There really should be no confusion; but pick up any mainstream article about HRT and you will see the immediate problem. There is an assumption in the media – and often by doctors themselves – that they are interchangeable and mean the same thing. They seem to believe that it does not matter which one you use but they are wrong. The synthetic forms are normally called progestins or progestogens, it differs from country to country.
Difference No 1
This is the easiest, most obvious and the simplest. One is natural the other is a chemical synthetic. The natural hormone is progesterone and the manufactured progestins/progestogens that appear in hormone therapy are chemicals.
Difference No 2
Progesterone is the hormone naturally produced by women in the ovaries. Progestins/progestogens mimic the effect of the natural hormone, but they are not identical to that produced in the body and so not recognised by it as such. It is a little bit like a key that has been copied from the original but when you put it in the lock does not quite fit or turn.
Progesterone is immediately identified by the body as natural to it, as the right fit so to speak, but the synthetics are not.
Difference No 3
This is a crucially important one. Natural progesterone has not been identified with any side effects, but the synthetics have a whole host that are associated with them. They are known to increase risks in the areas of cancer (breast, uterus and ovary), disorders of blood clotting (strokes, heart problems and deep vein thrombosis), and can worsen mood, PMS and depression in vulnerable women.
Difference No 4
Progestins/progestogens cannot reproduce exactly the effect of progesterone in the body, but a bio-identical natural progesterone cream can. Although not manufactured in the body it is recognised by it as being absolutely bioidentical to the real hormone. A hormone may be claimed to be natural, such as the oestrogen in the HRT product Premarin, but that is derived from the urine of pregnant mares. It natural to horses not humans.
However you choose to journey through the menopause, whether with HRT or bio-identical natural hormones, it helps to know just what your options are and exactly what is in the formulation you are using.