This post is current as of April 13, 2021 and will be updated as new data and recommendations are released.
In a testament to the marvels of modern science, three COVID-19 vaccines have been developed and granted emergency use authorization by the FDA (made by Pfizer, Moderna, and Johnson & Johnson) in the year since the pandemic took hold across the globe. While these vaccines differ a bit in how they work, the important thing they have in common is that they’re extremely effective in preventing severe cases of COVID-19.
We don’t have as much data as we’d like on their safety and effects in people who are pregnant or breastfeeding, and their long-term effects on fertility, as these people were excluded from previous stages of clinical trials for the vaccines. But based on preliminary surveillance data that is now being collected and analyzed by the CDC, the safety profile of these vaccines for people who are pregnant or breastfeeding looks very reassuring.
Recommendations made back in December 2020 from the Food and Drug Administration (FDA), Centers for Disease Control and Prevention (CDC), American College of Obstetricians and Gynecologists (ACOG), American Society of Reproductive Medicine (ASRM), the Society for Maternal-Fetal Medicine (SMFM), and the Academy of Breastfeeding Medicine (ABM) all suggested that those who are trying to conceive, pregnant, or breastfeeding have the option of getting the COVID-19 vaccine. These recommendations have not changed over the past 4 months as more data has come in to support them.
So, if you’re trying to get pregnant — or if you’re already pregnant — what should *you* do? Ultimately, this is going to come down to a personal choice.
In this post, we’ll help walk you through the safety considerations. We’ll review COVID-19 vaccine basics (including its efficacy and side effects), what we currently know about the effects of the vaccine in pregnant or breastfeeding/chestfeeding people, and whether there may be any effects of the vaccine on future fertility or reproductive outcomes.
COVID-19 vaccines + fertility: Main takeaways
- The FDA, CDC, ACOG, ABM, ASRM, and SMFM all suggest pregnant and breastfeeding/chestfeeding people should not be prevented from receiving the COVID-19 vaccine.
- People who were pregnant or breastfeeding/chestfeeding were excluded from the phase 3 trials evaluating COVID-19 vaccine efficacy, meaning we have no concrete data on the effects of the vaccine in this population.
- No studies specifically investigated the effect of the vaccine on chances of conception, and fetal or infant outcomes. But based on observational data in humans and animals, the chance that there is a harmful impact is low to absent.
- Early data from pregnant and breastfeeding/chestfeeding people who got vaccinated suggest that the benefits of the vaccine (aka COVID-19-fighting antibodies) may be passed along to a baby via the placenta or breast/chest milk.
Bottom line? Dr. Jane van Dis, an OB-GYN and medical advisor to Modern Fertility, says:
“There is every reason to think that, based on the mechanism and science of this vaccine, the risk to preconception, conceiving, or pregnant women is extremely low. Having said that, a conversation with your healthcare provider who understands your unique medical history should be an essential component of decision-making.” – Dr. Jane van Dis
According to ACOG, deciding to vaccinate is a personal choice and you should discuss it with your healthcare provider based on all available information and assessing current risk factors, such as personal medical history, virus activity level in your community, occupation and exposure risk, and any available information regarding fetal or neonatal safety. We’ll walk you through how to do this in more detail at the end of this article.
First up: What COVID-19 vaccines are authorized for use in the US?
Both the Pfizer and Moderna vaccines, which were the first two to get the FDA stamp of emergency use authorization, are mRNA vaccines, while the Johnson & Johnson vaccine is an adenovirus-based vaccine. Adenovirus-based vaccines have been around for a long time, and though the Pfizer and Moderna vaccines are the first-ever FDA-authorized mRNA-based vaccines, research on mRNA-based vaccines started almost 30 years ago.
At their core, all of the vaccines currently authorized for emergency use work in very similar ways, and none of them contain the actual COVID-19. Here’s a quick rundown on how the different vaccines work.
mRNA vaccines (Pfizer and Moderna)
The COVID-19 virus is notable for the spikes on its exterior, which are really just proteins called S proteins. When your body detects these spikes or S proteins, it recognizes them as intruders and the immune system gets to work trying to eradicate them.
The COVID-19 mRNA vaccines provide our bodies with the template to create these S proteins. When the molecular template gets injected, the body uses it to produce the unique S proteins. Once they’re detected, the immune system creates antibodies to destroy these proteins (and thus, would destroy any viruses that have these proteins on them). Both vaccines require one initial dose and a second dose about three weeks later.
Adenovirus vaccine (Johnson & Johnson)
The Johnson & Johnson vaccine relies on the same underlying logic: inject the body with something that jumpstarts the creation of S proteins, and provoke the immune system to create antibodies to destroy these proteins and any virus that has them on the surface.
