What is progesterone?
Progesterone is a steroid hormone produced mainly by the ovaries, specifically by the corpus luteum after ovulation. Smaller amounts are also made by the adrenal glands, and during pregnancy the placenta becomes the main source. Progesterone works alongside oestradiol to regulate the menstrual cycle, prepare the uterus for pregnancy and support early pregnancy if fertilisation occurs.
Blood tests measure progesterone in nanomoles per litre (nmol/L) in Australia, and the timing of the test is critical because levels change dramatically across the menstrual cycle. Progesterone is commonly measured to confirm ovulation, investigate fertility, assess cycle irregularities and monitor hormonal transitions such as perimenopause. You can read more in our guide to normal hormone levels in Australian adults.
Why does progesterone matter for long-term health and wellbeing?
Progesterone is far more than a reproductive hormone. It has calming effects on the brain (partly through its interaction with GABA receptors), supports sleep quality, influences mood, regulates body temperature, protects the endometrium from the effects of unopposed oestrogen and plays roles in bone health, cardiovascular health and the immune system. Low or fluctuating progesterone during perimenopause is a common driver of sleep disturbance, anxiety, heavy periods and mood changes.
Because progesterone balances oestrogen's effects, chronic imbalance between the two hormones is linked with conditions such as endometrial hyperplasia, heavy or painful periods, endometriosis and increased miscarriage risk. Tracking progesterone alongside oestradiol and other hormones gives useful preventative insight, particularly during the reproductive years and hormonal transitions. It is one of the hormone markers Vively considers as part of its baseline health testing and its dedicated perimenopause hormone test.
What is an ideal progesterone level?
There is no single ideal number, since progesterone varies enormously across the cycle, pregnancy, menopause and by sex. In premenopausal women, progesterone is very low in the follicular phase (typically under 3 nmol/L), then rises after ovulation. A mid-luteal (day 21 of a 28-day cycle, or 7 days before your expected period) progesterone above 16 nmol/L generally confirms that ovulation has occurred, and levels of 25 to 30 nmol/L or higher are often considered a robust ovulatory response.
In pregnancy, progesterone rises significantly across each trimester. In postmenopausal women not using hormone therapy, progesterone is very low, usually below 2.5 nmol/L. Adult men typically sit around 0.3 to 3 nmol/L, and progesterone is rarely tested unless investigating specific conditions such as congenital adrenal hyperplasia. Interpretation depends on your age, sex, cycle phase, pregnancy status, medications and other hormone markers.
What influences progesterone levels?
Ovulation is the most important influence, since progesterone rises significantly only if ovulation occurs. Anything that disrupts ovulation, such as PCOS, hypothalamic amenorrhoea, thyroid dysfunction, high prolactin, chronic stress, undernutrition, over-training or perimenopause, can lower progesterone. Sleep quality and cortisol also matter, since chronic stress and disrupted sleep can affect progesterone production over time.
Nutrition, body composition and micronutrient status all play a role in supporting healthy ovulation and progesterone. Medications including combined oral contraceptives (which suppress ovulation and natural progesterone production), progestogen-only contraceptives, HRT, some antidepressants, corticosteroids and antipsychotics can significantly affect results. Testing timing is one of the biggest factors, and results tested at the wrong point of the cycle can look misleadingly low.
What are the symptoms of low progesterone?
In women of reproductive age, low progesterone in the luteal phase is often linked with heavy or prolonged periods, short cycles, a short luteal phase, spotting before your period, PMS symptoms such as breast tenderness, bloating, headaches and mood changes, sleep disturbance, anxiety and difficulty conceiving. Recurrent miscarriage can sometimes be associated with luteal phase deficiency. Some women also experience worsening of oestrogen-related conditions such as fibroids and endometriosis due to relative oestrogen dominance.
During perimenopause, progesterone typically drops before oestradiol, contributing to symptoms such as sleep problems, mood changes, anxiety, heavy periods and cycle irregularity. Symptoms are rarely specific to progesterone alone, so testing and clinical context are more reliable than symptom checklists.
What causes low progesterone?
The most common cause of low luteal-phase progesterone is anovulation, where an egg is not released and the corpus luteum does not form to produce progesterone. Causes of anovulation include PCOS, perimenopause, premature ovarian insufficiency, hypothalamic amenorrhoea (often from severe undernutrition, extreme exercise, rapid weight loss or chronic stress), thyroid dysfunction and high prolactin. Luteal phase deficiency, where ovulation occurs but progesterone production is inadequate, is another possibility.
