healthHealth and Medicine

Fact Check: Are COVID-19 Vaccines Safe In Pregnancy?


Dr. Katie Spalding


Dr. Katie Spalding

Freelance Writer

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory.

Freelance Writer


TL;DR: yes. Image credit: Prostock-studio/

Stop us if you’ve heard this one: the COVID-19 vaccines cause miscarriage in 82 percent of pregnancies.

Or maybe you’ve seen that headline saying that “920 women lost their unborn babies after getting vaccinated”.


Here’s the good news: neither of those claims are honest. The bad news is that, well, pregnancy can be scary, and living through a pandemic is scary, and some people just love to use our fears against us. So let’s dive into the facts about COVID-19 vaccines and pregnancy – and see if we can bust some of the scary myths along the way.

Vaccines are safe and recommended in pregnancy

There’s no controversy here: both the Pfizer and the Moderna vaccine are safe for pregnant people and their fetuses. Data from tens of thousands of pregnant vaccine recipients has shown no increased risk of pregnancy or birth complications, and no identifiable risks to the fetus from getting the vaccines.

On top of that, we have data from the thousands who enrolled in the Centers for Disease Control and Prevention's (CDC) v-safe pregnancy registry. According to those numbers, 86 percent of pregnant people who get a COVID-19 vaccine go on to have a successful pregnancy. That’s the same number to be expected under normal circumstances.

What do Pfizer and Moderna have in common? They’re both mRNA vaccines. This is a new type of vaccine, but that shouldn’t worry you. All it means is that instead of a low or deactivated dose of the real virus, like you might get from a traditional vaccine, the shot delivers a dose of mRNA, or messenger ribonucleic acid. This is a special type of molecule that contains instructions for our cells to learn how to make a protein that will trigger an autoimmune response. The mRNA doesn’t interact with our DNA at all – in fact, as soon as our cells are finished with it, the mRNA is broken down and disposed of.

Image: British Society for Immunology

The other type of vaccine is a viral vector vaccine, which includes the Johnson & Johnson and Oxford/AstraZeneca vaccines. You might have heard that these vaccines aren’t safe in pregnancy because they cause blood clots. It's right to be cautious, but that’s not quite true.

It is true that these vaccines carry a tiny risk of a rare blood clotting disorder called vaccine-induced thrombosis and thrombocytopenia (VITT) – that was why the CDC temporarily paused the rollout of Johnson & Johnson vaccines earlier this year. It’s also true that being pregnant can mess with your body’s ability to clot properly – that’s always been true, COVID-19 or not.

But does pregnancy and a viral vector vaccine make you especially likely to get VITT? Not according to Britain’s Royal College of Obstetricians and Gynaecologists.

“[T]here is no evidence that pregnant or postpartum women are at higher risk of VITT than non-pregnant women,” they advise. “The risk of VITT is therefore extremely low with a first dose of the Oxford-AstraZeneca vaccine, and even lower with a second dose for those who were well after the first dose.”


“There is no known risk of VITT with the Pfizer-BioNTech and Moderna vaccines,” they add.

Image: British Society for Immunology

Being unvaccinated is extra dangerous in pregnancy

So maybe the vaccines aren’t as dangerous as you’ve heard, but what if you just want to play it safe? Well, experts advise that “playing it safe”, both for you and your baby, means getting the vaccine.

“Pregnant women do have an increased risk of severe COVID-19, of hospitalization, of intensive care admission, of death, and they have an increased risk of delivering prematurely, compared to pregnant women without COVID-19,” Paul Heath, professor of pediatric infectious diseases at St George’s, University of London, told The Guardian. “For that reason, we really do need to make sure that … we are vaccinating pregnant women [and] we are doing so in the most optimal way to ensure they are best protected.”

There’s a reason pregnant people are offered the flu jab and whooping cough vaccine: your body can’t protect itself as well as it usually can. That’s partly because your immune system is busy protecting the baby as well as you, and it’s partly because if your immune system is too good it could see the fetus as a threat and attack it (seriously).


