Is my baby's flat head normal, and what should I be looking at?

Maybe you noticed it during a feed, in a photo, or while they were sleeping on your chest. The back of your baby's head may look flatter than it did a few weeks ago, or one side might seem to sit differently from the other. You may be searching this on your phone, or working through it late at night when the house is finally quiet. Whatever brought you here, the question you're probably asking is some version of: is my baby's flat spot normal, or is this something to be worried about?

You're not overreacting. Flat spots in the first few months of life are one of the most common concerns Australian parents bring up at child and family health nurse visits, and looking into it is exactly what a switched-on parent does.

How common is baby flat head in Australia? More common than most parents realise. Clinical estimates suggest that between 18 and 19.7 per cent of healthy infants develop some degree of cranial flattening in the first few months of life. Among babies who sleep on their backs, which is essentially every Australian baby because that's the safe sleep position recommended here, the figure rises to roughly 25 to 30 per cent.

Severity typically peaks at around four months, when the brain is expanding fastest but a baby doesn't yet have the neck strength to move their own head during sleep. Most parents first notice a flat spot at six to eight weeks, once consistent sleep pressure has left a visible mark. If you're at two or three months with a baby who looks a little asymmetric, you're noticing this at exactly the age most parents do.

No. Flat spots are a mechanical response to a baby's skull resting in the same position during sleep, not a parenting failure. Back sleeping in Australia is the result of decades of safe sleep evidence and has dramatically reduced sudden infant death. It is not the cause of plagiocephaly. It does act as an accelerator in babies who already have some neck tightness, a strong head-turning preference, or a history of prematurity. You have not caused this, and you have not missed a window simply because you've only just noticed it.

The most reliable way to check baby head shape at home is from directly above, not from behind. Most parents look from behind because that's where the flat spot sits, but hair and the curve of the neck make even moderate flattening easy to miss.

Lay your baby flat on their back on a firm surface, stand directly above them, and look straight down at the top of the head. A symmetrical head looks broadly even from side to side. The ears sit in roughly the same position. The forehead projects evenly. The back of the head curves in a consistent arc. If one side at the back looks flatter than the other, that's positional plagiocephaly. If the back of the head looks evenly flat across both sides, with the head appearing wider and shorter than usual from above, that's brachycephaly.

Two specific things to add to the top-down check are ear alignment and forehead symmetry. In plagiocephaly, the asymmetry isn't limited to the back of the skull. As one side of the occiput flattens, the whole shape can shift forward on that side. The ear on the affected side tends to push forward. The forehead and cheek on the same side often come forward too, sometimes giving the head a trapezoid or parallelogram outline when viewed from above.

For a rough sense of the depth of the flat area, place your fingertips on opposite sides of the back of your baby's head, with their head centred. A typical adult fingertip is around 8 to 11 millimetres wide, which gives you a usable reference for the difference between the flat side and the rounded side.

The most useful observation you can pass on to a clinician is whether your baby has a favourite head position when lying on their back. A strong, consistent head-turning preference is the earliest sign of congenital muscular torticollis, a neck muscle imbalance that is the root cause of most positional flattening. If you've noticed a preference like this, mention it specifically when you raise the head shape concern.

Plagiocephaly vs brachycephaly: the two names get used interchangeably online, but they describe different shapes. Plagiocephaly is asymmetric flattening on one side at the back of the head. The flat spot sits on the left or the right, and the rest of the skull shifts as a result. Brachycephaly is symmetric flattening straight across the back, so the skull looks short from front to back and wider from side to side. From profile, a baby with brachycephaly often has a steeper or taller back of the head than a baby with a more rounded shape. Plenty of babies present with a mix of both.

Most flat spots in the first few months are positional and respond well to early action. A smaller number of head shape concerns are not positional and warrant prompt GP or paediatrician assessment rather than starting with self-guided resources. The signs to watch for are different in nature, not just more severe versions of plagiocephaly.

Craniosynostosis is the most important condition to rule out. It is rare, but it happens when one of the joints between the skull bones fuses prematurely, and it produces head shapes that are characteristically the opposite of what you see in positional flattening. If the ear is pushed forward on the same side as a flat forehead, a bulge sits behind the ear on one side, or the head looks long and narrow with a prominent forehead, these are patterns worth flagging with your GP.

Other red flags are less about skull shape and more about associated signs. Difficulty feeding, any breathing distress, a head shape that was clearly unusual from birth rather than developing gradually from around six to eight weeks, or any concerns about your baby's general development all warrant a GP conversation before you focus on the head shape itself.

If what you've described sounds like positional plagiocephaly or brachycephaly, you're in a useful position to act. The next sensible step is the free Baby Head Shape Guide, which walks you through a more detailed at-home check, a month-by-month view of what to expect, and how to have the first conversation with your child and family health nurse or paediatric physiotherapist.

If you want the science on why the next few months matter, the next article covers how the skull actually responds to early action and what the research says about acting now versus waiting.