Enlarged fontanelles are larger than expected soft spots for the age of a baby.
The skull of an infant or young child is made up of bony plates that allow for growth of the skull. The borders at which these plates intersect are called sutures or suture lines. The spaces where these connect, but are not completely joined, are called soft spots or fontanelle (fontanel or fonticulus).
Soft spot - large
Fontanelles allows for growth of the skull during an infant's first year. Slow or incomplete closure of the skull bones is most often the cause of a wide fontanelle.
For general information, see fontanelles.
Larger than normal fontanelles are most commonly caused by:
If you think that the fontanelles on your baby's head are excessively large, talk to your health care provider. Most of the time, this sign will have been seen during the baby's first medical exam.
An enlarged large fontanelle is almost always found by the health care provider during a physical exam.
Blood tests and imaging tests of the head may be done.