Chronic stress and poor sleep can affect progesterone through their impact on the HPA-axis, which shares pathways with reproductive hormones. Our guide to the cortisol blood test in Australia explores this connection in more detail. Medications such as combined oral contraceptives naturally suppress progesterone production, which is expected rather than a sign of dysfunction.
What are the symptoms of high progesterone?
The most common cause of high progesterone is pregnancy, and associated symptoms are largely pregnancy-related, including fatigue, breast tenderness, bloating, nausea, mood changes and mild drowsiness. Progesterone naturally has a sedating and calming effect, which is why some people notice increased tiredness or drowsiness in the second half of their cycle or during progesterone-based therapies.
Outside pregnancy, mildly elevated progesterone is usually within normal luteal-phase variation and does not typically cause problems. Very high progesterone in the absence of pregnancy is uncommon and may occasionally point to ovarian cysts, congenital adrenal hyperplasia, molar pregnancy or, rarely, ovarian tumours. In these cases, associated symptoms usually reflect the underlying condition rather than the progesterone level itself.
What causes high progesterone?
Pregnancy is by far the most common cause of persistently high progesterone. Beyond pregnancy, higher-than-expected progesterone can be seen in ovarian cysts (particularly corpus luteum cysts), congenital adrenal hyperplasia (where enzyme defects lead to a build-up of progesterone and its precursors), and molar pregnancy or hydatidiform mole. Some ovarian tumours can also produce progesterone, though this is rare.
Progesterone therapy is another common cause of raised results, including micronised progesterone (often used in HRT), progesterone pessaries, some progestogen-only contraceptives and hormonal IUDs. In these cases, elevated progesterone is expected rather than a concern. Any unexplained high progesterone, particularly when pregnancy has been ruled out, warrants medical review.
What does it mean if progesterone is outside the optimal range?
A low progesterone result in the luteal phase may reflect anovulation, luteal phase deficiency, perimenopause, PCOS, hypothalamic amenorrhoea, thyroid dysfunction, high prolactin, chronic stress or simply testing at the wrong time in the cycle. It does not diagnose any single condition on its own, but it can be an important signal, particularly when symptoms of cycle irregularity, PMS, sleep issues, mood changes or fertility difficulties are present.
A high progesterone usually reflects pregnancy, cycle timing or hormonal medications, and less commonly ovarian cysts, congenital adrenal hyperplasia or other underlying conditions. Both patterns should always be interpreted in the context of your cycle phase, symptoms, medications and other hormone markers, rather than as stand-alone results.
Can progesterone be normal but something still be wrong?
Yes, a normal progesterone result does not always rule out reproductive or hormonal issues. Because progesterone changes so much across the cycle, a single result can look "normal" while still masking issues such as inconsistent ovulation, luteal phase deficiency or perimenopausal fluctuations. In perimenopause particularly, progesterone can vary widely from cycle to cycle and month to month.
Timing of the test is critical, and progesterone measured at the wrong point of the cycle, in someone with irregular cycles or without confirming the day of the cycle, can be difficult to interpret. Combined oral contraceptives, hormonal IUDs and HRT can all affect results, and biotin supplements can interfere with some assays. This is why progesterone is best interpreted alongside oestradiol, FSH, LH, prolactin, TSH and other markers.
What other markers should be checked with progesterone?
Oestradiol is the most important companion, since the balance between the two hormones is what drives the menstrual cycle and endometrial health. FSH and LH give insight into cycle regulation and can help identify PCOS, menopause and hypothalamic amenorrhoea. Prolactin, TSH and free T4 are also important, since high prolactin and thyroid dysfunction can both disrupt ovulation and lower progesterone.
Testosterone, SHBG and free androgen index add insight, particularly when PCOS is suspected. AMH (anti-Mullerian hormone) reflects ovarian reserve, and hCG is added when pregnancy is being considered. 17-hydroxyprogesterone helps screen for congenital adrenal hyperplasia, and cortisol adds context around stress. Metabolic markers such as HbA1c, fasting insulin, vitamin D, ferritin and B12 complete the wider picture, and you can see the full set of markers Vively looks at through our tests page and shop tests page.
How can you improve progesterone to a healthier level?
