After the release of the mature egg, the empty follicle collapses developing its own blood supply. It becomes a temporary gland called the corpus luteum. The corpus luteum produces and secrets progesterone, which is the predominant hormone during luteal phase. Progesterone supports pregnancy if it is to occur. However it has many other functions.
Progesterone’s mains functions:
- reducing inflammation
- calming the nervous system
- soothing mood and improving sleep
- stimulating the building of bone tissue, and keeping oestrogen in check
Important: if you are taking hormonal birth control containing progesterone, you won’t get all this positive health benefits. This is because the progesterone in the pill is actually progestin and they are different molecules. Your body will produce progesterone when you ovulate and this is not the case if you ovulate.
Progesterone will slow you down and you might feel like needing more rest. You might also feel that your digestion is slower during your luteal period. These are because your body wants to protect you and it prepares in case it has to support a pregnancy. Slowing down your digestion gives more time to your gut to absorb nutrients from food in case it needs to support a developing embryo.
Your appetite might change and you might feel hungrier. Make sure you feed yourself correctly because otherwise your blood sugar will be unstable, making you crave and eat whatever you have at hand. Avoid comfort food and go for foods that are loaded with protein and complex carbs.
The production of progesterone can be detected as a rise in your basal body temperature. In the case you have conceived, progesterone will continue to be produced and 18 consecutive high temperatures will be the indicator for a suspected pregnancy.
If implantation happens, the cells in your endometrium swell and make your endometrium thicken to about 18mm (compared to 4mm at the start of the cycle). If implantation does not happen, your corpus luteum begins to disintegrate and about day 26 of a 28-day cycle, its secretory function ends. Menstruation begins and you return to your follicular phase.