some interesting info i found:

54. Close conformational and functional similarity of the SARS CoV-2 spike protein to the Syncytins has been observed. Syncytins are proteins essential for reproduction and this similarity could elicit a cross-reactive auto-immune reaction targeted to these proteins which could impact reproductive endpoints. This is supported by the observations that there is impaired spermatogenesis in some during and following the natural COVID-19 infection as well as the localization of spike protein to testes.“ Additionally, a placental pathology has been observed in some COVID-infected women reminiscent of pre-eclampsia, and Syncytin 1 knockout mice exhibit similar placental pathology coupled with the inability to carry to full term.*?

There have also been noted a significant number of miscarriages that have been reported in the VAERS reporting system following vaccination for COVID-19 to date. These all support the premise that the COVID-19 vaccines which direct the body to make the SARS-CoV-2 spike protein may be causing reproductive harm either directly through spike protein or through a cross-reaction mechanism with the endogenous Syncytins.

source: https://archive.org/details/fda-2021-p-0529-1053-attachment-1/page/16/mode/2up?q=protein