Sometimes, a baby’s head may be flattened on one side or at the back. This is usually due to prolonged pressure on that area from the position of the head, or premature joining of the spaces separating the bones of the skull. It is also known as “oblique head” or “flat head”.

Although it is not seen as a medical condition in the UK, it is still significant, as it can cause anxiety and worry for parents. It also results in cosmetic concerns. It is usually hard not to panic when your baby’s head is misshaped, especially for new mothers. However, you should know that the condition commonly resolves without any form of management.

Introduction 

Background

In the early 90s, a group of paediatricians discovered that placing a baby on its tummy to sleep was the main cause of sudden infant death syndrome. This led to recommendations to place a baby to sleep on their back.¹ Although there was a reduction in cases of death during sleep, there was also an increase in plagiocephaly due to the sleeping position which is shown to be rising yearly.² The condition must be detected early because it can easily be prevented and treatment options are widely available.

Anatomy of the skull

The skull, also known as the cranium, is the natural covering of the brain. It is made up of bones and soft tissues that connect the bones and allow their movement, called sutures. The bones of the skull include the frontal, parietal, temporal, and occipital bones.³

The skull of a baby is still flexible to allow the brain to grow and for ‘moulding’ at birth. However, there is an increased risk of distortion, known as plagiocephaly.³ This article will focus more on positional plagiocephaly, which is more common.⁴ It is usually benign (harmless) but can be severe concerning the level of deformity.⁵

Plagiocephaly (pronounced as play-jee-oh-sef-uh-lee) can be defined as an abnormal one-sided flattening of a baby’s head, usually at the back of the head. The baby has a normal head shape at birth and then it becomes flat after a few months. There are two main types of this condition.⁶ 

The onset of positional plagiocephaly can happen if a baby consistently sleeps with its head in the same position. This occurs because their skulls are very soft, allowing the bones to be shaped by pressure. Since the neck muscles of young babies are not strong, they often turn their heads to one side when laid on their backs.

If they frequently turn their heads to the same side, the skull can become flattened on that side and at the back. A slight amount of flattening generally resolves on its own. However, more significant flattening may remain permanent. Although this can be cosmetically unappealing, it does not impact brain function or development.⁷

Craniosynostosis (pronounced as kray-ni-oh-sin-os-toh-sis), on the other hand, is the early fusion of the baby’s skull bones before the baby’s brain is fully developed. It affects about 1 in 2500 people and can result in altered blood flow in the brain, raised pressure within the skull, cosmetic deformity, and may involve the deformity of the facial bones.

It can be primary, meaning that it occurs on its own. It can also be secondary, co-occurring with other birth defects. It can also be classified into simple and compound types.⁸ The simple type means that only one suture fuses while in the compound type, more than one suture fuses. The majority of cases occur from alterations in the genes during the development of a baby in the womb.⁹

Causes 

There are many risk factors for this condition, including birth injuries, multiple pregnancies, abnormalities that occur during the development of the baby, prematurity, and assisted delivery.⁶

Positional factors

 Sleeping position

This is the most common cause of plagiocephaly and results from an infant sleeping in the same position for a prolonged period. The part of the head having direct contact with the surface will be flattened after a long period and the part above it will follow suit. This can lead to deformation of both sides of the head and eventually cause it to have an irregular shape.  

Prolonged pressure on the skull

Premature babies, who have softer skulls compared to older babies, experience more often prolonged pressure on their skulls: An example of this is in premature babies who have softer skulls compared to their mature counterparts. In addition to this, they may have longer hospital stays and spend time in incubators with their heads being placed in the same position.

In utero factors

Limitedintrauterine space or positioning inside the womb

This can be caused by increased pressure inside the womb when there is more than one baby. The babies are unable to move freely in the womb and the constant force being applied on the head can cause plagiocephaly. A reduction in the volume of the amniotic fluid that protects the baby would also expose the baby’s head to increased pressure.

Congenital conditions

These include craniosynostosis, which has been described earlier. Another condition known as muscular torticollis is noticed at birth due to tight and short neck muscles. It occurs with plagiocephaly in up to 30% of cases. In this case, the baby holds their neck to one side constantly and is not able to tilt it to the other side. It can be corrected by simple exercises and consistently changing the position in which the baby is held. Eventually, the neck muscles will lengthen and the problem will be reversed.

Symptoms and signs

The condition occurs gradually, and most times is only noticed months after birth.⁶

• Asymmetrical skull shape: The other side of the head protrudes due to the bone at the back of the skull being pushed to that side
• Flattened or Misshapen head: meaning that the baby’s head does not have its natural shape. Instead of the normal round or oval shape, the back of the head may appear flat or the baby’s head will be elongated and narrow
• Facial asymmetry: The face could be involved if the pressure is continued for a long period resulting in a change of shape of the ear, nose, jaw, and eye sockets. Sometimes, hair may also be missing on the affected side
• Potential developmental delays or vision issues: There have been developmental delays, but this is more common with craniosynostosis. Vision problems could result from consequent deformation of the eye sockets

Diagnosis 

This condition is usually diagnosed when a baby is examined by the doctor or midwives at birth or during baby checks. If the head is examined and the physician is concerned, an X-ray of the skull may be done to ensure everything is fine.⁵

FAQs

How do I prevent my baby from having plagiocephaly?

The condition is not preventable before birth. However, there are a few things you can do to prevent it after your baby is born. You can ensure that your baby’s head is not placed in the same position for too long, by helping them turn their heads to the opposite side at certain intervals. You can also have supervised tummy time while your baby is awake to relieve pressure on the head. However, you should avoid lying your baby on the tummy when they are asleep as this increases the risk of sudden infant death syndrome.

My baby has a flat head, should I be worried?

Due to the increase in cases of flatheads, there has also been an increase in the number of referrals to the GP. Visit your doctor and they will give you the best advice on managing it. You should seek early for your baby’s head to be examined and rule out the possibility of premature joining of the skull bones.

Can my baby’s development be delayed?

There is not enough evidence to support this yet and plagiocephaly is not seen as a medical condition of concern in the UK. However, correcting the deformity for cosmetic reasons may be necessary, but there is not enough evidence to show that children have experienced more social discrimination from their peers. The head usually returns to its normal shape as your baby grows.

Is it my fault that my baby’s head is flat?

No. Flat head syndrome, referred to as positional plagiocephaly, can arise from various factors and is frequently difficult to prevent. However, you can seek a healthcare professional for your baby to relieve your worries or by placing them on their back, which is the recommended thing to do.

Summary 

There are two main types of plagiocephaly: positional or deformational plagiocephaly, and craniosynostosis. The first type is benign and mostly associated with cosmetic concerns. It is commonly caused by repeated external pressure on a baby’s head due to lying in one position for a long period. Another common cause is repeated pressure in the womb from having more than one baby or reduced fluid in the womb that protects the baby.

Premature babies are also at higher risk than babies born at term because of hypotonia, or prolonged hospital stay. The classical presentation is an uneven head shape where one side of the head is flattened, and the other side protrudes. The condition usually resolves as the baby grows and starts to walk or can turn their heads on their own.

Some babies may require physiotherapy due to tight muscles. In more extreme conditions, the baby may need to wear a helmet to correct the shape of the head. Overall, the condition does not affect the baby’s development.