Fontanelles are the soft spots on a newborn's skull where several cranial bones meet. These spaces are made of tough, fibrous connective tissue. They allow the rigid plates of the skull to overlap during birth, helping the baby pass through the narrow birth canal safely without brain injury. After birth, fontanelles provide the necessary room for rapid brain growth during infancy. Without these flexible gaps, the growing brain would face severe pressure constraints.
A healthy newborn has several fontanelles, but two major ones stand out for clinical assessment:
Assessing fontanelles requires patience and a gentle touch. Always examine the infant while the baby is quiet and resting in an upright or semi-upright position. Crying, vomiting, or lying flat can temporarily cause a false bulge. Use the pads of your clean fingers to gently palpate the skull. Feel for the size, contour, and tension of the membrane. Document whether the area feels flat, sunken, or raised.
Fontanelles do not close all at once. Each specific gap has its own expected timeline for bone ossification:
A sunken fontanelle often points toward dehydration, which is a frequent concern in pediatric wards due to severe diarrhea or vomiting. Conversely, a tense, bulging fontanelle suggests increased intracranial pressure. This pressure buildup can stem from hydrocephalus, meningitis, or intracranial hemorrhage. Nurses must report these abnormal findings immediately to the attending physician.
Abnormal timing of fontanelle closure reveals underlying health issues. Delayed closure or an unusually large anterior fontanelle can be a sign of rickets, hypothyroidism, or increased intracranial pressure. On the other hand, premature closure, known as craniosynostosis, restricts brain expansion and causes misshapen skulls unless surgically corrected.