Fontanels are soft spots on a baby's head which, during birth, enable the bony plates of the skull to flex, allowing the child's head to pass through the birth canal (Wikipedia.com).
There are two kind of fontanels and they vary in size.
The posterior fontanel, on the back of the head, is smaller, triangular in shape, and closes by six to eight weeks of age.
The anterior fontanel, on the top of the head, is larger, diamond shaped, and closes on your baby’s second birthday.
Until they close, it is fine to gently touch them when you give your baby his shower or brush his hair.
They may seem delicate and vulnerable. However the soft spots are covered by a thick membrane that protects the baby’s brain. For no reason you should put direct pressure or push on your baby’s fontanels.
At birth, the pediatrician will check your baby’s soft spots. At home, the fontanels can give you important information about the health of your baby. If you suspect any change in your baby’s fontanel you should inform the pediatrician immediately. A sunken looking fontanel may be the sign of dehydration. A bulging fontanel can be a sign of meningitis or hydrocephalus.
Keep an eye on your baby's fontanels as they can give you an indication of your baby’s health.