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Progesterone levels explained

Progesterone plays an important role in the menstrual cycle. But what is it, exactly? What does it do? And what progesterone levels are normal? We’ll answer all of your questions about this hormone. Read on to find out more…

What is progesterone?

Progesterone is a sex hormone that’s found in both men and women. Progesterone plays a key role in female reproductive health, and is particularly important in the later stages of the menstrual cycle (known as the luteal phase), as well as during pregnancy.

In females, progesterone is produced by the adrenal glands and the corpus luteum. This is a temporary structure found in the ovaries that’s closely linked to hormone production. Progesterone is produced during the second stage of the menstrual cycle, which begins after ovulation, and finishes when your next period starts. 

During the early stages of your menstrual cycle, progesterone levels are quite low. After ovulation, progesterone levels rise. This helps to soften the lining of the uterus, making it easier for a fertilized egg cell to implant. If the egg isn’t fertilized, your progesterone levels drop once more, causing the uterine lining to break down and shed, which is the start of your period.

If an egg is fertilized, progesterone levels will stay stable. This hormone plays a crucial role in your body’s function during pregnancy, as it stimulates blood vessels to supply the uterine lining, prompting nutrients to be delivered to the embryo as it develops. It’s also important for the development of placenta, and progesterone levels increase between the 9th and 32nd weeks of pregnancy.

The higher levels of progesterone during pregnancy stop our bodies from producing more eggs, and it also helps your body to start producing breast milk for when the baby is born.

As you get older, progesterone levels naturally drop. This, along with a drop in estrogen levels, is the cause of the physical symptoms women experience during menopause, including hot flashes, mood swings, vaginal dryness and fatigue. 

What is progestin?

Progesterone is a naturally occurring hormone. Progestin, on the other hand, is a synthetic hormone that’s created in a lab and designed to mimic progesterone. Progestin mimics the way progesterone acts in the body, and it was originally created when developing birth control pills, as natural progesterone can’t be absorbed well when taken orally.

It’s used in hormonal birth control, and can either be combined with estrogen (as in the combined bill, vaginal ring and birth control patch), or in progesterone-only birth control (like the progestin-only or mini pill, implant, hormonal IUDs and the injection). 

Progestin, when used in birth control, protects against pregnancy and prevents the ovaries from releasing an egg each month. It also thickens the cervical mucus, making it difficult for sperm to travel up the fallopian tubes and fertilize the egg cell.

What are normal progesterone levels?

Your progesterone levels vary throughout your menstrual cycle. Before you ovulate, they’ll naturally be lower. Then the corpus luteum produces progesterone after it releases an egg cell, progesterone levels naturally rise again, before dropping again if pregnancy doesn’t happen. The lower levels of progesterone in your body causes your uterine lining to break down, which kick-starts your period, and your progesterone levels become lower again.

Typical progesterone levels during the follicular stage of the menstrual cycle (the first stage of your cycle, which begins with your period, and ends with ovulation) range from 0.1 to 0.7 ng/mL. During the luteal phase, progesterone levels can be anything from 2 to 25 ng/mL.

As you approach perimenopause, progesterone levels can fluctuate a lot. Levels may drop below what’s typical for you, or they may be much higher than usual. During perimenopause, progesterone levels could be anywhere in the range of 0.89 to 24 ng/mL. 

It can vary from month to month, as women often ovulate less often during perimenopause. That means that you may have low progesterone levels during months when you haven’t ovulated, and high progesterone levels if you have ovulated.

It’s common to have low progesterone levels when you go through menopause. That’s because menopause means the end of ovulation, and progesterone is no longer produced in the corpus luteum. Progesterone does continue to be produced in the adrenal glands, though. During menopause, progesterone levels are typically 0.20 ng/mL or lower.

Progesterone and miscarriage 

There is also a link between low progesterone levels and pregnancy loss. Those who experience bleeding in early pregnancy may be offered progesterone to prevent miscarriage if they have experienced a pregnancy loss before. Bleeding in early pregnancy does not always result in miscarriage, but it’s important to talk to your doctor if it happens. 

H2: What do low progesterone levels mean?

It’s normal for progesterone levels to fluctuate throughout your menstrual cycle, but sometimes if it’s particularly low, it may cause you some health problems.

The main symptom of low progesterone levels is irregular periods and a shorter menstrual cycle. Typically, the luteal phase of your menstrual cycle, which occurs after ovulation, will be shorter than average. Rather than the typical 12 to 15 days of this phase, if you have lower progesterone, the luteal phase may only last 8 or 9 days.

As well as irregular menstrual cycles, symptoms of low progesterone levels include:

  • Mood swings
  • Depression
  • Sleep disturbances
  • Anxiety
  • Weight gain
  • Breast tenderness
  • Spotting between periods
  • Low sex drive
  • Headaches

You can also experience lower levels of progesterone during pregnancy, during which time you might experience symptoms including:

  • Spotting
  • Fatigue 
  • Abdominal pain
  • Breast tenderness
  • Vaginal dryness
  • Low blood sugar

If you have low progesterone levels, it can mean you have a high risk pregnancy. That’s because you may be more likely to experience ectopic pregnancy, recurrent pregnancy loss or early labor. You’re unlikely to develop lower progesterone levels during your pregnancy, but if you already have low progesterone, you may find it difficult to conceive, and there’s a risk of early pregnancy loss.

