The anterior fontanelle typically closes between about 7 and 18 months of age, with most sources indicating an average closure around 12 to 14 months. Some variation exists, with closure occurring as early as 4 months and as late as 24 months or even a bit beyond in some cases. The closure time can be influenced by factors such as sex (tending to close earlier in males) and ethnicity. If the fontanelle closes too early or remains open too long, it may indicate medical conditions requiring pediatric evaluation.

Details on Anterior Fontanelle Closure:

• Most commonly closes between 9 and 18 months, averaging 12 to 14 months.
• Some infants may have closure as early as 4 to 6 months or as late as 24 months.
• Boys tend to have earlier closure than girls.
• Closure outside normal ranges can indicate conditions like craniosynostosis (early closure) or hypothyroidism, Down syndrome, or increased intracranial pressure (delayed closure).
• Pediatricians monitor fontanelles during routine exams to track proper closure and head growth.

In summary, the typical timeframe for anterior fontanelle closure is within the first year to a year and a half of life, but with normal variation from under 6 months up to around 24 months or slightly more.