Progesterone is a female hormone, produced primarily in the ovary, primarily during the second half ("luteal phase") of the menstrual cycle. Men also produce progesterone, but only very small amounts.

Shortly after ovulation, progesterone levels rise quickly and remain elevated for about 10 days. 

  • If pregnancy occurs, the progesterone levels remain elevated. 
  • If pregnancy does not occur, then progesterone levels fall, provoking a menstrual flow.

Progesterone levels are sometimes used to evaluate a possible ectopic pregnancy:

  • If progesterone > 25, ectopic pregnancy is very unlikely
  • When less than 25, the results are not conclusive either way.

Elevations found in:

  • Pregnancy
  • Second half of the menstrual cycle
  • Congenital adrenal hyperplasia
  • Some hormone-producing tumors of the ovary

Decreases found in:

  • Polycystic Ovary Syndrome (PCO, Stein-Levinthal Syndrome)
  • Amenorrhea-Galactorrhea Syndrome
  • Luteal phase defects
  • Menopause
  • Ovarian failure

Normal Values*

Men < 1.0 ng/ml

(Proliferative Phase)

< 1.5 ng/ml
(Luteal Phase)
3-20 ng/ml

*These are general values taken from a variety of sources. The actual normal values may vary from lab to lab and from one type of testing protocol to another.


Gynecology and Obstetrics CD-ROM
Volumes 1-6
2004 Edition
Lippincott Williams & Wilkins
Copyright 2004
All Rights Reserved