I also suffered a miscarriage due to low progesterone. A pregnancy simply cannot continue if the body does not make sufficient prog to support it. Which was my case. I started on prog pessaries about 16 days after ovulation. I knew beforehand that my prog was low but my doctor (a fert spec) only put me on Pregnyl prior to conception, not the prog. I am not sure about the role that prog plays in implantation?? So we kept a very close eye on my prog levels up to and after conception. The pessaries are meant to help until your body produces enough prog but mine didn't through the preg. So I had 2 pess every day for about 2 weeks when I had another blood test. Then I started prog injections in addition to the pess. I stopped the pess about week 20 and stopped the inject about week 34! HTH