What Is Progesterone? Overview of the “Pregnancy Hormone”

Of all the hormones critical to pregnancy, progesterone is the one that takes the cake! It not only helps you get pregnant, but it also helps to maintain and support your pregnancy right up until delivery. 

So what exactly is progesterone and how can you ensure your body gets enough of it?

In this article, we’ll share all the details of what progesterone does during pregnancy, where your progesterone levels should be, and how you can get your levels tested. We’ll also examine various progesterone medications and strategies for boosting your progesterone levels naturally. 

What is progesterone?

Progesterone is a type of steroid hormone critical to the menstrual cycle and pregnancy. In non-pregnant women, it is produced by the adrenal glands as well as the corpus luteum (a temporary gland produced in the ovaries each cycle). In pregnant women, progesterone is also produced by the placenta throughout the duration of pregnancy. 

What does progesterone do? 

In women of reproductive age, the main role of progesterone is to support the functioning of the uterine lining and regulate the menstrual cycle. It also helps to control libido and sex drive, while also helping to prepare the body for pregnancy.

Progesterone is also a key hormone during pregnancy, due to its role in maintaining the uterine lining, preventing potentially harmful contractions, and priming the glands for breastfeeding. 

Progesterone and pregnancy

Please note that the following blood level progesterone ranges are measured in ng/mL, and are based on figures from the Mayo Clinic Laboratories.

Please note that Progesterone (measured in ng/mL) should not be confused with PdG (measured in ug/mL) the urine metabolite of progesterone (PdG), commonly used in at-home testing. Mira tracks PdG. All the information provided in this article about Progesterone is purely educational. Please always refer to your healthcare provider.
 

Before pregnancy

Before pregnancy, your progesterone levels can vary depending on which phase of the menstrual cycle you are in. For example, during the first half of the menstrual cycle (i.e. the follicular phase), progesterone typically stays below 0.89 ng/mL. 

However, during ovulation, the body ramps up the production of progesterone and levels can increase up to 12 ng/mL. After ovulation and throughout the second half of the cycle (i.e. the luteal phase), progesterone continues to remain elevated and can range between 1.8-24 ng/mL.

During this time, the goal of progesterone is to help create an environment that is conducive to fertilization. This includes thickening the uterine lining (which allows a fertilized egg to be accepted) and preventing muscle contractions (which could potentially disrupt the early fertilization and acceptance process). 

In the event that pregnancy does not occur, progesterone is still produced by the corpus luteum until the end of your cycle, before dropping and triggering your period. 

During pregnancy

During pregnancy, progesterone is produced by the corpus luteum in early pregnancy and then the placenta after around week 8-12. Common progesterone levels during pregnancy are as follows:

• First trimester: 11-44 ng/mL
• Second trimester: 25-83 ng/mL
• Third trimester: 58-214 ng/mL

Progesterone helps to support a pregnancy in many different ways. This includes preventing ovulation, making sure the uterine lining stays secure, and strengthening the pelvic wall muscles to prepare for labor. Progesterone also helps the body create the cervical mucus plug, which then helps to prevent early labor and infection. 

After pregnancy, progesterone levels should go back to their typical patterns within a month. However, every individual pregnancy is different and this time frame can vary. 

Testing progesterone

When it comes to being pregnant or trying to conceive, there are two different reasons why it’s helpful to know what your progesterone levels are:

• To confirm ovulation or
• To monitor the development of your pregnancy. 

Here’s a brief overview of potential progesterone testing methods you can utilize depending on your purpose for testing.  

To confirm ovulation

If you want to know whether or not you have ovulated during your current cycle, there are a few different testing options available. 

The first option is a standard at-home blood test or urine test (for example, from a company like Proov or Let’s Get Checked). With these types of tests, your result will be given as a “yes” or “no”, with a “yes” meaning that your progesterone levels are high enough to confirm ovulation, and a “no” meaning your progesterone levels are not high enough to confirm ovulation. 

