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During trying times, myths and falsehoods sprout like mushrooms after rainfall. One of many that has emerged so far during the Covid-19 pandemic is that vaccines against the disease will cause infertility in women.

It won’t.


The likely origin of this myth is a letter sent to the European Medicines Agency (the equivalent of the U.S. Food and Drug Administration) by two European anti-vaccination propagandists. They erroneously claimed that the “vaccine contains a spike protein called syncytin-1 [that is] vital for the human placenta in women.”

To be sure, syncytin-1 is vital for the human placenta. Destruction of this protein would disrupt its formation, leading to infertility or miscarriage. But the claim that Covid-19 vaccines either contain syncyntin-1 or the message to generate antibodies to it is false.

Sadly, false news travels fast. This claim has been — and continues to be — amplified on social media, and has prompted some women to worry about getting a Covid-19 vaccine and others to choose not to get vaccinated, even though it has been widely debunked.


In the early days of the pandemic, the American Society for Reproductive Medicine assembled a task force comprised of experts in infertility, epidemiology, infectious disease, and mental health, along with patient representatives. This group, which I am a member of, was charged with learning as much as possible about Covid-19 and synthesizing this knowledge into guidance documents for the field of reproductive medicine.

The initial phases of the pandemic were fraught with questions of whether individuals should continue trying to conceive during the pandemic. Is reproduction essential? (Yes.) Should infertility treatment be halted? (Temporarily.) Can Covid-19 infection cause birth defects? (Unknown early on.)

The rapid development of Covid-19 vaccines and their emergency use authorization added a new set of questions and concerns, and heightened the need for vaccine education and promotion.

Information from the Centers for Disease Control and Prevention shows that pregnant people are at high risk for developing severe Covid-19, and fare far worse than their nonpregnant counterparts. A large, multinational study of pregnant people with Covid-19 showed that infection earlier in pregnancy increased the risk for complications ranging from increased need for mechanical ventilation to fetal death. These findings highlight the importance of vaccination in people who are desiring or planning pregnancy, as well as those who are pregnant, to prevent severe Covid-19. The known risks of Covid-19 during pregnancy outweigh the theoretical risk of harm from Covid-19 vaccination.

To date, the safety profiles have been incredibly reassuring for each of the vaccines the FDA granted emergency use authorization. Serious adverse events were uncommon and were similar in both vaccine and placebo groups.

Yet pregnant people still worry about getting the vaccine, in part because they were excluded from the early Covid-19 vaccine trials. To be sure, these trials purposefully included women and men of color, making the results more generalizable, but the intentional exclusion of pregnant people caused more harm than good.

The exclusion of women from biomedical research isn’t a new phenomenon, even though the vast majority of medical conditions affecting humans are characterized, in part, by sex differences. In 1977, the Department of Health and Human Services recommended that clinical trials not include women of childbearing potential, a stance the department reversed in 1993. It wasn’t until 2016 that the National Institutes of Health created a new policy calling for sex inclusion that required organizations to factor in sex as a biological variable for research design, analysis, and reporting. Given that half of the population is female, the fact that this policy is so recent is shocking.

There has been a long history of protectionist policy targeting people of reproductive age. Some of this sensitivity is highly justified and emerged out of necessity after the atrocities committed against women by Nazi human experimentation. But the pendulum of human protection can also swing too far in the opposite direction.

Although pregnant individuals were excluded from the first large Covid-19 vaccine trials, the V-safe smartphone application was developed to capture data on the safety of vaccination outside of clinical trials. This web-based tool, which collects voluntary data from individuals who have received the Covid-19 vaccine, includes a pregnancy registry that gathers data on vaccination during pregnancy or the period before or after it. Even better, trials of Covid-19 vaccines that include pregnant people are now getting underway.

Preliminary data on Covid-19 vaccines and pregnancy were presented at the CDC’s Advisory Committee of Immunization Practices meeting on March 1. They demonstrated the safety of both the Pfizer/BioNTech and Moderna vaccines in more than 30,000 patients with pregnancies. Data from the V-safe pregnancy registry, with nearly 2,000 participants, were also reassuring, with rates of miscarriage, stillbirth, gestational diabetes, preeclampsia or gestational hypertension, eclampsia, and intrauterine growth restriction lower among the V-safe pregnancy registry participants compared to national rates.

Three of the leading professional organizations focused on pregnancy and fertility — the American Society for Reproductive Medicine, the American College of Obstetricians and Gynecologists, and the Society for Maternal Fetal Medicine — all recommend that pregnant people get vaccinated, as well as those considering pregnancy.

I received my first dose of Pfizer’s Covid-19 vaccine in mid-December and the second dose on Jan. 8. My most profound side effect was overwhelming joy. The vaccine represented a path forward, a way out of this pandemic. There was optimism in the air at the hospital where I received my shot, even though January was proving to be the worst month so far in the course of the pandemic.

As a reproductive endocrinologist and infertility specialist, I urge my patients to get vaccinated against Covid-19. I discuss what is known, what remains unknown, and address their fears and uncertainties. I feel confident that the data will continue to emerge showing the benefits of vaccination in eradicating severe disease.

Fertility myths are rampant, and experts in the field are constantly being called upon to discredit baseless claims. The claim that the Covid-19 vaccine causes infertility must be added to the long list of those that warrant debunking.

Eve C. Feinberg is a reproductive endocrinologist and infertility specialist, an associate professor of obstetrics and gynecology at the Northwestern University Feinberg School of Medicine, and a member of the American Society for Reproductive Medicine’s Covid-19 Task Force.