The American Academy of Family Physicians recommends introducing your baby to the sippy cup around the same time that you introduce solid food, probably around six months, so that she can get used to the idea of liquid coming from somewhere besides a bottle or breast. your baby probably won’t feel ready to start using the sippy as her main source of liquid for a while after that, until her grip strengthens and improves. The American Academy of Pediatrics recommends switching your baby to a regular cup by around her first birthday, though, and using a sippy can be a way of getting that process started.
Introducing sippy cups is one thing, but transitioning towards using them instead of bottles may be quite another. If your baby feels attached to her bottle, she may object to losing it, and may refuse to drink from the sippy cup. Whether you transition your baby away from the bottle gradually or go cold turkey, it’s important to pick a method and stick with it.
If you choose a more cold turkey approach, and your baby is old enough to comprehend a bit of what you’re saying, it may work better if she is given some warning before bottles leave the picture. In the case of a more gradual transition, starting with replacing the mid-day bottle with a cup, then the morning bottle, and lastly the evening, may go the smoothest. A gradual easing off of bottles can be taken at whatever speed you think may work best for your baby.
Several speech pathologists have spoken out against sippy cups with plastic spouts, saying that they may cause lisping or other speech problems. They tend to propose sippy cups with straws as an alternative.
Sippy cups are designed to be a relatively short-lived piece of transitional dishware between bottles and regular cups, and if they’re used for too long instead of moving on to the next step, they can cause a lot of the very issues you’re transitioning your baby off of bottles to get away from, including the potential for dental problems.
Baby bottle mouth (tooth decay starting on the backs of children’s front teeth due to sugars from liquids in bottles and sippy cups getting trapped in the space behind the teeth) is still a concern with sippy cups. Beyond that, though, the position of the hard-plastic sippy cup mouth against your baby’s baby teeth for too long could cause even her adult teeth to shift in response.
The American Dental Association recommends transitioning your baby from a sippy cup to a regular cup at around a year old.