Hello and welcome to HCM. Thank you for your query. To start off with I would like or you to know that your immune system is being suppressed so your body does not reject the embryo, recognizing it to be a foreign substance. The next thing is that, due to a suppressed immune system, your body is right now susceptible to infections and other infection-causing organisms which would have been taken care of if your immune system would have been active. Do not worry about the sore throat, report your complaints to your doctor and he/she shall decide the course of treatment, and choose an antibiotic which is safe (if required) in your condition. For the time being, you could use an antiseptic mouth wash (eg. chlorhexidine) to clean your throat from the harmful organisms. Yes, the stage of the embryo is good enough and still viable, although the chances of an embryo transfer to be successful with the first try are not a 100%, which is why more than one embryo is selected. Do not worry, even if this hatched embryo does not implant itself and result in a pregnancy, you still have at least one other embryo that should result in a pregnancy. Wishing you lots of luck and a safe and uneventful pregnancy ahead. I hope I have succeeded in providing the information you were looking for. Please feel free to write back to me for any further clarifications at: http://doctor.healthcaremagic.com/doctors/dr-shoaib-khan/64581 . I would gladly help you. Best wishes.