Soft spot (fontanelle): what it is, when it closes and when to worry

Fontanelle is the medical name for your baby's soft spot: a gap between the skull bones, covered by a tough membrane. HealthHub says the two you can feel are at the front and the back of the head. The front soft spot is diamond shaped, may bulge a little when your baby cries, and usually closes within 12 to 18 months. Gentle touching and hair washing are safe.

Why babies are born with soft spots

A newborn's skull is not one solid bone yet. Pregnancy, Birth and Baby, the Australian government health service, explains that it is made of bony plates held together by flexible joints called sutures. These let the head narrow slightly on the way through the birth canal, and then let it grow fast in the first years. The soft spots are the gaps where the plates meet, and the AAP says they are where the skull bones are still growing together.

That is also why many babies are born with a cone-shaped or uneven head. HealthHub says the skull bones overlap under pressure in the birth canal, and the head returns to a normal shape as your baby grows. Our newborn head shape guide covers moulding and flat spots.

What a normal soft spot looks and feels like

A normal soft spot feels soft and flat, Pregnancy, Birth and Baby says, and you may sometimes feel a slight pulse from the blood vessels underneath. HealthHub says the front one may bulge slightly when your baby cries or strains. If it starts to look or feel different from usual, show your doctor or polyclinic nurse.

Many parents are scared to touch it. The AAP says you needn't be afraid to touch these areas gently, because a thick, durable membrane protects the brain. Washing the hair and brushing off cradle cap over the soft spot is fine.

When the soft spots close

The back soft spot closes first. Pregnancy, Birth and Baby says it usually closes by about 2 months, and gives a wide normal range of 4 to 26 months for the front one. HealthHub says the front one usually closes within 12 to 18 months. A front soft spot that is still open at your baby's first birthday is expected.

A soft spot that closes very early is less common. The NHS lists a front soft spot that disappears before 1 year as one possible sign of craniosynostosis, where skull bones join too soon, and says to see a GP if you are worried about your child's head shape or size. Head size has its own chart too: HealthHub's digital Child Health Booklet compares head circumference from birth to 6 years against local growth charts. See growth percentile for how to read that chart.

A sunken or bulging soft spot: when to get help

A sunken soft spot can mean your baby is dehydrated. The NHS lists it with other signs: sunken eyes, few or no tears, fewer wet nappies than usual, and being drowsy or irritable. It says a soft spot that sinks inwards can be a sign of serious dehydration that needs urgent treatment.

A bulging or swollen soft spot is rarer and more serious. Pregnancy, Birth and Baby says it may point to conditions such as meningitis, bleeding in the brain or a build-up of fluid. NUH lists a bulging fontanelle as a key sign of meningitis in infants, and the NHS says a baby with meningitis may also not want to feed, have a high-pitched cry, or be stiff or floppy. If you think the soft spot is sunken or bulging, Pregnancy, Birth and Baby says to get medical advice immediately.

In Singapore, KKH says to go to the nearest paediatric emergency department if your child needs urgent attention, and to call 995 in an emergency. KKH also lists any fever or illness in a baby under 3 months as a reason to go to the Children's Emergency. See fever in a newborn.

Frequently asked questions

What is the soft spot on a baby's head?

It is a gap between the skull bones, called a fontanelle, where the bones are still growing together. It lets the head narrow slightly during birth and gives the skull room to grow.

When does the soft spot close?

The back one closes by about 2 months, Pregnancy, Birth and Baby says. The front one usually closes within 12 to 18 months, HealthHub says, though anywhere from 4 to 26 months can be normal.

Is it safe to touch my baby's soft spot?

Yes, gently. The AAP says a thick, durable membrane protects the brain, so normal handling, washing and brushing over it are fine.

Is it normal for the soft spot to bulge when my baby cries?

A slight bulge with crying or straining is normal, HealthHub says. A soft spot that looks swollen or bulging at other times, especially in a baby who is unwell, needs medical advice straight away.

Related terms

• Growth Percentile: How your baby's weight, length or head size compares with children of the same age, as plotted on a growth chart.
• Cradle Cap (Infantile Seborrhoeic Dermatitis): Greasy white or yellow scales on a baby's scalp. Harmless, not caused by poor hygiene, and it clears with time.
• Neonate (Newborn): The medical word for a newborn baby in the first 28 days of life.
• Health Booklet: The Child Health Booklet every Singapore baby gets at delivery. It records growth, milestones and every vaccination.
• Fever in a Newborn: A raised temperature in a baby under 3 months, which Singapore hospitals treat as a reason to come in straight away.

See every term in the glossary