Is it safe taking 300mg of bromelain supplements before frozen embryo transfer?

Probably: The chance of causing a problem appears to be relatively low, if you have no other illnesses. However, the benefit of taking it escapes me at the moment, so I am not sure why you would want to? It can interfere with blood clotting, which might cause a little more spotting with the transfer. As the process of art with frozen embryos is set, check with your doc. While maybe safe, there's no need?

Discuss w specialist: I recommend you not take any supplements you did not discuss with your fertility specialist. Their recommendation is more valuable than anything i could tell you since they have their own specific management plans. Good luck with the transfer.