Progesterone and fertility
Progesterone plays an important role in menstrual cycle and throughout pregnancy. It prepares the body for pregnancy in the event that a released egg is fertilised. If the egg is not fertilised, the corpus luteum breaks down, the production of progesterone falls and a new menstrual cycle begins.
During the early stages of pregnancy, the body increases the level of progesterone in order to sustain it. A sudden drop in progesterone can be associated with miss-carriage and early labour. Little amounts of progesterone are associated with heavy and irregular menstrual bleeding.
Source: https://www.yourhormones.info/hormones/progesterone/
Throughout the menstrual cycle, the levels of progesterone vary. Generally, progesterone increases in the second part of the cycle, after ovulation. This phase is called luteal phase. This rise is to prepare the body for an eventual pregnancy (to implant an egg if fertilisation occurs). If it’s not the case and pregnancy does not occur, then the levels of progesterone will fall. The drop in progesterone will trigger your next menstrual periods.
The role of progesterone does not stop at the maintenance of pregnancy. More recent studies have shown that it is an important immune regulator. Autoimmune/inflammatory diseases are more often met in females than in males. This is showing the importance of sex hormones in disease progression.
Progesterone and mental health
Progesterone has also non-reproductive functions. Research shows that it is involved in mood regulation and cognition. Oestrogen and progesterone complement each other. When fertilisation does not occur and the level of progesterone falls, there is a hormonal imbalance that happens in your body. This imbalance might trigger symptoms of depression, anxiety and irritability. Research shows that PMS is more often met at women that present a lower level of progesterone. Similarly, results suggest that women with lower levels of progesterone in the body have higher chances to develop post-partum depression after pregnancy.
What can you do?
If you want to know if you ovulate normally, you can get tested and see how your progesterone is doing. All you have to do is talk to your GP and ask for a blood test. Your GP can also tell you when it’s best to do the test. Generally, for best results you should test yourself 7 days before your next expected period, or between 18 to 24 days after the first day of your period.
Sources:
Tait, A. S., Butts, C. L., & Sternberg, E. M. (2008). The role of glucocorticoids and progestins in inflammatory, autoimmune, and infectious disease. Journal of leukocyte biology, 84(4), 924-931.