What Causes Baby Flat Head & What You Can Do (2026 Guide)

If you've noticed a flat or asymmetric patch on your baby's head, you're not alone. Positional flat head — the most common type — affects a significant number of Australian newborns and is almost always caused by external pressure on the skull rather than anything that happened during pregnancy or birth. The good news: when identified early, it's one of the most addressable concerns in newborn development.

What Is Positional Flat Head (Plagiocephaly)?

Positional plagiocephaly is a flattening of one area of a baby's skull that develops after birth as a result of sustained pressure on that area. The term comes from the Greek for "oblique head" — and it describes what parents usually see as a flat spot, often at the back or one side of the skull.

It's worth knowing that positional plagiocephaly is not associated with brain development problems. The skull is moulding around the brain, not the other way around. What's happening is purely structural — and in many cases, it resolves significantly with time and appropriate positional changes.

There's also brachycephaly (symmetrical flattening of the entire back of the skull, often with a wider head) and scaphocephaly (elongated, narrow head). These have different patterns and causes, but positional factors often play a role in all three. Any concern about head shape should be assessed by your GP or paediatrician, who can determine the type and recommend the right approach.

Why Are Newborns Vulnerable to Flat Head?

The answer is the very thing that makes birth possible: a soft, flexible skull. At birth, a newborn's skull bones have not yet fused — the fontanelles (soft spots) allow the head to compress safely through the birth canal and then expand again after birth. This same softness means the skull is highly responsive to external pressure in the weeks and months that follow.

Add to that the fact that newborns sleep up to 17 hours a day with zero neck muscle control — meaning their head rests on the same surface, often in the same position, for extraordinary amounts of cumulative time — and it becomes clear why positional influences on skull shape are so common in the first months of life.

The Most Common Causes of Baby Flat Head

Which Babies Are at Higher Risk?

While any newborn can develop positional flat head, certain factors increase risk:

• Firstborn children — less amniotic fluid relative to baby size in later weeks is thought to increase in-utero pressure
• Male babies — slightly higher rates of positional plagiocephaly are reported in boys, though the reasons aren't fully understood
• Babies who sleep in the same position — particularly those with a strong head-turning preference from the first weeks
• Babies with limited neck mobility — torticollis, even mild, dramatically increases the risk of positional flattening
• Babies who spend significant time in car seats and bouncers outside of actual travel — these seats add to cumulative supine time with the head in one position

What Parents Can Do — Practical Steps to Take Early

The earlier positional measures are started, the more effect they can have — because the skull is at its most malleable in the first three months. Here's what the evidence and paediatric guidance generally supports:

1. Supervised Tummy Time from Day One

This is the single most impactful thing most parents can do. Tummy time builds neck strength, reduces supine pressure, and supports motor development. Start with short sessions (even just 2–3 minutes) from the first week, and build up as your baby tolerates it. Aim for a total of at least 30 minutes spread across the day by 3 months. See our guide: Tummy Time and Flat Head — What Parents Need to Know.

2. Repositioning During Rest

Alternate which end of the cot your baby's head is at — babies tend to turn towards the light source or the room, so changing ends changes the preferred turning direction. Where possible, encourage your baby to turn their head to the non-preferred side by placing interesting things (your face, a mobile) on that side.

3. Limit Time in Car Seats and Bouncers When Not Travelling

Car seats and infant bouncers add to cumulative time with the head in a fixed position. They're necessary and safe for their intended purpose — but try to limit time in them when you're not actually in the car or needing the bouncer for settling.

4. Use a Supportive, Breathable Surface During Rest

The surface your baby's head rests on during sleep makes a difference. A flat, firm surface concentrates pressure at one point. An ergonomic concave surface — like the Ergo Sleep™ Baby Flat Head Pillow — is designed to help distribute that pressure more evenly across the contact area. It won't fix an existing flat spot, but it may help reduce concentrated pressure during the many hours of rest in the early weeks.

When to See a Doctor

See your paediatrician or GP if:

• You notice any flattening or asymmetry in your baby's skull that isn't improving after 6–8 weeks of repositioning
• Your baby consistently turns their head to one side and seems unable or unwilling to turn the other way
• Your baby's ear position seems uneven, or one cheek appears more prominent than the other
• The flattening appears to be getting more pronounced rather than improving
• You are concerned for any reason — early assessment is always better than waiting

Your GP or paediatrician can assess the type and severity of head shape variation and refer to a physiotherapist, osteopath, or specialist if needed. In more pronounced cases, or cases presenting after 5–6 months, they may discuss helmet therapy (cranial orthosis) as an option.

Also see: Baby Head Shape Pillow | Plagiocephaly Pillow — Supportive Positioning | Baby Flat Head — When to Worry