Because progesterone rises after ovulation, the most effective way to support healthy progesterone is to support regular ovulation. This usually means eating a balanced diet with adequate energy, protein, healthy fats, fibre and micronutrients like iron, iodine, zinc, magnesium, vitamin D and B vitamins, avoiding extreme calorie restriction and over-training, achieving a healthy body composition and managing stress. Prioritising 7 to 9 hours of quality sleep and reducing alcohol intake also support hormonal balance.
Treating underlying conditions such as PCOS, thyroid disorders, high prolactin, coeliac disease or fatty liver often improves ovulation and progesterone. For confirmed low progesterone in the luteal phase, particularly in the context of fertility or perimenopausal symptoms, your GP or specialist may prescribe micronised progesterone (available in Australia on prescription). Vively's how it works page explains how testing, monitoring and dietitian coaching combine to make sustainable change practical.
When does progesterone need medical review?
See your GP if you have irregular or absent periods, very heavy or painful periods, spotting between periods, ongoing PMS or premenstrual mood changes, difficulty conceiving, recurrent miscarriage, or perimenopausal symptoms such as sleep disturbance, mood swings and heavy bleeding. Symptoms suggesting PCOS, endometriosis, thyroid dysfunction or high prolactin also warrant clinical review.
Clinical input is important during pregnancy, when planning pregnancy, when starting or stopping hormonal contraceptives or HRT, and when investigating unexplained low progesterone in a younger woman (which may suggest premature ovarian insufficiency). Any unexplained high progesterone outside pregnancy, or symptoms suggestive of ovarian cysts, should be reviewed promptly. Progesterone should never be self-diagnosed, as it is one piece of a bigger clinical picture your GP, endocrinologist or gynaecologist can help you interpret.
How does Vively help you understand progesterone?
Progesterone is one of the hormone markers included in Vively's female-focused testing options, including the Perimenopause Hormone Test and the Vively Baseline Health Check, alongside oestradiol, FSH, LH, testosterone, SHBG, prolactin, thyroid function, metabolic and inflammation markers and more than 60 other biomarkers in total. Because progesterone shifts across the cycle, Vively's perimenopause testing pairs samples across the cycle to give a clearer picture of how your hormones are actually changing. Rather than looking at progesterone in isolation, Vively interprets it in context with your other results, cycle phase, symptoms, life stage, medications and lifestyle.
A registered nurse reviews your results with you one on one, and accredited practising dietitians support the changes that follow. Because your markers are retested over time, you can see how nutrition, movement, sleep, stress management and, where appropriate, medical treatment are actually shifting your hormonal profile. Start at the Vively homepage or explore the full range of tests in the Vively shop.
References
- Royal College of Pathologists of Australasia. RCPA Manual: Progesterone. https://www.rcpa.edu.au/Manuals/RCPA-Manual/Pathology-Tests/P/Progesterone
- Healthdirect Australia. Progesterone. https://www.healthdirect.gov.au/
- Better Health Channel, Victorian Department of Health. Menstrual cycle. https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/menstrual-cycle
- Royal Australian College of General Practitioners. Managing menopausal symptoms. https://www.racgp.org.au/clinical-resources/clinical-guidelines/key-racgp-guidelines/view-all-racgp-guidelines
- Australasian Menopause Society. Position statements and resources. https://www.menopause.org.au/
- Jean Hailes for Women's Health. Menstrual cycle, PCOS and menopause. https://www.jeanhailes.org.au/
- Teede HJ, Tay CT, Laven J, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Fertility and Sterility. 2023;120(4):767 to 793.
- Practice Committee of the American Society for Reproductive Medicine. Current clinical irrelevance of luteal phase deficiency: a committee opinion. Fertility and Sterility. 2015;103(4):e27 to e32.
- The European Society of Human Reproduction and Embryology (ESHRE). Management of women with premature ovarian insufficiency. Human Reproduction. 2016;31(5):926 to 937.
- Prior JC. Progesterone for symptomatic perimenopause treatment: progesterone politics, physiology and potential for perimenopause. Facts, Views and Vision in ObGyn. 2011;3(2):109 to 120.
- Cleveland Clinic. Progesterone. https://my.clevelandclinic.org/health/articles/24562-progesterone
- Mayo Clinic. Progesterone test. https://www.mayoclinic.org/
- National Institutes of Health, MedlinePlus. Progesterone test. https://medlineplus.gov/lab-tests/progesterone-test/
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