Antibodies, resulting from either vaccination against or infection with COVID-19 do not impact female fertility, according to new research.
No statistically significant differences in women's rates of embryo implantation were found between those who had antibodies to COVID-19 and those who did not.
'We hope that all reproductive-aged women will be more confident getting the COVID-19 vaccine, given Dr Morris's findings that the vaccine does not cause female sterility' said Dr Hugh Taylor, president of the American Society for Reproductive Medicine (ASRM).
Concerns over a potential autoimmune response towards a protein involved in embryo implantation, called syncytin-1, arose due to its structural similarities with the SARS-CoV-2 spike proteins, the virus that leads to COVID-19. Such an immune response, if present, would inhibit the syncytin-1 protein which helps blastocysts attach to the endometrium and develop the placenta.
Previous research had yet to show any reactivity between syncytin-1 and the SARS-CoV-2 spike proteins. However, this study, published in ASRM's Fertility & Sterility Reports, by Dr Randy Morris, head of the IVF1 fertility clinic in Chicago, Illinois was the first to use human data.
The pregnancy rates of 143 women were examined, 88 of whom had tested negative for COVID-19 antibodies, and 55 women who had tested positive. Twenty of the women with antibodies had been previously infected with COVID-19 whilst 35 had received the Pfizer or Moderna mRNA COVID-19 vaccines.
In vitro frozen embryo transfer was used as a model to assess the impact of COVID-19 on the rates of embryo implantation within the endometrium. Before the transfer of a blastocyst-stage embryo into their uterus, each woman underwent treatments to raise their oestrogen and progesterone levels in order to thicken their endometrium linings. Successful embryo implantation was characterised with elevated levels of human chorionic gonadotropin, a hormone produced by the placenta during pregnancy, recorded eight days after the transfer.
The reaction of over 3000 proteins found in humans, including syncytin-1, with SARS-CoV-2 antibodies was investigated in a separate study performed by scientists at Yale University School of Medicine, New Haven, Connecticut. The research, headed by Dr Akiko Iwasaki, found no such reactivity between syncytin-1 and the SARS-CoV-2 antibodies.
It is hoped that the new clinical research by Dr Morris, coupled with laboratory studies such as that of Dr Iwasaki, will provide further reassurance to many women who wish to have children, that the COVID-19 vaccines are safe with no short or long-term effects on fertility.
'This, and other studies of this nature, further reinforce the ASRM COVID Task Force guidance that, no matter where you are in the family-building process, the COVID-19 vaccine is safe and saves lives' concluded Dr Taylor.