Progesterone is a steroid hormone released in the ovaries, and is necessary for the implantation of the fertilized egg in the uterus and maintaining pregnancy. Progesterone is also used to regulate abnormal menstrual cycles and helps kickstart menstrual cycles that have abruptly stopped (known as amenorrhea).
Progesterone is necessary for sperm production and maturation as well as testosterone production. Progesterone is actually a building block for testosterone, so levels that are too low can lead to testosterone deficiency.
Blood progesterone levels are usually below 3.18 nmol/L in healthy cis males.
Progesterone plays a key role in pregnancy and fertility, including:
If you’re experiencing infertility, your doctor may order a progesterone blood test. Levels of progesterone should spike after ovulation, so monitoring this hormone can help confirm that a patient successfully ovulated. Progesterone may also be monitored throughout pregnancy. Progesterone levels will vary based on the stage of the menstrual cycle and whether someone is pregnant or in menopause.
High progesterone levels can indicate successful ovulation or pregnancy (as pregnant people have approximately 10 times higher levels of progesterone). Excessively high progesterone levels may indicate an ovarian cyst or ovarian cancer. Low progesterone levels increase the chance of preterm birth and miscarriage, and are linked to reduced fertility.
Progesterone (also called progestin) can be used as a form of birth control, such as “the pill.” Progesterone hormone replacement therapy may be prescribed if: