Hilary Duff reveals 'brutal' COVID-19 diagnosis — how do respiratory illnesses affect pregnancy?

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Hilary Duff has COVID-19 again while pregnant — and she said this time, it's "brutal."

The actress took to social media over the weekend to say she and her husband, Matthew Koma, 36, contracted the virus after a family Disneyland trip. She shared a dark selfie from bed to her Instagram Stories, writing in on-screen text, "COVID brutal this time," along with a thumbs-down emoji.

The "How I Met Your Father" star's post came a few days after she announced in a post she is expecting her fourth child, and her husband sharing a family photo with Duff showing off her pregnant belly.

In a recent Instagram Story, the 36-year-old shared her kids haven't been diagnosed yet, so she and her husband "now wear masks again."

Duff was also diagnosed with COVID-19 in her 2020 pregnancy, when she shared quarantine updates with her fans.

But what's it like having a respiratory illness when pregnant, and are there any specific risks?

Winter bugs are already making the rounds, making these fall and winter seasons a bit tricky for expecting moms. In the midst of it all, Yahoo Canada spoke with Dr. Isabelle Boucoiran to help moms-to-be navigate their pregnancy journey through the common respiratory illnesses in Canada.

How do respiratory illnesses like COVID-19 and RSV impact pregnant people?

The United States and Canada could see a "syndemic" this year, as COVID-19, flu and RSV cases rise — possibly higher than last year.

Boucoiran, an OBGYN at CHU Sainte-Justine pediatric centre in Montreal, tells Yahoo Canada each of these illnesses bring on unique risks for expecting mothers and unborn babies.

However, one thing respiratory illnesses do have in common is their impact on the lungs. When a person is in their third trimester of pregnancy, with a bigger baby in their belly, there is less room for the lungs to expand.

"The respiratory capacity is smaller, but the women need to breathe for two. And so if she had less oxygen, it's going to be a higher risk for her to be quickly overwhelmed by respiratory distress, because you need more oxygen than any other adult," Boucoiran explained.

Also, it can impact breast milk production postpartum. "Every time you have a severe stress to the body, it's more difficult for the breast milk production to start and be effective," the doctor added.

Here are the risks and unique symptoms associated with each illness.

What are the risks in pregnancy and COVID-19?

Pregnant women experience the same symptoms as the general population when infected with COVID-19, Boucoiran said. These include fever, cough and shortness of breath.

Boucoiran emphasized these symptoms are often nonspecific, making early detection crucial.

Risks

Contracting COVID-19 during pregnancy elevates the risk of the following:

• Higher risk of death

• Preterm delivery

• Severe pneumonia

What's been known since the start of the pandemic is COVID-19 brings a higher risk of admission into ICU for pregnant people.

The third trimester poses particular challenges due to reduced lung capacity, Boucoiran explained, making pregnant women more susceptible to respiratory distress.

Are there any long-term risks?

Boucoiran said she is not aware of any evidence COVID-19 infections during pregnancy comes with long-term risks for the birthing parent. However, "if the infection in pregnant pregnancy leads to a preterm birth, of course, there is a long-term impact on the health of the newborn."

Those risks in preterm newborns can include:

• Higher risk of death

• Higher risk of chronic respiratory disease (with the need for oxygen long-term)

• Higher risk of developmental delay

How does influenza impact pregnancy and newborns?

Symptoms of influenza, commonly known as the flu, mirror those experienced by the general population. These include fever, body aches and respiratory symptoms.

Risks

Influenza poses risks of severe pneumonia in pregnant women and respiratory distress in newborns.

The third trimester, in particular, sees an elevated risk of admission to hospital for pregnant people. They are likely to have "more dramatic" symptoms due to the lower respiratory capacity, Boucoiran explained.

Does RSV pose special risks to pregnant people?

Respiratory syncytial virus (RSV) in pregnant women presents with flu-like symptoms, including headaches and fever. However, there is no known direct risk of lung infection for the pregnant person herself during pregnancy.

Risks

Unlike COVID-19 and influenza, RSV does not pose a direct risk to the pregnant person.

It typically does not contribute to pneumonia in the parent. However, Boucoiran cautioned RSV can lead to severe respiratory infections in newborns.

How are pregnant people treated for respiratory illness?

When it comes to treating respiratory illnesses in pregnant people, Boucoiran said antivirals are reserved for that demographic, as they are for people who are immunocompromised. These can be, for example, Paxlovid for COVID or Tamiflu for influenza.

However, there aren't many available everywhere and they can be expensive, she explained. It is also only given in early stages of the disease.

"Sometimes, by the time we see the pregnant woman, it's kind of too late," she said.

"So, you cannot think that because we have this treatment available, there is no need to be vaccinated."

How can pregnant people protect themselves this winter?

Boucoiran said, by now, most people know of the basic hygiene measures to protect themselves from illnesses.

"It's washing their hands, wearing a mask if they go to a public place, like maybe public transport ... avoiding any contact with people who are sick," Boucoiran advised.

"And the first advice is, of course, being vaccinated."

Boucoiran assured "both COVID-19 and influenza vaccines are recommended right now for pregnant women."

The flu shot is recommended to those who haven't had the flu yet this season, while the COVID-19 vaccine is recommended to those who haven't been infected in at least 6 months.

"Being vaccinated is protection for the woman's health during pregnancy, but because the antibody is going through the placenta, vaccination is going to also protect the newborn for this the first month of life," the expert said. That first month of life is crucial for newborns' health due to high risk of severe respiratory illness.

She also highlighted an RSV vaccine for pregnant women that "should" become available in Canada in 2024, offering additional protection for newborns. Called Abrysvo, the RSV vaccine was approved by the U.S. Food & Drug Administration in August, and is already being used in some European countries.

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