What Should PdG Levels Be After Ovulation?

After ovulation, PdG (pregnanediol-3-glucuronide) levels in urine should rise to at least 5 μg/mL, and staying above that threshold for three consecutive days is the standard used to confirm that ovulation actually occurred. That said, the number on any single test strip or reading depends heavily on when you test relative to ovulation, how hydrated you are, and what kind of test you’re using. The relationship between PdG and your actual progesterone production is real but surprisingly easy to distort.

What PdG Actually Measures

PdG is not progesterone itself. After your ovaries release progesterone, your liver breaks it down through a series of chemical reductions, then attaches a sugar molecule to make the compound water-soluble enough to leave through your kidneys. That end product, pregnanediol-3-glucuronide, is what home urine tests detect. Because it’s a downstream metabolite rather than the hormone itself, PdG levels reflect progesterone production with a slight time lag and some added variability from liver metabolism and kidney function.

The reason PdG is useful despite being indirect is that the change after ovulation is dramatic. In women with confirmed ovulation, the median luteal-phase increase in urinary PdG is around 427%, which dwarfs the increase seen when measuring progesterone directly in blood using standard lab platforms.¹ That steep rise is precisely what makes a simple threshold test workable for home use. Before ovulation, PdG is low; after ovulation, it jumps enough that even a relatively crude measurement can detect the shift.

The 5 μg/mL Threshold

The number you’ll see cited most often in both clinical literature and on the packaging of home PdG tests is 5 μg/mL. Studies using ultrasound to verify that an egg was actually released found that three consecutive urine tests at or above 5 μg/mL, collected after the LH surge, confirmed ovulation with 100% specificity.² In plain terms, when those criteria were met, every single woman in the study had genuinely ovulated. No false positives.

That 5 μg/mL figure is conservative by design. Some women ovulate and produce enough progesterone to confirm it at lower levels. Research using an at-home quantitative monitoring system found that ovulation could be confirmed with PdG values as low as 2.5 μg/mL when the algorithm tracked the rise from an individual’s baseline rather than applying a single fixed cutoff.³ The takeaway is that 5 μg/mL is the number that works across the widest range of women with the lowest error rate. If your personal values consistently land between 2.5 and 5, that doesn’t automatically mean something is wrong, but it does mean a fixed-threshold test strip might miss your confirmation window.

When the Rise Happens

PdG doesn’t spike the instant you ovulate. Progesterone production ramps up over the first day or two after the egg is released, and then it takes additional time for your body to metabolize that progesterone and excrete enough PdG to register in urine. Classic endocrine work showed that urinary pregnanediol glucuronide increased at least two-fold from the day of the midcycle LH peak to the predicted time of ovulation, roughly 24 to 48 hours later, tracking in parallel with the rise in blood progesterone.⁴

In practice, most women won’t see a clear positive on a PdG threshold test until about two to three days after the LH surge. Testing too early is one of the most common reasons for a confusing negative result. If you got a positive LH test yesterday and a negative PdG test today, that’s expected physiology, not evidence that ovulation failed. The progesterone simply hasn’t had enough time to be metabolized and concentrated in your urine yet.

After that initial climb, PdG typically remains elevated throughout the luteal phase before dropping in the days leading up to your period. If conception occurs, progesterone production continues and PdG stays elevated. The overall pattern is a sustained plateau rather than a single spike, which is why the three-consecutive-day testing approach works well.

Why Your Hydration Level Matters More Than You Think

Here’s something that catches a lot of people off guard: how much water you drink can make or break a PdG reading. Because PdG is measured as a concentration in urine (micrograms per milliliter), drinking a large amount of fluid dilutes the sample. A study specifically examining this found that when urine was concentrated enough (specific gravity at or above 1.015), PdG and blood progesterone correlated well. But when urine was more dilute than that threshold, the correlation fell apart or disappeared entirely.⁵

This is the main reason most test instructions tell you to use your first morning urine. Overnight, you’re not drinking water, so urine concentrates. A mid-afternoon sample after you’ve been sipping water all day could easily read below 5 μg/mL even when your ovaries are producing plenty of progesterone. If you’re getting inconsistent PdG results, hydration status is the first variable to check before worrying about your hormone levels.

