Your baby's misshapen head

Almost every parent who arrives at this page searched for the same things first: baby helmet, flat head, how much it costs. And what they mostly found was people selling helmets.

So let us start with what actually has to be settled, which is something else: is this head misshapen because the baby always rests on the same side, or because one of the sutures of the skull closed early? They are two completely different situations. The first is common, harmless and almost always corrects itself. The second is rare and is operated on.

The two situations

Positional flat head. A baby's skull is soft and is moulded by sustained pressure. Since babies have been laid on their backs to sleep — a recommendation that dramatically reduced sudden infant death and one that must go on being followed — flattening of the back of the head has increased greatly. In a series of 440 healthy babies born at term, 46.6 per cent had some degree of positional plagiocephaly between seven and twelve weeks, and in 78.3 per cent it was mild.

It frequently goes with a torticollis: the baby has one neck muscle tighter than the other, always turns to the same side, and always rests on the same area. Treating that torticollis is a central part of the treatment, and often the part that pays off most.

Craniosynostosis. The bones of a newborn's skull are separated by sutures that allow the head to grow. If one closes early, the skull stops growing in that direction and grows too much in the other: that is why the deformity takes characteristic shapes. It occurs in around one in 2,500 births according to the United States centres for disease control, and in prospective registries in some 5.5 per 10,000. It is rare, and that is why it is described as a needle in a haystack of positional flat heads.

How they are told apart

None of these signs replaces examination by a doctor, but they are the ones that guide you in practice.

• The shape. The positional kind flattens one side of the back of the head and pushes the ear and the forehead on that same side forwards: seen from above, the head forms a parallelogram. The commonest craniosynostosis, by contrast, produces a long, narrow head, like a keel; other forms give a triangular forehead, or flattening with the eyebrow raised on one side only.
• The course. The positional kind appears after birth and gets worse over the first few months; it usually improves once the baby starts to sit up and turn unaided. Craniosynostosis is usually noticeable at birth or very soon after, and gets progressively worse.
• Changes of position. If the head improves when the baby's position is varied systematically, it is positional. If nothing changes, it needs investigating.
• The edge of the suture. Sometimes a hard, raised ridge can be felt along the line where there should be an open suture.

When any doubt remains, it is investigated. The first scan is usually an ultrasound of the sutures, which involves no radiation, and in some cases a very low dose CT with three-dimensional reconstruction.

The helmet: what the evidence says

This is the question that dominates every search on the subject, so we answer it with the best data there is.

The only well conducted randomised trial took 84 babies of five to six months with moderate to severe deformity and allocated them at random to a helmet or to the natural course, without a helmet. At twenty-four months:

• Full recovery with a helmet: 10 out of 39, 26 per cent.
• Full recovery without a helmet: 9 out of 40, 23 per cent.
• No statistical difference between the two groups.

And the other figure from the same trial, the one that is almost never mentioned: 100 per cent of the parents in the helmet group reported at least one adverse effect. Skin irritation in 96 per cent, a bad smell in 76, a feeling that the helmet got in the way of physical contact with the baby in 77, sweating in 71, pain in 33. The authors' conclusion, in their own words, was that they advise against the helmet as a standard treatment in healthy babies.

Now, honesty demands the counterweight. A 2025 meta-analysis of thirteen studies and 1,189 babies did find that the helmet reduces the skull asymmetry indices further, measured with callipers. But most of those studies are not randomised and the heterogeneity between them is very high.

Put in one sentence: the helmet improves the millimetres that get measured; the only randomised trial did not find that it changes the proportion of skulls that end up normal at two years, and it documented discomfort in every baby who wore one. There are specific indications where a helmet makes sense — severe cases, deformities that do not respond, some post-operative cases — and that indication is best set by someone who does not sell helmets.

What you will hear that is not true

"If the head is misshapen, a helmet has to go on now." The only randomised trial available found no difference in the proportion of babies whose heads became normal: 26 per cent with a helmet against 23 per cent without one, in moderate to severe cases.

"A flat head means brain damage or delay." Positional plagiocephaly is a problem with the shape of the skull, not with the brain. It affects nearly half of healthy babies at three months, and in four out of five it is mild.

"It settles on its own, nothing needs doing." True for the positional kind; false and potentially serious for craniosynostosis. The value of this appointment is precisely to tell one from the other, not to reassure by default.

"Osteopathy or craniosacral therapy corrects the head." The randomised trial that set out to assess early osteopathic manipulation for preventing positional deformity had to be stopped early for lack of recruitment and gave no conclusive result. What does have a place in treatment is physiotherapy directed at the torticollis, which is a different thing.

"So the baby should sleep on the front, then." No. Sleeping on the back saves lives. What is called for is more tummy time while the baby is awake and supervised, alternating the side of the cot and the side you feed from, and limiting the hours spent in the car seat and in baby bouncers.

What will happen at the appointment

The head will be looked at from above, which is the view that shows the real shape, and from the front and from behind. The sutures and the fontanelle will be felt. The head circumference will be measured and compared with the previous check-ups: the curve matters more than any single measurement.

The neck will be assessed, looking for torticollis, and you will be asked how the baby sleeps, how long is spent in the car seat, whether the head always turns to the same side and whether the flattening changed with the positions.

And if the picture is positional and mild, what is called for is a repositioning plan and physiotherapy, with a review in a few weeks. No imaging is needed for that.

Questions worth writing down before you go

• Is this positional, or does craniosynostosis have to be ruled out?
• Is any test needed, and which one involves the least radiation?
• Is there a torticollis? Is physiotherapy called for?
• What specific plan of positions do I follow at home, and when do we review it?
• If a helmet is proposed at some point, what is the indication in my child based on?
• If it is craniosynostosis, at what age is it best to operate, and why at that age?

The questions people ask most