If you’re pregnant, you likely already know that there is an increased risk of contracting severe COVID-19, meaning you are much more likely to be really sick if you catch SARS-CoV-2, the virus behind the pandemic. That happens for a couple of reasons. First, the immune system—the part of your body that fights infections—works differently during pregnancy in order to protect your baby. Second, SARS-CoV-2 targets the lungs, which are already working hard during pregnancy to oxygenate the extra blood needed to supply the fetus with nutrients and oxygen.
Because of these risks, the vast majority of providers and organizations who work with pregnant and lactating people recommend the COVID-19 vaccine to their patients. The vaccine works by training your immune system to recognize the SARS-CoV-2 virus. Thus, if you’re exposed to the virus after you’ve been vaccinated, your immune system has a head start on fighting it. It’s a little bit like taking a test that you’ve studied for (vaccination) versus one you haven’t (no vaccination). You’re much more likely to get a better grade on the test you’ve studied for, just as vaccination gives your immune system a better chance at being able to cope with the virus before it causes severe disease.
The technology that’s used in both the Pfizer and Moderna vaccines has been around for a while. These vaccines each work by introducing (via injection) part of the blueprint for a viral protein. The body’s cells make the viral protein, and then the immune system learns to recognize it. There’s no danger of infection because the protein that gets made is only one tiny piece of the virus.
That said, whenever a new vaccine is introduced, it’s not uncommon for people to be cautious about receiving it during pregnancy, at least in part because pregnant people are not usually included in clinical trials. Without inclusion in clinical trials and the resulting data, it is not always clear how pregnant people will react to a vaccine. In the case of the currently approved COVID-19 vaccines, there is now a lot of data that shows them to be safe and effective during pregnancy.
While pregnant, though, the fear of miscarriage is often present. To evaluate the risk of miscarriage after receiving the COVID-19 vaccine, researchers in Norway, the United States, and Canada performed an analysis on data of more than 750 pregnant people in Norway who received the COVID-19 vaccine in the first trimester of pregnancy. At the time they collected the data, the COVID-19 vaccine was not recommended for people in their first trimester, but the people in their sample likely received the vaccine before they knew they were pregnant. The researchers, who published their results on October 20 in The New England Journal of Medicine, found that there was “no evidence for an increased risk for early pregnancy loss after Covid-19 vaccination.” 
This is great news for anyone who is pregnant and has worried about the COVID-19 vaccine. The U.S. Centers for Disease Control and Prevention (CDC) recommends that people who are pregnant, may be pregnant, have recently been pregnant, and might become pregnant receive a COVID-19 vaccine. According to the CDC, “the benefits of receiving a COVID-19 vaccine outweigh any known or potential risks of vaccination during pregnancy.”  Another reason to get vaccinated is that it has been shown that there is a risk of miscarriage associated with COVID-19 infections.  In addition to miscarriage, COVID-19 infection in pregnancy can also increase the risk of preterm birth.
The known and potential benefits of vaccination are also a good reason to get vaccinated for COVID-19 during pregnancy. According to the CDC, “vaccination of pregnant people builds antibodies that might protect their baby.” And in a research study published in September 2021, the authors showed that babies whose mothers were vaccinated during pregnancy had antibodies in their umbilical cord blood. 
- C. Magnus et al., “Covid-19 Vaccination during Pregnancy and First-Trimester Miscarriage,” The New England Journal of Medicine, 2021.
- “COVID-19 Vaccines While Pregnant or Breastfeeding,” CDC, 2021.
- N. Kazemi et al., “COVID-19 and cause of pregnancy loss during the pandemic: A systematic review,” PLOS ONE, 2021.
- J. Gray et al., “Coronavirus disease 2019 vaccine response in pregnant and lactating women: a cohort study,” American Journal of Obstetrics & Gynecology, 2021.