Croup is an inflammation of the larynx (throat), trachea (windpipe), and bronchi (tubes that connect the trachea to the lungs). It occurs primarily in young children.

Croup arises from a respiratory infection or a condition that irritates the airway. The resulting inflammation causes a person to have a bark-like cough and noisy breathing sounds (stridor).

This article discusses croup in newborns, including symptoms, causes, when to seek help, diagnosis, treatment, and prevention.

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Each year, croup affects about 3% of children in the United States, generally between the ages of 6 months and 3 years. An estimated 85% of croup cases are mild, with less than 1% being severe. It is less common in newborns.

Infants may experience worse cases of croup than older children. A 2020 study identified being less than 2 years of age as a risk factor for hospitalization and severe croup.

The World Health Organization (WHO) defines a newborn, or neonate, as a child less than 28 days old. It describes children of this age as being their most medically vulnerable.

Croup is serious when it affects a child’s ability to breathe. However, it is treatable, so severe complications such as pneumonia or death are rare.

The core symptoms of croup are a barking cough and stridor breath sounds when inhaling. Stridor is a high pitched, whistling, or squeaking sound.

Other symptoms may include:

Symptoms stem from airway inflammation that interferes with breathing.

The type of underlying conditions that lead to croup can also affect symptoms. Spasmodic croup from allergies or reflux usually occurs without fever. Some instances of infection-borne croup may also present without an elevated body temperature.

About 75% of infections leading to croup occur because of the parainfluenza virus. Other viruses can also cause croup, as well as bacterial infections, allergies, and reflux.

A parent or caregiver should consider contacting a healthcare professional with any sign of illness in a newborn.

Parents or caregivers should seek urgent medical assistance if a newborn is:

  • struggling to breathe
  • showing chest and neck retractions when they breathe
  • unable to swallow
  • making whistling or squeaking sounds when breathing
  • unusually sleepy
  • very pale
  • becoming cyanotic (blue tinge to lips, nails, or skin)
  • showing signs of dehydration, such as fewer wet diapers or sunken fontanel
  • unusually irritable and unable to settle

Healthcare professionals usually diagnose croup with an exam and symptom evaluation.

The most common tool for determining croup severity is the Westley score, which groups symptoms into five categories:

  • inspiratory stridor
  • retractions
  • air entry
  • cyanosis
  • level of consciousness

Healthcare professionals use their assessments of these symptoms to categorize croup as mild, moderate, or severe.

Usually, signs and symptoms are sufficient for a diagnosis.

Occasionally, healthcare professionals may also take a nasal swab for testing or order an X-ray to rule out obstructive issues such as a foreign body in the airway.

In infants under 6 months, healthcare professionals will typically also include evaluations for other causes of airway obstruction or narrowing.

Treatment depends on croup severity.

Dexamethasone is a corticosteroid that reduces inflammation to ease croup symptoms. Healthcare professionals administer this medication according to body weight and can determine the appropriate dosage for an infant.

Many children with mild croup need only one dose of dexamethasone. Those with moderate to severe cases may also receive epinephrine, oxygen, and, in rare cases, intubation.

If a healthcare professional suspects that a bacterial infection is the cause of croup, they may prescribe an antibiotic.

They might also treat severe croup from influenza A or B with an antiviral neuraminidase inhibitor.

Home treatment for croup includes keeping the infant:

  • hydrated
  • comfortable
  • calm

Stress, fear, and excessive crying can cause airway inflammation to worsen, so comforting and soothing the infant can help ease symptoms.

Keeping a child’s head elevated can also help, but it is not recommended to use pillows or other bedding material for babies under 12 months of age.

Breathing cool air may ease symptoms if parents or caregivers dress their infant warmly enough for exposure to a reduced-temperature environment.

If parents or caregivers sleep in the same room as the infant at night, it is easier to monitor their breathing to watch for problems.

According to the Centers for Disease Control and Prevention (CDC), the human parainfluenza viruses (HPIVs) associated with croup are transmissible via infectious droplets, either through direct contact or airborne spread.

An HPIV infection is the most contagious during its early stages.

Hygiene measures such as handwashing and surface disinfecting can provide some protection.

Anyone with an HPIV infection should safeguard against airborne transmission to infants. Breathing, coughing, and sneezing are examples of how HPIV can spread.

Although most cases of croup originate from HPIV, routine childhood vaccinations can protect older children against some of the other infections that can cause croup. This reduces the chance of spreading an infection to an infant too young to be vaccinated.

The following are three frequently asked questions about croup in newborns.

How contagious is croup to a newborn?

Croup may be more contagious to a newborn than an older child since infants have underdeveloped immune systems.

According to the CDC, an estimated 75% of children 5 years of age or older have antibodies against HPIV-1 and HPIV-2, the virus types most often associated with croup.

What does croup sound like in newborns?

Any breathing abnormalities in an infant should be evaluated promptly by a healthcare professional.

In newborns, croup stridor has a gasping, strangulation-like sound. A croup cough has a hoarse, barking sound.

Can a baby lay down with croup?

Croup symptoms may worsen at night during sleep. Keeping a child’s head elevated may make breathing easier. However, using bedding materials such as a blanket or pillow is not advisable for children under 12 months of age.

Croup is an airway inflammation that causes noisy breathing and a bark-like cough. It occurs most commonly in young children. It is less common in newborns. However, if a newborn develops croup, it can be more severe than in children of an older age.

The cause of croup is usually the human parainfluenza virus, but other types of infection can also contribute. Allergies and reflux can also cause croup.

Most cases of croup are mild and resolve with home treatment or after a single dose of dexamethasone from a doctor. Occasionally, hospitalization is required.