As a speech therapist who works with kids, I've been asked this question on more than one occasion so I thought I would address this issue here on this blog. From my own experience, I think this is not true and maybe just one of those things that you heard from your mother and she heard from her mother and so on.
I have found a great article on this exact subject and she also think this is a myth. She talks about the pros and cons of your baby/toddler using a pacifier and she does give suggestions for finding other ways to help your toddler self soothe.
In the first part of her article Laura addresses using sippy cups and how this can effect your child's speech and even more so cause dental problems if used too much. Laura's article is worth reading if you are concerned about your toddler using a sippy cup or a pacifier. Her website is teachmetotalk.com and if you follow this link it will take you straight to this article. I'm sure you'll find this article as informative as I did.
