Progesterone

Progesterone is a hormone that plays a central role in the menstrual cycle, pregnancy, and overall hormonal balance. Produced mainly by the ovaries after ovulation, specifically by a temporary structure called the corpus luteum, progesterone prepares the lining of the womb to receive a fertilised egg and helps maintain the early stages of pregnancy. Beyond reproduction, progesterone also influences mood, sleep quality, and the way your body manages inflammation, making it an important marker for your general wellbeing. You can think of progesterone as the hormone that gets things ready and keeps things calm. After ovulation, progesterone rises to create a nurturing environment in the womb, and if pregnancy does not occur, it drops away, triggering menstruation and the start of a new cycle. This rise and fall is a perfectly healthy rhythm that your body repeats each month. Progesterone also has a gently calming effect on the brain, it interacts with receptors that promote relaxation and restful sleep, which is why some women notice changes in their sleep patterns or mood at different points in their cycle. In men, progesterone is produced in small amounts by the adrenal glands and testes and serves as a precursor for other hormones, including cortisol and testosterone.

Because progesterone levels change dramatically throughout the menstrual cycle, the timing of your blood test is particularly important. Levels are typically at their highest about a week after ovulation, during the luteal phase, and are very low during the first half of the cycle. Stress can affect progesterone production, as can significant changes in body weight, intense exercise, and age, levels naturally decline in the years leading up to and during the menopause. Certain medications, including hormonal contraceptives and progesterone supplements, will also influence your results. If your progesterone level is outside the range your clinician expects, especially in relation to where you are in your cycle, your GP can help interpret it and discuss what it means for your health.