The posterior fontanel should be completely closed by?

The posterior fontanel, which is located at the back of an infant's skull, typically closes by the age of 2 to 3 months. While there may be slight individual variations, the general consensus in pediatric development is that the closure occurs around this timeframe. This closure is an important developmental milestone, as it signifies that the bones of the skull have fused adequately to provide protection for the developing brain.

In contrast, the anterior fontanel, located at the front of the skull, remains open for a longer period, usually until about 12 to 18 months of age. Monitoring the closure of both fontanels is crucial for healthcare providers to assess the growth and development of an infant's cranial structure and overall health.