Progestin is the synthetic form. However one really needs to read the label to know which is which. Another clue is if you need a prescription for it, it's not natural. Synthetic progestins have undergone molecular alternations at unusual positions. The body knows how to read the molecules of natural progesterone and goes to work metabolizing it properly.
Progesterone is a single hormone produced by the body for many functions.
It is not just a sex hormone. Helps brain function and normalize sleep John Lee, MD suggests that a trans-dermal cream be used because this is the product that the studies were done with, with very positive results. Besides the beneficial effect on hormonal activity in the body another interesting fact came out of these studies. In relationship to Osteoporosis it was noted that women how had the most bone loss showed greater increase in new bone growth when using the progesterone cream. Dr. Lee does not suggest using wild yam pills, tea or tinctures.