Bulging Fontanelle

What is a Bulging Fontanelle?

A bulging fontanelle is a soft spot in a baby’s developing skull that curves outward. It is considered a medical emergency, as it can be a sign of serious underlying issues with the baby’s brain.

Did your baby have a bulging fontanelle after a traumatic birth? Our team is here to answer any questions you may have.

The human skull is made of many bones, which join together to protect the brain. The lines at which they fuse are called sutures. When a baby is born, these sutures are not yet all firmly joined together. This allows the head to be a bit more flexible as it passes through the birth canal. It also makes it easier for the baby’s brain to grow.

After birth, minerals are added to the sutures, which allow them to harden and slowly close. 

The membrane-covered spaces where sutures have not yet fused the skull bones together are called fontanelles, or soft spots.

The most prominent soft spot is called the anterior fontanelle; it is located at the top of the baby’s head, and typically closes between seven and 19 months of age. In some babies, the posterior fontanelle (at the back of the head) can be felt; it typically closes between one and two months.

what is a bulging fontanelle?

What is a Normal vs Bulging Fontanelle?

A healthy fontanelle should be firm to the touch and curve slightly inward. Sometimes, if a baby is crying, lying down, or vomiting, the fontanelle may appear to bulge slightly, but should return to normal when the baby is in a calm, upright position. If the baby’s fontanelle quickly returns to normal, it is not a true bulging fontanelle.

However, if an infant has a bulging fontanelle that curves outward even after you have gotten them to calm down and put them in an upright position, this is a medical emergency. It is especially concerning if the baby also has a fever or appears to be excessively sleepy.

What to Do When Your Baby Has a Bulging Fontanelle

If your baby has a bulging soft spot, do not wait for a doctor’s appointment – go to the nearest emergency room for immediate attention.

A bulging fontanelle can be indicative of several serious conditions, including encephalitis (inflammation of the brain, which can lead to permanent brain damage or even death).

Sunken Fontanelle

Sometimes new parents may observe a sunken fontanelle. In this case, the baby’s soft spots appear depressed or concave, sinking below the level of the surrounding skull. This usually indicates dehydration, which can result from diarrhea, vomiting, insufficient fluid intake, and excessive heat exposure. Fewer wet diapers can sound the alarm for dehydration.

While both of these conditions require medical attention, a bulging fontanelle is generally considered more urgent due to its potential link to serious intracranial issues and pressure in the brain.

What Can Cause a Bulging Fontanelle?

Understanding the potential causes of a bulging fontanelle allows parents and caregivers to recognize when urgent care is needed. While a soft, flat fontanelle is normal, a noticeably raised one can signal various medical conditions. It is important to know that a bulging at the baby’s soft spot can be a sign of several different underlying conditions. 

Common causes of a bulging fontanelle include:

Less common causes include:

  • Brain tumor or abscess
  • Lyme disease
  • Addison’s disease
  • Congestive heart failure
  • Leukemia
  • Electrolyte disturbance
  • Hyperthyroidism
  • Male syrup urine disease (the body can’t properly break down proteins)
  • Anemia

Do a Baby’s Fontanelles Affect Head Shape?

A bulging fontanelle itself doesn’t necessarily cause an abnormal head shape. A bulging fontanelle is specifically about the baby’s soft spot being raised or swollen, not about the overall head shape. 

However, the underlying conditions causing the bulging fontanelle might sometimes affect the head shape, such as:

  • Hydrocephalus can cause an enlarged head circumference over time.
  • Certain craniosynostosis types (premature fusion of skull bones) can cause both abnormal head shape and potentially a bulging fontanelle.

How Do Doctors Diagnose the Cause of Bulging Fontanelles?

To determine the cause of bulging fontanelles, your baby’s pediatrician or emergency room doctor will perform a physical examination, ask questions about the baby’s medical history, and perform a variety of diagnostic tests.

They will likely ask questions such as the following:

  • Which of the fontanelles (soft spots) appears to be bulging (e.g. top of the baby’s head, back of the head, or elsewhere)?
  • Is the fontanelle consistently bulging, or does it come and go?
  • Does it look normal when the baby is calm or upright?
  • When did you first see the bulging?
  • Does the baby have a fever?
  • Is the baby irritable or lethargic?
  • Are there any other symptoms?

Diagnostic tests may include the following (among others):

  • CT scan
  • MRI
  • Lumbar puncture (spinal tap)

How Do Doctors Treat a Baby with a Bulging Fontanelle?

It’s important to note that the bulging fontanelle itself is not causing these problems. Rather, it’s an indicator of the underlying condition, which is responsible for the various symptoms and potential complications.

Early detection and treatment of the underlying cause are crucial to prevent or minimize long-term effects. This is why a bulging fontanelle is considered a medical emergency requiring immediate evaluation.

Therefore, to manage a baby with a bulging fontanelle, medical professionals must address the underlying cause. Treatment is then tailored to address the specific condition identified, which may range from antibiotics for infections to surgical interventions for conditions like hydrocephalus. 

Throughout the process, the medical team closely monitors the baby’s overall health and neurological status. The primary goal is to resolve the underlying issue, which in turn should normalize the appearance of the fontanelle. 

Bulging Fontanelle, Birth Injury, and Medical Malpractice

Many of the conditions that underlie bulging fontanelles (e.g. encephalitis, hydrocephalus, meningitis, hypoxic-ischemic encephalopathy, intracranial hemorrhage, and head trauma) are types of birth injury. In many cases, these birth injuries are preventable with proper medical care during pregnancy, birth, and the neonatal period.

If a medical professional or organization fails to provide proper care, and this causes harm to the baby, it constitutes medical malpractice. It is also malpractice if a doctor fails to diagnose or take warning signs of injury seriously, such as a bulging fontanelle.

Get Legal Help

Has your child or loved one been harmed by a birth injury that could have been prevented? The attorneys at ABC Law Centers: Birth Injury Lawyers (Reiter & Walsh, P.C.) may be able to help. We only focus on birth injury cases, so we have the legal and medical expertise necessary to effectively advocate for our clients. Please reach out today for a free case review – in fact, you pay nothing throughout the entire legal process unless we win or favorably settle your case.


  1. Fontanelles – bulging: MedlinePlus Medical Encyclopedia. (n.d.). Retrieved November 2, 2018, from https://medlineplus.gov/ency/article/003310.htm
  2. Bulging fontanelle: Causes, Symptoms and Diagnosis. (n.d.). Retrieved November 2, 2018, from https://www.healthline.com/symptom/bulging-fontanelle