HCG, or human chorionic gonadotropin, is a hormone your body produces during pregnancy. It’s the hormone that pregnancy tests detect, and its levels in your blood or urine can tell you a lot about how a pregnancy is progressing. In non-pregnant individuals, hCG levels sit below 5 mIU/mL. Once pregnancy begins, those numbers climb rapidly and can reach well over 100,000 mIU/mL by the end of the first trimester.
What HCG Does in Your Body
HCG’s primary job is to keep your pregnancy going in the earliest weeks. After a fertilized egg implants in the uterine wall, cells that will eventually form the placenta start releasing hCG. This hormone signals the corpus luteum (a temporary structure on the ovary) to keep producing progesterone, which maintains the uterine lining and prevents menstrual bleeding. Without hCG, progesterone levels would drop and the pregnancy couldn’t sustain itself.
As the placenta matures and takes over progesterone production on its own, hCG levels naturally decline. This is why hCG peaks early and then drops during the second and third trimesters.
Normal HCG Levels by Week
HCG levels vary enormously from one healthy pregnancy to the next, so what matters most is the trend rather than any single number. That said, here are the expected ranges based on weeks since the last menstrual period, according to UCSF Health:
- 3 weeks: 5 to 72 mIU/mL
- 4 weeks: 10 to 708 mIU/mL
- 5 weeks: 217 to 8,245 mIU/mL
- 6 weeks: 152 to 32,177 mIU/mL
- 7 weeks: 4,059 to 153,767 mIU/mL
- 8 weeks: 31,366 to 149,094 mIU/mL
- 9 weeks: 59,109 to 135,901 mIU/mL
- 10 weeks: 44,186 to 170,409 mIU/mL
- 12 weeks: 27,107 to 201,165 mIU/mL
- 14 weeks: 24,302 to 93,646 mIU/mL
- 16 weeks: 8,904 to 55,332 mIU/mL
- 18 weeks: 9,649 to 55,271 mIU/mL
Notice how wide these ranges are. At 6 weeks, a perfectly normal pregnancy could have an hCG level of 152 or 32,177. A single reading that seems “low” or “high” compared to online charts doesn’t tell you much on its own.
How Fast HCG Should Rise
In early pregnancy, hCG levels typically double every 1.4 to 2.1 days. The traditional benchmark is that hCG should increase by at least 53% over 48 hours in a viable pregnancy. More recent research has found that the slowest acceptable rise for a healthy pregnancy can be as low as 35% over two days, so a slightly slower doubling time doesn’t automatically signal a problem.
The median pattern looks something like this: a 50% increase after one day, a 124% increase after two days, and a 400% increase after four days. Levels peak around weeks 9 and 10 of pregnancy, then gradually decline through the second trimester as the placenta takes over hormone production.
When HCG Is Lower Than Expected
HCG levels that rise more slowly than the 53% threshold over 48 hours may indicate a pregnancy that isn’t developing normally, but the numbers alone can’t tell you why. Both a miscarriage and an ectopic pregnancy (where the embryo implants outside the uterus) can produce slow-rising hCG, and the pattern of decline looks similar in the early stages.
If hCG is rising but not doubling appropriately, your provider will typically repeat the blood test in 48 hours to track the trend. A declining hCG that drops 35% to 50% over two days generally points toward a pregnancy that is ending on its own. If the decline is slower than that expected rate, it raises concern about ectopic pregnancy, which needs closer monitoring. A slow decline doesn’t confirm an ectopic pregnancy by itself, but it does flag the need for further evaluation, usually with ultrasound.
When HCG Is Higher Than Expected
Higher-than-expected hCG levels have a few possible explanations. The most common is simply carrying twins or multiples, since more placental tissue means more hCG production. Another possibility is a molar pregnancy (a type of gestational trophoblastic disease), where the placental tissue grows abnormally. Complete molar pregnancies tend to produce markedly elevated hCG, while partial molar pregnancies may be only mildly elevated.
In rare cases, extremely high hCG levels point to more serious conditions like gestational choriocarcinoma, a type of cancer that can develop from placental tissue weeks to months after any pregnancy.
HCG in People Who Aren’t Pregnant
A positive hCG result outside of pregnancy isn’t always a false alarm. Several real conditions can produce detectable levels. Certain cancers, including breast, lung, gastrointestinal, kidney, and testicular tumors, can secrete hCG. People going through menopause may have mildly elevated hCG from pituitary gland production, and chronic kidney disease can raise levels because the kidneys aren’t clearing the hormone efficiently (though these readings typically stay below 25 to 100 mIU/mL).
Exogenous sources matter too. Fertility treatments that involve an hCG trigger shot will cause a temporary spike that clears within 24 to 48 hours. HCG has also been marketed for weight loss and used by athletes to boost testosterone production, both of which will trigger a positive test.
True false positives do happen occasionally. Heterophilic antibodies (immune proteins that interfere with lab assays), high bilirubin or hemoglobin levels, and even rheumatoid factor can cause the test to read positive when no hCG is actually present. If a result doesn’t match the clinical picture, a different testing method can usually sort it out.
Blood Tests vs. Urine Tests
Home pregnancy tests and most point-of-care urine tests detect hCG at a threshold of about 25 mIU/mL. That means they won’t pick up very early pregnancies when hCG is still in single digits. This is why testing too early often produces a false negative.
A quantitative blood test (often called a beta hCG) measures the exact concentration of hCG in your bloodstream and can detect much lower levels. This is the test providers use to track how hCG changes over time, since the specific number matters for assessing viability. A single qualitative test (positive or negative) tells you whether hCG is present. A quantitative test tells you how much.
How Long HCG Takes to Clear
After delivery, hCG drops quickly. In one study, the median time for hCG to become undetectable after birth was 14 days, with a range of 8 to 24 days. After a miscarriage or pregnancy loss, the timeline is similar but depends on how far along the pregnancy was and the hCG level at the time of the loss. Higher starting levels take longer to clear.
This matters practically because a pregnancy test taken within a few weeks of delivery or pregnancy loss may still read positive even though the pregnancy has ended. If you’re tracking hCG after a loss, your provider will likely repeat blood draws until the level falls below 5 mIU/mL to confirm it has fully resolved.