Ajax Harwood Clinic
Progesterone (incl. day 21 test)
Full name: Progesterone (including 'day 21 progesterone')
This test is useful only in specific situations — it's not right for everyone who asks about it.
What this test is
Progesterone is a hormone your body makes after you ovulate. The main proven use is to check that you ovulated. This is often part of a fertility check-up. It is timed to about a week before your next period. Some call this a day 21 test. It is not a good way to diagnose menopause on its own. It is not a good way to check hormone balance either. The level changes a lot through your cycle. If you are trying to get pregnant, ask about this test. It works best when timed right. If the question is menopause symptoms, your history usually gives the answer. A blood test is often not needed.
Want to see the full clinical reasoning? The reference we use for this test is open to anyone — it is detailed and written for clinicians, and you are welcome to read it.
Open the clinician reference →Looking for other tests, or more on a condition an ND raised? Explore ask.ajaxharwoodclinic.com →
General health information for Ajax Harwood Clinic patients and the public — not medical advice, and not a substitute for seeing your own doctor. Last reviewed 2026-09-24.