Switching back and forth from breast to artificial nipple is a lot to ask of a baby in the early days of learning to breastfeed. A baby who tries to suck at the breast the way she sucks on a bottle nipple or a pacifier will quickly become frustrated and may cry, fuss, or refuse to nurse. She won't get much milk, and she may have a difficult time learning to breastfeed effectively. Sucking on a pacifier can also interfere with a mother's milk supply and eventually with infant growth. Babies who satisfy some of their sucking needs with an artificial nipple will spend less time stimulating the breast, possibly interfering with milk production.
Pacifiers can be risky for breastfed babies.
When it comes to comforting newborns, they are not right for the job, and mothers should avoid them until breastfeeding is well established, at least for the first three or four weeks. Pacifiers should not be offered to babies who are having trouble learning to latch on or to suck correctly, or to babies whose mothers are concerned about their milk supply or about their baby fussing at the breast. Instead, newborns who need to suck should be offered mother's breast. Some babies will nurse almost continuously, or for long periods of time in their first few days. This is good for them.