Along with monitoring and further testing when needed, hCG levels are especially helpful in determining whether the pregnancy is progressing normally, is at risk for a miscarriage, or is showing signs of other complications. Below, we will take a more in-depth look at hCG levels, how they’re measured, the different variations, and what they can mean throughout your pregnancy.
What Is hCG?
As soon as you become pregnant, your body begins producing hCG, which can be found in the blood as early as 11 days after conception. This hormone is found in early embryos and eventually becomes part of the developing placenta, which is a temporary organ that acts as the baby’s lifeline throughout pregnancy. HCG also stimulates the corpus luteum to produce progesterone, which is essential for a developing fetus. When a physician wants to confirm a pregnancy, they may order one or more quantitative hCG blood tests. The test identifies the amount of hCG in the pregnant person’s blood, expressed as an amount by milli-international units of hCG hormone per milliliter of blood (mIU/ml).
Measuring hCG Levels
The purpose of measuring hCG levels is to help determine the age of the fetus and whether the pregnancy is facing a potential complication, such as an impending miscarriage or an abnormal, ectopic, or molar pregnancy. HCG is also used as part of the screening test for Down Syndrome. As the body starts to prepare for pregnancy after conception, hCG levels quickly rise in the early weeks and begin to decline slightly as you get closer to birth. This is because once the placenta is fully formed, it supplies the progesterone needed to sustain the pregnancy, so assistance from hCG is no longer needed. While there is a wide variation in hCG levels, researchers have identified ranges of hCG typical of most pregnancies, based on the number of weeks from the last menstrual period. It is measured by obtaining a blood sample.
Under 9 weeks: 455 - 142,584 mIU/ml9 - 12 weeks: 22,655 - 164,125 mIU/ml13 - 16 weeks: 4,618 - 132,084 mIU/ml17 - 24 weeks: 5,637 - 49,392 mIU/ml25 - 40 weeks: 3,354 - 74,719 mIU/mlNon-pregnant people: <5.0 mIU/mlPostmenopausal people: <9.5 mIU/ml
Variation in hCG Ranges
If you know your hCG number, it is tempting to compare it to the range of typical hCG results. But remember that your exact level of hCG is less important than how it changes over time. Plus, these ranges are based on the length of the pregnancy dated from the last menstrual period. Anyone with abnormal cycles may see significant variation in these ranges. For example, a person with six-week menstrual cycles should fall roughly two weeks behind someone with four-week menstrual cycles. In other words, at eight weeks after their last menstrual period, they should fall roughly in the same range as a person with four-week menstrual cycles would at six weeks after their last cycle began.
How Physicians Interpret hCG Results
Many people with routine pregnancies don’t ever get their hCG levels monitored. But if you do, note that any single hCG test does not tell much about the health of the pregnancy. Individual people have a wide variation in hCG levels, and the same person may experience a big difference in hCG numbers from one pregnancy to the next. Plus, if you are pregnant with multiples, the hCG levels will be quite a bit higher than with singleton pregnancies. Physicians look at the trend in the number of two or more tests. The hCG doubling time, over two separate blood tests spread over a period of days, usually provides more useful information than a single hCG level when evaluating a pregnancy. In most cases, the number will double over a period of 48 to 72 hours. These levels tend to double at this rate for about the first four weeks of pregnancy. They will continue to increase until you reach your eighth or eleventh week, when they typically reach their peak. As helpful as it is to measure hCG levels, these numbers alone are not sufficient for diagnosing issues during pregnancy. While they can indicate a problem, your doctor will also take into account any symptoms and perform ultrasounds to verify what’s going on.
When hCG Results Can Signal a Problem
In instances where a first hCG measurement is lower than expected, a second test will most likely be ordered. Additionally. when there is cause to worry about miscarriage due to previous loss or other symptoms, hCG levels may be monitored, When there is a decline in the level of hCG from the first test to the second test, this often means a miscarriage is likely, also known as an impending miscarriage. Lower than average hCG levels may also indicate an ectopic pregnancy, which is one that occurs outside of the uterus. Unfortunately, an ectopic pregnancy cannot be carried to term and requires immediate treatment. This includes either medicine or surgery to end the pregnancy. Note that there is nothing you can do to increase your hCG levels when they’re in decline, or, sadly, to prevent an early miscarriage if it is happening. Typically, when an early miscarriage occurs there is a chromosomal abnormality or another issue with the embryo that causes the pregnancy to not be viable (and the body responds by lowering the hCG levels). If your hCG levels are below average or declining during the initial weeks of pregnancy, your doctor will take a closer look with an ultrasound. If a miscarriage is diagnosed, treatment can vary. An incomplete miscarriage occurs when the pregnancy tissue begins to pass on its own. Your doctor may recommend waiting until it passes naturally, or will prescribe a medication to help pass the tissue. Another option includes a dilation and curettage (D&C) procedure, in which the doctor uses an instrument to remove the remaining tissue inside the uterus.
Impending miscarriageEctopic pregnancy
Higher than average hCG levels can indicate:
Carrying multiplesMiscalculation of your last periodMolar pregnancyAbnormal growth on the uterus
If your hCG levels are higher than average, they can indicate the following:
Miscalculation of your last periodMolar pregnancyAbnormal growth on the uterus
If there is suspicion of a molar pregnancy, it can be partial or complete. A partial molar pregnancy means that there is some fetal development, but an abnormal placenta. A complete molar pregnancy means there is an abnormal placenta and no fetus development.
A Word From Verywell
After conception, your body begins rapidly producing the hormone hCG, which is essential for a developing fetus. HCG levels typically double every two to three days during the first six weeks of pregnancy before peaking between weeks eight and eleven. Your doctor will monitor your hCG levels to determine whether the pregnancy is progressing normally. That said, hCG levels may vary from person to person. Because every pregnancy is different, it’s important not to compare your levels to anyone else. Try not to read too much into any single measurement, as what really matters, in early pregnancy, is whether your hCG levels are increasing. If you are concerned about your hCG measurements, you should contact your doctor about any questions you have. If your numbers are higher or lower than average, your doctor will monitor any accompanying symptoms and perform ultrasounds when necessary. While hCG numbers are important, they are not the sole factor in determining any issues. Your doctor will keep you updated every step of the way to ensure your pregnancy remains healthy and on the right track!