But it also means that pregnant people who get COVID-19 are more likely to get severely ill. The chances are still low, but they’re higher than for the non-pregnant population, especially in the third trimester – and that can result in your baby being born early.

Even more alarmingly, not getting vaccinated against it COVID-19 can raise your risk of suffering miscarriage or stillbirth. One huge study, covering 340,000 pregnancies in England, found that contracting the virus while pregnant could increase the risk of stillbirth by a factor of two and a half.

"While it is reassuring that the overall increases in the rate of stillbirth and pre-term birth remain low, this study does show that the risk of stillbirth or premature birth may be increased in women who have the infection around the time of birth,” explained study co-author Asma Khalil. “This highlights the importance of COVID-19 vaccination for pregnant women; it reduces the risk not just to themselves, but also to their babies.”

Getting vaccinated is good for your baby

So let’s recap: vaccines aren’t dangerous for pregnant people, getting COVID-19 is. 


It's worth remembering, the vaccine doesn’t just protect you. Your baby will benefit too.

“We now have evidence that antibodies created by the vaccine can travel through the placenta to the baby before birth and also during lactation,” said Cosmas Van De Ven, a maternal-fetal medicine specialist at University of Michigan Health Von Voigtlander Women’s Hospital. “This is reassuring news for pregnant people who want to get vaccinated but may still be hesitant. The research shows no evidence of any harm – only benefits – for newborns.”

Multiple studies have shown the same result: babies receive antibodies for the COVID-19 virus from mRNA-vaccinated mothers through the placenta and, later, breastmilk. Not only that, but they get those antibodies at substantially higher rates than if their mother simply caught the virus – in other words, getting vaccinated offers more protection for much less risk.

“Studies continue to reinforce the importance of vaccines during pregnancy and their power to protect two lives at once by preventing severe illness in both moms and babies,” said Van De Ven. 


Research is still ongoing

If you’re still worried, that’s understandable. Early trials of the various vaccines explicitly excluded pregnant people, and data was lacking for quite a while. But that’s changing.

Just this week, the UK government announced a new clinical trial specifically to investigate vaccinations in pregnancy. While the aim of the trial is to discover the optimum schedule for vaccine delivery, the researchers also hope to figure out the details of any potential side effects for mother and baby – and thereby reassure pregnant people who are hesitant to get the vaccine.

“The [uptake] of vaccination in pregnancy at the moment is disappointing, it's low – less than a third,” study lead Paul Heath told Sky News. “I suspect that one of the reasons for that is that they do not feel confident enough about vaccination. Perhaps participating in a trial will give them that confidence.”

The first results from this trial are expected later this year, but they should concur with what medical professionals are already saying: that the vaccines are safe and effective for pregnant people.


“The data we have are good, and provide some safety reassurance,” Khalil told Sky News. “But what we want to aspire to is the top quality, the high quality data from randomized controlled trials which this trial will provide.”


Although any new vaccine carries some risk, experts say that for pregnant people, the risk posed by COVID-19 is likely much more severe. The medical advice is to get vaccinated. It’s safe, it benefits both you and the baby, and not getting the vaccine increases your risk of serious illness and even stillbirth.

“It is OK if a patient decides on her own that she wants to get the vaccine in pregnancy, with the understanding that she knows the potential risks,” said Dr Jessica Shepherd, an obstetrician/gynecologist and chief medical officer of VeryWell. “[But] we do have science that clearly indicates that vaccination does decrease disease process, disease progression, and death.

“Risk vs. benefit, in the end at this point, is transmission and death vs. protection.”


Want more from our Fact Check series? Cutting through the overwhelming information (and misinformation) out there to give you the clearest explanation of the science so far. Does COVID impact fertility? Can you catch COVID if you're fully vaccinated? And more

 This Week in IFLScience

Receive our biggest science stories to your inbox weekly!


healthHealth and Medicine
  • tag
  • pandemic,

  • vaccines,

  • pregnancy,

  • covid-19