Progesterone is the primary hormone of the luteal phase and pregnancy, produced by the corpus luteum after ovulation and by the placenta during pregnancy. Timing of test is critical — a mid-luteal sample (day 21 of a typical 28-day cycle, or approximately 7 days post-ovulation) confirms ovulation and assesses luteal-phase adequacy. Progesterone works alongside estradiol and other hormones to regulate the menstrual cycle, prepare the endometrium for implantation, and maintain pregnancy.
Analyzed in accredited Swedish clinical laboratories (ISO 15189). Used to support clinician-directed evaluation and monitoring. Not a stand-alone diagnosis.
If you are menstruating and want to confirm whether you are actually ovulating, or if you experience irregular cycles, anovulation, luteal-phase symptoms (spotting, mood changes, breast tenderness), or unexplained infertility, progesterone testing is revealing. A single mid-luteal progesterone level tells you whether ovulation occurred and whether the corpus luteum is producing adequate hormone to support a potential pregnancy.
If you are on menopause hormone therapy (MHT) with estrogen, understanding your progesterone or progestin exposure helps optimize endometrial protection — a key consideration in European MHT guidelines. If you are pregnant, progesterone tracking in early pregnancy can assess risk of miscarriage or ectopic pregnancy, though this is typically managed in specialist care.
Confirms ovulation. A mid-luteal progesterone > 16 nmol/L definitively shows that ovulation occurred. This is the single most useful clinical application of the test.
Identifies luteal-phase defects. Low mid-luteal progesterone in the context of regular cycles may indicate inadequate corpus luteum function, anovulation, or conditions like PCOS that disrupt ovulation.
Assesses pregnancy viability. In early pregnancy, rising progesterone supports endometrial stability and placental development. Declining or low levels can signal risk of miscarriage or ectopic pregnancy.
Guides MHT optimization. Progesterone or progestin dose in menopause hormone therapy directly affects endometrial protection and cardiovascular-metabolic outcomes; knowing circulating levels informs dose titration.
Contextualizes cycle symptoms. Elevated progesterone in the luteal phase should correlate with typical luteal symptoms. Absence of expected progesterone rise despite reported symptoms suggests anovulation or other dysfunction.
Clarifies reproductive hormonal status. When paired with estradiol, LH, FSH, and TSH, progesterone completes the hormonal picture of menstrual or menopausal status.
Role in the menstrual cycle. After ovulation, the remnant of the ovarian follicle (the corpus luteum) secretes progesterone for approximately 14 days. This maintains the secretory endometrium — a thick, nutrient-rich lining ready for implantation. Progesterone also suppresses further follicle growth and maintains cervical mucus viscosity. If fertilization does not occur, progesterone levels fall sharply, triggering menstruation. If pregnancy occurs, the developing placenta takes over progesterone production by around week 8, sustaining the pregnancy through the second and third trimesters.
Mechanism at tissue and cellular level. Progesterone binds to progesterone receptors (PR-A and PR-B) in target tissues including the endometrium, breast, brain, bone, and vasculature. These receptors modulate gene expression to prepare tissues for pregnancy, stabilize mood, support bone remodeling, and influence cardiometabolic function. In the endometrium specifically, progesterone induces secretory changes and reduces proliferation — a protective effect against unopposed estrogen-driven endometrial hyperplasia. Low or absent progesterone in the setting of ongoing estrogen exposure (as in anovulation or inadequately opposed MHT) increases endometrial cancer risk.
Life-stage variations. In pre-ovulatory women, follicular-phase progesterone is very low (< 3 nmol/L). After ovulation, mid-luteal levels should rise to > 16 nmol/L. Postmenopausal women without MHT have minimal progesterone (< 1 nmol/L). In pregnancy, progesterone rises progressively to several hundred nmol/L by the third trimester. In men, progesterone is minimal and clinically irrelevant.
Detects anovulation and reproductive dysfunction. Many women with irregular cycles or PCOS are anovulatory — they do not ovulate regularly, and thus do not produce progesterone. This has implications beyond fertility: anovulation leaves the endometrium unopposed to estrogen, raising endometrial cancer risk, and it disrupts the normal hormonal rhythm that supports metabolic health, bone density, and mood regulation.
