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  • Writer's pictureDr Andy Raffles

Closure of the Fontanelle (soft spot on the skull)

Updated: Aug 8, 2019

The soft spot or fontanelle is another example of the amazing design of the human body. At birth there are several fontanelles or soft spots, but the front or anterior fontanelle is the largest. The loose connections of the skull bones that intersect in the soft spots make labour and delivery possible. Without this flexible anatomy, either human babies would have to have smaller brains or human mothers would have to have wider hips if babies were to be born.

The skin over the soft spot is strong and consists of a surprisingly tough fibrous membrane layer, protecting the brain underneath, and covered in skin. You cannot hurt babies by gently washing or brushing their heads. Sometimes the fontanelle swells when the baby is crying and goes flat when the crying stops – this is quite normal. It also functions as a shock absorber if the baby bangs it’s head, the soft spot cushions and protects - making the skull function rather like a cycle helmet.

At birth, babies' soft spots come in a very wide range of sizes. If the soft spot is small, it will usually enlarge over the first several months. Equally, large ones tend to get smaller. By the time a baby is several months old, the anterior fontanelle is usually still easily felt. A persistent, larger anterior fontanelle is usually completely fine, providing development and other features of the baby are normal. It may rarely be associated with a variety of uncommon disorders, but in that case there is nearly always other obvious problems and the delayed closure or large fontanelle is just one of many features which may be associated with something more significant.

For most children the anterior fontanelle closes not long after they become steady on their feet (at 9 to 18 months). It stays open just long enough to protect them as they stumble their way towards walking on their own. An open fontanelle at any age, if not associated with some other findings usually has no significance at all. If you are concerned, or a health care worker has made a remark regarding something to do with your baby’s fontanelle – i.e. too big, too small, closed early, closed late – seek an expert opinion from your GP, or ask one of our Paediatricians to see your baby.

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