Baby Fontanelles: Everything You Need To Know

When a birth happens, the baby’s fontanelles turn out to be a topic of conversation in families. Some worry about their size, their fluffiness or that time passes and they remain open.

All doubts are logical and understandable, since adults do not have fontanelles like a baby does. We are struck by their presence and the possibility of pressing them or manifesting a heartbeat.

What happens is that, at birth, the bones of the skull are not fully connected and closed to each other. This, precisely, allows the child to exit through the birth canal, reducing its head diameter. One bone is placed on top of another and the head is sharpened, changing its shape.

At birth we do not have 6 bones in the skull as when we are adults, but there are some more. This happens, for example, with the frontal bone, which is divided into two parts when we are babies. Over time, these bones will join together in a process called ossification.

The areas of union of the bones of the skull are the sutures. Between the sutures are the baby’s fontanelles, still soft and of considerable size. Thanks to them, the child’s head can be enlarged without problems following the growth of the body.

The main fontanelles of a baby are two: the anterior and the posterior. There are other soft spaces that are also fontanelles, but smaller in size and that tend to close earlier. Once closed, where they were we will find solid bone.

Skull sutures and their relationship to the baby’s fontanelles

Sutures are the junction areas between the bones of the skull. As we clarified before, in babies the sutures contain fontanelles, that is, soft spaces that are not yet bones, but on which ossification will occur.

As long as the sutures are not ossified, they are mobile. We could say that they are joints, in a sense. As the baby grows, this soft tissue between the sutures expands and becomes bone, until, closing completely, cranial growth is complete.

The most important sutures of the head are:

• Methopic: it is the one that separates, at birth, the frontal bone into two parts. It runs along the forehead and reaches the nose.
• Sagittal: it is the one that runs through the skull from back to front, through the middle.
• Coronal: runs through the skull from side to side, transverse to the sagittal.
• Lambdoid: joins the parietal bones to the occipital bone, at the back.

When do the baby’s fontanelles close?

The fontanelles have to close, although they do not do so immediately at birth. They carry a process that accompanies the growth of the child and that, based on those times, causes ossification.

The expected dates for the closure of the baby’s fontanelles are estimates. It does not mean that all children coincide on these dates, but they should serve as a reference to make a consultation with a pediatrician:

• The anterior fontanelle should close and completely ossify by about 18 months of life.
• On the other hand, the posterior fontanelle closes around the fourth month of life, being much smaller than the previous one.

If the closing time is prolonged, a medical consultation is required. The pediatrician will evaluate the size of the baby’s fontanelles, their consistency and the rest of the child’s health. If something indicates that you can wait a little longer, it will be recommended to wait for a new control.

If there are doubts about a pathological process, the pediatrician may request an ultrasound of the skull. This study does not represent risks for the child and allows to rule out diseases such as craniosynthesis or hydrocephalus.

Deformations of the fontanelles

There are signs in the baby’s fontanelles that warn of the existence of an abnormality. Parents should be aware of this in order to consult with a health professional in a timely manner.

First, we must clarify that the beats that are perceived in this tissue are normal and cannot be considered an abnormality. The fontanelles of the baby have many blood vessels and transmit the heartbeat.

However, if there is a bulge, this can be a problem. If it happens when crying, it is usually benign, since it responds to increased intracranial pressure. Now, if the lump is in the quiet moment, an evaluation for hydrocephalus should be done.

A sunken fontanel could be a sign of dehydration. It appears more frequently in babies with severe gastroenteritis that causes multiple vomiting, preventing them from drinking fluids.

The importance of baby fontanelles

The fontanelles of the baby are very important and it is normal to be worried about them if we are new parents. If in doubt, it is better to consult a pediatrician to remove them and be sure. In general, there will be no problems with this anatomical area, but it can warn us of other pathological processes.