Ensures adequate endometrial protection in MHT. Estrogen-only MHT increases endometrial cancer risk; progesterone or progestin addition is essential. Testing helps confirm adequate progesterone exposure and guides dose adjustments to maximize protective benefit while minimizing side effects.
Clarifies infertility and miscarriage risk. A woman attempting pregnancy with no progesterone rise likely has ovulation failure; adequate mid-luteal progesterone is necessary (though not always sufficient) for implantation and early pregnancy maintenance. Progesterone support may reduce miscarriage risk in specific contexts.
Supports cardiometabolic interpretation. Progesterone influences insulin sensitivity, blood pressure, and lipid metabolism in complex ways — often opposite to estrogen effects. Understanding progesterone status contextualizes cardiovascular markers like blood pressure, triglycerides, and inflammatory markers that fluctuate across the cycle.
Follicular phase (cycle days 1–14): < 3 nmol/L — minimal, pre-ovulatory baseline.
Mid-luteal phase (cycle day 21, or 7 days post-ovulation): > 16 nmol/L indicates ovulation; > 30 nmol/L is reassuring for adequate corpus luteum function.
Postmenopausal (not on MHT): < 1 nmol/L.
Pregnancy (first trimester): typically 30–100 nmol/L; rises progressively to several hundred nmol/L by third trimester.
Men: < 2 nmol/L; not clinically useful.
The critical threshold is mid-luteal > 16 nmol/L, which confirms ovulation occurred. Levels below this in the luteal phase suggest anovulation or luteal-phase defect. A single mid-luteal sample is far more informative than multiple samples — timing is everything with progesterone.
Low mid-luteal progesterone (< 16 nmol/L). This indicates no ovulation occurred in that cycle (anovulation) or that the corpus luteum is producing insufficient progesterone. Low mid-luteal progesterone may reflect PCOS, thyroid dysfunction, elevated prolactin, hypothalamic amenorrhea, or simply an ovulatory cycle in an otherwise regular woman. Anovulation over time increases endometrial cancer risk due to unopposed estrogen. If infertility is a concern, absent ovulation must be addressed.
Optimal mid-luteal progesterone (16–30 nmol/L). Ovulation is confirmed. This range supports normal endometrial secretory changes and is generally adequate for pregnancy. If accompanied by typical luteal-phase symptoms (breast tenderness, mood changes, sleep shifts), hormonal rhythm is intact.
High mid-luteal progesterone (> 30 nmol/L). Robust ovulation and corpus luteum function. This is reassuring for fertility and endometrial health. Extremely elevated progesterone outside pregnancy (e.g., > 60 nmol/L) is rare and may reflect a corpus luteum cyst, adrenal tumor, or congenital adrenal hyperplasia (CAH) — conditions requiring specialist evaluation.
Very high progesterone in non-pregnant women (> 100 nmol/L). In the absence of pregnancy, this is abnormal and warrants investigation for tumor, CAH, or other endocrine disorder.
Factors that influence progesterone. Timing of the test is the dominant factor — a follicular-phase sample will always be low even in an ovulating woman. Luteal-phase samples taken < 7 days post-ovulation may be falsely low. Stress, intense exercise, sleep deprivation, acute illness, and certain medications (some anticonvulsants, benzodiazepines, opioids) can suppress progesterone. Hormonal contraceptives eliminate natural ovulation and progesterone production. Pregnancy status must be known; progesterone is expected to be elevated in early and ongoing pregnancy.
Anovulation (PCOS, thyroid dysfunction, hypothalamic amenorrhea). PCOS is the most common cause of anovulation and low luteal progesterone in reproductive-age women. Thyroid disease (hypo- or hyperthyroidism), elevated prolactin, and severe energy deficit (from overtraining, undereating, or high stress) can all suppress the GnRH pulse generator and prevent ovulation. Without ovulation, the corpus luteum never forms, and progesterone remains low.
