The “mother of life’ steroid hormone from the progestogen group. It is secreted during the second half of a woman’s menstrual cycle and is important in the early stages of pregnancy by enriching the endometrial lining of the uterus. It’s the big female sex hormone along with oestrogen.


  • The happiness hormone! Most associated with positive effects on mood, however changes can regulate your appetite and sleep cycle by influencing serotonin levels.
  • Low levels can lead to irritability, insomnia, low libido, breast tenderness, headaches, weight gain and food cravings – yes often those symptoms of PMS.
  • Stimulates the growth of blood vessels that supply the lining of the womb and signals to secrete nutrients to nourish an early embryo, further preparing the lining to allow a fertilised egg to implant.
  • From a fertility and pregnancy perspective, this hormone rises to stimulate the growth of breast tissue (whilst pausing lactation), strengthens pelvic muscles by reducing muscular contractions in the uterus.
  • Produced in the ovaries but also in the adrenal glands and placenta.
  • High levels of progesterone are normal (although too high can be a risk of ovarian cancer). Low levels are more concerning – causing irregular menstrual cycles, or cause miscarriage during early pregnancy, although its normal for levels to fall during menopause.
  • Men produce progesterone in their adrenal glands, as it’s required for sperm development. Additionally, it supports healthy bones, heart, liver and brain tissue in men and women, including central nervous system needs by regulating cognition and mitochondrial function.
  • It is the oldest known hormone on record.


As you can see hormones are very complex. It is always important to test your hormones with your practitioner to understand exactly what’s happening. Testing progesterone is recommended on day 21 of your cycle, however this is based on a 28-day cycle that not all of us have.

If you know when to expect your period it’s best to count 7 days before then. So if you have a 35-day cycle progesterone test approximately day 28. If your cycles are not regular then ovulation timing can assist, which can be detected with egg-white mucus observations, BBT charting or LH pee strips.

No reason to test progesterone prior to ovulation, if on oral contraception or post-menopause as there is little progesterone.

Interested to know about other hormones?

Become a pro about prolactin
The good and bad on testosterone
We talk all things progesterone

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