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Trying to conceive and not sure if you’re ovulating? You may want to take a PdG test.
PdG is a urine marker of progesterone. Like progesterone, PdG rises after an egg is released. So if PdG climbs in the luteal phase, it’s proof you did in fact ovulate!
But if you’ve never tried a PdG test, you may be wondering how these tests work. Read on to get the nitty-gritty on PdG tests and how to tell if they’re right for you.
What is a PdG test?
PdG is short for pregnanediol glucuronide. As mentioned, PdG is a metabolite of the hormone progesterone. After progesterone circulates in your bloodstream, it’s excreted from your body as the urine marker PdG.
PdG tests measure PdG in your pee to tell whether you ovulated that cycle.
How do PdG tests work?
It’s simple. You pee into a cup and insert a PdG test strip into the urine. The test then measures how much PdG is in your urine. Easy peasy.
That said, not all PdG tests work the same. Some tests are based on thresholds. This means they give a positive result if your PdG crosses a certain mark (usually 5 ug/mL). If PdG rises above that mark, the test will say you ovulated.
Other PdG tests (like Inito) are quantitative and give your actual hormone values. These tests confirm ovulation and give you a clear picture of your PdG levels.
No matter which PdG test you choose, always use your first-morning urine. PdG is most concentrated in your urine right when you wake up. So you’ll get the most accurate results with your first pee of the day.
PdG test vs. progesterone test
Wondering if PdG tests are the same as progesterone tests? Not exactly. PdG tests and progesterone tests have a common goal: to confirm ovulation. They just do it in different ways.
Progesterone tests take a blood sample to measure your progesterone levels. These tests are highly accurate. But they require a doctor’s visit, which can make them inconvenient (not to mention painful!).
PdG tests, on the other hand, are done at home and measure the urine marker of progesterone. You still get ovulation confirmation – just in a convenient, non-invasive way.
While the method may differ, both tests provide accurate results. Blood and urine testing also show similar hormone trends, even though their actual values may differ.
Why do I need a PdG test?
Ovulation confirmation is the main reason to take a PdG test. As you know, pregnancy can’t happen without ovulation. And unfortunately, ovulation doesn’t happen every cycle for every woman.
It’s estimated that over a third of all menstrual cycles are anovulatory, meaning ovulation doesn’t occur. PdG tests are an easy way to confirm you are indeed ovulating. This can give you peace of mind, or prompt you to seek the right help to get your hormones in a healthier range.
PdG tests can also help you monitor your progesterone levels during the implantation window. The implantation window is the period when your uterus is primed for a fertilized egg to attach.
High progesterone levels in the luteal phase can help make implantation more successful. Progesterone nourishes the uterine lining, making it thick and sticky so a fertilized egg can implant.
One study found that when PdG levels remained high in the luteal phase, there was a 92% chance of successful pregnancy. When PdG levels were not elevated, only 19% of women carried the pregnancy to term. So clearly, high progesterone levels are key if you’re TTC.
Learn more: The Importance of Progesterone Production During Early Pregnancy
When to test PdG after ovulation?
Ovulation occurs about 12-14 days before your next cycle. And progesterone typically peaks between 6 to 8 days after ovulation. That’s why PdG is usually tested for around 7 days past ovulation (DPO).
Meaning, your PdG would peak at roughly day 21 if you have a textbook 28-day cycle. This is why progesterone testing is usually done on day 21 of the cycle.
The trouble is, only 16% of women have a 28-day cycle and only 20% ovulate on day 14 of their cycle. A good rule of thumb is to test on 7 DPO of your cycle.
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Is a PdG test the same thing as an OPK?
Nope. OPKs are used before ovulation, while PdG tests are taken after ovulation.
Ovulation predictor kits (OPKs), also known as ovulation tests, do just what their name implies: they predict ovulation. But they don’t confirm it.
OPKs detect the luteinizing hormone (LH) in your urine. LH surges 24-36 hours before an egg is released. OPKs help pinpoint your fertile days so you know when to have sex if you want a sperm and egg to meet.
PdG tests, on the other hand, measure a urine marker of progesterone to confirm ovulation. Progesterone rises after an egg breaks free from the follicle. So if PdG goes up in the luteal phase, you can rest easy knowing ovulation occurred.
What will affect my PdG test results?
A few things can skew PdG results and lead to false positives and false negatives.
