You’ve most likely heard of progesterone when it’s discussed alongside oestrogen, as one of the two main female sex hormones that control your cycle.
Progesterone is part of the family of progestogens, a group of hormones made by the human body. Its name comes from its role in supporting gestation (or in simpler terms, pregnancy) and originates from the Latin word “gestare”, meaning “to carry or to bear.”
We know what you’re thinking, and it’s a good question: why is something that naturally supports pregnancy used as contraception?
Let’s break it down. Natural progesterone is not actually used in contraceptives; instead, a synthetic, man-made version of progesterone called a ‘progestin’ is used. These, alongside our natural progestogens, all interact with progesterone receptors in our cells, which can affect and interrupt our cycle in various different ways.
Naturally occurring progesterone
Made by the body, progesterone is secreted by the Corpus Luteum on the ovary after ovulation has occurred (a corpus what, you ask? Here’s an article if you’d like to get up to speed).
Progesterone maintains the lining of the uterus to allow for the implantation of a fertilised egg. If fertilisation doesn’t happen then the Corpus Luteum stops secreting the hormone, the uterine lining breaks down and a period occurs. If fertilisation and implantation do occur, then progesterone secretion continues by the Corpus Luteum until the placenta takes over the majority of hormone production by the eighth week of pregnancy1.
- Leung PCK and Adashi EY. The Ovary. Elsevier. 2003. Second edition. Chapter 12 p214. Available from: https://doi.org/10.1016/B978-0-12-444562-8.X5000-9