Why newborn heads are not round

A newborn's skull is made of separate plates that have not yet fused, joined by the fontanelles and the sutures between them. That is what allows the head to change shape on the way out, and it is why a head that looked alarming in the delivery room usually looks ordinary within days.

The American Academy of Pediatrics describes what you are seeing: "When born, babies may have an elongated shape of their head, and may also have scalp swelling in the area pushed out first during birth. If you press gently on this area, your finger may even leave a small indentation. This swelling (called 'caput') is not serious and should disappear in a few days."

The four things parents notice

Moulding — the cone head

The overlapping of the skull plates during a vaginal birth gives the pointed or elongated shape. It is most obvious after a long labour or an assisted birth, and it resolves as the plates settle back. Babies born by planned caesarean often have rounder heads from the start, for the same reason. This is days, not weeks.

Caput — the soft swelling that pits

Soft, boggy swelling of the scalp over the part of the head that led the way. The AAP's marker is that pressing it can leave a small indentation, and that it goes in a few days. It crosses the suture lines because it sits above the skull bones, in the scalp itself.

Cephalohaematoma — the firmer lump

This one worries parents more, because it can appear or grow in the days after birth rather than shrinking. The AAP describes it precisely: "Sometimes there may be swelling under a newborn's scalp, present on one or both sides, which is firm or springs right back after it is gently pressed. This type of swelling is likely a cephalohematoma, and is caused by the intense pressure on the head during labor." Crucially, the AAP adds that "while not serious, it represents some bleeding along the outer side of the skull bones — not inside the brain — and usually takes six to ten weeks to disappear."

Six to ten weeks is a long time to look at a lump, which is why knowing the number helps. As it resolves it can feel harder around the edge before it flattens.

Flat spots from lying down

This one develops later, over weeks and months, and it is the commonest of the lot. The NHS explains: "Some babies get a flat head when they're a few months old because they spend a lot of time lying down. It's usually nothing to worry about and gets better as they get older." The NHS names two patterns — plagiocephaly, flat on one side so the head looks uneven and the ears may not line up, and brachycephaly, flat at the back so the head looks wide with the front bulging forwards.

The reassurance is unusually direct: "Apart from affecting how your baby's head looks, flat head syndrome does not cause any other symptoms. It does not affect their brain or development."

What actually helps a flat spot

The NHS's own list, and the order matters:

Do not change your baby's sleeping position. The NHS is explicit: babies should always sleep on their back to reduce the risk of sudden infant death syndrome. Head shape is never a reason to alter this.
Plenty of supervised tummy time while awake during the day, never leaving your baby alone on their tummy.
Change the position of toys and mobiles when your baby is lying on their back, to encourage them to turn their head both ways.
Vary the side you feed and carry from.
Limit time lying in a pram or sitting in a car seat — the NHS says to take your baby out as soon as you arrive.

The HSE gives the same instruction from the safe sleep side: always place your baby on their back with their feet to the foot of the cot, and if your baby always lies with their head in the same position they may develop a flat head, so make sure they sometimes face left and sometimes right, moving their head while they are lying on their back.

Helmets

The NHS position is a single sentence and it is worth quoting: "Helmets and headbands are not available on the NHS to treat flat head syndrome because there's not enough evidence to show they work." The NHS also says treatment is not usually needed and that flattening "often gets better in around 1 to 2 years" as the head grows and your baby spends less time lying down.

The two things that need checking

Torticollis — a head always turned the same way. The NHS lists tight neck muscles as a cause of flat head, because they make a baby rest their head on the same side and they may not be able to turn it. The NHS says to see a GP if your baby's head is always tilted to one side or they have difficulty turning their head, and that physiotherapy may be offered with gentle exercises. The AAP treats positional skull flattening and torticollis together for the same reason: the flattening is often the visible sign of the neck problem.

Craniosynostosis — early fusion of the skull plates. The NHS notes that some babies are born with a flat head, which may happen with prematurity and is usually nothing to worry about, but "rarely it can be a sign of something more serious, such as a condition called craniosynostosis". This is where one or more of the joints between the skull bones closes too early, so the head grows in a distorted direction. It is uncommon, it is diagnosed by a clinician, and the trigger to raise it is an unusual head shape that is not improving or is getting worse.

Who checks, and when

NICE's postnatal care guideline NG194 specifies that the complete newborn examination within 72 hours of birth, and again at six to eight weeks, includes the head and fontanelles, face and general symmetry of the head and facial features. NICE also says head circumference is measured in the first week and at around eight weeks and plotted on a growth chart. Those two checks are where head shape and head growth get looked at systematically, so they are the natural place to raise a concern.

When to call

Contact your midwife, health visitor, public health nurse or GP if:

You are concerned about the shape or size of your baby's head — the NHS's own wording, and it needs no further justification.
Your baby's head is always tilted to one side, or they have difficulty turning their head.
A flat spot is getting worse rather than better.
The head shape looks unusual and has not improved over the first months.
A lump on the head is growing, is hot, or the skin over it is red.

Call your local emergency number (999 in the UK and Ireland, 911 in the US and Canada, 000 in Australia, 111 in New Zealand) if your baby: has a bulging or tense fontanelle when calm and upright; has a temperature of 38C (100.4F) or above or below 36C (96.8F); is unresponsive or unrousable; has a weak, abnormally high-pitched or continuous cry; looks pale, ashen, mottled or blue; is grunting or breathing over 60 breaths a minute; has neck stiffness, a seizure, or a rash that does not fade under a pressed glass. Those are NICE's red flags for serious illness in young babies.

What to let go of

The NHS's line does most of the work here: flat head syndrome does not affect the brain or development. Nothing about early head shape predicts anything about your baby. The interventions that matter are free ones — tummy time, varied positioning, less time in seats — and the one thing you must not do to fix a head shape is change where your baby sleeps or how they are laid down.

Newborn Head Shape After Birth