A baby is born with several fontanels. These are more commonly known as soft spots. They provide the skull with the flexibility needed to pass through the birth canal. This flexibility also allows your baby’s brain and skull to grow during the first year of life. In newborns, soft spots are found on the top, back, and sides of the head.
The number of soft spots on your baby’s head depends on their age. The fontanel on the back of the head usually disappears by 1 to 2 months of age. You may never be able to feel or see this one. The one on the top of the head remains present until your baby is between 7 and 19 months old.
A baby’s soft spots should be relatively firm and curve ever so slightly inward. A soft spot with a noticeable inward curve is known as a sunken fontanel.
This condition requires immediate medical attention. It’s usually easy to treat.
There are several potential causes of sunken fontanel.
- Dehydration: Dehydration takes place when your body loses more fluid than you drink. The most common cause of water loss from the body is excessive sweating. Read more about dehydration here. This condition is considered a medical emergency. Urgent care may be required.
- Kwashiorkor: Kwashiorkor is a serious form of malnutrition caused by a lack of protein. Learn how to spot this condition and how to prevent it.
- Failure to thrive: A child is said to have failure to thrive when they don't meet recognized standards of growth. Find out more about how failure to thrive is defined and treated here.
- Toxic megacolon: Toxic megacolon is a rare, life-threatening widening of the large intestine and is usually a complication of inflammatory bowel disease (IBD). Learn about the symptoms, diagnosis, and treatment of toxic megacolon here. This condition is considered a medical emergency. Urgent care may be required.
- Diabetes insipidus: Diabetes insipidus (DI) is not a form of diabetes. Instead, it's a rare condition that occurs when your kidneys are not able to conserve water. Find out how this condition is diagnosed and treated.
If your baby has a sunken fontanel, you should seek medical attention as soon as possible. This isn’t a symptom you should try to treat at home.
When the doctor examines your baby, they’ll first do a physical examination. This includes looking at and feeling the affected area. The doctor will also likely assess your baby’s skin elasticity, or turgor. Poor elasticity can also be a sign of low fluid levels. The amount of moisture in the eyes and mouth can also provide clues about your baby’s level of hydration.
Second, the doctor will ask you about your baby’s symptoms. It’s important to provide as much information as possible. The doctor will likely want to know when the problem appeared and how you would rank the severity of the symptom considering the normal appearance of your baby’s soft spots. Note whether the baby has been sick recently or if the baby recently had any bouts of vomiting or diarrhea. Tell the doctor if there was a recent period during which your baby perspired more than usual, if your baby seems thirsty, and whether your baby’s level of alertness seems normal.
The doctor may then order one or more tests. These might involve taking a blood or urine sample. Specific tests may include a complete blood count (CBC). This blood test measures the number of red and white blood cells as well as their components to detect infection or anemia, which can occur with dehydration. A urinalysis involves a number of tests to check urine for abnormalities that might indicate dehydration.
Another test you may need is a comprehensive metabolic panel. This blood analysis involves a number of tests that assess how well various chemicals in the body are breaking down and using food. It can help detect malnutrition.
If dehydration is the confirmed cause of a sunken fontanel, your baby will either receive fluids by mouth if they aren’t vomiting and are alert or through an intravenous (IV) line inserted into their arm. This will likely bring fluid levels in the body back up to where they should be. If malnutrition is the cause, your baby will likely receive oral or IV nutrients as well as fluids.
The best way to prevent a sunken fontanel is to prevent the most common cause of it, which is dehydration. Some tips to prevent dehydration include giving your child adequate amounts of fluids and seeking medical help if you have a sick baby who you believe is in danger of becoming dehydrated. You should also increase the amount of fluids given as soon as your baby vomits or has diarrhea.
Check with your child’s doctor if you have questions about breast-feeding or how much formula to give your baby. Talk to your doctor if you’re breast-feeding and you think you might have trouble with your breast-milk supply. You can also contact breast-feeding support groups or explore the option of supplementing your breast-milk supply with formula.