Progesterone is safe during pregnancy !!
I stay in USA and I am currently 2 weeks pregnant with one previous miscarriage. The fact that my doctor here put me on progesterone 200 mg by mouth right after I conceived rules out what "Anonymous" had just stated, that it's not used in western countries. It's very much in use specially if you had earlier miscarriages .. Its absolutely safe and has zero side effects .. On the contrary it helps to hold your pregnancy better and stop any spotting/ bleeding. You can take it by mouth or apply orally... depends on your choice.
However having said that, miscarriage is your body's way of dealing with a wrong /mis formed pregnancy. If it were to happen within first 3 months, unfortunately it would happen, you cannot stop it. But minor hormonal deficiencies can definitely be ruled out by prescribing progesterone tablets (sustin 200 mg / prometrium 200 mg) ... hope that helps !!