Certified Pediatric Nurse (CPN)

Which of the following assessment findings are normal in a healthy 6 month old?

1. Closed anterior and posterior fontanel

2. Open anterior and posterior fontanel

3. Closed anterior and open posterior fontanel

4. Open anterior and closed posterior fontanel

The correct answer is: Open anterior and closed posterior fontanel

For a healthy 6-month-old infant, the assessment finding of an open anterior fontanel and a closed posterior fontanel is typical. At this age, the posterior fontanel, located at the back of the baby's head, usually closes by 2 to 3 months of age. By the time a child reaches 6 months, this fontanel should be closed, indicating normal development and the healthy progression of skull growth. Conversely, the anterior fontanel, which is the larger soft spot on the top of the baby's head, typically remains open until around 12 to 18 months. It allows for the rapid growth of the brain during the first year of life. Therefore, it being open at 6 months is also a normal finding and essential for accommodating the growing brain. Closed anterior and posterior fontanels suggest an advanced maturation that is not typical at 6 months, while an open posterior fontanel is not common for this age, reinforcing why the open anterior and closed posterior fontanel is the normal finding in a healthy 6-month-old.