Fontanelles are the soft spots between the bones of a baby's skull, which allow the head to pass through the birth canal and the brain to grow. The small one at the back usually closes within the first few months; the larger one on top usually closes between 12 and 18 months.
Key takeaways
- Gently touching the soft spot, for example when washing hair, is safe.
- It may move slightly with your baby's heartbeat.
- A very sunken or bulging fontanelle can be a warning sign.
When to talk to your doctor
Seek urgent medical help if the fontanelle looks very sunken (a possible sign of dehydration) or bulges and stays tense while your baby is calm and upright, especially with fever, vomiting or unusual sleepiness.
