evidence: Information around this is still emerging, but the data so far suggests that mRNA in the vaccines doesn't cross the placenta. Exactly why that's the case is complicated - so here's a quick explainer. [...] Do the Covid-19 vaccines cause damage to the placenta? Since the beginning of the vaccine roll out, there have been false rumours that the Pfizer vaccine could cause damage to the placenta. There is no evidence to support this. We have written more about this previously.