When you’re a new parent, you learn that you need to protect that soft spot, or fontanelle, on your baby’s head. It rarely requires much attention, but it reminds you just how fragile your infant is.
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That’s why, if something changes — is the soft spot sunken in a little? — you may worry there’s something wrong.
“It is a good indicator of the baby’s potential hydration status and brain status,” she says. “It’s like an automatic pressure sensor.”
What is the fontanelle?
The fontanelle is the space between different plates of a baby’s skull that will eventually come together. This aspect of an infant’s skull structure typically allows for easy delivery through the birth canal and for rapid head growth during the first year of life, Dr. Recinos says.
There are actually two soft spots — one at the back of the head and another on top. The posterior one closes within a few months of birth, while the top fontanelle typically remains until just past a child’s first birthday.
Dr. Recinos explains what changes in the fontanelle can tell you about your infant’s health.
Sunken in soft spot
This is often a sign of dehydration, she says. It may occur if your child is sick and not getting enough fluids.
What you should do: See your pediatrician if the sunken appearance persists and you can’t get your baby to take in more fluids.
Swollen soft spot
After a fall, a swollen soft spot (particularly if it’s accompanied by vomiting) is sometimes a sign of head trauma.
What you should do: Seek medical treatment right away.
Bulging soft spot
Fluid buildup (hydrocephalus) can cause rapid head growth and can make the soft spot look “full,” Dr. Recinos says.
A bulging fontanelle also might signal internal bleeding or a tumor or mass causing pressure in the head.
What you should do: If their soft spot is bulging, that’s a reason to seek care from your pediatrician, she says.
Seek emergency care if your infant exhibits fatigue, vomiting or unusual mental status along with the fontanelle’s fullness. Treatment for these conditions may include surgery to insert a shunt that relieves fluid buildup or to remove any underlying mass, Dr. Recinos says.
Disappearing soft spot
Most of the time the soft spot is obvious, particularly on a newborn. But at times it can seem to disappear quickly.
This may scare parents, but it typically means it’s just a “quiet fontanelle,” not that it has fused together prematurely, Dr. Recinos says.
As long as your child’s head is growing normally, all is probably well, she says. But your pediatrician may suggest an imaging test to make sure the fontanelle is still open.
Occasionally, though, the skull bones do close earlier than normal on one side, causing craniosynostosis. Depending on which bones fused, the baby may develop an abnormal head shape. For example, sagittal craniosynostosis, the most common form, results in a longer head that is shaped somewhat like a football.
What you should do: Children with craniosynostosis may need surgery to open the fused bones and reshape the skull. In some cases, the child will wear a helmet afterward until the site heals and the head shape normalizes.
Soft spot that doesn’t close
If the soft spot stays big or doesn’t close after about a year, it is sometimes a sign of a genetic condition such as congenital hypothyroidism.
What you should do: Talk to your doctor about treatment options.
The bottom line? If you have any questions or concerns about your baby’s soft spot, it’s a good idea to check in with your pediatrician to make sure all is well.