Struggling to Get Pregnant? Your Progesterone Levels May Be to Blame

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Editor’s note: Any medical advice presented here is expressly the views of the writer and Red Tricycle cannot verify any claims made. Please consult with your healthcare provider about what works best for you.

When I started to suspect I had an ovulatory disorder that meant my progesterone levels weren’t rising properly after ovulation, I went to my doctor and asked for a supplement. Although he was reluctant, he prescribed it for me. A couple of cycles later, I was pregnant and gave birth to my beautiful daughter who is now 6. But after my experience, I discovered there was a significant lack of knowledge in women’s health surrounding low progesterone and supplementation. Many women and their doctors did not understand or believe in the power of progesterone.

Unfortunately, some misconceptions are still common today. Read on to understand more about progesterone, why it’s important, and two common misconceptions that could be preventing women from uncovering what could be an easy fix.   

Why Is Progesterone Important?  

Progesterone is the hormone released after ovulation. It is required to prepare the uterus to receive an embryo, should conception have occurred and is essential to have adequate levels of progesterone for a long enough period of time after ovulation for a successful pregnancy.

What is misunderstood, however, is that a common problem with ovulation typically manifests as progesterone deficiency. Many doctors question if low progesterone is a real diagnosis and whether or not adding progesterone supplements can actually help.

Misconception #1: Studies Show Progesterone Supplements Don’t Help Fix Problems with Ovulation.

When I asked my doctor for a progesterone supplement, he gave it to me—not because he thought it would work, but because taking the supplement wouldn’t harm me. This lack of faith in the effectiveness of progesterone supplements stems from a study conducted in 2016. This study followed 836 women. When a woman got a positive pregnancy test, half were given vaginal progesterone and the other half were given nothing. Live birth rates were only 2% higher in the progesterone supplement group. So, the study concluded that progesterone supplementation didn’t really help.

But this experiment was flawed. Basic biology tells us that progesterone is required to prepare the uterine lining for implantation—which is why it is released by the ovary right after ovulation. So, by the time a woman got a positive pregnancy test, the embryo had likely already implanted. Providing progesterone after confirmed pregnancy was almost “too late” since progesterone is critically needed to prepare the uterus for conception. This study was highly publicized when it was published, so the information spread widely to doctors and women.

In 2017, another study was published. In this experiment, women were given progesterone at the start of their luteal phase (3 days after ovulation) so that they were able to have high levels before implantation and getting a positive pregnancy test. The results of this study showed a 17% increase in live birth rates. 

In fact, there are many studies that show progesterone supplementation starting after ovulation increases live birth rates. So when supplementing, it’s important to mimic the time when the body would have released progesterone as well—which is right after ovulation, not after implantation has already occurred. 

Misconception #2: A Blood Test Is the Best & Only Way to Confirm Ovulation. 

If you suspect you have a lack of ovulation or suboptimal ovulation (i.e. a progesterone deficiency), your doctor may order a day-21 progesterone blood test. A day-21 blood test aims to measure progesterone at the point in your cycle when it should be the highest—seven days after ovulation (given ovulation occurs on day 14). However, there are a few reasons a blood test can fall short. 

First, a day-21 blood test assumes you ovulate on day 14 of your cycle. But, every cycle is different in length, so one woman may ovulate before or after day 14. When this happens, progesterone still should be high seven days after ovulation, but that may not necessarily occur exactly on the 21st day of your cycle. This means that you could get a negative result when in reality, your progesterone is fine. Additionally, a one point in time measurement doesn’t always show the full picture. In my case, progesterone levels would rise, then fall a bit too quickly to be considered “healthy”. I would get a positive day-21 test and doctors would think I was fine, but my progesterone levels weren’t actually adequate over time. 

Second, progesterone is secreted into the blood in pulses. Studies have shown that serum progesterone levels can fluctuate eight times in the course of a single day. So, progesterone can range from 3-30 ng/ml, depending on what time of day you draw blood. This makes it extremely difficult for doctors to know if the amount of serum progesterone in your blood draw is actually enough to support successful conception. At 8 a.m., your progesterone levels could look great, but at 4 p.m., they could be low. 

So, what does this all mean for you? 

The most important thing for you to do is stay informed and ask your doctor the right questions. The good news is that there are other ways to confirm successful ovulation at home so that you can understand this important piece of the fertility puzzle! 

After progesterone circulates through the blood, it is then passed into the liver where it is metabolized and secreted into urine as PdG (Pregnanediol Glucuronide). Studies have shown that PdG levels, first thing in morning urine show an average of the serum progesterone levels from the day before. Because PdG shows an average, this makes it a better way to measure the overall progesterone production after ovulation. Add to this, testing PdG through urine is non-invasive, it’s simple to track levels over several days, allowing for a more complete ovulation picture. 

Understanding the importance of progesterone and the most effective ways to test for it can empower you with valuable information and help your better advocate for yourself on your TTC journey.