New research suggests that lengthy use of pacifiers can cause speech problems. Breastfeeding is associated with positive developments in speech:
The authors of the study noted that other research suggests that use of a pacifier or thumb-sucking for less than three years also increases the risk of a speech problem. The sucking motion may change the normal shape of the dental arch and bite. Breastfeeding, however, seems to promote positive oral development.
“The development of coordinated breathing, chewing, swallowing and speech articulation has been shown to be associated with breastfeeding. It is believed that breastfeeding promotes mobility, strength and posture of the speech organs,” the authors wrote.