How long does it take for an infant’s anterior fontanelle to close completely?

Everyone is born with fontanelles—how much do people actually know about them? How long does it take for a fontanelle to fully close? Many may not be entirely clear on this. So, how long does it take for an infant’s fontanelle to close completely?

How Long Does It Take for an Infant’s Fontanelle to Close Completely?

An infant’s anterior fontanelle typically closes between 12 and 18 months of age. Fontanelle closure serves as an important indicator of brain development, and parents should closely monitor its status. Generally, the anterior fontanelle closes no later than 18 months after birth. However, in some infants, closure may occur as early as 5–6 months. A normal anterior fontanelle appears flat or slightly depressed and pulsates gently in synchrony with the infant’s heartbeat; light palpation commonly reveals a soft, yielding sensation. Premature closure before 6 months may suggest microcephaly or impaired brain development, whereas delayed closure beyond 18 months may indicate underlying conditions.

Infants with delayed fontanelle closure may be at increased risk for hydrocephalus, rickets, or other disorders. If the fontanelle appears bulging, intracranial pressure may be elevated—a potentially dangerous condition. Note: In traditional Chinese medicine (TCM), “Tianlinggai” (literally “heavenly spirit cover”) refers to the calvaria—the top portion of the skull—and is also used as a medicinal ingredient. Anatomically, the “Tianlinggai” corresponds to the cranial vault—the bony structure covering the top of the head—which provides essential protection for the brain.

The cranial vault is one of the most vital skeletal structures in the human body. Damage to it poses severe, life-threatening risks. It is also the strongest bone in the human body, composed of six bones: the frontal, temporal, parietal, occipital, sphenoid, and ethmoid bones—hence it is sometimes referred to as the “six-bone skull.” We hope this explanation has been helpful!