Mid-luteal progesterone

A mid-luteal progesterone, often called a day 21 test, is taken roughly seven days before the expected period rather than strictly on day 21. A clearly raised level confirms ovulation occurred in that cycle. If your cycles are long or irregular, the timing must be adjusted or the result will be misleading.

Also known as: day 21 progesterone, progesterone test

Last reviewed: 10 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.