What Is Flat Head Syndrome?



What Is Flat Head Syndrome? Causes, Types and Helmet Treatment

Quick answer: Flat head syndrome is flattening of part of the baby's skull caused by repeated or sustained pressure. Two main types: plagiocephaly (asymmetric, one-sided) and brachycephaly (symmetric flattening across the whole back of the head).

• Most common cause: The widespread adoption of back sleeping (to prevent SIDS) has increased the frequency of positional flattening.
• Does it self-correct? Mild cases largely resolve with repositioning alone. Moderate to severe flattening may require helmet assessment.
• Craniosynostosis difference: In flat head syndrome the sutures are open; in craniosynostosis a suture is closed. A doctor distinguishes between the two.

What Is Flat Head Syndrome?

Flat head syndrome (positional plagiocephaly or deformational plagiocephaly) is flattening of an area of the baby's skull caused by sustained or repeated pressure on that area. Skull bones are still soft and flexible in the first months and are therefore susceptible to prolonged pressure.

The term is sometimes used as a general umbrella. Sub-types include:

• Plagiocephaly: Asymmetric flattening in one corner of the skull; unequal positioning of the face, forehead, or ears may be visible.
• Brachycephaly: Symmetric flattening across the back of the skull; the head appears shorter front-to-back and wider side-to-side.

What Causes Flat Head Syndrome?

• Back-lying sleep position: The back-lying sleep position recommended since 1992 to prevent SIDS has increased the frequency of positional flattening. Safe sleep remains correct — the risk is managed with simple measures.
• Torticollis: Neck muscle tightness causes the baby to always turn the head the same way, placing more pressure on one side.
• Premature birth: The skull is softer; more susceptible to pressure during intensive care.
• Intrauterine pressure: Multiple pregnancy, oligohydramnios, or a confined uterine environment.

When Should You See a Doctor?

Seek specialist advice in the following situations:

• Flattening or asymmetry is not improving after 6–8 weeks of repositioning
• One ear has shifted forward; forehead asymmetry is obvious
• Restricted head rotation or neck tightness
• A hard ridge or prominent line on the skull, or deviation from growth curve

How Is Flat Head Syndrome Treated?

• Repositioning: Alternating the direction the baby's head points in the cot each day; changing which side the baby wakes up facing. Details: repositioning guide.
• Tummy time (prone play): 30–60 minutes per day on the tummy while awake and supervised is recommended.
• Physiotherapy: If torticollis is present, neck exercises are assessed together.
• Head-shaping helmet (HKM Pro): Assessment is recommended at 3–6 months for moderate to severe cases. The helmet guides the skull's free growth direction to correct the shape.

You can submit a pre-assessment request to have your baby evaluated.

Does Flat Head Syndrome Affect Intelligence?

Positional flat head syndrome does not directly affect brain development. Even when the skull shape changes, the brain continues its own growth. However, if accompanying torticollis is not treated early, motor development may be affected — which is why early diagnosis and repositioning work are important.

Frequently Asked Questions

Does flat head resolve on its own?

Mild cases commonly resolve with repositioning within the first 6 months. Moderate to severe flattening is recommended for helmet assessment; helmet therapy is most effective when started early.

How is flat head distinguished from craniosynostosis?

In positional flat head, the skull sutures are open. In craniosynostosis, a suture is closed and the skull shows a more pronounced deformity pattern. A doctor's examination — with imaging if needed — makes the definitive distinction.

What age is the helmet fitted?

The optimal period is 3–6 months. Effectiveness decreases as ossification increases beyond 9 months; however, assessment is still recommended for late referrals as benefits remain possible.

Related: What Is Plagiocephaly?, What Is Brachycephaly?, Helmet Therapy (HKM Pro).