How a progesterone blood test confirms ovulation
Evidence last assessed 2026-10-10.
In short
- What the research shows
- A blood progesterone of 5 ng/mL or more, from day 8 of the cycle onward, confirms an ovulation in that cycle.
- What it doesn't show
- It does not say which day, and a lower result can simply mean the blood was drawn too early or too late.
- When it's worth raising with a professional
- Your clinician can tell you which day of your cycle to have the test, so the result can be read.
- Tests and appointments
- Cycles
See studies and method
What the evidence says
Progesterone in the blood rises only after ovulation and peaks about a week later. A single result at or above about 5 ng/mL (about 16 nmol/L), from day 8 of the cycle onward, confirms an ovulation in that cycle. It does not say which day.
A classic study took a single result above 3 ng/mL in the second half of the cycle as evidence of ovulation. How high a single value is depends heavily on the day it is drawn, and a study of single random samples supported a higher threshold of about 5 ng/mL, which is the stricter one used here. 1 ng/mL is about 3.18 nmol/L.
What this does not show
A result below the threshold does not show that ovulation did not happen: it may simply have been drawn too early or too late. The threshold studies were not in women with a specific condition, and labs report in different units; a unit that cannot be read is never interpreted.
Sources, as Neta holds them
Israel R, Mishell DR Jr, Stone SC, Thorneycroft IH, Moyer DL. Single luteal phase serum progesterone assay as an indicator of ovulation. Am J Obstet Gynecol. 1972;112(8):1043-6. doi:10.1016/0002-9378(72)90178-0
People compared with each other
Wathen NC, Perry L, Lilford RJ, Chard T. Interpretation of single progesterone measurement in diagnosis of anovulation and defective luteal phase: observations on analysis of the normal range. Br Med J (Clin Res Ed). 1984;288(6410):7-9. doi:10.1136/bmj.288.6410.7
Daily diary, each person compared with herself
Leiva R, Bouchard T, Boehringer H, Abulla S, Ecochard R. Random serum progesterone threshold to confirm ovulation. Steroids. 2015;101:125-9. doi:10.1016/j.steroids.2015.06.013
Daily diary, each person compared with herself