Flat Head Syndrome Plagiocephaly Brachycephaly

Overview

Flat head syndrome is the everyday name for two common shapes a baby's head can develop when it rests on the same spot too often. Plagiocephaly (say: play-jee-oh-SEFF-uh-lee) means one side of the back of the head is flattened, so the head looks a little uneven or lopsided when seen from above. Brachycephaly (say: brack-ee-SEFF-uh-lee) means the whole back of the head is flattened, making the head look wider and shorter than usual. Some babies have a mix of both. The important thing to know is that this is about the shape of the skull, not the brain inside it. In most babies the head shape improves on its own as they grow and start to sit, roll and move around.

Yes, it is very common. Some studies suggest that around 1 in 5 babies have some flattening of the head by about 4 months of age, and many of these cases are mild and settle without any treatment.

It affects babies, especially in the first 6 months of life when the skull is soft and grows quickly. It is more common in babies who were born early, twins or multiples, babies who always lie in the same position, and babies with a stiff neck muscle (called torticollis) that makes them prefer turning their head one way. It is not caused by anything a parent did wrong.

Symptoms

Common symptoms

• A flat patch on one side of the back of the head, or a flat area across the whole back of the head
• The head looks uneven or lopsided when viewed from above
• One ear may sit slightly further forward than the other
• The forehead may look a little more pushed forward on one side
• Hair may grow unevenly over the flat area
• A baby who tends to look or turn towards one side most of the time

Symptoms in children

• Head shape differences are usually noticed by parents or a health visitor in the first few months
• Some babies with flattening also have a tight neck muscle, so they find it hard to turn their head both ways
• A flat spot can sometimes make it harder for a baby to practise turning their head, which can keep the flattening going
• Most babies are completely well in themselves — feeding, playing and developing as normal

Symptoms in older adults

• This is a condition of babies and young children. Adults are not affected by flat head syndrome in the same way.
• An adult whose head shape changed suddenly, or who has new head pain, swelling or tenderness, should see a doctor promptly — that would not be flat head syndrome.

Causes

Main causes

• Pressure on the same part of a soft, growing skull — usually from lying in the same position
• Sleeping on the back, which is the safest sleep position but can lead to flattening if the head rests on one spot for long periods
• Long stretches in car seats, bouncers, swings or prams, where the head stays against a firm surface
• A tight neck muscle (torticollis), which makes a baby prefer turning their head to one side
• Being born early, because the skull is softer and the baby spends more time lying down

Risk factors

• Being a first baby, or one of twins or multiples
• Premature birth or low birth weight
• A preference for lying with the head turned to one side
• Limited tummy time or limited time being held upright
• A tight or shortened neck muscle
• Needing a longer stay in hospital or time in special care

When to see a doctor

See a doctor urgently if:

• Your baby seems unwell in themselves — poor feeding, very sleepy, or a high temperature
• Your baby cannot or will not turn their head to one side, or seems in pain when they do
• The head shape is changing quickly, or one side of the face looks different from the other
• You notice a hard, raised ridge along one of the joints of the skull
• Your baby seems to be missing developmental milestones, such as not holding their head up

Book a routine appointment if:

• You are worried about the shape of your baby's head at any point — it is always fine to ask
• The flattening does not seem to be improving by around 5 to 6 months
• You would like advice on tummy time, carrying positions or safe sleep
• Your baby always turns their head to the same side

Diagnosis

Usually no special tests are needed. A doctor or health visitor will look at your baby's head from above and from the side, feel the skull gently, check how your baby turns their head and neck, and ask about sleeping and feeding habits. They will also check that the skull joints feel normal, to rule out a rare condition called craniosynostosis (say: kray-nee-oh-sin-oh-STOH-sis), where the skull bones join up too early. Measurements of the head are taken at routine baby checks, and these help show whether growth is on track.

Tests that may be done

• Physical examination of the head, neck and face
• Head circumference measurement, plotted on a growth chart
• Watching how your baby moves their head and neck in all directions
• Questions about sleep position, car seat use and tummy time
• Rarely, a scan of the skull — but only if the doctor suspects the skull joints are closing early or is unsure about the shape

What to expect at your appointment

The appointment is usually quick and gentle. Your doctor will talk you through what they see and whether they think it is mild or needs a closer look. Many babies are simply monitored with a follow-up in a few weeks or months. If a neck muscle tightness is found, you may be referred to a physiotherapist who can show you simple stretches and handling tips. If there is any concern about the skull joints, you may be referred to a specialist team.

