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What Causes Low Progesterone?

Written by Dr. Amy Beckley, PhD, Founder and Inventor of the Proov test the first and only FDA-cleared test to confirm successful ovulation at home.

Written on 10/15/20

Low progesterone is something you may have heard of before. In the fertility world, low progesterone is a common issue that can make it more difficult to get pregnant. 

But what causes low progesterone and how do you know if you have it? Having a better understanding of your progesterone levels can help you conceive faster!

What is progesterone?

Progesterone is the hormone produced by the corpus luteum (empty follicle) after ovulation occurs. It is the hormone responsible for stabilizing the uterine lining to make it “sticky” enough to receive an embryo. Progesterone creates a healthy uterine environment in which an embryo can thrive. 

 what causes low progesterone

Progesterone is the hormone produced by the corpus luteum after ovulation has occurred. 

Progesterone levels need to rise post-ovulation and remain adequately elevated for a few days during the luteal phase to allow for the best possible chance at conception. Without sufficient progesterone levels, it can be more difficult to successfully conceive. 

What causes low progesterone?

There are a few different reasons your progesterone levels may be low during the luteal phase. Here are a few:

Anovulatory cycles: Anovulatory cycles refer to cycles where ovulation does not occur. Without the release of an egg, there is no empty follicle to produce progesterone. Anovulatory cycles are common in women with PCOS, who may have hormone imbalances that prevent ovulation from occurring. If you suspect you may have PCOS or are experiencing anovulatory cycles, we recommend consulting your doctor.

Hypothyroidism: Hypothyroidism means the thyroid gland cannot produce enough T3 and T4 hormones, which are the hormones that regulate the entire endocrine system. These hormones allow your body to produce adequate amounts of progesterone. Without enough T3 and T4, your body may struggle to produce progesterone. Your doctor can run tests on your thyroid to detect hypothyroidism. 

 what causes low progesterone

When the thyroid gland struggles to produce enough T3 or T4, your body may have difficulty producing sufficient amounts of progesterone.

Increased cortisol production: Cortisol is the stress hormone and, along with progesterone, is produced on the hormone pathway. This means that cortisol and progesterone are made of the similar “ingredients.” If your body is under a lot of stress and needs more cortisol, it will “steal” progesterone from your reproductive system to accommodate. Increased stress and excessive exercise can impact your cortisol levels. 

Abnormal bodyweight: Progesterone levels can be affected by an abnormally low or abnormally high body fat percentage. Women need a certain amount of body fat in order to cycle naturally and ovulate. If your body fat percentage is too low, you may fail to ovulate meaning you also won’t produce progesterone. On the other hand, abnormally high fat levels can cause overproduction of estrogen, as fat cells produce estrogen. Since estrogen and progesterone must stay balanced, excess estrogen can lead to low progesterone.

What are the symptoms of low progesterone?

Sometimes women with low progesterone will experience symptoms such as PMS, menstrual cramps, spotting before your period, or mood swings. In other cases, low progesterone may be the cause of infertility or miscarriage

How can I test my progesterone levels?

There are two ways to measure your progesterone levels: through a serum progesterone blood draw and PdG (progesterone metabolite) urine testing. 

Serum progesterone blood tests
Serum progesterone blood draws are quantitative, meaning they give an exact progesterone level. They’re most commonly taken on cycle day 21 — about 7 days after ovulation, when progesterone levels should be elevated.

 what causes low progesterone

Serum progesterone blood tests are quantitative and are usually taken on cycle day 21, or 7 days after the day of suspected ovulation.

However, serum progesterone tests have their drawbacks. First, these tests are timed based on a textbook cycle length of 28 days and on ovulation occurring on day 14. Studies show that 95% of women have a cycle length between 22 and 36 days, meaning that ovulation could occur before or after day 14. If you ovulate earlier or later than day 14, your progesterone blood test could give you an inaccurate assumption about your levels. 

Additionally, serum tests only show progesterone levels at one point in time. But, serum progesterone can fluctuate up to 8 times in one day. This means that if you have a test done at 8 am, you could get a different result then if you had your blood drawn at 3 pm. 

PdG — progesterone metabolite — tests

PdG testing, on the other hand, measures progesterone metabolite levels in urine and provides qualitative (positive or negative) results. After progesterone circulates through the blood, it gets metabolized by the liver into PdG. PdG levels in urine are only elevated when progesterone is also elevated. 

While PdG testing does not offer an exact progesterone level, they do allow for testing over multiple days since they are non-invasive. Most PdG tests are designed to turn positive at a certain threshold, for example 5 ug/ml of PdG (which, according to published studies correlates to about 10 ng/ml of progesterone in blood).

Proov is the first and only FDA-cleared PdG test kit for ovulation confirmation. Proov allows for PdG testing over several days to confirm successful ovulation, meaning PdG levels remained adequately elevated for long enough after ovulation to allow for the best possible chance at conception. 

what causes low progesterone

What can I do if my progesterone levels are low?

If a progesterone blood test or PdG test shows your levels may be low, we always recommend consulting your doctor. But not to worry — there are many options for increasing your levels:

Herbal supplements: Herbals such as red raspberry leaf, maca, and vitex have been shown to boost progesterone production. Always consult your doctor before taking any supplements!

Seed cycling: Seed cycling is a natural way to promote a hormone balance that involves eating certain seeds during certain phases of your cycle. During the follicular phase — the first half of your cycle — pumpkin and flax seeds can promote estrogen production. Then after ovulation, during the luteal phase (the second half of your cycle), sunflower and sesame seeds boost progesterone production.

Diet changes: Some foods, such as beans, spinach and broccoli, have been shown to increase progesterone production.

Prescription medications: There are several medications your doctor may be able to prescribe to increase your progesterone levels. If you are interested in prescription medication, we recommend consulting your doctor.

While low progesterone can be frustrating, there are many ways to measure and treat your progesterone levels to help you reach your fertility goals faster!