Getting a COVID-19 mRNA vaccine did not affect pregnancy rates for women trying to conceive with in vitro fertilization or ovarian response to treatment, findings of a new study indicate.
The study was led by Sarit Avraham, MD, with the IVF unit, department of obstetrics and gynecology, Shamir Medical Center in Tzrifi, Israel. The findings were published online in Fertility and Sterility in a preproof version.
“Women should be vaccinated for COVID-19 prior to attempting to conceive via IVF treatments, given the higher risk of severe illness in pregnant women,” the authors wrote.
Doubts arose from “the theoretical concept of the supposed similarity between the SARS-CoV-2 spike protein and the syncytin protein that is speculated to take part in the fertilization process and the formation of the placenta,” the authors wrote.
Some then assumed that the COVID vaccine might kick off an immune response that could affect implantation and pregnancy. But this study and others before it found otherwise.
Researchers included 200 vaccinated women trying to conceive with IVF treatments in the retrospective study, and compared them with 200 unvaccinated patients of similar age (average age in both groups, 36 years) who were not previously infected with COVID-19. All the women were undergoing IVF from January to April 2021 and all the vaccinated women completed two doses of the BNT162b2 (Pfizer/BioNTech) vaccine at least 2 weeks before ovarian stimulation.
Researchers compared the average number of oocytes retrieved and clinical pregnancy rates between the two groups.
No difference between groups
Two hundred patients underwent oocyte retrieval 14-68 days after receiving a COVID shot; there was no significant difference by vaccination status in the number retrieved per cycle (10.63 in the vaccinated group vs. 10.72 in the unvaccinated group; P = .93).
There was also no difference in the clinical pregnancy rates after fresh embryo transfers. The rate among 128 vaccinated patients was 32.8% versus 33.1% in the 133 unvaccinated patients (P = .96), with 42 and 44 clinical pregnancies, respectively.
A total of 113 patients (66 in the study group and 47 in the controls) underwent freeze-all cycles to preserve fertility and fertilization rates were similar between vaccinated and unvaccinated (55.43% vaccinated vs. 54.29% unvaccinated; P = .73). The average number of cryopreserved embryos was 3.59 (vaccinated) versus 3.28 (unvaccinated) (P = .80).
In a subanalysis of outcomes by age, researchers found vaccination status had no effect on number of oocytes or pregnancy rates in the 39-and-older group. That’s important because it shows the vaccine did not affect outcomes even in a population with reduced ovarian reserves, the authors wrote.
The authors noted one of the study’s limitations is that it didn’t include information about vaccination or past infection status of the male partners.
Question should be put to rest
Sarah Cross, MD, a maternal-fetal medicine specialist at the University of Minnesota, Minneapolis, said the study is the biggest she’s seen that concludes COVID vaccinations are safe and highly encouraged for women before trying to conceive, but other smaller studies have come to the same conclusion.
Dr. Sarah Cross
She pointed to research including a study from 2021 with similar findings that concluded: “Physicians and public health personnel can counsel women of reproductive age that neither previous illness with COVID-19 nor antibodies produced from vaccination to COVID-19 will cause sterility.”
She said she thinks the question of whether COVID shots are safe with IVF has been answered and the results of the latest study add proof to counter misinformation around the issue.
“The COVID-19 vaccine does not affect fertility,” she said. “I don’t know how many more [studies] we need.”
The harm is in not getting vaccinated, she said. Pregnancy significantly increases a woman’s chance of getting severe COVID, the need for hospitalization, mechanical ventilation, and risk of death.
“I personally have never had a hospitalized patient who’s been vaccinated,” Dr. Cross said. “The worst thing for the fetus is to have a critically ill mother.”
Dr. Cross, whose high-risk patients include those seeking counseling before IVF, added: “I would counsel all of them that they should absolutely get vaccinated prior to pregnancy, when they’re pregnant, whenever it is, as soon as they possibly can.”
The study authors and Dr. Cross report no relevant financial relationships.