there is a lot of sagging then a breast lift is necessary. Also, changes can occur after surgery that contribute to sagging, such as weight gain, pregnancy and aging.

It's not a matter of the implants staying up.  The issue is that skin is prone to stretching and sagging again.  An implant adds weight to the breast and can cause further stretching.  You should see a board certified plastic surgeon in your area to see if you would benefit from a lift in addition to an augment.

Best,

The appearance of the breast after augmentation is related to the preoperative look. Therefore, augmentation of a sagging breast leads to a fuller, but still sagging breast.

Some patients are fine with this. They can do their own lift with a great bra, and avoid the scars and expense of a surgical breast lift.

Secondly, placing implants that are too large will create sagging over time. This is especially true of saline implants, which are about 20% heavier than silicone gel devices.

Yes, this is true and an accurate observation.'
The real problem is that many of the best breast lift techniques require multiple or lengthy scars. Becasue the healing of scars is unpredictable, many women elect to undergo a breast augmentation alone.
However, to answer your question on greater detail, there are many factors that can make a breast look saggy (ptotic) and include looking at:

location of the breast tissue on the chest wall
location of the nipple & areola relative to the crease
location of the gland relative to the crease
size of the areola
amount of skin superior to the areola
amount of skin from the areola to the crease
degree of breast contriction and lack of lower pole fullness with a downward looking nipple & areola

Treating all or some of these factors come into play when considering a breast lift. In many cases a small scar may result in a nice improvement with minimal side effects. In other instances, the correction requires many scars and this is deemed undesireable by patients who prefer to have larger breasts that you can apppreciate in clothing. Unfortunately, you are judging the results in the nude and this is not the way the majority of paitents reveal their breast augmentation results to the rest of world.

Sometimes, a breast lift (mastopexy) may be necessary to lift the breasts when an augmentation is done simultaneously. It all depends on how much sagginess, or ptosis, is present before any surgery. A small amount of ptosis can be fixed with an augmentation alone. However, with increasing amounts of ptosis the complexity of the type of lift increases. The types of mastopexies include periareolar lift, vertical lift, and Wise pattern lift. Let your local plastic surgeon determine which one is right for you to accomplish your specific goals. Good luck!

Some of the photos you're describing may be of women who may have needed a breast lift (mastopexy) as well as an augmentation, and chose to only have the augmentation because they did not want the extra incisions of a lift. In these cases, the breasts may look just fine in a bra or swimsuit, but sag when not supported. The good news is that these patients still have the option of a lift and it can be done as a second procedure. Remember, while an implant alone will give some lift to the breasts, it is minimal, and often a breast lift procedure must be added to get the best, long term results.
Dr. S

Breast augmentation primarily achieves an increase in breast volume. Although, to a small extent, implants can lift the breasts, many women need a breast lift in addition to breast augmentation. Depending on the patient's anatomy, this may be accomplished at the same time as breast augmentation, or may require a second surgery. The incisions also vary depending on the amount of sagginess, but the most common incisions are a small incision just around the areola to a "lollipop" incision (around the areola and a vertical incision extending inferiorly). In patient's with really saggy breasts, sometimes an anchor incision is required, which consists of incisions around the areola, a vertical incision, and an incision is the crease at the bottom of the breast,
If you've had 3 kids and currently have saggy breasts, you probably need a lift in addition to a breast augmentation. Your best best is to seek consultation with a board certified plastic surgeon in your area.
Hope this helps. Best of luck.