You might assume that correcting for dilution by adjusting PdG values against creatinine, the way labs sometimes do for other urine tests, would fix the problem. It doesn’t. Research found that creatinine adjustment of PdG actually introduced measurement error rather than reducing it, and this was especially problematic in older individuals. The recommendation from the researchers was straightforward: don’t use creatinine correction for PdG.⁶ Testing concentrated morning urine without any mathematical adjustment remains the most reliable approach.

What Low PdG After Ovulation Can Tell You

If you ovulate but your PdG levels stay stubbornly low, or rise and then drop prematurely, that could indicate a luteal phase problem. This is an area where PdG tracking gets genuinely useful beyond just answering “did I ovulate?” and starts providing information about the quality of the luteal phase itself.

Researchers comparing daily PdG excretion in normal versus luteal-phase-deficient cycles found something interesting: the total amount of PdG excreted across the entire luteal phase didn’t differ between the two groups. What did differ was the timing. Women with deficient cycles excreted significantly less PdG during the first five days of the luteal phase.⁷ So if your PdG takes an unusually long time to climb after ovulation, that slow start could matter even if you eventually reach adequate levels.

This means a single PdG test on, say, day seven of the luteal phase might look normal in someone whose early luteal support was actually weak. Daily tracking through the early luteal phase is more informative than a one-off midluteal measurement for catching this pattern.

Periovulatory PdG and Predicting Luteal Phase Problems

The relationship between PdG and luteal phase health gets even more nuanced when you look at what happens around the time of ovulation itself. A study analyzing hormonal predictors of abnormal luteal phases in otherwise normally cycling women found that PdG levels near ovulation could predict several types of problems. A high periovulatory PdG level was associated with both short luteal phases and a pattern where PdG started normal but then dropped off. A low periovulatory PdG level, on the other hand, predicted an overall low midluteal PdG level and a pattern where PdG started low but eventually normalized.⁸

The practical lesson here is that PdG doesn’t just matter in the luteal phase itself. What’s happening with your progesterone metabolites in the days immediately surrounding ovulation contains real information about how the rest of the cycle is likely to play out. For people using home monitoring, this suggests that tracking PdG through the periovulatory window, not just after a confirmed LH surge, adds value. It’s not something most consumer test kits emphasize, but it’s something the research supports.

Why Three Consecutive Days Matters

A single PdG reading above 5 μg/mL doesn’t confirm ovulation on its own. The three-day protocol exists because progesterone from an unruptured follicle or other hormonal sources can occasionally push PdG above threshold for a day without true ovulation having occurred. Requiring three consecutive days above threshold was what achieved 100% specificity in ultrasound-confirmed studies.²

This is worth understanding because many people test PdG once, see a positive, and consider the question settled. That single positive means your progesterone is elevated, which is encouraging, but it doesn’t carry the same weight as three days running. If you’re using PdG to time intercourse for conception or to retrospectively confirm your fertile window, the three-day confirmation gives you much more confidence.

If you get two positives followed by a negative, that’s harder to interpret. It could mean dilute urine on the third day, or it could indicate an unstable corpus luteum that isn’t maintaining consistent progesterone output. Retesting with first morning urine is the logical next step before drawing conclusions.

Home Tests Versus Lab Tests

Most home PdG test strips use a simple threshold format: the line appears (or the reader gives a positive) when PdG is above a set cutoff, usually 5 μg/mL. You get a yes-or-no answer, not a number. Quantitative home systems that give you an actual concentration reading exist but cost more and are less widely available.

A blood progesterone test from your doctor measures something different, the hormone itself rather than its urinary metabolite, and the numbers are in different units (typically ng/mL for serum progesterone). A midluteal serum progesterone above about 3 ng/mL is generally taken as evidence of ovulation, while values above 10 ng/mL suggest robust luteal function. These numbers don’t convert directly to PdG values because the relationship between blood progesterone and urinary PdG depends on individual variation in metabolism, kidney function, and urine concentration.

