Low levels of the hormone progesterone can cause miscarriage. In order to understand how this occurs, we must first understand the role progesterone plays in the menstrual cycle and pregnancy. Progesterone levels increase after ovulation. If an egg is fertilized, progesterone helps prepare the uterus for implantation. Level drop if no egg is fertilized and a woman's period begins. If a pregnancy occurs, progesterone levels stay high throughout the pregnancy. Until the first eight or ten weeks of pregnancy, progesterone is produced by the ovaries. Somewhere toward the end of the first trimester, progesterone production is taken over by the placenta.
If a pregnant woman has low levels of progesterone in the early weeks of pregnancy, some doctors will prescribe supplementary progesterone. This can take the form of vaginal suppositories or intramuscular injections taken either once or twice a day. A word of caution here; some of these suppositories can be very expensive if your insurance doesn't cover them or doesn't cover them fully. I filled a prescription for some a few years ago when I had not such great insurance and the price tag was $600!
Unfortunately, while low progesterone can definitely be a cause of miscarriage, science has not conclusively proven that progesterone supplementation can prevent a miscarriage. Some doctors feel low progesterone is more a symptom of a doomed pregnancy than the actual cause of the the loss itself. They feel that progesterone supplementation only prolongs a pregnancy which inevitably will fail anyway. Some doctors contend the a woman's body does not process synthetic progesterone as effectively as that actually made in the body and therefore progesterone supplementation is ineffective.
However, while there is no evidence proving the effectiveness of supplementation for women with low progesterone in early pregnancy, there doesn't seem to be any concrete evidence against it either. From my personal experiences and what I've read, most doctors seem willing to prescribe supplemental progesterone in some form for pregnant patients who have low progesterone. In the case of three of my miscarriages, I had low progesterone and was prescribed suppositories twice and injections once. I went on to miscarry later (between 14 and 16 weeks) for unknown reasons but at the end of the first trimester, my doctor said my levels had improved to the point where I no longer needed the progesterone.
If you try again and your doctor prescribes progesterone suppositories or injections please note a couple of things. First, some of these suppositories can be very expensive if your insurance doesn't cover them or doesn't cover them fully. I filled a prescription for some a few years ago when I had not such great insurance and the price tag was $600! Second, not all pharmacies seem to keep progesterone on hand. My pharmacy had to special order the suppositories in both cases. I had to get the injectable progesterone from a different pharmacy entirely as mine couldn't get it at all.