What causes high progesterone?

There are several reasons that your progesterone could be at lower levels than normal. These include:

  • Polycystic ovary syndrome: If you have PCOS, an egg may not be released during ovulation every month, or it may not develop as it should, which can result in lower levels of progesterone.
  • Hyperthyroidism: Hormonal imbalance can be linked to thyroid conditions such as an overactive thyroid. Talk to your healthcare professional if you have (or think you may have) a thyroid condition to learn more.
  • High prolactin levels: Prolactin is the hormone that lets your body know that it needs to produce breast milk when you’re pregnant or breastfeeding. If your prolactin levels are too high, then it can interfere with the production of other hormones, like estrogen and progesterone.
  • High cortisol levels: Really stressed? It could be affecting your progesterone levels. When you’re very stressed, your body produces more cortisol, which can affect production of progesterone.
  • Menopause: As explained above, your body produces less progesterone as you enter the menopause, which leads to symptoms like mood swings, vaginal dryness, headaches and depression. A combination of low progesterone and low estrogen can cause night sweats and hot flashes.
  • Ovarian cancer: Although less common than the other causes listed here, ovarian cancer could be the cause of higher levels of progesterone, so it’s important to get tested by your healthcare provider if you have any concerns.
  • Adrenal gland disorders: As progesterone is produced by your adrenal glands as well as the corpus luteum, high levels of the hormone could indicate an issue with your adrenals rather than your reproductive system.

Symptoms of high progesterone levels

Just as you can have low progesterone levels, they can also be higher than average. This can cause symptoms such as breast tenderness, fatigue, thinning hair, weight gain, and anxiety. Elevated levels aren’t usually anything to worry about, but it could indicate underlying health conditions, so it’s always a good idea to talk to your healthcare professional if you have any questions or concerns.

Testing progesterone levels

If you’re concerned about your progesterone levels, you can get them tested. One of the main reasons for getting a test is to check that you’re ovulating, which is important if you’re planning a pregnancy.

You should get tested when your progesterone levels are naturally at their highest, which is during the luteal phase of your menstrual cycle. Your doctor may do a serum progesterone test, which measures the levels of progesterone in your blood. 

They’ll ask you about any medications you’re taking, as some medications can affect your progesterone levels. Other drugs can increase the complications of getting blood drawn, so it’s important to let your healthcare provider know about any medications you’re taking before you have the test.

They’ll do a blood test and send the blood sample away to be examined in a laboratory. You’ll get a result measured in ng/mL, telling you your exact progesterone levels.

The blood test results will show whether your levels are outside of the normal ng/mL range for your circumstances, depending on what stage you’re at in your menstrual cycle, what trimester you’re in if you’re pregnant, or if you’re postmenopausal.

If your level of progesterone is elevated during the luteal phase, then it’s an indicator that you’re likely ovulating. If your levels are lower than the normal range, then it’s likely that you’re not ovulating.

If you have an irregular menstrual cycle, you may have to get several progesterone serum tests to identify if and when you’re ovulating and when during your menstrual cycle it occurs. This can help you to better plan a pregnancy if you’re trying for a baby.

If your progesterone levels are considered to be abnormal, your healthcare provider may recommend that you get treatment or additional tests. 

There are various options available if you want to increase your progesterone levels, particularly if you’re trying to conceive. These include hormone replacement therapy, progesterone supplements and creams, a nutrient-rich diet, and more exercise.

Hormone-free birth control

Natural Cycles created the first FDA cleared birth control app. It’s powered by an algorithm that tracks your basal body temperature. This data can tell you where you are in your cycle, so you know your own fertility. Whether you’re looking to prevent or plan pregnancy, Natural Cycles will teach you more about your own body so you can better understand what’s normal for you.

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Written By

Lauren McKay

Lauren McKay is a writer and journalist with more than ten years of experience writing across a variety of topics. She is a passionate advocate for driving women’s health knowledge and is a trained yoga teacher. She earned a Masters in Creative Writing from the University of Glasgow and currently lives in Scotland.

Jack in a suit and tie holding a microphone and giving a presentation.

Scientifically Reviewed

Jack Pearson

Dr. Jack Pearson is a previously HCPC registered Embryologist with a PhD in reproductive medicine. Prior to joining Natural Cycles leading Medical Affairs, he worked for more than 10 years in a clinical setting working at some of the busiest fertility clinics in the UK. Today he spends most of his time working with experts at the world’s leading institutions to carry out important research with the vision to further the field of female health. He earned his PhD from the University of Sheffield specializing in Sperm Metabolism and currently lives in London.

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