Kaplan Obstetrics (OB) Practice Test 2025 - Free OB Practice Questions and Study Guide

The posterior fontanelle, which is the soft spot on a newborn's head located at the junction of the parietal and occipital bones, typically closes within 6 to 8 weeks after delivery. This closure represents the time it takes for the bones of the skull to fuse together, providing added protection to the baby’s brain as it develops.

The closure of the posterior fontanelle is a normal developmental milestone. It occurs earlier than the closure of the anterior fontanelle, which generally closes between 12 to 18 months of age. Understanding the timing of these closures is important for healthcare professionals in monitoring an infant's growth and development, as well as in assessing any potential abnormalities in cranial growth or shape.

This knowledge can reassure new parents that the rapid bone development and changes in the fontanelles are typical during the early weeks of life, ensuring the infant's head can accommodate the growing brain.