Hi... a friend of mine has a 5 month old baby and I have a 18 month old baby and I saw that her 5 month olds pacifier is the same size as my 18 month old... so I was just wondering will that do anything to that babies mouth being that the 5 month old is sucking a pacifier meant for a 18 month old please let me know thanks..

It might. My son had a pacifier for a long time. 18 month size up until about 4 years (I know he was too old) when we took him into the dentist the roof of his mouth developed a strange curve as well as his teeth began to have an arch appearance. She told us to stop the pacifier. And within about 6 months his roof of his mouth and teeth improved to a normal shape.

If you plan on continuing the paci I would use the appropriate size to avoid my sons situation.

I have learned that the pacifier is a miracle worker in comforting a child but should be taken away at an age when they are unable to protest.