There are a lot of different reasons a woman might have multiple miscarriages, from chromosomal abnormalities to blood clotting issues, and how effective any given treatment will be really depends on what the root problem is. I have heard about women being put on progesterone suppositories to treat recurrent pregnancy loss, but those suppositories would only be helpful if the reason you're miscarrying is due to a hormonal imbalance, e.g. you have a luteal phase defect. From what I've read, that isn't the case for most women.
How long have you been trying to conceive? Have you seen a reproductive endocrinologist yet?