Why doctors are so worried about pregnant people getting COVID-19

Canadians who are pregnant are at higher risk for severe illness if they get COVID-19, yet many are still hesitating to get vaccinated, experts say. 

"It's terribly concerning," said Dr. Deborah Money, an obstetrics and gynecology professor who specializes in reproductive infectious diseases at the University of British Columbia in Vancouver.  

"Pregnant women are undervaccinated compared to the rest of the population for sure," said Money, who works with CanCOVID-Preg, which tracks COVID-19 in pregnancies across the country.

Early in the pandemic, data on the potential effects of COVID-19 on pregnant people and fetuses was limited — and pregnant people weren't included in clinical vaccine trials. Even the World Health Organization failed to provide clear advice on vaccination for pregnant people in the early days, which contributed to uncertainty among both pregnant people and the primary care providers trying to give them the best medical advice on vaccination. 

But during the last several months, there has been growing consensus among experts that not only are COVID-19 vaccines safe for pregnant people, but also that pregnant people are among the groups at highest risk of serious illness if they are infected with the virus — and there can be consequences for their babies too. 

CBC News talked to obstetrician-gynecologists, immunologists and an infectious disease expert to get the most up-to-date facts. Here's what we know. 

Pregnant people who become infected with COVID-19 are more likely than non-pregnant people in their age group to become critically ill, said Dr. Alexander Wong, an infectious diseases expert in Regina. Saskatchewan is battling such high rates of COVID-19 hospitalization that it has had to fly critically ill patients to hospitals in other provinces. 

Being fully vaccinated "dramatically" reduces that risk, Wong said.

Evidence from around the world continues to back that up, and Money said her team is in the midst of publishing a study "showing substantially higher rates of hospitalization, ICU admission and higher rates of pre-term birth" among pregnant women in Canada who weren't vaccinated.

One key reason pregnant people are so vulnerable to infections like COVID-19, immunology experts say, is that their immune systems have lowered defences.   

"When a person is pregnant, they're somewhat immunosuppressed because from the immune system's perspective, the developing fetus is actually a foreign invader," said Angela Rasmussen, a virologist at the University of Saskatchewan's Vaccine and Infectious Disease Organization (VIDO) in Saskatoon. 

There are "substantial rearrangements of the immune system" during pregnancy so it doesn't start attacking the developing fetus, she said. 

But vaccination triggers an effective immune response against specific threats like COVID-19, she said, so pregnant people "should definitely get vaccinated."  

More research is showing that not only is getting vaccinated safe for both parent and fetus — it likely has protective benefits after the baby is born, obstetrician-gynecologists and immunology experts told CBC News.