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Fact check: COVID-19 vaccines are safe for pregnant and breastfeeding mothers

As hospitalizations climb, B.C. is calling on pregnant women to get vaccinated. Still concerned? We answer your questions.
pregnant vaccination
A pregnant woman is vaccinated. B.C. health officials are telling pregnant people to get vaccinated against COVID-19 as soon as possible.

When the Pfizer-BioNTech and Moderna COVID-19 vaccines were approved back in December 2020, they came with a lot of caveats: no children or immunocompromised, and if you are pregnant or breastfeeding, speak to your doctor.

For Vancouver resident Trang Tran, it all pushed her to wait. 

“I was worried about the health of my baby,” she said.

That changed when Tran visited family in Vietnam, a country that saw cases climb from single digits to over 11,500 in late August. Soon she fell ill with the virus.

“They’re facing the new Delta variant. It’s crazy there,” said Tran after she returned.

Coming home, she said all her pregnant friends had been vaccinated. That, she said, finally pushed her to get her first shot of the COVID-19 vaccine. 

But despite an increasing number of studies showing COVID-19 vaccines are safe — from conception to pregnancy and breastfeeding — for many other pregnant women, doubt remains. 

On Monday, provincial health officer Dr. Bonnie Henry urged those who are pregnant to get vaccinated after a number of young pregnant women were admitted to intensive care units. 

"We have seen this happen particularly since we started to see [the] Delta [variant] transmitting more easily; we've seen the tragic outcomes of that across the province," Henry said.

Glacier Media spoke to Dr. Deborah Money, a professor in the University of British Columbia's department of obstetrics and gynecology, to help separate fact from fiction around vaccines and pregnancy.

How have COVID-19 vaccines been tested on pregnant people or those trying to conceive? 

The original mRNA vaccine trials did not include women who were pregnant or planning to be pregnant. But as with any trial, unplanned pregnancies happen. 

“In those, there was absolutely no adverse effects noted related to the pregnancy,” says Money. 

In the nine months since the vaccine was approved in North America, health authorities have been tracking real-world outcomes in several groups. 

In the United States alone, there are over 160,000 women who have received the vaccine during pregnancy. In Canada, we don't have the exact numbers, but in Ontario, 40,000 pregnant women had their outcomes tracked with some positive results.

“In all of that information, both Canadian and internationally, there is no safety signal of any concern of adverse effects in pregnancy versus non-pregnant,” says Money.

“Pregnant women make perfectly good antibody responses, and there doesn't appear to be any evidence that they have any reduced effectiveness from these vaccines.”

Do COVID-19 vaccines increase the risk of a miscarriage?

Unfortunately, says Money, humans miscarry at quite high rates.

But according to all the data, she says there is no evidence for an increase in the rate of miscarriage related to a COVID-19 vaccine.

“You could, unfortunately, have a vaccine and have a miscarriage because of the commonality of miscarriages. And so it can happen in conjunction, but there's no evidence to suggest it's the cause.”

Can vaccines damage the placenta?

“So that's a curious one that has been circulating in social media related to a completely incorrect suggestion that the spike protein is similar to Syncytin-1, which is one of the key proteins in a very complex organ, the placenta,” says Money.

“There's nothing that gives us any support for the spike protein even getting into the placenta or affecting the placenta in any way.”

Has there been enough testing to know if mRNA vaccine technology causes infertility or not?

“First off, mRNA technology is not as new as people seem to believe it to be. mRNA technology has been around for decades, and has been utilized for the development of several vaccines prior to the COVID vaccine, including Ebola vaccines, CMV (cytomegalovirus) vaccines, HIV vaccines,” says Money.

“Some have been successful, and some haven't (not related to the mRNA technology, but more related to the disease they're trying to prevent).”

“There are no vaccines of any stripe that have ever caused infertility. And there's no data to support that the COVID vaccine could or would cause infertility.”

Are mRNA vaccines basically gene therapy that manipulates a pregnant woman’s — and baby’s — DNA?

“That one is just so not true,” says Money. 

At the heart of human cells lies DNA, the blueprint to create all the body’s building blocks.

Those buildings blocks, known as proteins, need direct instructions before they are created. To do that, DNA — stuck inside the cell's nucleus — needs a messenger. That’s where messenger RNA (mRNA) comes in. By copying a chunk of DNA, mRNA acts as a short-order recipe card for protein creation outside of the nucleus.

An mRNA vaccine piggybacks on that process, supplying our body with the missing recipe to the viral spike protein of a coronavirus. That protein teaches the immune system how to create neutralizing antibodies against the SAR-CoV-2 virus. If the virus shows up, the antibodies attack.

“That message doesn't go anywhere else. It just gets used and destroyed,” says Money. “It can't go back in and alter the genetic code.”

“It’s blocked. And that's a fact of biology... so mRNA of any kind, be it from a vaccine or from ourselves, can’t go back into the genetic code.”

When a pregnant woman gets a vaccine, does that transfer over to the unborn child?

“That's actually not the way vaccines work,” says Money. 

The mRNA vaccines work by triggering a local immune response, say, in the arm. In the case of a Pfizer or Moderna COVID-19 vaccine, the message is used as instructions to make the spike protein. Then it auto-destructs. 

“The mRNA is not incorporated into our cells in any way, shape, or form — not our cells in the arm, nor our cells in the reproductive systems,” says Money.

What does happen, she says, is the pregnant woman will circulate antibodies through her bloodstream, and to a varying degree, cross over to the unborn baby, depending on the stage of the pregnancy.

“That's a good thing because those crossing antibodies protect the infant.”

How will a COVID-19 vaccine affect a mom and baby if they are breastfeeding?

Money says that if a mother gets a vaccine during the time of breastfeeding, she will likely transfer some of the antibodies made in her system into her breast milk, and then the baby will get some antibody protection.

Do unvaccinated pregnant women get sicker from COVID-19 than unvaccinated people who aren't pregnant?

“At the very beginning, there was a hesitancy to make recommendations until we had more information,” says Money. 

Then information began to come through. 

Doctors have found the number of pre-term births in mothers with COVID-19 have more than doubled to 13.6 per cent. It’s a phenomenon not limited to COVID-19 patients with serious illness. 

Higher hospitalization rates first started coming to Money’s attention overseas. But by the early summer, even in Canada, the data was clear that pregnant women were being hospitalized and ending up in the ICU in greater rates.

Now, Money says pregnant women are hospitalized and admitted to ICUs at three to four times the rate as non-pregnant people.

“Let me tell you, as an obstetrician, a pregnant woman in the ICU is not a good thing for the pregnancy and that baby,” she says.

Money continues, “This is in exclusively and unvaccinated women... these are very, very sick individuals. And this is happening here in British Columbia. And we've seen it, sadly, across the country in the harder hit provinces like Alberta and Saskatchewan right now.”

The numbers have gone up over the past two months, but Money says the data is time-delayed and is mostly from before the Delta variant became dominant in the province.  

Severity, says Money, is only expected to look worse once we get more recent data.

Should pregnant women take any precautions before they are vaccinated against COVID-19?

"Only if they still have unanswered questions. But we are urging people who, particularly people who are planning to get pregnant, this would be the perfect time to get vaccinated... It's imperative that women planning to become pregnant or pregnant right now, really seriously look at ways to protect themselves,” says the obstetrician.

"My colleagues who were dealing with this in the ICU around the province are very worried.”

With files from Tyler Orton