Treatment

For most babies, treatment is about changing daily habits rather than medical procedures. The aim is to take pressure off the flat area and give the head time to round out naturally, while keeping sleep safe. Because the skull is soft and growing, small changes made early often make a big difference.

Self-care at home

• Give your baby tummy time every day while they are awake and you are watching — start with a minute or two and build up gradually
• Alternate the direction your baby lies in the cot, so they turn their head different ways to look at you or the room
• Change the position of the cot or the way your baby faces in it every few days
• Hold your baby upright and carry them in different positions during the day, taking pressure off the back of the head
• Limit long stretches in car seats, bouncers, swings and prams when your baby is not travelling
• When your baby is awake and supervised, try side-lying play and different positions
• Keep following safe sleep guidance: baby on their back, on a firm flat mattress, with no pillows, wedges or head-shaping cushions

Medical treatments

If a tight neck muscle is found, a physiotherapist can teach you gentle stretches and handling techniques to help your baby turn their head more freely. Some families ask about helmet therapy — a custom-made helmet worn for part of the day to guide head shape. Evidence for how well it works is mixed, and it is not routinely offered in most health services; it is sometimes considered for moderate to severe flattening that has not improved with positioning, and would be discussed with a specialist. Any decisions about treatment should be made with your baby's healthcare team, who will explain the benefits and limitations.

When is surgery considered?

Surgery is not used to treat ordinary flat head syndrome. It may be considered only in the rare situation where the skull joints have closed too early (craniosynostosis), which is a different condition. A specialist team would explain this in detail if it were ever suspected.

Living with this condition

Day to day, you can fold small changes into your normal routine — a few minutes of tummy time, swapping which end of the cot your baby's head goes, and carrying them upright more often. These small habits add up. Try not to spend the day watching the flat spot; instead, check the shape every couple of weeks so you can see gradual changes rather than day-to-day ones.

Lifestyle tips

• Build tummy time into nappy changes or playtime so it becomes automatic
• Use a sling or carrier for some of the day, which keeps pressure off the back of the head
• Alternate sides when feeding and when cuddling
• Keep up with your baby's routine health and development reviews
• Take photos from above every few weeks if it helps you track progress — but not too often

Diet and exercise

There is no special diet for flat head syndrome. Feeding your baby as usual — breast milk or formula — supports normal growth, and a growing brain and skull are what help the head shape round out. For exercise, think of tummy time as your baby's workout: it strengthens the neck, shoulders and arms and takes pressure off the back of the head. Short, frequent sessions are better than one long one, and always stay with your baby during tummy time.

Mental health and emotional wellbeing

Many parents feel worried, or even guilty, when they notice a flat spot. It helps to know this is common and is not caused by anything you did wrong — the back-sleeping advice that protects babies from sudden infant death is exactly why flattening happens sometimes. If you are feeling anxious or low, or you are checking your baby's head constantly, talk to your health visitor or doctor. Support is available, and sharing your worries usually makes them feel lighter.

Prevention

You cannot fully prevent flat head syndrome, and it is not your fault if it happens. What you can do is reduce the time your baby's head rests on the same spot: plenty of supervised tummy time, varied positions when awake, carrying your baby upright, and changing the direction they face in the cot. The most important safety point is that these changes should only happen while your baby is awake and watched. Always place your baby on their back to sleep, and never use pillows, positioners or head-shaped cushions — these increase the risk of sleep accidents.

Screening programmes

There is no specific screening test for flat head syndrome, but head shape and head size are checked at routine baby reviews, such as the newborn check and the reviews in the first few months. These appointments are a good chance to raise any worries.

Complications

If left untreated

• For most babies, nothing — the shape gradually improves as they grow and move more
• Some children keep a mild unevenness of the head shape, which is usually hidden by hair and causes no problems
• Rarely, more noticeable flattening can affect how glasses or helmets fit later, or how the jaw lines up — this is uncommon and would be discussed with a specialist
• If a tight neck muscle is not addressed, a baby may keep preferring one side, which can delay rolling or head control
• Very rarely, flattening is due to early joining of the skull bones, which needs specialist care

Long-term outlook

The outlook is very good. Most babies with flat head syndrome see their head shape improve steadily over the first year or two, especially once they can sit, crawl and spend less time lying down. Even when a small difference in shape remains, it is usually mild and does not affect how a child learns, plays or grows. If you have any worries along the way, your health visitor or doctor can check things and reassure you.

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