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Blood Test Tracker

Progesterone

A hormone made after ovulation that prepares the uterus for a pregnancy. A mid-luteal level is often used to check whether ovulation happened.

AI-drafted. Awaiting verificationAlso called P4LOINC 2839-9

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The usual range for Progesterone depends on sex. Choose female or male above to see where you stand.

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What it is

Progesterone is a hormone that rises in the second half of the menstrual cycle, after an ovary releases an egg. It gets the lining of the uterus ready for a fertilized egg. If you don't become pregnant, levels fall and your period starts. If you do, levels keep rising, and after the placenta forms it makes most of the progesterone. The adrenal glands also make small amounts.

Why it matters

A blood progesterone level is mostly used to check whether ovulation happened in a cycle. The same number means different things at different points in the cycle, in pregnancy, after menopause and in men, so timing is part of the result. It is also used in some fertility treatments and, less often now, in early pregnancy problems. One result is a snapshot, and your clinician reads it with your cycle dates, symptoms and other tests.

If it’s low

A low level in the weeks after ovulation can mean ovulation did not happen that cycle, or that the sample was drawn too early or too late. Low levels are expected before ovulation, after menopause and in men. In early pregnancy, a low level has been linked to ectopic pregnancy or miscarriage, but other tests are used more often now, and one level can't tell what is happening.

Common causes

  • Blood drawn too early or too late in the cycle
  • A cycle without ovulation (anovulation), which can come with irregular or missed periods
  • Polycystic ovary syndrome (PCOS)
  • High stress, perimenopause or menopause
  • A thyroid disorder or a high prolactin level
  • Ectopic pregnancy or miscarriage, when it is measured in early pregnancy

What can help

  • Ask whether the test was timed correctly for your cycle length, and whether to repeat it
  • Ask whether thyroid and prolactin tests would help explain missed or irregular periods
  • Talk with your clinician before changing any hormone or supplement

If it’s high

A high level is expected after ovulation and during pregnancy, so it may be normal for the day your blood was drawn. Outside those times, higher levels can be linked to an ovarian cyst or to adrenal gland conditions. In pregnancy, a level higher than expected can be linked to having more than one baby. Your clinician can put the number in context.

Common causes

  • Blood drawn in the luteal phase, after ovulation, when a high level is expected
  • Pregnancy, including twins or more
  • Progesterone medicines, which can change the result
  • An ovarian cyst
  • Adrenal gland conditions, including congenital adrenal hyperplasia (uncommon)
  • A molar pregnancy, an abnormal growth of tissue in the uterus (rare)
  • Ovarian or adrenal cancer (rare)

What can help

  • Tell your clinician your cycle dates and any hormone medicines, so the result can be read at the right point in your cycle
  • Ask whether another test is needed to explain a high level outside of pregnancy or the luteal phase

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

The usual range depends on sex. Choose women or men to see the one that applies.

ASRM mid-luteal ovulation threshold (2021)

  • At or below the ovulation thresholdbelow 3 ng/mL
  • Above 3 ng/mL: presumptive evidence of recent ovulation3 and above ng/mL

If this applies to you

Progesterone means a little more for some people. Open the one that fits you.

Trying to conceive

A mid-luteal progesterone test shows whether you ovulated in that cycle. NICE offers it even when cycles are regular, while ASRM says a regular cycle is usually enough to show ovulation. ASRM suggests timing the test about 1 week before your next period is due, rather than always on day 21.

Blood tests for trying to conceive, including IVF

What can affect your result

  • Where you are in the menstrual cycle: it is low before ovulation and high after it
  • Pregnancy: levels keep rising, and the placenta makes most of it later on
  • Menopause and sex: levels are very low after menopause and in men
  • Hours of the day: luteal levels can swing about sevenfold within hours
  • Hormone medicines, including progesterone treatment, which can change or cross-react in the test
  • Lab method: immunoassays and LC-MS/MS can give different numbers
  • Timing: luteal progesterone can swing about sevenfold over a few hours, so one sample shows whether ovulation happened but not how well the luteal phase worked (ASRM 2021).
  • Hormones and medicines: many medicines can interfere with the result, so tell the person ordering the test about everything you take, including birth control and progesterone treatment (MedlinePlus).
  • Metabolites of oral micronized progesterone can cross-react in some immunoassays, so a result during treatment may not match the hormone itself (Ghazal 2022).
  • Biotin: high-dose supplements can falsely raise results on competitive immunoassays, which are used for small hormones like progesterone (Ghazal 2022).
  • Method: direct immunoassays can cross-react with related steroids (Ghazal 2022), so results from different methods may not match.

