Worried about your baby's head shape? Dr Yehudi Gordon has the answers

Extract taken from Mother and Baby Health: The A-Z of pregnancy, birth and beyond (Ebury)

Nature prepares your baby for the pressures of the birth by ensuring skull bones can easily slide over one another. As a consequence, the head may mould into an alarming shape. The moulding will smooth out within a few days, but two areas known as fontanelles remain soft for longer. They are a part of the skull structure, enabling it to expand as the brain enlarges. The average head circumference of a newborn is about 32cm (13in).

Each fontanelle consists of a sheet of tough fibrous material that bridges the gap between growing bones. This area is no more sensitive than any other area of the skull and is immensely strong. When your baby is quiet you may be able to see or feel his pulse here. The posterior (back) fontanelle marks where the skull bones at the back of the head join. It cannot usually be felt beyond the fourth month, although being unable to feel the posterior frontanelle before this is not abnormal, nor is it uncommon. Very rarely, the posterior fontanelle may be closed, when the bones have fused too early, usually before the thrid month. This is usually linked with an unusually shaped or small head. The larger fontanelle at the front of the head (the anterior - 'front' - fontanelle) remains obvious until it closes around 18 months. Early or late closure of the anterior fontanelle is not usually cause for concern.

The fontanelles do rise and fall with normal breathing, and this is of no concern. If they appear sunken, accompanied by a dry mouth and perhaps sunken eyes, this may be a sign of dehydration. If they appear to bulge it may indicate meningitis or hydrocephalus, when there is swelling within the brain. If your baby's fontanelles appear shrunken or swollen, visit your doctor.

Flattened head (Plagiocephaly)
If your baby's head appears flattened on one side behind the ear, this is most likely due to his sleeping postion as he habitually turns his head to one side. You could alter your baby's head postition from night to night to cure this. Otherwise it will right itself when your baby begins to sit. Typically, flattening improves at around four to eight months, and is usually gone by 2-2.5 years of age. Recently a range of helmet has been offered (at a cost), with the claim that hey speed up what is a naturally occurring healing process, but their usefulness is highly questionable. The flattening is likely to disappear naturally, and you can help your baby by ensuring he has lots of playtime on his tummy and is carried in a sling by you or other adults. Some professionals suggest that flattening may arise when babies are left lying on their backs, or sitting in a car seat or rocker chair for excessive amounts of time. This is referred to as 'positional plagiocephaly'.

Rarely, a flattened hea may be a sign of Wry Neck, where there is tightness or tearing in one of the strap muscles. This can be treated with physiotherapy or osteopathy.

Hydrocephalus
The term hydrocephalus comes from two Greek words meaning 'water in the head'. It affects one in 6,000 babies in the UK. The 'water' is cerebrospinal fluid (CSF) that does not drain away as usual. Because it is constantly produced but cannot get out, CSF accumulates, causing raised pressure, the brain tissue stretches and is squashed and the head gets larger. The effects of hydrocephalus include pressure on the eyes that may lead to a squint or impaired vision, and symptoms related to raised intercranial pressure such as vomiting, drowsiness, fits and failure to thrive. Later in childhoon, there may be effects on concentration, memory or co-ordination.

Premature birth is the most common cause of hydrocephalus because there is a higher risk of bleeding into the berain, which may block the absorptions system. Before birth a congenital abnormality such as Spina Bifida or infection with Toxoplasmosis may be a cause. Meningitis after birth may also casue inflammation that blocks the CSF pathways. Cysts and tumours are extremely unusual causes.

• Hydrocephalus is usually treated with an operation that allow the CSF to drain, via a shunt, into the bloodstream. Occasionally a shunt may be put in place using amniocentisis during pregnancy and will be replaced with a more permanent shunt after birth. More recent techniques for making an opening in the skull instead of using a shunt are suitable for some types of hydrocephalus.
  
• Most children with hydrocephalus are educated in mainstream education - sometimes with extra healp if they have learning difficulties. If the treatment is working effectively, the prospects are good. The system of shunting has been used since the 1960s and many adults have grown up with shunts without complications.

Small Head (Microcephaly)
About 40 per cent of babies whose heads are small for age and gender have no abnormalities related to development. However, in some 60 per cent of cases the head size relates to an abnormally small brain and there are associated learning difficulties, perhaps also a high-pitched cry, poor, feeding, fits, or stiffness of the limb muscles.

A small brain is usually caused by the early failure of brain growth in pregnancy due to chromosomal abnormalities, infection, recreational drugs or excess alcohol intack. After the birth, microcephaly may occur as a result of severe foetal distrss and asphyxia with brain injury, infection, or an underactive thyroid gland. Close follow-up is usual, but the extent of the problem is usually not evident for seven to nine years.

Microcephaly may be associated with fusion of the skull bones earlier than the usual fifth or sixth month after birth. Early fusion can restrict space for the brain to grow adn may make the head look small or oddly shaped, depending on which skull bones fuse. Sometimes surgery may be needed to prevent damage to the developing brain.

Buy Mother and Baby Health: The A-Z of pregnancy, birth and beyond by Dr Yehudi Gordon and Harriet Sharkey, Andy Raffles and Felicity Fine, published by Ebury press.