Progesterone
Hormones coordinate different functions in the body by carrying messages through the blood to the organs. These signals tell the body what to do and when to do it. Hormones are essential for life and health1.
All women who wish to become pregnant need progesterone to help their uterus prepare for and maintain a pregnancy1. So, you may need to know the progesterone level if you want to get pregnant2.
About progesterone
Progesterone is a sex hormone (like estrogens and androgens). It belongs to a group of steroid hormones. Its main functions are to regulate menstruation and support pregnancy in the female body3.
Progesterone, like estrogen, plays an important role in normal mammary gland development. Also, progesterone may demonstrate a neuroprotective effect and helps neurons to survive3.
In females, progesterone is produced in the ovaries, and its level depends on different points of the menstrual cycle. In males, the adrenal glands can also produce progesterone3.
Progesterone and Pregnancy
Called “the pregnancy hormone”, natural progesterone is essential before pregnancy and has a crucial role in its maintenance based on different mechanisms4.
During the menstrual cycle, when an egg is released from the ovary at the time of ovulation (approximately day 14), the remnants of the ovarian follicle that enclose the developing egg form a structure called the ‘corpus luteum’, which translates as ‘yellow body’ due to its appearance. This releases progesterone. Progesterone helps prepare the body for pregnancy and provides a good environment for the implantation of a fertilized egg5.
If the egg is not fertilized, the corpus luteum breaks down, the production of progesterone falls and a new menstrual cycle begins5.
If an egg is fertilized, the corpus luteum doesn’t break down and continues to produce progesterone. This progesterone stimulates the growth of blood vessels that supply the lining of the endometrium. It also prompts the endometrium to provide nutrients to the developing embryo. Once the placenta has formed, it also produces progesterone. Eventually, the placenta is the leading producer of progesterone during pregnancy5.
During pregnancy, progesterone plays a number of important roles:
- stimulates the growth of maternal breast tissue5
- decreases uterine contraction to prevent labor prematurely6
- prevents lactation5
- strengthens the pelvic wall muscles before labor5
What’s a normal progesterone level?
Progesterone levels are measured with a blood test. It’s important to remember that progesterone levels fluctuate throughout the menstrual cycle, so that levels can vary throughout the month2.
Progesterone levels are measured in nanograms per millilitre (ng/mL)2. The chart below lists normal levels of progesterone for an adult female during different points of the menstrual cycle.
| Stage | Progesterone level (ng/mL) |
| pre-ovulation2 | 0.1-0.7 |
| Ovulation7 | ≤ 12 |
| post-ovulation2 | 2–25 |
Progesterone is found in much lower levels in men and isn’t typically tested unless adrenal gland dysfunction is suspected. Normal levels are less than 0.20 ng/mL7.
Keep in mind that results can vary between laboratories. If you’re not sure about your test results, contact your doctor.
A normal level of progesterone is needed for a pregnancy to progress normally. Elevated progesterone is uncommon, but it can be a sign of certain disorders, for example, congenital adrenal hyperplasia or some ovarian cysts and tumors. If progesterone levels are too low, irregular and heavy menstrual bleeding can occur5.
Progesterone level during pregnancy2:
| Stage | Progesterone level (ng/mL) |
| first trimester | 10–44 |
| second trimester | 19.5–82.5 |
| third trimester | 65–290 |
Elevated or low progesterone levels during pregnancy are quite uncommon but they can be a sign of certain conditions. For example, elevated progesterone during pregnancy can mean that you have twins2.
Decreased progesterone during pregnancy could be the result of one of the following2,5:
- An ectopic pregnancy
- A miscarriage or early labor
- A threatened miscarriage (when there is vaginal bleeding, spotting and/or cramping)
References
- Hormones https://my.clevelandclinic.org/health/articles/22464-hormones (Last access 17.06.2022).
- Progesterone https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=167&ContentID=progesterone (Last access 17.06.2022).
- Cable JK, Grider MH. Physiology, Progesterone. Available from: https://www.ncbi.nlm.nih.gov/books/NBK558960/ (Last access 17.06.2022).
- Di Renzo GC, et al. Progesterone in normal and pathological pregnancy. Horm Mol Biol Clin Investig. 2016;27(1):35-48.
- Progesterone_ Hormones https://www.yourhormones.info/hormones/progesterone/ (Last access 17.06.2022).
- Preterm birth, prolonged labor influenced by progesterone balance https://www.sciencedaily.com/releases/2021/03/210311185953.htm (Last access 17.06.2022).
- Everything You Need to Know About Progesterone https://www.healthline.com/health/progesterone-function#normal-levels-chart (Last access 17.06.2022).