The key difference is in how the different vaccines tell your body to produce the S proteins. The Pfizer and Moderna vaccines deliver the message in the form of mRNA, while the Johnson & Johnson vaccine delivers the message in the form of DNA that is attached to a non-harmful, inactivated virus (the “adenovirus”). Because DNA breaks down more slowly than mRNA, the Johnson & Johnson vaccine can be stored at warmer temperatures — while the Pfizer vaccine has to be stored at temperatures below -76 degrees Fahrenheit (brrr), the Johnson & Johnson vaccine can be stored at normal refrigeration temperature (between 36 and 46 degrees Fahrenheit) for several months. Unlike the two-dose Pfizer and Moderna vaccines, the Johnson & Johnson vaccine requires a single dose.
All of this said, on April 13, 2021, the CDC and FDA released a joint statement recommending a pause in the administration of the Johnson & Johnson vaccine "out of an abundance of caution" as they investigate six reported cases (out of 6.8 million doses) of a very rare type of blood clot called cerebral venous sinus thrombosis (CVST) in people with ovaries ages 18-48. While the incidence of CVST in the general population varies from study to study, the estimated rate of occurrence is between 2 and 5 per million cases a year.
What do we know about the efficacy, safety, and side effects of the COVID-19 vaccines?
All COVID-19 vaccines are pretty remarkable in terms of how well they protect against serious illness and death. They’re all 100% effective in protecting against death from COVID-19, and between 85 and 100% effective in preventing serious COVID-19 illness. To put it in perspective: The yearly flu shot is usually between 40% and 60% effective.
The safety and side effect profile of these vaccines is similar to that of other common vaccines. It’s not uncommon to experience pain at the injection site, fatigue, or headaches. Some people may also experience flu-like symptoms. None of these side effects are clinically concerning, but they should be addressed by a physician if they don’t go away within three days. As we mentioned earlier, however, the CDC and FDA recommended a pause in administration of the Johnson & Johnson vaccine on April 13, 2021 "out of an abundance of caution" as they investigate six reported cases (out of 6.8 million doses) of a rare type of blood clot.
It’s important to know that none of the COVID-19 vaccines use the live virus that causes COVID-19 (so if you get the vaccine, you aren’t getting COVID-19 injected into your body). And, though they provide your body with the DNA or mRNA to stimulate the creation of antibodies, these vaccines can’t change your own DNA.
Are the COVID-19 vaccines safe if you’re currently trying to get pregnant or want to have kids one day?
Large-scale, long-term data on the effects of the COVID-19 vaccine on fertility don’t exist yet — after all, we didn’t even know what COVID-19 was until early in 2020. Not enough time has elapsed for us to fully understand whether there are any long-term effects of either the virus itself or its mRNA vaccine.
Here’s what we *do* know so far about links between the COVID-19 vaccine and fertility.
- Neither the CDC, ACOG, nor SMFM have cautioned against getting the vaccine for people who may want kids now or in the future. Similarly, the majority of vaccines are safe (and several are specifically recommended!) for people trying to conceive.
- ASRM’s official statement says: “The Task Force does not recommend withholding the vaccine from patients who are planning to conceive, who are currently pregnant, or who are lactating.”
- Twelve people in the vaccine arm of the Pfizer trial got pregnant, meaning the vaccine doesn’t cause infertility; their fertility-related outcomes and health are now being followed closely.
- There was a now-debunked (by numerous experts) article claiming that the COVID-19 vaccine could cause infertility in people with ovaries because the vaccine would cause the body to attack a protein that’s crucial to the formation of the placenta (the organ that provides a fetus nutrients during pregnancy). Though this important placental protein and S protein produced by the COVID-19 vaccine have similar biological functions (they both cause membrane fusion), they are not related, nor are they structurally similar enough for a vaccine targeting one to affect the other. Read reproductive endocrinologist Dr. Lora Shahine’s take on this for more info.
- Data from earlier trial phases doesn’t suggest that the COVID-19 vaccine would affect future fertility.
If you are currently trying to get pregnant or thinking about starting, we’ve created a guide detailing some factors you and your partner may want to consider. And speaking of your partner (if you have one): They should consider getting vaccinated too, even if they’re not the one trying to get pregnant. If someone trying to get pregnant decides not to get the COVID-19 vaccine, it may be all the more important for the people they spend time with to get vaccinated.
Dr. Sharon Briggs, head of clinical product and research here at Modern Fertility, gives the following advice:
“If you are currently thinking about getting pregnant and concerned about the lack of data on safety in pregnant people, getting vaccinated before you start trying to conceive is a great option.”
Is the COVID-19 vaccine safe if you are currently pregnant?
