I know they will not prevent a miscarriage that is meant to be, because I have taken them before on prior pregnancies. This pregnancy is the furthest Ive ever gotten, so I am nervous that my doctor said to stop the suppositories next Thursday (10 weeks, 2 days) without doing any blood work. I have googled, and apparently many doctors think they are not necessary after week 10 as your placenta should have taken over, while other doctors recommend they be used longer. I plan to call the nurse tomorrow and tell her about my anxiety at stopping so early, but I was curious if there is anybody else reading this board in a similar position. I have enough of them already to go another 2-3 weeks, plus 5 refills available. They were prescribed by the specialist doctor who graduated me to the ob/gyn. Im going to call them first, actually.