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The part of a baby’s skull that is not hardened yet and is soft to touch is called the soft spot.
The soft spot is a vulnerable area on the head and serves a specific purpose through the baby’s development. So why do babies have a soft spot and how long do they have it?
Find out all about a baby’s soft spot and how to take care of it in this MomJunction post.
What Is A Baby’s Soft Spot?
A baby’s soft spots are the spaces between the skull bones that do not fuse and are instead covered by a tough membrane (1). The medical term for the soft spot is fontanelle or fontanel. It is essential to understand the structure of a baby’s skull to understand the purpose of fontanelle.
Structure of baby’s skull:
The skull may seem like a single bone, but it comprises several bones fused by a fibrous band of tissue called cranial sutures. In babies, the skull is made of six bones: one frontal bone (forehead bone), one occipital bone (bottom rear bone of the skull), two parietal bones (top skull bone), and two temporal bones (bone next to the ears) (2).
These bones are not fused in babies as they are in adults. The infant’s skull bones have considerable gaps referred to as fontanelles, which are filled by a soft yet tough connective membrane. Since they are softer than the rest of the skull, fontanelles are also called soft spots.
What Is The Function Of A Baby’s Soft Spot?
The soft spot serves two primary functions:
- Allows skull compression during childbirth: Fontanelles make it easier for the baby to pass through the birth canal by allowing the skull bones to compress.
- Permits rapid growth of the brain: The baby’s brain can experience rapid growth, which would not be possible if the skull bones are fused together. Soft spots help keep the skull flexible thus allowing it to expand easily every time the baby’s brain grows a little.
How Many Soft Spots Do Babies Have?
An infant has two soft spots (3):
- Anterior fontanelle is present on top of the baby’s head, and one that most parents are quite likely to know and feel. Anterior fontanelle marks the point of intersection of the frontal and parietal bones.
- Posterior fontanelle is present at the back of the head. It can be less conspicuous than the anterior fontanelle. It marks the meeting point of the parietal and occipital bone.
When Do Soft Spots Close?
The anterior fontanelle can close any time between nine and 18 months, although it may remain open after 18 months and close at the age of 24 months. The posterior fontanelle closes by the time the baby is two months old. The early closure of posterior fontanelle often makes it inconspicuous to parents when compared to the prominent anterior fontanelle.
When To Worry About The Baby’s Soft Spot?
Fontanelle-related complications can have a lasting impact on the baby’s growth. The following are common problems to affect a baby’s soft spot:
- A Sunken fontanelle is when either of the fontanelles sinks at its place, causing a visible curvature from outside. Sunken fontanelle can happen due to dehydration and malnutrition (4). A baby can dehydrate due to chronic diarrhea and vomiting while malnutrition occurs when the baby gets inadequate feed.
- Bulging fontanelle causes the fontanelle to puff and bulge outwards. You may be able to feel it when you run your hand gently on the baby’s skull. A bulging fontanelle can be a result of a nervous system infection or any other complication involving the brain or spinal cord.
Meningitis (infection of the membrane covering the brain), encephalitis (inflammation of the brain), and hydrocephalus (accumulation of fluid within the brain) are a few conditions that can make the fontanelle bulge (5). A soft spot can bulge due to injury, which is quite common in infants that experience abusive head trauma (6).
The fontanelle may even bulge when the infant cries or vomits. But if the fontanelle returns to the normal position and if the baby is otherwise healthy, then there is no reason to worry.
- Enlarged fontanelles are the soft spots that cover a larger area than they should. This can happen due to several complications and congenital problems including Down syndrome, hydrocephalus, intrauterine growth retardation (IUGR), premature birth, and brittle bone disease (7).
- Craniosynostosis is the condition where the baby is born with fused skull bones and no fontanelles. A lack of soft spot and fused skull bones leaves little space for the brain to expand thus leading to several complications. Faulty genes commonly cause craniosynostosis (8).
- Congenital dermoid cyst of the fontanelle is a rare condition where the baby is born with a large bulging cyst right on top of the soft spot. The cyst constitutes only 0.2% of all cases of cysts, is not painful but needs to be removed (9). The baby’s doctor can suggest the best age for removal of the cyst. There is seldom a case of recurrence after cyst removal.
Any problem with the fontanelle is a medical emergency, and you must take the baby to the doctor.
You may sometimes feel a pulse on the baby’s soft spot, which is due to the pressure of blood flowing through the blood vessels around the fontanelle. The pulsation will correspond to the baby’s heartbeat and is nothing to worry about (10).
How To Take Care Of Baby’s Soft Spot?
No special care is needed to protect the fontanelle. But you should take a few precautions and adhere to some best practices for the baby’s safety.
- Keep baby’s head supported: Babies do not have the necessary neck muscles to keep their head stiff and straight. Leaving the head unsupported may make it flop and cause injury. Remember to support your baby’s head with your hand every time you pick them up and even while holding them in your arms. A sudden jerk or movement is enough to cause head injury, which can lead to problems with the fontanelle as well.
- Be watchful of illness: If you suspect something wrong with the fontanelle, including a change in the shape, take the baby to a doctor right away. It helps to catch any problem early, which helps in a timely resolution.
The soft spots do not last forever, as the bones grow over them to fuse the skull together eventually. Despite its short stint, the fontanelle plays a crucial role in childbirth and allows the baby’s brain to grow rapidly without any complications. So care for it until it naturally disappears.
Did you ever notice fontanelles on your baby’s head? Do tell us in the comment section below.
References:
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