In non-pregnant women, a normal hCG level is less than 5 mIU/mL. In healthy men, it’s less than 2 mIU/mL. During pregnancy, hCG rises dramatically, starting around 5 mIU/mL in week 3 and peaking anywhere from 25,700 to 288,000 mIU/mL between weeks 9 and 12. After that peak, levels gradually decline for the rest of the pregnancy.
What hCG Is and Why It Matters
Human chorionic gonadotropin (hCG) is a hormone produced by the placenta shortly after a fertilized egg implants in the uterus. It’s the hormone that pregnancy tests detect, both the urine strips you buy at a drugstore and the blood tests ordered by a doctor. A blood test measures the exact amount of hCG in your system (reported in mIU/mL), while a home test simply tells you whether the level is above a certain threshold.
A level of 5 mIU/mL or higher is generally considered a positive pregnancy result. Anything below 5 in a non-pregnant woman is normal background noise. Because hCG rises so rapidly in early pregnancy, even a day or two can make a big difference in your reading, which is why the timing of the test matters a lot when interpreting results.
hCG Levels by Week of Pregnancy
The ranges below are measured from the first day of your last menstrual period, which is how most doctors and labs count gestational weeks. These numbers come from Cleveland Clinic reference data, but keep in mind that normal ranges can vary slightly between laboratories.
- Week 3: 5 to 50 mIU/mL
- Week 4: 5 to 426 mIU/mL
- Week 5: 18 to 7,340 mIU/mL
- Week 6: 1,080 to 56,500 mIU/mL
- Weeks 7 to 8: 7,650 to 229,000 mIU/mL
- Weeks 9 to 12: 25,700 to 288,000 mIU/mL
- Weeks 13 to 16: 13,300 to 254,000 mIU/mL
- Weeks 17 to 24: 4,060 to 165,400 mIU/mL
- Weeks 25 to 40: 3,640 to 117,000 mIU/mL
Notice how wide these ranges are. At week 5, one healthy pregnancy might measure 18 mIU/mL while another measures 7,000. Both are normal. A single hCG reading tells you very little on its own. What matters more is the trend: how your levels change over time.
How Fast hCG Should Rise
You’ve probably heard that hCG “doubles every 48 hours” in early pregnancy. That rule of thumb is widely repeated, but it comes from a small study of just 20 patients and uses an 85% confidence interval. Real-world data tells a more nuanced story.
A study published in Fertility and Sterility found that among ongoing pregnancies, the average 48-hour hCG rise was about 159%, but the range was enormous: anywhere from a 9.5% increase to nearly a 700% increase. In practical terms, a rise as modest as about 11% over 48 hours still gave a 50% chance of the pregnancy continuing. A rise of roughly 107% gave a 75% chance. And a rise of about 203% or more gave a 90% chance of an ongoing pregnancy.
So if your hCG isn’t doubling perfectly every two days, that alone doesn’t mean something is wrong. Your doctor will look at the overall pattern across multiple blood draws rather than fixating on one interval.
When hCG Peaks and Declines
hCG levels climb steeply through the first trimester, reaching their highest point somewhere between weeks 8 and 12. At the peak, levels typically fall between 25,700 and 288,000 mIU/mL, though some sources cite peaks as high as 290,000 depending on the lab. This peak roughly coincides with the worst stretch of pregnancy nausea for many women, since hCG is thought to play a role in morning sickness.
After the first trimester, levels drop steadily. By the second trimester (weeks 13 to 16), the upper end of the range has already fallen. By the third trimester, levels can be as low as 3,640 mIU/mL and still be perfectly normal. This decline doesn’t mean anything is wrong with the pregnancy. It simply reflects the placenta taking over hormone production through other pathways.
What Higher Than Expected Levels Mean
If your hCG comes back significantly above the typical range for your gestational age, a few explanations are possible. The most common is that your dates are slightly off, meaning you’re a bit further along than estimated. The next most common reason is a multiple pregnancy. Carrying twins or triplets naturally produces more placental tissue and therefore more hCG.
In rarer cases, unusually high hCG points to a molar pregnancy. This occurs when a sperm fertilizes an egg incorrectly, creating abnormal tissue in the uterus instead of a viable embryo. In a complete molar pregnancy, a sperm fertilizes an empty egg with no genetic material, and no fetus develops. In a partial molar pregnancy, two sperm fertilize a single egg, and an abnormal placenta forms alongside a non-viable embryo. Molar pregnancies produce abnormally high hCG levels and require treatment to remove the tissue.
What Lower Than Expected Levels Mean
Low or slowly rising hCG doesn’t automatically signal a problem, but it does prompt closer monitoring. The most common explanations are an early pregnancy where the dates are simply off by a few days, or a pregnancy that isn’t progressing normally.
When hCG rises very slowly or plateaus in early pregnancy, doctors consider the possibility of a miscarriage or an ectopic pregnancy (where the embryo implants outside the uterus, usually in a fallopian tube). Neither can be diagnosed by hCG alone. An ultrasound and repeat blood draws over several days are typically needed to clarify what’s happening. A declining hCG level, rather than a rising one, generally indicates the pregnancy is no longer viable.
How Long hCG Stays in Your System
After a delivery or pregnancy loss, hCG doesn’t vanish overnight. How quickly it clears depends largely on how high it was to begin with. A study of 443 women who experienced miscarriages found that hCG dropped by 35 to 50 percent within two days and by 66 to 87 percent within a week of the pregnancy resolving.
If a pregnancy ended very early, around weeks 2 to 4, hCG levels were low to begin with and clear quickly. If the loss happened closer to the end of the first trimester, when hCG can be in the tens or hundreds of thousands, it takes longer. You might still get a positive result on a home pregnancy test for a week to several weeks afterward, even though the pregnancy has ended. This doesn’t mean you’re still pregnant. It simply means trace amounts of the hormone remain in your system.
Why a Single Number Isn’t Enough
The most important thing to understand about hCG is that the ranges are extremely broad at every stage of pregnancy. Two women at the exact same gestational age can have hCG levels that differ by a factor of 100 or more, and both can be completely healthy. A single blood draw is useful for confirming that hCG is present, but it rarely tells the whole story. The trend across two or more draws, spaced 48 to 72 hours apart, gives a much clearer picture of whether a pregnancy is developing normally. If you’ve had bloodwork and are anxious about a number that seems high or low, the follow-up draw is where the real information comes from.