Already during pregnancy some future mums worry that they will have problems with breastfeeding because of flat nipples. In fact, the nipple shape usually is not very important.
Do not worry in advance. After all, we feed with a breast and not with a nipple. The baby must catch the breast in such a way that he has a significant part of the areola in his mouth, because it is the areola that is sucked by the baby, and not the nipple. Moreover, with the hormones secreted after the birth, nipples become more flexible and after a few days of intense suckling they usually stretch without additional aid. Also, sometimes the baby adapts to the shape of the breast and, as he does not even know that it could look different, the flat or even convex (inverted) nipple is not a problem.
However, sometimes, when the baby is incorrectly latched on, he tries to catch the nipple alone, and, because it is flat, he is unsuccessful. Then he is irritated and refuses to suck. As a result of this situation, the breasts non stimulated by suckling will produce less milk. Therefore, this problem must be solved quickly.
First of all, amend your technique for latching the baby on. Focus on teaching him how to catch and suck the areola, then the nipple shape will not be important.
Between feedings you can wear special correcting pads (niplettes), so the nipple stands out filling an opening in the shield. You should remove them for feeding. You can start using these shields during the pregnancy (when there is no risk of the premature birth).
Small devices which delicately suck the nipple into a plastic thimble-like "hood" using air drawn into a special syringe are very popular amongst mums with flat or inverted nipples. The nipple sucked into the thimble "pops out" and when it remains in this position for a few hours a day (between feedings), then after several weeks the desired shape becomes fixed. Such device can be purchased at a pharmacy.
When the baby cannot grasp the nipple and, in consequence, sucks incorrectly or not at all, you must regularly stimulate lactation by extracting milk with a breast pump. This device sucks the breast, so it helps a lot to "pull out" flat nipples.
Even when the baby cannot suck the breast effectively yet, do not supplement breastfeeding with formula. Milk extracted with the breast pump should be given in a way facilitating learning a correct way of suckling the breast (read about it in the chapter Methods for giving breast milk).
Sometimes the baby cannot grasp the breast because the nipple has become too flat due to breast fullness. In the 2 - 4 day from the birth, lactation is at its peak and the amount of milk exceeds the baby's demand. Milk filled breasts are so swollen that they are hard to grasp. A helpful solution in that case is to extract some milk before feeding, to soften the breast and "release" the nipple.