Will using a sippy cup impair my 8 1/2-month-old's speech?
That was just fine to start the cup as you did to have your daughter practice drinking from the cup. There is some evidence, however, that overuse of sippy cups may have similar effects to those associated with overuse, or longterm use, of bottles and pacifiers: It may cause problems with oral development, teeth alignment, and possibly speech.
The biggest concern is how much time a baby
spends with that cup, bottle nipple, pacifier, or thumb in her mouth. As a baby
approaches 9 to 12 months, ideally parents should try to limit the amount of time the child has any of those things in her mouth. So you want to avoid having your daughter cruising around the house with the sippy cup or bottle in her mouth. But certainly offering drinks from the cup at meals or snacks is very appropriate and will not cause problems. Try to wean her from bottles by 1 year or soon after, again for the same reasons to limit how much time she's sucking on those nipples. Also, by that age she should be getting more of her nutrition intake from solid foods and less from breast milk or formula.