Hormone that rises after ovulation: used to confirm ovulation in cycle tracking.
What it is
Progesterone in nmol/L. A mid-luteal sample (often day 21 in a 28-day cycle) helps confirm ovulation; adjust timing for cycle length.
Progesterone rises after ovulation from the corpus luteum. Mid-luteal levels (commonly day 21 of a 28-day cycle, adjusted for cycle length) are used to confirm ovulation. Reported in nmol/L.
Why it matters
Low mid-luteal progesterone may suggest anovulation in the right context. Contraception and fertility treatments change interpretation entirely.
This guide is educational only and cannot diagnose you. Discuss results, especially anything outside your laboratory’s reference interval, or that does not match how you feel, with a GP or other appropriately qualified clinician.
A appropriately timed low progesterone may suggest that cycle did not ovulate. Contraception, fertility drugs, and pregnancy change interpretation completely. Spot progesterone without cycle context wastes the test.
This guide is educational only and cannot diagnose you. Discuss results, especially anything outside your laboratory’s reference interval, or that does not match how you feel, with a GP or other appropriately qualified clinician.
How it affects the body
Progesterone prepares the endometrium and has thermogenic and calming neuromodulatory effects in the luteal phase.
Progesterone prepares the endometrium for possible implantation, raises basal temperature slightly, and modulates mood and fluid balance in the luteal phase via receptors in many tissues.
For athletes
Athletes tracking cycles for performance should align sample timing with a clinician or fertility-aware GP: wrong-day samples waste money and cause false worry.
Athletes tracking cycles for performance or fertility should diarise cycle length and time the sample with clinic advice. Luteal deficiency conversations belong with specialists, not social-media hormone protocols.
