A: Jan, although your baby's wiggling is unnerving, it's probably normal and just a phase that she'll outgrow. Most young children have a little trouble falling asleep and need a calming bedtime ritual. Some children fall asleep after their parents give them a bath, book, song, and a kiss; and others have a self-soothing habit such as sucking their thumb, using a pacifier, twirling their hair, or wiggling their bottom.

When babies have a habit of wiggling their bottoms when going to sleep, it is often a form of masturbation or self-stimulation of the genitals for comfort or pleasure. This is nothing to be alarmed about. In fact, masturbation is normal and healthy, and it often begins in the toddler and preschool years. Children most often do it when they're sleepy, bored, or watching television. Since it's normal, you don't need to do anything to stop it—simply leave her to fall asleep. If it really bothers you, however, you could try offering her a blanket or cuddly toy instead to help her fall asleep.

Common causes of babies wiggling their bottoms:

• Diaper rash: If your baby has redness around her bottom, consult your doctor for treatment.
• Sensitivity to soap: Some soaps with perfumes and antiperspirants, or bubble bath, can irritate baby girls' vaginas. If you're using one of these soaps or bubble bath, stop and switch to a baby soap and see if it helps.
• Pinworm infection: Young children can get an infection of pinworms, an intestinal parasite. At bedtime, the worm crawls out of the child's anus and lays its microscopic eggs on the child's bottom, causing itching.
  
  You might notice the ½-inch, white, thread-like worm in her stool; or you can take a flashlight to look at your child's anus after she falls asleep. If you see a pinworm, call the doctor to get the treatment.