New mothers are encouraged to breast feed their newborns for the nutritional benefits.  Encouragement comes from the American Academy of Pediatrics (AAP), the American College of Obstetrics and Gynecology (ACOG), and The World Health Organization (WHO); not to mention family and friends.
For a new mother experiencing difficulty with breast feeding, "advice" is abundant and often conflicting. A 2011 review has shown that the use of a pacifier does not affect breast feeding success up to 4 months of age. The review can be found at:  http://www2.cochrane.org/reviews/en/ab007202.html