Progesterone During Pregnancy: Benefits, Safety & Concerns

Question
Hello my sister is 3 weeks pregnant and she had a miscarriage just a year ago and she was already having problems with this pregnancy and her Doctor put her on Progesterone 100mg and now she is having a lot of problems she is bleeding and having cramps and she is so afraid that she is going to lose the baby. My question is what is progesterone and is it safe to take while pregnant and if it is safe to take why would a Doctor recommend her to take it?

Answer
In general, if a miscarriage is destined to happen, there is no way to stop it. Rarely, it may be due to a lack of progesterone which is why it was prescribed. In general, most miscarriages happen because there was an error during cell division early in the pregnancy and the proper number of chromosomes were not evenly divided between the cells.