What’s the difference between progesterone and PdG?
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 7/26/21
So what is the difference between progesterone and PdG? Keep reading to find out!
Here at Proov, we’re about all things hormones! One of our favorite hormones — as you probably know by now — is progesterone.
However, you also may know that our first product, Proov Confirm, is the first and only FDA cleared PdG test to confirm successful ovulation at home. So what is the difference between progesterone and PdG? Keep reading to find out!
What’s the difference between progesterone and PdG?
To put it simply, PdG is a marker of progesterone. After progesterone circulates through your bloodstream, it gets metabolized by your liver and is excreted from the body in the form of Pregnanediol Glucuronide, or PdG for short. Basically, progesterone is what shows up in your blood and PdG is what shows up in your urine after ovulation.
Since progesterone and PdG appear in different places, there are key differences in how they’re measured. Progesterone is measured in blood, while PdG is measured in urine.
The presence of progesterone or PdG tells you the same thing; either one confirms ovulation. Elevated and sustained levels of progesterone, and therefore PdG, after ovulation are necessary for supporting implantation and conception. Let’s dive into why both are so important!
What is progesterone and why is it important?
Progesterone is one of the main female reproductive hormones and plays a huge role in conception, which is why it is also sometimes called “the pregnancy hormone.”
It is only produced after ovulation by the empty follicle from which the egg was released, also called the corpus luteum. Progesterone should rise and remain elevated during the second half of your cycle — the luteal phase — in order to allow for a healthy cycle and best possible chance at conception.
Progesterone’s main job is to create a healthy uterine environment in which an embryo can thrive. Essentially, progesterone ensures your uterine lining is “sticky” enough to allow an embryo implant. It also makes sure an implanted embryo can get the nutrients it needs to grow and develop.
If an egg is not released, meaning you did not ovulate (also called anovulation), then there will be no progesterone production. Thus, a presence of progesterone in blood above a certain threshold confirms ovulation.
Sometimes, a woman may not produce enough progesterone after ovulation. This can make it more difficult for conception to occur, and therefore can make it hard to get pregnant. Insufficient progesterone production can also cut your luteal phase shorter than the healthy 11 days, meaning there may not be enough time for an embryo to implant.
But, like other hormones, progesterone can play a big role in many other aspects of your health, such as:
- Our mood can be influenced by progesterone, which acts as a natural antidepressant, diminishes anxiety, and may even be able to help with postpartum depression.
- PMS (premenstrual syndrome) symptoms may be relieved with the help of progesterone supplementation. When progesterone levels drop too soon and too abruptly during the luteal phase, this may trigger PMS symptoms like mood swings, bloating, cravings, and breast soreness.
- Our sleep patterns may be influenced by progesterone as hormonal imbalances have been shown to cause sleep problems in women.
- Healthy bones are linked to optimal levels of progesterone, which has been used to help prevent and treat osteoporosis.
Additionally, insufficient progesterone levels after ovulation may lead to estrogen dominance, a common hormonal imbalance among women. Estrogen dominance poses many health risks and, when left untreated, may increase your odds of developing an endometrial, breast, or ovarian cancer, or increases your risk of heart attack, stroke, thyroid disease, and excessive weight gain.
Insufficient progesterone production can also cut your luteal phase shorter than the healthy 11 days, meaning there may not be enough time for an embryo to implant.
What is PdG and why is it important?
As we mentioned PdG (Pregnanediol Glucuronide) is the major urinary marker (also called a metabolite) of progesterone. Studies show that PdG levels in first morning urine correlate to an average of all progesterone levels from the day before.
Like progesterone, PdG is essential for supporting conception and healthy pregnancy. In fact, studies show that the presence of PdG during the luteal phase increases the chances of successful pregnancy from just 19% all the way to 92%. That’s a significant increase!
How do I measure progesterone and PdG?
While the presence of both progesterone and PdG can confirm ovulation, there is a big difference in how they’re measured. While progesterone levels are measured in blood via a blood draw, PdG levels are measured in urine via a urine-based test strip.
Typically, serum progesterone blood draws are taken on cycle day 21, about 7 days after ovulation when levels should be elevated. However, this assumes every woman has exactly a 28-day cycle and always ovulates on cycle day 14, which we know isn’t necessarily true.
A normal cycle can last anywhere from 21-35 days, meaning ovulation could absolutely occur before or after cycle day 14. This means a cycle day 21 progesterone blood test could provide inaccurate assumptions about progesterone levels after ovulation.
Additionally, studies show that serum progesterone levels can fluctuate drastically — up to 8-fold in just 90 minutes! This means that if you get your blood drawn at 8 am, you could get a very different result than if you got it drawn at 2 pm, meaning you may end up with inaccurate results.
While a serum progesterone level over 5 ng/ml confirms ovulation, we know that progesterone levels need to remain elevated for several days during the luteal phase to support implantation and allow for the best possible chance at conception. It’s entirely possible for your levels to be good one day, then drop the next. But with a one-point-in-time blood test, you wouldn’t know this was happening unless you were tested several days in a row — ouch!
Proov Confirm is the first FDA cleared PdG test kit to confirm successful ovulation at home.
This is where PdG comes in! Since PdG can only be measured via urine, it is a non-invasive way to determine if your post-ovulation levels look good.
Proov PdG tests are the first and only FDA cleared PdG tests to confirm successful ovulation at home. Successful ovulation refers to an ovulatory event in which an egg is released and PdG levels remain adequately elevated for long enough during the luteal phase to allow for the best possible chance at conception.
With the patented Proov PdG testing protocol, you can ensure you get the most valuable information out of your PdG test results. We recommend testing daily on day 7, 8, 9, and 10 past peak fertility (i.e. a positive LH test). During this testing window, we like to see 3-4 positive PdG tests (with a positive result on 10 DPP) to confirm that ovulation was in fact successful and your post-ovulation PdG levels look good. This can significantly increase your chance at successful pregnancy!
Understanding the similarities and differences between progesterone and PdG can arm you with powerful information to help you get pregnant faster!