Some babies start sucking their thumbs or fingers as newborns, while others never have the desire to put their fingers in their mouths. Don't worry about it at this age. Even if your child continues for years to suck her thumb, she will eventually only do it when she sleeps or is very tired.

If you are concerned that your child's thumb-sucking is getting in the way of her learning to speak or using her hands, try not to take her hand out of her mouth or make her conscious of what she's doing. Instead, say something like, “I can't understand you with your thumb in your mouth,” which gives her the choice to remove his thumb.

Keep in mind that pacifiers are different from thumbs. The World Health Organization recommends against pacifier use because it requires the parent to supply something to the child rather than letting the child independently develop the habit of soothing herself. While sucking is a natural reflex, a pacifier is not natural. The pacifier may signal to a one-year-old that crying is unacceptable, even though crying is one of a one-year-old's few means of communication.

Some people also believe that thumb-sucking is an easier habit to break than pacifier use. At this age, you might want to consider weaning your child from the use of a pacifier. If your child uses a pacifier a lot, try to decrease the amount of time it is available to her. Most daycare centers and schools will discourage the use of a pacifier.

One unintended consequence of thumb-sucking is irritation of the skin, caused by the constant moisture and the friction of teeth and tongue. You may need to put an adhesive bandage on your one-year-old's thumb if the irritation gets red and painful. If you use lotion to soothe your one-year-old's skin, be sure it is safe for him to ingest and contains no petroleum byproducts or other toxic chemicals. If the skin gets too raw, talk to your doctor about creams or ointments that are safe to use (even if they end up in your child's mouth).

The taste of the lotion or the presence of a bandage will discourage thumb-sucking to an extent (although your child may be one of the rare children who will suck either thumb, not just one). You might need to alternate these solutions with time for her to suck her thumb, keeping in mind that your child is sucking her thumb as a way of reassuring and soothing herself. Try not to make the irritation a source of conflict. The calmer you are about the thumb-sucking, the easier it will be for your child to give it up when she needs to.