What is progesterone?
Progesterone is a hormone produced in the ovaries that regulates menstruation and supports pregnancy. Although your progesterone levels fluctuate naturally, knowing whether your progesterone is too low or too high can offer you valuable insights into your fertility, ovulation and overall reproductive health.
What does progesterone do?
During ovulation, progesterone levels increase to prepare the uterine lining or endometrium for an egg. If conception does not occur, progesterone levels drop, and the endometrium is shed during your menstrual period. If an egg is fertilized, progesterone levels increase to support the pregnancy. Over time, progesterone production decreases as you approach menopause.
What do your progesterone levels mean?
As you go through your menstrual cycle, your levels of progesterone naturally increase and decrease at different phases. These changes in hormone levels can indicate where you are in the menstrual cycle and when ovulation may occur.
Progesterone levels fluctuate depending on the time of day and where you are in your monthly cycle. At the start of your menstrual cycle (i.e., the menstrual phase), progesterone levels drop in tandem with estrogen levels, causing the uterine lining to shed. Next, in the follicular phase, progesterone levels remain low while other hormones are released to help stimulate the ovaries to start producing follicles. Then, progesterone levels increase right after ovulation and peak during the luteal phase (the phase after ovulation and before menstruation).
Progesterone levels can be checked through a blood test, and your healthcare provider can help you determine what your progesterone level should be based on where you are in your cycle.
What are the symptoms of high and low progesterone?
Symptoms of low progesterone in persons who are not pregnant may include:
- Irregular menstrual periods
- Difficulty conceiving
- Mood changes
- Trouble sleeping
- Hot flashes
Symptoms of low progesterone in persons who are pregnant may include:
- Spotting (light bleeding)
- Low blood sugar
- Fatigue
In persons who are pregnant, low progesterone levels may put you at increased risk of miscarriage, ectopic pregnancy or preterm labor.
For those assigned female at birth, testing your progesterone levels can be an effective method for assessing your hormonal health.
If you are experiencing elevated levels of progesterone, you may not experience any adverse symptoms. In rare cases, it may be a sign of polycystic ovary syndrome (PCOS) or adrenal cancer.
When should I test my progesterone levels?
A progesterone blood test can give you an accurate reading of your body’s progesterone levels at the time of the blood draw. Due to the natural fluctuations of progesterone in the body, it is recommended to test your levels on day 21 of a 28-day cycle, or 7 days before your next period.
Another way to look at progesterone is with a pregnanediol glucuronide (PdG) test. A PdG test is a qualitative urine test that identifies whether or not the major metabolite of progesterone is detectable in your urine, but not the amount of that metabolite. PdG tests can be used to determine if ovulation has occurred recently.
If you are unsure which test is right for you, consider talking to your healthcare provider about which test matches your needs.
If you are curious about your fertility and ovulation, it may be worthwhile to check your progesterone levels. Labcorp OnDemand offers a Progesterone Test that can be a first step in finding the answers you need.
