After some initial concern, Jose Siberon, a vice president of a reinsurance company in Charlotte, NC, and his wife decided to get vaccinated for COVID-19 in April. The couple’s kids were going back to school in person and he worried that they might bring the virus home. Plus many people in their community weren’t following masking and social distancing guidelines.
But the Siberons aren’t planning on vaccinating their teenage daughter, who is newly eligible for a shot, anytime soon. “Our biggest concern is about how it affects the female body and fertility,” he explains.
Even though he has shed other vaccine fears, Siberon, like thousands of others around the country, is worried about one particularly pernicious COVID-19 vaccine myth: that the vaccines interfere with a woman’s ability to conceive or lead to worrisome birth outcomes.
“It’s out there on social media and it’s really frightening to women,” says reproductive endocrinologist Staci E. Pollack, MD, associate professor in the Department of Obstetrics & Gynecology and Women’s Health at Montefiore Health System and Albert Einstein College of Medicine in New York. “But there’s no evidence for this at all.”
How We Got Here
Unlike some vaccine myths, this one can be traced right to the source. In late 2020, a German doctor and vaccine skeptic named Wolfgang Wodarg teamed up with a former Pfizer employee to try to delay the approval of the Pfizer/BioNTech vaccine in Europe.
The issue concerned the protein called syncytin-1, which is similar to part of the spike protein from SARS-CoV-2, says Michael Tsimis, MD, a maternal-fetal medicine specialist at Spectrum Health in Grand Rapids, MI. Syncytin-1 is an important component of the placenta in mammals and the argument was that the vaccine might also cause the body to attack and reject the protein in the human placenta, causing infertility.
The two men published their speculation in a blog post last December that went viral, arousing fears. But, says Tsimis, “the spike proteins are actually completely different, and no connection exists.”
Yet the misinformation persists, even as fact-checking websites have tried to debunk the claims. Facebook labels them as “false information.”
Even so, according to a UK survey from last December, more than 25% of unvaccinated women ages 18 to 34 said they will pass on the vaccines due to fertility fears, compared with 18% of people overall, says Victoria Male, PhD, a lecturer in reproductive immunology at Imperial College London.
Much Ado About Nothing
Even as fertility concerns persist, as more and more people get vaccinated, there is little to suggest an impact on fertility.
In the Pfizer trial of its mRNA vaccine, 23 women became pregnant after receiving the shot and no adverse outcomes were reported, says Tsimis. One of the women had a miscarriage, but it was later disclosed that she had gotten the placebo — not the vaccine.
Overall, Male says, there have been no differences in the numbers of pregnancies and miscarriages between women who were vaccinated with the available vaccines and those in control groups who weren’t.
Other research is even more compelling. In a June preprint study (not yet peer-reviewed), Israeli researchers looked at IVF cycle outcomes before and after vaccination with the Pfizer vaccine in a group of 47 women. The parameters included the number of eggs retrieved, the number of mature eggs retrieved, the fertilization rate, and eventual pregnancies.
The result: “There were no significant differences before and after, which was very reassuring,” says study author Myriam Safrai, MD, an OB-GYN at Hadassah-Hebrew University Medical Center in Jerusalem.
Likewise, sperm seem to be unaffected by COVID vaccines. In a recently published study in JAMA, researchers from the University of Miami Miller School of Medicine found that sperm parameters, including concentration, count, and motility (movement), were the same before and after vaccination in a group of 45 men.
More good news has come from the CDC’s v-safe program, in which a smartphone app lets users report vaccine side effects and helps the agency track health outcomes. “The program has amassed over 3,900 individuals with over 800 completed pregnancies who were followed longitudinally,” says Tsimis. “There was no increase in rates of miscarriage, stillbirth, preterm birth, small babies, congenital abnormalities or neonatal death.” These findings were published last month in the New England Journal of Medicine.
Finally, the American Society of Reproductive Medicine, the Society for Maternal-Fetal Medicine, the American College of Obstetrics and Gynecology, and the CDC all recommend getting vaccinated for COVID-19, even if you’re pregnant, Pollack says. “We know the risks of COVID are worse.”
COVID’s Effects on Fertility
In fact, while the vaccines do not seem to affect a woman’s chance of conceiving, the infection is clearly harmful during pregnancy, particularly in the third trimester.
“If you’re pregnant and get COVID, your infection is worse,” explains Pollack. “And you’re going to be more likely to be intubated, to be in an ICU, to undergo preterm labor, or to need a C-section.”
According to an ongoing review of births in the British Medical Journal, which was updated in March, pregnant people with COVID have twice the risk for a preterm birth or a stillbirth. “And it’s more likely your baby will have to go to intensive care,” Male says.
“The experience of my colleagues who are obstetricians is that the reason the babies are being born preterm is because the doctors choose to deliver them to try and save the mum rather than because people are spontaneously going into labor,” Male says.
COVID also seems to compromise men’s fertility. Research shows that men with COVID have a lower sperm count, reduced sperm motility, and more abnormally shaped sperm. “We know that COVID can impair sperm,” says Safrai. “We don’t know for how long.”
The vaccine-fertility myth could not be more frustrating for those entrusted with looking after women’s reproductive health. “The thing that scares me as a fertility doctor is that COVID is so much more dangerous if you get pregnant, and this risk may be increased for marginalized populations, women of color, where there’s a lot of vaccine hesitancy already,” says Pollack. “So the very population that’s the most hesitant is the one that we really would like to get the vaccine to protect them.”
For helpful resources when talking to patients about pregnancy, fertility, and the COVID-19 vaccines, see: