Babies sometimes develop a flattened head when they're a few months old, usually as a result of them spending a lot of time lying on their back.
This is known as flat head syndrome, and there are 2 main types:
These problems are quite common, affecting around 1 in every 5 babies at some point.
In most cases they aren't a major cause for concern, as they don't have any effect on the brain and the head shape will often improve by itself over time.
Your baby won't experience any pain or other symptoms, or any problems with their general development.
The skull is made up of plates of bone that strengthen and join together as a child gets older.
A young baby's skull is still relatively soft and can change shape if there's constant pressure on a particular part of their head.
Reasons why this may happen include:
Occasionally, a flattened head can be caused by the plates of the skull joining together too early. This is known as craniosynostosis.
Speak to your health visitor or GP if you're concerned about the shape of your baby's head or think they may have problems turning their head.
They can examine your baby's head and suggest things you can do to help.
A slightly flattened head isn't usually anything to worry about, but it's a good idea to get advice early on so you can take steps to stop it getting any worse.
The shape of your baby's head should improve naturally over time as their skull develops and they start moving their head, rolling around and crawling.
To take pressure off the flattened part of your baby's head:
If your baby has difficulty turning their head, physiotherapy may help loosen and strengthen their neck muscles.
Corrective surgery may be needed if they have craniosynostosis.
There are specially designed helmets and headbands that some people claim can help improve the shape of a baby's skull as they grow.
These devices apply pressure to "bulging" parts of the skull and relieve pressure from other parts, potentially allowing growth in the flatter areas.
Treatment is started when the child's skull is still soft, usually at around 5 or 6 months old, and the device is worn almost continuously (up to 23 hours a day) for several months.
But these helmets and headbands generally aren't recommended because:
Some people try special curved mattresses that are designed to distribute the weight of a baby's head over a larger area so less pressure is placed on a particular point of their skull.
These are cheaper than helmets and headbands, but there's currently only limited evidence to suggest they may help.
Mild flattening of the head will usually improve if you use the simple measures described on this page, although it may be a couple of months before you start to notice an improvement.
Your baby's head may not return to a completely perfect shape, but by the time they're 1 or 2 years old any flattening will be barely noticeable.
More severe cases will also get better over time, although some flattening will usually remain.
The appearance of your child's head should improve as they become more mobile and their hair grows.
It's very rare for a child to experience problems such as teasing when they reach school age.
You may consider using a helmet or headband if you're worried about your child, but it's not clear whether these always work.
You should also bear in mind the inconvenience, expense and possible discomfort for you and your child.