Croup is a highly contagious viral infection that affects the respiratory system, causing the inflammation and swelling of the vocal cords (also known as the larynx) and the windpipe (also known as the trachea). This swelling narrows the airway to the lungs, resulting in difficulties in breathing, and patients have a barking cough resembling that of a seal.¹ 

The condition most commonly affects infants and children, as the swelling will more significantly impact their breathing due to their windpipes being naturally narrower and still developing.² However, because of how infectious croup is, it can be easily passed on to adults, including pregnant people. 

Croup, like other respiratory infections, will likely lead to more severe symptoms in people who are pregnant compared to people who are not.³ Due to its potentially significant impact on pregnant people, it is important to spread awareness about this viral infection. This article will detail the causes, symptoms, diagnosis and treatment options for croup in pregnancy.  

Causes of croup

Croup is commonly caused by an infection from a virus (tiny germs that spread throughout our body by invading our cells to reproduce).¹ Viruses which have been linked to croup include:

• Parainfluenza virus - This is the most common type of virus which leads to croup
• Respiratory syncytial virus
• Adenovirus
• Influenza viruses
• Measles virus
• Enterovirus¹

The viral infection causing croup is spread through direct contact with a patient. This includes breathing in infected air, drinking from the same cup as an infected person, or using the same cutlery to eat. 

Croup infection typically starts in the nose and throat, from where the virus then spreads into the airways of the lungs and the respiratory system, leading to inflammation and swelling.¹ 

Other potential causes of croup include:

• Allergies - If someone is allergic to certain environmental substances such as pollen or dust mites and inhales them, this can result in the swelling of their airways (croup)⁴ 
• Acid reflux - Pregnant people are commonly subjected to acid reflux, also known as heartburn. This is when stomach acid flows back up the oesophagus, which is the tube connecting our mouth to our stomach. This backwash irritates the oesophagus walls, in turn leading to swelling and croup symptoms.⁵ 
• Breathing in irritants - Someone may develop croup if they have breathed in chemicals which irritate their airway, resulting in swelling and inflammation. Such irritants include chemical fumes, cigarette smoke, or smog¹
• Bacteria - Sometimes bacterial infections can worsen viral croup, leading to more significant symptoms and making it more difficult for patients to breathe.¹

Symptoms of croup

Most cases of croup lead to mild symptoms, which often worsen during the night when the patient is lying down. Croup remains contagious as long as symptoms persist.⁶ The following are the most common croup symptoms:

• Barking cough, which sounds similar to a seal’s bark
• Sore throat
• Blocked or runny nose
• Fever
• Laryngitis - This is when a patient loses their voice
• Swollen lymph nodes⁶ 

However, croup can sometimes also progress and become severe in pregnant people. The infection becomes concerning when the following symptoms occur:

• Stridor - This is when a patient makes a whistling noise when inhaling while resting
• Difficulties in swallowing
• Difficulties in breathing
• Cyanosis - This is when the skin around the nose, mouth and fingernails of patients turn blueish⁶

These significant symptoms are indicators that the patient is in respiratory distress (when the patient is not getting enough oxygen due to serious troubles in their breathing). If a pregnant person experiences these severe croup symptoms, then they require immediate medical attention, as respiratory distress leads to several potential risks:

• Preterm labour - Severe respiratory infections, including croup, can result in a pregnant person giving birth early. This is because the body’s immune response to the viral infection can provoke early contractions. If a baby is born prematurely, there are certain health risks which could occur, including problems with the respiratory system and developmental issues.⁷ 
• Hypoxia - When croup patients experience respiratory distress, coupled with the swelling in their airway, they are not breathing in sufficient oxygen. When this occurs, the body goes into a state called hypoxia. Hypoxia in a pregnant person not only means not enough oxygen is being delivered to their organs, but also not enough oxygen is being delivered to their baby. This in turn could lead to foetal distress.⁸

Why are pregnant people more likely to experience severe croup symptoms?

Although generally, in both children and adults, croup tends to be mild, pregnant people are more likely to suffer more significantly from croup compared to non-pregnant adults. This is largely due to the physical changes that occur in their body during pregnancy. Due to pregnancy hormones and the developing foetus, various organs, including the lungs, undergo anatomical changes. Such changes in the lungs can in turn affect the respiratory system’s ability to clear viral infections such as croup, in turn leading to more severe symptoms.⁹ 

Additionally, the immune system also undergoes changes when someone is pregnant, which can lead to a decreased ability to fight off certain harmful foreign substances, such as respiratory viruses.⁹  

Diagnosing croup in pregnancy

When a pregnant person goes to the doctor presenting croup symptoms, in order to diagnose the patient, the medic will first evaluate their medical history and will enquire about the duration and severity of their symptoms.⁸ 

In order to confirm the diagnosis, doctors can then use the following tests on pregnant people:

• Blood tests - This will assess whether the cause of the infection is viral or bacterial
• Pulse oximetry - The amount of oxygen in the patient’s blood will be measured, to assess respiratory distress. This is done using a small device called an oximeter⁸

Treatment options for croup in pregnancy

Mild croup symptoms can be treated even using home remedies. These include:

• Using a cool-mist humidifier to alleviate irritation of the windpipe
• Sleeping with the window open, to allow cool air to come through, will also help improve croup symptoms
• Gargling salt water to help reduce soreness in the throat
• Sleeping with an extra pillow to keep the head elevated, to allow better breathing during the night.⁸

If symptoms do not improve after a week with such home treatments, or if symptoms are more severe, then it is best to visit a doctor, who will be able to suggest appropriate treatment.⁸ Common examples of croup treatment include:

• If a patient has difficulties in breathing, an oxygen mask can be given to croup patients, to ensure adequate oxygen is being given to both the pregnant person and their baby
• Whilst someone is pregnant, it is advised that they try to avoid all medication possible, as it could affect the development of the baby. However, if deemed necessary due to severe croup symptoms, pregnant people can be prescribed mild pain relief medications which are safe for pregnancy use, to alleviate symptoms. An example of a safe medication for pregnant people includes prednisolone.¹⁰

With such treatment options, symptoms of croup typically clear up within a week.⁸

Prevention of croup in pregnancy

In order to prevent pregnant people from catching croup, there are various ways to avoid this:

• Washing hands with soap and water frequently
• Avoiding anyone who is infected with croup until their symptoms are gone
• If one cannot avoid coming into contact with someone who has croup, it is advised to wear a face mask
• Avoiding sharing utensils with other people
• Disinfecting surfaces of the house (such as door handles)

Conclusion

Croup is a contagious viral respiratory infection that can affect pregnant people, which results in the inflammation and swelling of the vocal cords and windpipe, leading to symptoms of a barking cough and difficulties in breathing. Other causes of this infection include inhaling allergens or irritants, acid reflux and bacterial infections. It is important to treat croup in pregnant people, particularly if symptoms are severe, as if not this could lead to respiratory distress in the pregnant person, in turn having effects on the health of the baby. Thankfully, croup is easily treatable, with remedy options including using a cool mist humidifier, gargling salt water, oxygen support or safe mild pain relief medications.