There are a couple of soft spots on a baby’s head — fontanelles. Pediatricians always examine them on infants. And parents may have questions.
Why do babies have soft spots?
They are needed, firstly, to make it easier for the baby to pass through the birth canal (the bones of the skull are movable and can slide on top of each other so that the head becomes narrower).
And secondly, they provide space for a rapidly growing brain in the first year of life.
My baby only has one fontanelle, instead of two. Why?
Newborns actually have four fontanelles. The largest one is on the top of the head, shaped like a rhombus, between the two frontal and two parietal bones.
There’s also a small fontanel on the back of the head, about 0.2-0.3 inches (5-7 mm), and two very small ones on the sides.
The side fontanelles usually close right after birth, and the small one at the back closes around two months of age, so it’s normal if you can’t find it. Doctors will monitor the anterior fontanel for about a year [1].
What is the average size of the anterior fontanelle?
There isn't a single average size for normal fontanelles, as it varies by region. On average, the anterior fontanelle size is:
1 inch (2.5 cm) in the Asian region
1.24 inches (3.15 cm) in the African region
0.93 inches (2.35 cm) in the Americas
0.79 inches (2 cm) in Europe [2]
In the first months of life, this soft spot on the top of the head may not decrease but rather increase as the baby's brain grows quickly, causing the bones to move apart to provide the necessary space [1].
When should the anterior fontanelle close?
For about 40% of infants, the anterior fontanelle closes around their first birthday. By the age of two, it should be closed in all healthy children [1].
Is early closure dangerous?
Early closure can interfere with brain growth and development [2] or indicate endocrine disorders [1].
However, if the fontanelle closes around three months, it may not be a cause for alarm. The doctor will examine the baby to rule out any pathologies. Sometimes the fontanelle may appear closed but is still open, which can be determined with an X-ray [1] or ultrasound [3].
What does a sunken or convex fontanelle mean?
A sunken fontanelle can indicate dehydration, but it's more reliable to monitor how your baby is filling diapers and eating.
A convex fontanelle can be a sign of increased intracranial pressure and may indicate a genetic or infectious disease [1, 2].
However, if the baby is cheerful and not showing any signs of distress, it may just be a peculiarity. Regardless, it's important to discuss any concerns with a pediatrician right away.
What should I do if the fontanelle is pulsating?
A pulsating fontanelle is normal. It's more noticeable when you hold the baby vertically than when they are lying down.
Photo: shutterstock