The research comparing automated serum progesterone assays to urinary PdG found that different lab platforms didn’t even agree with each other perfectly. The luteal-phase percent increase varied substantially between two serum progesterone assay platforms and the PdG assay.¹ The cross-reactivity between the serum assays and urinary PdG was very low, under 1%, meaning the serum platforms were measuring something largely separate from what shows up in urine.⁹ If your home PdG tests look good but a blood progesterone test comes back borderline, or vice versa, the discrepancy may reflect measurement differences rather than a real hormonal problem.

Combining PdG With Other Tracking Methods

PdG works best as part of a larger picture rather than in isolation. A review of currently available ovulation-tracking methods emphasized that no single marker covers both the fertile window and luteal-phase confirmation as well as a combination of approaches does.¹⁰ LH testing tells you ovulation is about to happen, cervical mucus changes provide a real-time fertility signal, and basal body temperature confirms that progesterone is present after the fact. PdG fills a specific niche: it’s the most direct urine-based way to confirm that the corpus luteum is actually producing progesterone after ovulation.

Where PdG adds the most value is for people who want to confirm ovulation without relying on the temperature shift, which can be disrupted by poor sleep, illness, alcohol, or inconsistent wake times. PdG doesn’t care whether you slept well. It cares whether your ovary made progesterone. For people with irregular cycles or conditions that make temperature tracking unreliable, PdG fills a gap that temperature alone leaves open.

That said, PdG can’t tell you when to have intercourse for conception. By the time PdG rises, your fertile window is already closing or closed. PdG is a retrospective confirmation tool, not a prospective prediction tool. Pairing an LH test (which forecasts ovulation) with PdG testing a few days later (which confirms it happened) gives you both sides of the picture.

Cycle-to-Cycle Variation in the Same Person

Even in women with consistently healthy cycles, PdG levels fluctuate from one month to the next. The corpus luteum that forms after ovulation is a temporary endocrine gland, and its progesterone output depends on factors like the size and vascularity of the follicle that produced it, the quality of the LH signal, and individual variation in the hormonal cascade that supports it. Two ovulatory cycles in the same woman can produce meaningfully different PdG peaks.

Research on abnormal luteal phases in normally cycling women found that patterns like short luteal phases or abnormal PdG trajectories occurred sporadically, not as a fixed trait. The periovulatory hormonal environment of that particular cycle influenced what happened afterward.⁸ One bad PdG reading in one cycle doesn’t define your fertility. Patterns across multiple cycles are far more informative than any single month’s data.

This is also why comparing your PdG numbers to someone else’s isn’t particularly useful. Two women can both be ovulating with healthy luteal function and have noticeably different PdG concentrations, because their livers metabolize progesterone at different rates, their kidneys concentrate urine differently, and their baseline progesterone output varies. The question to ask is not “is my PdG as high as hers?” but “does my PdG rise consistently from my own pre-ovulatory baseline, and does it stay elevated for an adequate number of days?”

When to Involve a Doctor

PdG home testing is useful for confirming ovulation and getting a rough sense of luteal-phase adequacy, but it has limits. If you’ve been tracking PdG for several cycles and consistently fail to see a rise above threshold using first morning urine, that’s worth discussing with a reproductive endocrinologist. The same applies if you see a rise that’s consistently very brief, lasting fewer than ten days before dropping off, since a short luteal phase can interfere with implantation.

Keep in mind that PdG testing alone cannot diagnose conditions like PCOS, thyroid disorders, or hyperprolactinemia, all of which can affect ovulation and progesterone production. It can raise a flag that something deserves further investigation, but the investigation itself typically requires blood work, ultrasound, or both. Treating PdG as a screening signal rather than a diagnostic test puts it in the right context: useful, accessible, and genuinely informative, but not a substitute for clinical evaluation when something appears off.