Can the COVID vaccine affect fertility?

It takes years of research and development before a new drug or vaccine is offered to the public. Some people are hesitant to accept a treatment when it’s first released due to concerns about safety and side effects.

But because of how widespread COVID-19 has been since the start of the pandemic, scientists have been able to evaluate whether the vaccine might cause infertility and have concluded that it does not.

While the misconceptions, myths, and misinformation can add a lot to the anxiety that exists around the pandemic and the vaccine, it’s important to look at the evidence to understand where the myth came from and what the evidence shows. Let’s take a closer look at this misconception and see why it’s untrue. 

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In short, no, the COVID vaccine does not cause infertility. 

To understand this, it’s important to remember how mRNA vaccines work. It’s a complicated process, but basically, this type of vaccine trains your immune system to recognize the virus and generate antibodies to protect you should you be exposed in the future.

So, where did the infertility misconception come from? In 2020, a researcher claimed that the vaccine might cause our immune systems to respond to a protein called syncytin-1, which plays an important role in reproduction (Sajjadi, 2021). 

Though there is no scientific evidence supporting his claim, the myth spread quickly and internet searches for terms like “COVID vaccine and infertility” rose rapidly. The belief that the vaccine causes infertility became a significant reason for vaccine hesitancy in many areas around the world (Sallam, 2021).

In response to the original claims, a study was done comparing fertility among people who had antibodies (from vaccination or from contracting the virus) and those who didn’t have antibodies. Participants then underwent in vitro fertilization, where frozen embryos were implanted in their uteruses, and the study found that vaccination had no effect on a person’s ability to conceive (Morris, 2021).

As early as the clinical trial stage, researchers saw that the vaccine did not impact female fertility. No participants were pregnant before enrolling in the trials, but 53 people became pregnant during the trial (Male, 2021).

Since the vaccines were made available to the general public, the Centers for Disease Control and Prevention (CDC) established a system called V-safe for keeping track of any adverse effects the vaccine might have in terms of fertility or pregnancy. 

Pregnancy occurred in the trials for both Pfizer-BioNTech and Moderna vaccines at roughly the same rate in placebo groups as it did in those receiving the vaccine (FDA, 2020a; FDA, 2020b).

As is the case for females, the COVID vaccine doesn’t cause infertility in men. One small study found that sperm count, sperm production, and semen volume were unaffected by the vaccine (Gonzalez, 2021).  

Research has even found that getting at least one dose of the COVID vaccine could be beneficial. Another study noted the vaccine could decrease the risk of testicular diseases like orchitis (swollen, inflamed testicles) (Carto, 2021). 

There have been reports that people who have had COVID or those who have been vaccinated have seen changes in their menstrual cycles, including changes in the duration and volume of bleeding, as well as changes in menstrual cramps. Due to these reports, there is now extensive research into whether the vaccine or the virus itself might be affecting peoples’ periods. 

A small study exploring menstrual changes showed that there were no changes in hormone levels among people who had COVID-19, despite self-reported changes in duration and volume of bleeding. Still, researchers are diving deep into these claims to see what connection, if any, exists (Li, 2021). 

While researchers aren’t sure yet if there’s a connection, stress and weight changes related to the pandemic are both things that we know can affect your period. For example, stress can block the hormone fluctuations that typically regulate your menstrual cycle, so people under a lot of stress may notice that their periods have become irregular.

Extreme weight loss can also be a form of stress for the body, and can also cause your period to stop. If you’re experiencing significant changes in your menstrual cycle, it might be time to consult with your gynecologist or an endocrinologist.  

The Centers for Disease Control and Prevention (CDC) recommends getting a COVID vaccine if you are pregnant, planning to become pregnant, or breastfeeding (CDC, 2021b).

Also, the vaccine does not cross the placenta and therefore doesn’t reach the developing fetus, and it doesn’t enter the breastmilk, so researchers have found there to be no cause for concern for people who are pregnant or nursing (ASRM, 2021; Golan, 2021).

This advice is critical because even though the vaccine doesn’t cause infertility, there’s evidence that COVID might. Severe disease can cause inflammation and tissue damage in the testicles and ovaries.

Some cases have reported decreased sperm count and testicular inflammation. Others found that undergoing in vitro fertilization (IVF) before or after a COVID infection produced fewer high-quality embryos (Orvieto, 2021; Rajak, 2021). 

As we mentioned earlier, COVID is also dangerous to anyone who is pregnant. A study of over 2,000 women found those who contracted COVID during pregnancy had an increased risk of preeclampsia (extremely high blood pressure), severe infection, premature birth, and even death (Villar, 2021).  

If it can harm the mother, COVID can certainly harm a vulnerable developing fetus. The inflammation caused by COVID can damage a fetus’s brain. Some studies suggest it can attack the placenta and be transmitted to the fetus, causing severe sickness or death (Figuieredo, 2021; Schwarz, 2020).

The CDC also found that the risk of stillbirth is roughly doubled in people who develop COVID-19 while pregnant, especially in people infected with the Delta variant (CDC, 2021c).

The CDC has established a registry for anyone who is pregnant to enroll in. You’re eligible to enroll if you got pregnant before or shortly after getting vaccinated. The information collected is then used to learn more about the vaccine’s safety during pregnancy (CDC, 2021a). 

COVID vaccines can’t cause infertility, but there is growing evidence the virus itself can. Vaccines are still the best way to protect yourself––including your reproductive health.

This is especially important if you are pregnant or looking to become pregnant since people who are pregnant and unvaccinated are at high risk of complications from COVID-19. If you are hesitant about getting vaccinated, reach out to your healthcare provider or OB/GYN to get more information about vaccine safety.

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How we reviewed this article

Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

Current version

November 26, 2021

Written by

Gina Allegretti, MD

Fact checked by

Yael Cooperman, MD

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About the medical reviewer

Yael Cooperman, MD, Ro

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.