False positive PdG tests may be due to:
- Progesterone supplements. Progesterone supplements, whether natural or synthetic, can result in a false positive.
- LUFS. While rare, some women may experience luteinized unruptured follicle syndrome (LUFS). With LUFS, a dominant follicle forms and produces progesterone. But it fails to break open, so an egg isn’t released.
False negatives on PdG tests may happen due to:
- Urinary factors. If you take a PdG test after drinking a lot of water, PdG won’t be as concentrated in your urine. This can lead to a false negative. That’s why it’s always best to test with your first urine of the day.
- Levels from baseline. Threshold-based tests can create false positives. If your PdG rises but doesn’t hit the threshold, you’ll get a negative result, even if ovulation has occurred.
How do I know my PdG test result is normal?
Here’s a peek at what normal PdG levels look like before and after ovulation:
As you can see, any PdG levels between 6-40 ug/mL after ovulation are considered normal.
Learn More: Progesterone Levels After Ovulation Day by Day: What to Expect
In general, PdG levels over 5 ug/mL for three consecutive days indicate ovulation. However, some research shows this threshold isn’t accurate for everyone.
One study found that PdG levels over 5 ug/mL confirm ovulation in only 82% of cycles. Meaning, threshold-based tests may miss the mark 18% of the time.
However, if you use the Inito fertility monitor to test your PdG levels, the accuracy of confirming ovulation is 99%. Inito confirms ovulation by monitoring a steady consistent rise in PdG levels from your baseline values unique to you without sticking to a threshold value.
If you become pregnant, progesterone and its metabolite PdG continue rising throughout your pregnancy and peak in the third trimester. High progesterone levels nourish the developing embryo, prevent uterine contractions that can cause preterm labor, and prep the breasts for milk production.
If fertilization doesn’t occur, PdG falls back to its baseline, and you get your period.
How long after ovulation does PdG rise?
It’s different for everyone. For some women, progesterone and its metabolite PdG levels rise shortly after ovulation. For others, it may take 3-4 days to see a consistent rise in progesterone and PdG. It can even take 7 days or more to see a PdG rise after ovulation.
This is all normal. And it varies from cycle to cycle. The important thing is to look for a steady, consistent rise in PdG over several days. That’s what confirms ovulation.
Here are some charts where PdG rises on different days after ovulation and helps confirm ovulation.
How is a PdG test done?
If you want to keep tabs on your PdG without trekking to the doctor, Inito can help.
The Inito Fertility Monitor lets you see your actual PdG levels with a simple at-home test. This helps you confirm ovulation, even if your hormone levels are outside the norm.
Inito also measures FSH, LH, and estrogen to predict ovulation and pinpoint your fertile window. That way you know when to have sex for the best chance of conception. And Inito does this all from a single urine test. That said, Inito cannot be used to track PdG levels for confirming or monitoring pregnancy.
So if you could use a helping hand on your conception journey, check out Inito today.
Takeaways
- PdG is a urine marker of the hormone progesterone.
- PdG tests detect elevated levels of PdG in your urine to confirm ovulation.
- Some PdG tests can also ensure progesterone is high enough to support implantation.
- Progesterone usually peaks at around 7 days after you ovulate. So that’s typically when PdG tests are done.
- False positives on PdG tests may be due to progesterone supplements or LUFS. Urinary factors and PdG baseline levels may lead to false negatives.
- Use the Inito fertility monitor to track your fertile window and confirm whether you actually ovulated.
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- Using Quantitative Hormonal Fertility Monitors to Evaluate the Luteal Phase: Proof of Concept Case Study – PMC
- Effect of hydration on random levels of urinary pregnanediol glucuronide
- Progesterone Blood Level – an overview | ScienceDirect Topics
- The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study – PMC
- Menstrual Cycle Length and Patterns in a Global Cohort of Women Using a Mobile Phone App: Retrospective Cohort Study
- The value of urinary pregnanediol estimation for monitoring early pregnancies
- Ovulation Prevalence in Women with Spontaneous Normal-Length Menstrual Cycles – A Population-Based Cohort from HUNT3, Norway – PMC
- Real-life insights on menstrual cycles and ovulation using big data – PMC
- Accuracy of single progesterone test to predict early pregnancy outcome in women with pain or bleeding: meta-analysis of cohort studies
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