The mRNA COVID-19 vaccine and pregnancy: What you need to know if you're pregnant, trying to get pregnant, or breastfeeding

pregnant woman getting COVID-19 vaccine

When federal regulators approved the first two COVID-19 vaccines for general use in the U.S., they gave pregnant people and those who are breastfeeding the option to decide whether to get the immunization. But they stopped short of recommending it outright. That’s because pregnancy is a medical condition that typically excludes people from participating in clinical trials to study the safety and effectiveness of a drug. Excluding this group of people meant there was little data available.

While there are currently no known risks of receiving the COVID-19 vaccine while pregnant, scientists are in the process of gathering additional data to learn more.

Knowing many patients have questions about whether to get the vaccine when it’s offered to them, University of Chicago Medicine reproductive health experts specializing in maternal-fetal medicine, reproductive endocrinology and infertility, high-risk pregnancies and general obstetrics answered common questions about the vaccine and pregnancy.

Here’s what Abbe Kordik, MD, Assistant Professor of Obstetrics and Gynecology; Joana R. Lopes Perdigao, MD, Associate Professor of Obstetrics and Gynecology; Maryam Siddiqui, MD, Associate Professor of Obstetrics and Gynecology; and A. Musa Zamah, MD, PhD, Associate Professor of Obstetrics and Gynecology had to say.

Can I get a COVID-19 vaccine if I’m pregnant, planning to become pregnant, or currently breastfeeding?

The CDC has indicated that the vaccine may be administered to those who are pregnant. Additionally, several professional societies have advocated for pregnant people to be vaccinated. However, if you have questions or concerns, you should discuss them with your healthcare provider. The CDC says those who are pregnant should weigh the following when deciding whether to get the vaccine:

  • your individual risk of acquiring the virus (both to community transmission and your occupation)
  • the potential damaging health outcomes of contracting COVID-19 while you’re pregnant
  • the side effects that you may experience after receiving the vaccine
  • the safety and efficacy data currently available.

If I don’t get vaccinated, what are the risks of contracting COVID-19 during pregnancy?

While the overall risk of experiencing a severe course of COVID-19 is low, if you’re pregnant you have an increased risk of getting severely ill if you contract COVID-19. That means you have an increased risk of hospitalization, ICU admission, extracorporeal membrane oxygenation (ECMO) treatment and death.

Some preliminary studies have indicated a slightly increased risk of preterm birth for babies born to mothers with COVID-19, but this is likely because doctors are likely to recommend premature birth for the mother’s wellbeing if she is sick with the coronavirus.

Have the COVID-19 vaccines been tested in pregnant or breastfeeding people?

Pregnant people were not specifically included in the clinical trials; this is due to historical restrictions on including those who are pregnant in clinical trials. While the vaccine manufacturers do plan to conduct these clinical trials at a later date, they are currently focused on completing the first Phase 3 trials and distributing vaccines under the Emergency Use Authorization (EUA). Pfizer/BioNTech has also stated that they are conducting DART studies in animal models to determine if there are any negative side effects of the COVID-19 vaccine in pregnancy; these studies are frequently used to make determinations about what medical treatments should be offered to pregnant people in the absence of human clinical trial data.

During the Pfizer/BioNTech vaccine clinical trials, 23 people became pregnant after receiving the vaccine. As far as physicians are aware, there have been no adverse effects yet reported in those people, but more data is required.

Do I need to delay getting pregnant or fertility treatments if I’m planning on getting vaccinated?

Current recommendations say there is no reason to delay conception. If you become pregnant after receiving your first dose of the COVID-19 vaccine, you should not delay getting the second booster dose as scheduled. The only possible risk physicians are currently aware of with the vaccine is the possibility of a fever following the second dose, a side effect experienced by around 10-15% of vaccine recipients. In animal studies, high fevers in early pregnancy have been associated with a slight increase in risk of birth defects and pregnancy loss. If this is a concern, the current recommendation is that you take a pregnancy-safe fever reducer such as Tylenol if you experience a fever after getting vaccinated. You may also wish to take Tylenol proactively before getting vaccinated to help prevent a fever.

If you are undergoing fertility treatments, the current recommendation is to continue the treatments and to get vaccinated. Speak with your physician and/or fertility specialists to make the decision that is best for you.

When during pregnancy should I get vaccinated?

In order to maximize protection against COVID-19, we recommend individuals get the vaccine as soon as it is offered.

Can the vaccine affect my fetus during pregnancy or reach my baby through breastfeeding?

The mRNA vaccines work by presenting your body with a small set of genetic instructions for producing the SARS-CoV-2 spike protein. Your body generates the protein and allows your immune system to learn what the protein looks like so it can recognize the protein if you should ever encounter the actual SARS-CoV-2 virus and prepare an immune response to keep you from getting sick. mRNA is extremely short-lived and easily degraded; this is why the vaccine must be stored at such cold temperatures and used quickly after preparation. Once the vaccine has been injected into your arm, your body either uses the instructions to make those spike proteins or it rapidly breaks down the small amount of mRNA that’s remaining. It is therefore extremely unlikely that any of the mRNA would be able to get into breast milk or into the fetus through the placenta. Additionally, because it’s so easily degraded, it cannot survive the acidic environment of your baby’s stomach.

Will the vaccine cause infertility or damage to the placenta?

There is also no evidence that the COVID-19 vaccine would reduce your natural fertility or harm the placenta or fetus. While the COVID-19 vaccine is new, the mechanism of action of this mRNA vaccine and existing safety data provide reassurance regarding the safety of COVID-19 mRNA vaccines during pregnancy.

Will breastfeeding pass immunity on to the baby?

If you are vaccinated during late pregnancy, it is likely that the antibodies your body produces in response to the vaccine will be passed to the fetus through the placenta and may provide some protection against COVID-19, the same way a flu vaccine can help protect your baby against the flu. Because of the biology of the COVID-19 vaccine, we do not believe that breastfeeding will provide any antibody protection to the baby. However, we do not yet have any data on this point and it should be clarified in future studies.

Why is the U.S. allowing vaccines for those who are pregnant, but the U.K. isn’t?

Because the vaccines have not yet been tested in those who are pregnant, the U.K. has opted to wait for more data before recommending vaccinations for that group. Here in the U.S., our regulators decided to give people in this group the option to get the vaccine if they choose.

Will you recommend that your patients get vaccinated? Are you getting vaccinated?

We agree with the position of the American College of Obstetricians and Gynecologists, the Society for Maternal-Fetal Medicine and the CDC that this is an individualized decision and pregnant/breastfeeding people should be offered the choice to get vaccinated.

While data is still being collected about these vaccines, we believe that in the vast majority of cases, the benefits outweigh the risks, and the vaccine is much safer than contracting COVID-19.

Some of us are breastfeeding; we all have patients, friends, and family that we want to protect, and we are all looking forward to getting vaccinated as soon as we are eligible.

For more answers to common questions about the COVID-19 vaccine, read: Q&A: What you need to know about the COVID-19 vaccine

Meet Our Physician Contributors