However, it’s important to note that these tests use a standard benchmark threshold for confirming ovulation – meaning they may not be able to fully account for individual hormonal patterns and ranges. 

If you’d like to know your exact progesterone levels and fluctuation patterns to confirm ovulation, another option is to use Mira’s Confirm Wands. These wands enable you to measure and track your numeric PdG levels (the urine metabolite of progesterone) so that you are always in the know about how your progesterone levels change throughout your cycle.

If you have tried multiple at-home hormone testing methods without success, it may be time to schedule an appointment with your doctor. They can help you determine if there are any underlying problems making it difficult to confirm ovulation. 

Please note that urine PdG should only be used for confirming ovulation. Mira Confirm Wands are not designed nor approved or cleared for monitoring early pregnancy status, miscarriage, fetal health tracking, or other diagnostic uses for which progesterone might be an indicator.

To monitor the health of your pregnancy

If you are already pregnant and need to have your progesterone levels checked in order to monitor your pregnancy, this can be done at your doctor’s office with a blood test. After going in to give a blood sample, your doctor will give you a call and let you know what your numeric progesterone levels were at the time of your test. They can then use this information to assess your progress, monitor the health of your baby, and make further recommendations for your pregnancy. 

Progesterone and fertility treatment 

Because progesterone is so vital in the early stages of pregnancy, doctors often recommend taking certain progesterone medications. This is especially true in cases of recurrent miscarriage, as well as in cases involving in vitro fertilization (IVF). 

Taking progesterone is risk-free, safe for both mother and baby, and may help to maintain pregnancies that would otherwise end in miscarriage. In fact, one recent study found that the use of micronized progesterone could help to prevent over 8,000 miscarriages each year.  

Form of progesterone 

When it comes to actually taking progesterone as a medication, there are multiple forms available. Here is an overview of each form, including what it’s typically used for and common side effects.

Oral

Oral progesterone is most commonly used by women who are undergoing menopausal hormonal therapy (MHT) due to menopause. It may also be used by women of reproductive age to treat amenorrhea (i.e. the absence of a period). 

The most common side effects of oral progesterone include chest pain, chills, flu-like symptoms, and/or difficulties with urination. Other less common side effects include nipple discharge, inversion of the nipple, and lumps in the breasts or underarms.

 

Vaginal

Vaginal progesterone can also be used to treat amenorrhea. However, it is also often used alongside certain fertility procedures (such as IVF) or during the early stages of pregnancy to support the pregnancy. It is commonly prescribed as either a suppository or as a gel. 

The most common side effects of vaginal progesterone include vaginal irritation or itching, yeast infection, headache, or nausea. Other less common side effects that require medical attention include vaginal bleeding, painful urination, severe headache, or chest pain.

Injection

Progesterone injections are also used to treat irregular periods, absent periods, or abnormal uterine bleeding. They may also be used during IVF treatment. The most common side effects of progesterone injections include swelling around the injection site, nausea, and/or dizziness. Other less common side effects that require medical attention include skin rash, nipple discharge, difficulty with breathing, and changes in vision. 

Progesterone vs progestins – what’s the difference?

When reading about progesterone and progesterone supplements, you may find yourself feeling a bit confused at the various terminology. To clarify, here are some major distinctions between progesterone and progestins. 

Progesterone is the term used to describe the actual steroid hormone that is produced in the body. This is the hormone that controls many functions of the reproductive process and pregnancy. Progesterone is also the term used to describe progesterone medication (often referred to as micronized progesterone). This type of progesterone has an identical molecular structure to the natural progesterone found in the body. 

Progestins are synthetic steroid hormones designed to have “progesterone-like” properties. They are used in oral contraceptives, and they are often used to treat irregular periods, absent periods, and certain cancers. What separates progestins from progesterones is the fact that although progestins behave similarly to natural progesterone, their molecular structure is different.

Progesterone FAQs