Luteal-phase defect (rare). In rare cases, ovulation occurs but the corpus luteum produces inadequate progesterone despite apparently normal LH and FSH patterns. This is controversial diagnostically and may reflect previous ovarian damage, aging, or autoimmune ovarian inflammation. True isolated luteal-phase defect is clinically rare.
Age and ovarian reserve. As women age and enter the perimenopausal transition, ovulation becomes increasingly erratic and corpus luteum function declines. Cycles may be anovulatory or have shortened luteal phases with lower progesterone. This is a normal part of reproductive aging.
Endometriosis and adenomyosis. These conditions may disrupt normal ovulation or corpus luteum function, though progesterone is not reliably diagnostic for either; imaging and clinical context are needed.
Elevated progesterone outside pregnancy. Adrenal tumors, congenital adrenal hyperplasia (CAH), corpus luteum cysts, or rarely, functional ovarian cysts can produce excess progesterone. This requires specialist imaging and hormonal profiling to diagnose.
Ensure ovulation first. If progesterone is low because ovulation is not occurring, the priority is restoring ovulation. This depends on the underlying cause: in PCOS, reducing insulin resistance through improved glycemic control, sustained training, and micronutrient sufficiency can restore ovulation. In thyroid disease, achieving euthyroid status is essential. In hypothalamic amenorrhea, resolving energy deficit (by eating more, training less intensely, or managing stress) often restores ovulation within weeks to months. No supplement or herb reliably induces ovulation once the metabolic drivers are identified — these are system-level interventions.
Support corpus luteum function once ovulation is present. If ovulation occurs but luteal progesterone is borderline low, supporting the metabolic and micronutritional basis of ovulation helps. Adequate carbohydrate intake in the luteal phase supports progesterone production (the luteal phase is slightly more insulin-resistant and energy-demanding than the follicular phase). Vitamin A, B vitamins, vitamin C, and zinc all support steroidogenesis; deficiency in any impairs progesterone synthesis. Sleep disruption and chronic stress suppress GnRH pulsatility and can reduce corpus luteum lifespan; normalizing sleep and stress management can improve luteal-phase hormone production.
MHT optimization. If on MHT, the form and dose of progesterone or progestin determine circulating levels and endometrial protection. Micronized progesterone (oral or vaginal) has better metabolic and tolerability profiles than synthetic progestins per recent European guidance. Transdermal estradiol with oral or vaginal micronized progesterone is a common evidence-based regimen. Progestin-only approaches (levonorgestrel-releasing IUS, megestrol acetate) are alternatives but carry different metabolic profiles. Optimization depends on individual metabolic risk and side-effect tolerance — this is a conversation for a longevity doctor or gynecologist.
The right intervention depends on whether ovulation is present, whether progesterone is truly low, the underlying cause (PCOS, thyroid, energy deficit, MHT dosing), and the individual's full metabolic and reproductive context. That is precisely the kind of personalized hormone mapping that a Loovi longevity doctor helps clarify through consultation.
A single progesterone value without context is nearly useless — timing is everything. A follicular-phase progesterone will be low even in a perfectly ovulating woman; a mid-luteal value of 15 nmol/L looks anovulatory but could reflect poor timing (measured too early in the luteal phase) rather than true anovulation. Progesterone must be interpreted alongside estradiol, LH, FSH, and TSH to understand the full hormonal landscape. In MHT, understanding circulating estradiol and progesterone or progestin together guides endometrial protection and cardiometabolic risk. In pregnancy, progesterone is one signal among many — hCG doubling time, ultrasound findings, and clinical symptoms all matter.
Loovi's 120+ biomarkers tracked annually include progesterone alongside estradiol, testosterone, SHBG, TSH, cortisol, and a full metabolic panel. This gives you the complete hormonal picture — cycle phase timing, ovulation status, metabolic drivers of hormone production, and how all of these shift seasonally and with aging. One-off progesterone testing is a starting point; continuous tracking with personalized interpretation from a longevity doctor is how you actually optimize hormonal health.
