Painful nipples are so common, many in the breastfeeding world consider pain normal when you first start to nurse. Most of the time, the pain can be improved by simply learning to correctly latch your baby. If you try all the tricks and the pain does not completely resolve, then there is an anatomic cause that must be corrected in order to fix the problem.
The nipple has almost all of the sensory nerves of the breast. This means it is incredibly delicate and reactive, so when it is gently stimulated with warmth and moisture (i.e. your baby’s mouth), your brain secretes oxytocin and pushes out breast milk. All those nerve endings also make your nipple more prone to injury, so it must sit all the way in the back of your baby’s throat when he nurses, away from moving parts.
Nipple pain is ALWAYS caused by a shallow latch. And a shallow latch is ALWAYS caused by a restricted gape. Until the gape and latch are corrected, the cause of the pain will not improve on its own. That’s not to say that the pain always continues. Sometimes damage and scarring to your nipples make them less sensitive. But if you continue to nurse through the pain (as you are incorrectly told to do) without fixing the underlying problem, there can be terrible consequences.
Since pain means a shallow latch, it also means your baby is working very hard to get the milk out. If your baby does not have a deep latch, he can’t completely empty your breasts. This has two consequences: 1. Your breasts will make less and less milk and deplete your supply over time. 2. You will be more prone to engorgement, plugged ducts and mastitis. Pain also makes your brain secrete cortisol, which is a stress hormone, instead of oxytocin, which is a love hormone. These hormone abnormalities lead to poor sleep and postpartum depression (for up to 6 months after you stop nursing). They also interfere with your ability to bond with your baby.