M.B.
It depends on the Dr. For both my pregnancies I was with a fertility specialist who was extra cautious about everything. She preferred the progesterone level to be above 20. My first pregnancy she had me on progesterone suppositories 2x daily for the first 13 weeks. For this second preganancy for some reason the number kept dropping, etc. and she put me on 1x daily progesterone injections. I started to get close to dropping below again and asked what would happen then and she said they would put me on 2x daily injections, thankfully I never I had to do that. At around 13 weeks she took me off and we are crusing along at 25 weeks. Good luck!