The point in your cycle matters far more than the time of day. To check whether you ovulated, the American Society for Reproductive Medicine says to draw the sample about 1 week before your next period is expected, rather than on a fixed day such as day 21. Progesterone starts to rise around ovulation, keeps rising for about 6 to 10 days, then falls if you don't become pregnant (MedlinePlus). If you do, it keeps rising.

When to talk to a clinician

If you are or might be pregnant and have vaginal bleeding, pain in your lower back or belly, or cramping on one side, contact a clinician promptly, because an ectopic pregnancy can be a medical emergency (MedlinePlus). If you are not pregnant, an unexpected result doesn't need urgent action by itself. Talk with a clinician if you have missed or very irregular periods, or are having trouble getting pregnant.

Questions you could ask

  • On which day of my cycle should I have this test?
  • Was my blood drawn at a point in my cycle when a higher level is expected?
  • Could a medicine or fertility treatment I take affect this result?
  • Is another test needed to explain it?
  • Was my sample timed correctly for my cycle?
  • Should we repeat the test in another cycle?

Questions people ask

Is day 21 always the right day for a progesterone test?

No. The American Society for Reproductive Medicine says to draw it about 1 week before your next period is expected. That is day 21 only if your cycle is about 28 days long. With a longer cycle, the right day is later.

My level is under 3 ng/mL. Does that mean I didn't ovulate?

Not necessarily. A level above 3 ng/mL is taken as presumptive evidence of recent ovulation, but a lower level can also happen if the sample was drawn too early or too late. Ask your clinician whether to repeat the test.

How do I convert ng/mL to nmol/L?

Multiply ng/mL by 3.18 to get nmol/L. For example, 5 ng/mL is about 15.9 nmol/L. To go the other way, divide nmol/L by 3.18.

Show the science and sources

Units

  • 1 ng/mL = 1 ng/mL
  • 1 ng/mL = 3.18 nmol/L
  • 1 ng/mL = 100 ng/dL
  • 1 ng/mL = 1000 pg/mL

Open the Progesterone unit converter

For clinicians and researchers

Progesterone is a steroid hormone made by the corpus luteum after ovulation, by the placenta once it takes over from the corpus luteum (hCG supports luteal production for the first 4 to 6 weeks of pregnancy), and in small amounts by the adrenal glands. Luteal secretion is pulsatile, with a roughly sevenfold swing over a few hours, so a single value can confirm ovulation but cannot grade luteal function (ASRM 2021). ASRM treats a mid-luteal level above 3 ng/mL as presumptive and sufficient evidence of recent ovulation, with the sample drawn about 1 week before the expected period, not on a fixed cycle day. Most routine assays are competitive immunoassays, which are vulnerable to cross-reaction and to biotin interference (falsely high); dihydroprogesterone from micronized progesterone therapy has been reported to cross-react (Ghazal 2022). LC-MS/MS methods avoid immunoassay cross-reaction. Unit conversion: ng/mL x 3.18 = nmol/L (molecular weight 314.5).

LOINC 2839-9 (primary), 14890-8, 83109-9, 83110-7. Specimen: serum-or-plasma.

Sources

  1. Serum progesterone, MedlinePlus Medical Encyclopedia (National Library of Medicine)
  2. Progesterone Test, MedlinePlus (National Library of Medicine)
  3. Fertility evaluation of infertile women: a committee opinion, American Society for Reproductive Medicine (Fertility and Sterility) (2021)
  4. Hormone Immunoassay Interference: A 2021 Update, Annals of Laboratory Medicine (Ghazal, Brabant, Prie, Piketty) (2022)
  5. A rational diagnostic approach to the "phantom hCG" and other clinical scenarios in which a patient is thought to be pregnant but is not, Therapeutic Advances in Reproductive Health (Oyatogun et al.) (2021)
  6. Progesterone (PubChem compound 5994), PubChem (National Library of Medicine)
  7. Establishing Reference Intervals for Sex Hormones on the Analytical Platforms Advia Centaur and Immulite 2000XP, Annals of Laboratory Medicine (Schüring et al.) (2016)

AI-drafted. Awaiting verification. Last reviewed 2026-10-03. How we build and check these pages.

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