Progesterone and Period Delay: Understanding Cycle Changes After IVF

Question
Hi-
How can you say in one of your answers that progesterone can bring in the period? My understanding is that progesterone delay Period since it protects the endometrium lining in the uterus.  Please clarify. I've done an IVF/PGD and been taking progesterone since ovulation. Implantation was done a week ago and I'm on day 26 of my cycle.. Still no period.  Am I pregnant?  my menstrual cycle is usually 25 days.

Answer
There are many properties of progesterone. If you hve not gotten your period for several months,  taking progesteone (ten mg twice a day f0r five days)  will bring on your period within 10 days.   If      you are trying to maintain a pegnancy,  you can ake progesterone every day until 12 weeks gestatation.