Teenagers, pregnant moms, or women in general may be concerned about so-called inverted nipples.
An inverted nipple is 'turned inside' instead of pointing outside. It appears like a indentation in the middle of the areola.
An inverted nipple is usually not of any medical concern as such. For most girls, it is only a cosmetic thing, and as such, you can for the most part have a peace of mind of it.
However, the nipple inversion can also be a symptom of some medical conditions. This is only if it suddenly becomes inverted after first being erect (everted). This could be one symptom of breast abscess, mastitis, mammary duct ectasia, or even inflammatory breast cancer. So, in that type of situation you want to see a doctor.
Also, an inverted nipple can make breastfeeding harder. The milk can still come out of the nipple, but it is harder for the baby to grab the nipple and suck on it.
Fortunately, inverted nipples often evert during pregnancy, as the adhesions at the base of the nipple that bind the skin to the underlying tissue loosen up and the skin becomes more elastic.
However, you don't necessarily have to wait for that, either:
You can try. It is possible to "coach" the inverted nipple out so it becomes an 'outie' and everts.
To do this, one could try simple rubbing and nipple stimulation. Try massage around the nipple so as to loosen those adhesions. Try put both thumbs at the base of the nipple and then pull both of them outward.
Another possibility is to use a breast shell, or something called Niplette from Philips Avent company. These products exert a suction on the nipple which pulls the nipple out. When worn for a long time, this change can become permanent.
Plastic surgeons offer two kinds of corrective surgeries to make an inverted nipple erect. In one kind, the milk ducts are cut, and there is no chance of breastfeeding later. In the other kind, milk ducts are preserved. However, even in this second kind of surgery, the nerve supply to the nipple is cut, and this can make breastfeeding impossible.
Any surgery to the nipple area is therefore very risky, in terms of breastfeeding ability. Please think through this carefully, before opting for inverted nipple surgery. Some women find out too late (after the surgery), and are gravely disappointed that their ability to breastfeed has been taken away.
You can find more pictures of inverted/flat nipples on the following webpages:
Also, you can visit plastic surgery websites' "before/after" pictures for inverted nipples to see what inverted nipples look like. Note: any surgery and cutting to the nipple area is likely to affect breastfeeding ability.