New York, NY—Social media is filled with misleading information about the effect of COVID-19 vaccination on fertility, and pharmacists often are bombarded with questions about it. A new study provides additional reassurance for concerned young adults.

In a report published in Obstetrics & Gynecology, researchers determined that vaccination against COVID-19 did not affect fertility outcomes in patients undergoing IVF. The study team from the Icahn School of Medicine at Mount Sinai Reproductive Medicine Associates of New York compared rates of fertilization, pregnancy, and early miscarriage in IVF patients who had received two doses of Pfizer or Moderna vaccines against those who had not been vaccinated.

"This is one of the largest studies to review fertility and IVF cycle outcomes in patients who received COVID-19 vaccinations. The study found no significant differences in response to ovarian stimulation, egg quality, embryo development, or pregnancy outcomes between the vaccinated compared to unvaccinated patients," stated first author Devora A. Aharon, MD, a fellow in reproductive endocrinology and infertility at Icahn Mount Sinai and RMA of New York. "Our findings that vaccination had no impact on these outcomes should be reassuring to those who are trying to conceive or are in early pregnancy."

The study sought to determine if mRNA vaccination is associated with controlled ovarian hyperstimulation or early pregnancy outcomes. The retrospective cohort study included patients between February and September 2021 who underwent controlled ovarian hyperstimulation or single euploid frozen-thawed embryo transfer at a single academic center.

Defined as the primary outcome was the fertilization rate for controlled ovarian hyperstimulation and the clinical pregnancy rate for frozen-thawed embryo transfer. Researchers also looked at outcomes for controlled ovarian hyperstimulation, including eggs retrieved, mature oocytes retrieved, mature oocytes ratio, blastulation rate, and euploid rate. The secondary outcomes for frozen-thawed embryo transfer included pregnancy rate, ongoing pregnancy rate, biochemical pregnancy loss rate, and clinical pregnancy loss rate, the authors advise.

Results indicate that among 222 vaccinated patients and 983 unvaccinated patients who underwent controlled ovarian hyperstimulation cycles between February and September 2021, no association was found on adjusted analysis between COVID-19 vaccination and fertilization rate (β = 0.02 ± 0.02, P = .20) or any of the secondary outcomes assessed: eggs retrieved (β = 0.01 ± 0.57, P = .99), mature oocytes retrieved (β = 0.26 ± 0.47, P = .58), mature oocytes ratio (β = 0.02 ± 0.01, P = .12), blastulation rate (β = 0.02 ± 0.02, P = .27), or euploid rate (β = 0.05 ± 0.03, P = .08).

In addition, among 214 vaccinated patients and 733 unvaccinated patients undergoing single euploid frozen-thawed embryo transfer, adjusted analysis also identified no significant association between vaccination and clinical pregnancy (adjusted odds ratio [aOR] 0.79, 95% CI 0.54-1.16) or any of the secondary outcomes: pregnancy (aOR 0.88, 95% CI 0.58-1.33), ongoing pregnancy (aOR 0.90, 95% CI 0.61-1.31), biochemical pregnancy loss (aOR 1.21, 95% CI 0.69-2.14), or clinical pregnancy loss (aOR 1.02, 95% CI 0.51-2.06).

"Administration of COVID-19 mRNA vaccines was not associated with an adverse effect on stimulation or early pregnancy outcomes after IVF," the authors conclude. "Our findings contribute to the growing body of evidence regarding the safety of COVID-19 vaccination in women who are trying to conceive."

The authors decry that while data on vaccine safety profiles in pregnancy are increasing, vaccination rates among pregnant women remain low.

"Vaccine hesitancy can be attributed in part to a concern regarding possible homology between the SARS-CoV-2 spike protein targeted by the vaccine and the placental syncitin-1 protein, potentially resulting in infertility," they explain. "This theory was discredited by immunology experts because any sequence similarity between the proteins is extremely limited and unlikely to cause cross-reactivity."

Researchers point out that studies to this point have found no association of the COVID-19 mRNA vaccine with markers of fertility, including oocyte and embryo development. They add that the number of participants has been small, which led to their larger study.

"By leveraging science and big data, we can help reassure patients of reproductive age and enable them to make the best decisions for themselves. It will give people comfort to know that the COVID-19 vaccine does not affect their reproductive potential," said senior author Alan B. Copperman, MD, division director and clinical professor of obstetrics, gynecology and reproductive science at Icahn Mount Sinai and director of RMA of New York, which is recognized internationally as a leading center of reproductive medicine.

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