Let’s start with recs from trusted medical experts: ACOG recommends that “pregnant patients who decline vaccination should be supported in their decision” and that in these cases, the importance of safety measures like mask wearing, social distancing, and hand washing should be emphasized.
According to ASRM, "Patients undergoing fertility treatment and pregnant patients should be encouraged to receive vaccination based on eligibility criteria. Since the vaccine is not a live virus, there is no reason to delay pregnancy attempts because of vaccination administration or to defer treatment until the second dose has been administered."
The recommendations from trusted medical experts are starting to receive support from epidemiological data from the CDC. Through its v-safe and VAERS programs, the CDC is closely monitoring post-vaccine side effects and outcomes in people who choose to participate. In their first public presentation of the data, researchers found no differences in pregnancy outcomes (like miscarriages), pregnancy complications (like gestational diabetes or hypertension), or neonatal factors (like preterm birth or abnormalities) in people who got a COVID-19 vaccine while pregnant. In this same presentation, they noted that the side effect profile of vaccines didn’t differ based on whether someone was pregnant at the time of vaccination. Rumors also sprung up a few weeks ago about a link between miscarriages and COVID-19 vaccination in the UK, but that claim has been debunked. While we’ll need larger samples and longer follow-up periods to better understand the safety and efficacy of these vaccines in pregnant people, this initial data suggests that the vaccines do not negatively impact pregnancy or neonatal outcomes.
Newer data also suggests that the earlier on in a pregnancy someone gets vaccinated, the more likely they are to pass antibodies on to their newborns. In a study of 27 people who got the vaccine during their third trimester, researchers found that newborns of people who got vaccinated earlier were more likely to have COVID-19 antibodies, as compared to newborns of people who got vaccinated close to the time of delivery.
So, why are there questions about safety? Pregnant people are often excluded from clinical trials. While this is standard practice due to unanticipated harmful effects on a developing fetus during clinical trials, it’s difficult because there is often very little data on whether many medications and vaccines are safe for pregnant people. (For more on the ethics of including pregnant people in trials, we’d recommend ACOG’s committee opinion on the topic.)
The COVID-19 vaccine trials were no exception: People were not allowed to participate if they were pregnant or breastfeeding/chestfeeding at enrollment. Because of that, it’s not possible to conclusively say that the COVID-19 vaccine is safe or unsafe for this population. Pfizer recently announced plans to systematically evaluate the vaccine’s efficacy and safety in pregnant people, meaning we’ll have some more concrete numbers later in 2021.
Even before we had the preliminary data from the CDC on pregnancy and COVID-19 vaccines, there were many reasons to believe that the vaccine would be safe for all, regardless of whether or not someone is pregnant.
- Numerous vaccines have been given to pregnant and breastfeeding/chestfeeding people for decades, without any negative effect on fertility-related outcomes.
- Based on the completed clinical trial phases thus far, there aren’t any signals to suggest that the effect of the vaccine would be different for people who are pregnant.
- Likewise, based on completed trial phases looking at the effects of the vaccine in cells and in lab animals, there aren’t signals to suggest the vaccine would have any effect on fetal or infant development. (Specifically, there were no detected abnormalities in offspring of lab rats given the COVID-19 vaccine during pregnancy.)
Also worth noting: Pregnant people are 5x more likely to have severe symptoms if they contract COVID-19 relative to non-pregnant people. The likelihood of getting COVID-19 and its severe symptoms during pregnancy should be weighed against what we know (or, more accurately, what we don’t yet know) about potential risks of the COVID-19 vaccine in pregnant people. In some states like California, pregnant people are grouped with people who have certain conditions like diabetes, cancer, and heart conditions as being “high risk” and are being prioritized for vaccination.
It’s for these reasons that influential organizations like the FDA, CDC, ACOG, and SMFM have all issued statements saying that pregnant people should not be barred from receiving the COVID-19 vaccine if they want it. Though it’s suggested that people talk to their doctor about it before making a decision, this isn’t a requirement.
While there aren’t reasons to believe the COVID-19 vaccine would be harmful for people who are currently pregnant, some might choose to withhold getting the vaccine until more data from this population is available. Vaccine trials including pregnant people are currently underway, but it’s unclear when data from these trials will be released.
Is the COVID-19 vaccine safe if you are currently breastfeeding/chestfeeding?
Breastfeeding/chestfeeding people were excluded from the vaccine trials that we currently have data on, meaning we haven’t yet seen firsthand how the vaccine affects breastfeeding/chestfeeding people and their babies. But we have reason to believe that the vaccine is safe for these groups because there isn’t a scientifically plausible mechanism by which the vaccine could cause harm. In fact, getting the vaccine while breastfeeding/chestfeeding could potentially protect babies from getting COVID-19.
