Plagiocephaly (flat head syndrome)

Plagiocephaly is a flat spot on one side of the back of a baby's head. It is very common, and usually happens because babies spend a lot of time lying on their backs, which is the safest way for them to sleep. Related shapes include brachycephaly (flat across the whole back of the head) and scaphocephaly (long and narrow).

Positional flattening affects head shape only. It does not affect your baby's brain development.

Common signs

• A flat area on one side or the back of the head
• One ear or one side of the forehead pushed slightly forward
• Your baby always turning their head to the same side (sometimes because of tight neck muscles, called torticollis)

What helps

For mild flattening, simple changes often help:

• plenty of supervised tummy time while your baby is awake
• changing which way your baby faces in the cot, and how you hold and feed them
• physiotherapy if your baby has tight neck muscles

When a helmet may help

If the flattening is moderate to severe, or isn't improving with repositioning, a custom cranial remoulding helmet can guide the head towards a more even shape while it grows. Helmets work best when started at around [4–6 months]. We measure your baby's head [with a quick, painless 3D scan], explain the results, and tell you honestly whether a helmet is likely to make a difference. [Link: see our helmet service page for what treatment involves.]

When to see a doctor

Ask your doctor to check your baby if:

• the head was an unusual shape from birth, or is getting worse despite repositioning
• you can feel a hard ridge along part of the skull
• the soft spot (fontanelle) seems to have closed very early
• you have any concerns about your baby's development.

These can be signs of craniosynostosis, a different condition that needs a specialist.