For a typical 28-day cycle, day 21 of the cycle (7 days after presumed ovulation) is the standard mid-luteal timing. If your cycle is shorter or longer, adjust: day 21 of a 26-day cycle, day 23 of a 30-day cycle. If you track ovulation via LH surge (ovulation predictor kit) or basal body temperature, test 7 days after the surge or temperature shift. Testing in the follicular phase (days 1–10) or early luteal (days 15–18) will show falsely low progesterone even in an ovulating woman.
No. PCOS is diagnosed by ultrasound (polycystic ovaries), clinical signs (irregular cycles, hirsutism, acne), and biochemistry (elevated androgens, normal or high LH/FSH ratio). Low mid-luteal progesterone is consistent with anovulation, which is common in PCOS, but progesterone alone does not diagnose PCOS. You need the full picture: testosterone, SHBG, LH, FSH, pelvic ultrasound, and menstrual history.
Progesterone and estradiol have opposing metabolic effects. Progesterone slightly increases metabolic rate and reduces insulin sensitivity in the luteal phase — meaning the body burns slightly more calories but uses glucose less efficiently. Low progesterone itself does not typically cause weight gain, but anovulation (low progesterone) often clusters with PCOS and insulin resistance, which do drive weight gain and metabolic dysfunction. The weight issue is usually the underlying metabolic disorder, not the low progesterone.
Progesterone testing is not a routine standard vårdcentral test without clinical indication (infertility, irregular cycles, MHT dose optimization, or miscarriage risk evaluation). If your doctor suspects anovulation or luteal-phase defect, it may be ordered through the public system. For preventive tracking or optimization in the context of longevity testing, this is typically a private service — which is where Loovi testing comes in.
Acute intense exercise in the 48 hours before blood draw can mildly suppress progesterone; avoid vigorous training the day of or day before your test. Sleep deprivation and chronic stress suppress GnRH pulsatility, which can reduce corpus luteum lifespan and lower luteal-phase progesterone over time. A single night of poor sleep before a single test is unlikely to dramatically alter progesterone, but chronic stress or sleep loss can lower it meaningfully. Fasting is not required for progesterone testing.
Progesterone is the body's natural hormone; micronized progesterone (a form that improves absorption) has a metabolic profile closer to endogenous progesterone. Synthetic progestins (like megestrol acetate, levonorgestrel, norethisterone) are structurally different and have different metabolic effects — some are more androgenic, some more estrogenic. Micronized progesterone carries lower cardiovascular and metabolic risk per recent European guidelines, though all progestational agents carry some VTE (venous thromboembolism) risk when combined with estrogen. The choice depends on tolerability, side effects, and cardiometabolic risk profile — not something to optimize without expert guidance.
Progesterone supplementation is not a first-line treatment for low luteal progesterone or recurrent miscarriage. If anovulation is the cause of low progesterone, the priority is restoring ovulation, not supplementing progesterone. If ovulation is present but progesterone is borderline, supporting the metabolic drivers (energy intake, sleep, stress, micronutrients) is the first step. In recurrent early miscarriage with confirmed low progesterone, some specialists support progesterone therapy in early pregnancy, but this requires careful clinical assessment — it is not a standard preventive approach and should only be undertaken under specialist care.
In early pregnancy (weeks 1–8), the corpus luteum produces progesterone, which typically rises from 30 nmol/L at conception to 100+ nmol/L by week 8. Around week 8–10, the placenta takes over, and progesterone production increases progressively, reaching several hundred nmol/L by the third trimester (often 400–600 nmol/L or more). Low progesterone in early pregnancy (below expected for gestational age) can signal miscarriage risk, ectopic pregnancy, or placental dysfunction — but low progesterone alone is not diagnostic; ultrasound and hCG trends are essential for clinical assessment.
No. Progesterone in men is < 2 nmol/L and has no clinical utility. Male reproductive function depends on testosterone, not progesterone. If a man's progesterone is elevated (> 5 nmol/L), it may reflect an adrenal or testicular tumor, but this is vanishingly rare and would be investigated through testosterone and other androgen testing, not progesterone.