According to a recent statement from the Academy of Breastfeeding Medicine (ABM), it is likely that the antibodies created in response to the COVID-19 vaccine would transfer into breast/chest milk, providing the baby with these antibodies and strengthening their ability to counter COVID-19 if they were exposed. Some initial studies based on small samples do indeed find COVID-19 antibodies in breast/chest milk of people who previously had the virus, though we’re still waiting on data on how those antibodies may (or may not) protect and affect breastfeeding/chestfeeding babies.
More generally, of all commonly administered vaccines, there are only two that the CDC recommends holding off on while breastfeeding/chestfeeding — the smallpox and yellow fever vaccines, both of which contain a weakened version of the actual virus (unlike the mRNA COVID-19 vaccines, which don’t contain any trace of live virus).
Does the COVID-19 vaccine affect your period?
Most vaccine trials do not ask about temporary changes in menstrual cycles when asking participants to report on side effects. This means that we generally have very little understanding of if and how vaccines affect menstrual bleeding or timing. There are reasons to think there could be links here, as recently outlined by Dr. Jen Gunter. Any changes between menstrual cycle-related characteristics and the vaccine could be indirectly caused by the stress of getting vaccinated. Or these changes could be a direct effect of the immune system response that is initiated by vaccines on the uterine lining.
While there are anecdotal reports of temporary changes in period-related characteristics post-vaccine, systematic data on these changes is currently lacking. A group of researchers at University of Illinois are changing this by running an IRB-approved study of periods in people who have recently gotten the COVID-19 vaccine. For more information and to decide if you’d like to participate (if/once you’re eligible!), click here.
What are the factors to consider when deciding if you should get the vaccine?
As more and more people have a chance to get the vaccine, it’ll become increasingly important for them to weigh several factors when deciding whether or not getting the COVID-19 vaccine is the right choice.
Here are some things to consider:
- What is the level of community spread in your area? Check out this resource from Johns Hopkins (which is updated daily) to get an idea of community spread in your county.
- Does your job or lifestyle put you at higher risk of contracting COVID-19? For example, it is more important for essential and frontline workers who may have to interact with people on a day-to-day basis to get vaccinated because they may be at higher risk of contracting COVID-19.
- Do you have any health- or lifestyle-related risk factors that put you at greater risk for severe illness if you were to contract COVID-19? People who have heart conditions, diabetes, a higher body-fat percentage, type 2 diabetes, and who are immunocompromised are at greater risk for severe symptoms of COVID-19 if contracted and may benefit more from getting vaccinated.
- How do the known side effects of the COVID-19 vaccine compare to the potential side effects of the virus? Though roughly 30% of COVID-19 cases are asymptomatic (i.e., there are no noticeable symptoms), 70% of people will experience symptoms — and these symptoms are similar to or more severe than the known side effects of the vaccine.
- Finally, how are you personally weighing the preliminary data we have on the effect of the COVID-19 vaccine and fertility and the recommendations by trusted health institutions suggesting there is likely to be no evidence of an effect? Some people are comfortable trusting reputable health institutions to guide their decision-making, while others may prefer to make decisions based on lots of data that they can evaluate themselves.
We found this decision tool to be very helpful.
Bottom line: Should you get the COVID-19 vaccine?
Based on all the available data, all of the COVID-19 vaccines authorized for emergency use by the FDA are very safe and effective for the vast majority of people. But because not enough time has elapsed since the beginning of clinical trials and because of the exclusion of pregnant and breastfeeding/chestfeeding people in those trials, we can’t make any definitive statements about the effect of the vaccine on fertility and fetal/infant development.
Preliminary surveillance data suggests that the COVID-19 vaccine does not have a negative effect on pregnancy or neonatal outcomes. And, based on data from earlier trial phases, other vaccines, and our knowledge of how mRNA and adenovirus vaccines work, multiple influential health organizations agree that COVID-19 vaccines likely will have no negative effects on reproductive health and fertility-related outcomes, and therefore haven’t barred people who are pregnant, breastfeeding/chestfeeding, or trying to conceive from getting the vaccine.
People in these groups should be aware of the potential risks and benefits associated with the vaccine, as well as the risks of COVID-19 when contracted. Ultimately, this is a personal decision, and you should discuss it with a healthcare provider who understands your medical history.
In the meantime, before the vaccine becomes available for the population at large, it’s as important as ever that we stick to physical distancing, mask wearing, plenty of sanitizing, and other forms of self-care to keep physically and mentally healthy.
This article was medically reviewed by Dr. Jane van Dis, MD, FACOG. Dr. van Dis is a practicing OB-GYN, volunteer clinical faculty at USC Keck School of Medicine where she serves on the Gender Equity in Medicine and Science Committee, CEO of Equity Quotient, co-founder of OB Best Practice, and co-founder of TIME'S UP Healthcare.