Increased head circumference

Considerations:
Increase in head circumference during infancy and childhood normally represent growth of the brain. Normal growth parameters have been determined by years of measuring infants and children. An increasing head circumference that exceeds the normal and well-established standards is frequently a cause for concern that something is causing the above normal head size other than normal brain growth.As a rule of thumb, a newborn's head is usually about 2 centimeters larger than the chest size. Between 6 months and 2 years old, both measurements are about equal, after 2 years old the chest size becomes larger than the head.

Head circumferences usually are obtained from birth up to 18 months while the head is growing and the bones of the head have not yet fused. These measurements are plotted by the physician on a graph along with the child's height and weight. A series of measurements over time, such as those done during routine well-baby visits, that show an abnormally increased rate of head growth often can provide more valuable information than a single measurement that is larger than expected. The first step is to determine if the increased circumference is simply a normal variant such as coming from a family with a history of large heads or if there is some other cause for the increased size. Once it is determined that the cause is an abnormal condition, then a diagnosis must be made.

See also bulging fontanels .

Common Causes:
Genetic (one or more members of the immediate family with larger than average head sizes
    • familial large head

Although rare, the following are the more common causes of increased head circumference:

  • hydrocephalus - this condition occurs when fluid collects in the ventricles of the brain and around the brain. In infants and children less than 18 months (before the bones of the head fuse together) it can cause a slow to rapid increase in head size. Hydrocephalus can have many causes (congenital, post-traumatic, or obstructive)
  • achondroplasia (a genetic condition with an incidence of approximately 1 in 20,000 to 1 in 25,000 births)
  • neurofibromatosis (a genetic condition with an incidence of approximately 1 in 3000 to 1 in 4000)

The following is a list of extremely rare causes of increased head circumference:

Note: There may be other causes of increased head circumference. This list is not all inclusive, and the causes are not presented in order of likelihood. The causes of this symptom can include unlikely diseases and medications. Furthermore, the causes may vary based on age and gender of the affected person, as well as on the specific characteristics of the symptom such as location, quality, time course, aggravating factors, relieving factors, and associated complaints.

Home care:

Call Your Healthcare Provider If:
There is excessive crying over a period of time and the baby's fontanel is full or bulging ( when he or she is quiet and in a head up position)
(Note: An abnormally large head is a finding that usually is detected by the health care provider during a routine well-baby exam.)

What to Expect:
The medical history will be obtained and a physical examination performed.

Medical history questions documenting increased head circumference in detail may include:
  • time pattern
    • When did you first notice that the baby's head seemed large?
    • Does the baby's head size seem to be increasing faster (in proportion to the growth of the body)?

  • other
    • What other symptoms are also present (especially changes in brain or nervous system functions)?
    • Lethargy or excessive crying

Physical examination may include repeated measurements of the head circumference over a period of time to confirm that the head circumference has significantly increased; however, in some cases a single measurement is sufficient to confirm a significant increase.

Diagnostic tests may vary depending on the suspected cause, but often include:

After seeing your health care provider:
If a diagnosis was made by your health care provider as to the cause of increased head circumference, you may want to note that diagnosis in your personal medical record. You may also want to document your own measurements of the head circumference.


This illustration shows the "sutures" or anatomical lines where the bony plates of the skull join together. These sutures can be easily felt in the newborn infant. The diamond shaped space on the top of the skull and the smaller space further to the back are often referred to as the "soft spot" in young infants.