Thumb sucking is the childhood habit of putting the thumb in the mouth for comfort or to relieve stress.
About half of all children suck their thumbs during infancy, with most starting in the first weeks of life. Ultrasound pictures of intrauterine life have even shown fetuses sucking their thumbs. One way that infants explore their world is by putting objects in their mouths and sucking on them. Thumb sucking appears to be a natural habit of children in all parts of the world. Sucking the thumb is soothing for a small child, and many children continue this habit for comfort and security into the early school years. Thumb sucking is most prevalent in children under two, and most children give up the habit on their own by age four.
Thumb sucking by itself is not a cause or symptom of physical or psychological problems. It is not known why some children suck their thumbs longer than others. More girls than boys suck their thumbs beyond age two. Researchers speculate that boys receive stronger negative messages from parents and peers that thumb sucking is infantile and not acceptable. Thumb sucking offers security to a child, but this behavior does not imply that the child is insecure. Most children have some sort of self-comforting ritual that may involve sucking the thumb, fingers, or a pacifier, pulling or twisting their hair, or stroking or sucking a soft toy or blanket. These are all normal habits of infancy that are eventually outgrown.
Some nineteenth-century physicians feared a variety of consequences from thumb sucking, such as weak moral character, and earlier generations of parents were advised to break this habit forcibly. Parents were sometimes told to place mechanical constraints on their children's hands to keep their thumbs out of their mouths. Children's thumbs were sometimes coated with a bitter substance, taped, or covered with gloves. It was also considered necessary to shame and humiliate the thumb sucker.
Modern doctors find few negative health effects of thumb sucking, even if prolonged, and parents are urged to let their children outgrow the habit on their own. Thumb sucking may be more of a problem for the parent than the child, if the parent is unsettled by the behavior. Weaning a young child from the habit before he or she is ready is usually difficult and may only prolong the thumb sucking.
Some children suck their thumbs before they are even born, and others begin sucking their thumbs soon after birth. All or nearly all infants suck on their fingers, thumbs, or a pacifier. This is completely normal and very common.
Thumb sucking is most common in children who are younger than two years old. Many children stop sucking their thumbs by age three or four without any intervention.
Preschool children may begin to become embarrassed by their thumb sucking if the children with whom they interact do not suck their thumbs and make fun of them. Most children in this age group who still suck their thumbs will stop on their own, and intervening may stress the child and make the problem worse. Even when they have stopped thumb sucking during the day, children may continue it as part of a nighttime falling sleep ritual.
Most children have stopped sucking their thumbs before they begin school, or else stop sucking shortly thereafter, usually in response to peer pressure . If a school age child seems distressed about his or her thumb sucking, the parent may want to suggest ways in which they can work together to wean the child from the thumb. If the child does not want to give up thumb sucking, the dentist should be consulted to ensure that it is not doing any damage to the alignment of the teeth.
There are a few cases where thumb sucking may become a problem. If a school-age child sucks his or her thumb and is teased by classmates, the child may wish to quit and need help either from parents or a counselor. Some dentists warn of misalignment of permanent teeth if a child of five or six sucks the thumb with a lot of
Parents tend to be more concerned with thumb sucking than is actually warranted. Until the child is five or six, or there starts to be a problem with speech formation or teeth alignment, thumb sucking is not a problem.
When to call the doctor
If the child continues to suck his or her thumb after age five or six, or sucks it frequently or very hard after age three or four, the doctor may have helpful suggestions for the concerned parent. If the child's teeth are becoming misaligned because of thumb sucking the dentist should be consulted. If the thumb sucking is combined with other problems such as anxiety a doctor should be consulted.
Dionne, Wanda. Little Thumb. Gretna, LA: Pelican Publishing Company, 2001.
International Association of Orofacial Myology. 970 Elizabeth Street, Denver, CO 80209. Web site: http://www.iaom.com.
Tish Davidson, A.M.