hCG Levels and Miscarriage

Doctors Use This Blood Test to Help Diagnose a Pregnancy Loss

pregnant woman having blood drawn
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Your doctor may use your hCG levels to diagnose whether you're having a miscarriage. You may be interested in learning more about what your hCG levels mean. 

Human chorionic gonadotropin, or hCG, is a hormone produced in the body during pregnancy. An hCG blood test measures the level of hCG detectable in the blood. The tests can be qualitative (returning a yes/no answer about whether the woman has hCG in her blood) or quantitative (returning a measurement of the amount of hCG in the blood).

Why Doctors Order hCG Blood Tests

Some doctors test hCG levels in early pregnancy as a routine part of prenatal care for all women.

Others use urine-based hCG tests to confirm pregnancy. They may and order an hCG blood test only when they need more information about what is going on in a particular patient’s pregnancy. A woman having vaginal bleeding in pregnancy or other miscarriage symptoms may undergo an hCG blood test, for example.

Doctors may want to see whether or not the hCG is in a normal range for a specific point in pregnancy, or they may want to look at hCG doubling times in blood tests over a period of days to get an idea of whether the pregnancy is progressing as it should be.

Serial hCG Blood Tests

Serial hCG blood tests are two quantitative hCG blood tests done two to three days apart. In early pregnancy, the hCG level usually doubles roughly every two to three days. If the hCG doubling time is slower or if the level decreases over time, this is a possible sign of miscarriage or ectopic pregnancy.

If you are having hCG levels checked because of miscarriage symptoms in early pregnancy, your doctor will most likely need you to have serial blood tests rather than a single hCG level in order to get information on how your pregnancy is progressing.

hCG Levels and Miscarriage

Your doctor is the best person to tell you what your hCG levels mean, because normal hCG levels vary heavily from person to person, and single hCG levels (even single low hCG levels) do not give much information on how a pregnancy is progressing.

Your doctor can compare the information from your hCG results to other information in your medical history, such as whether or not you are having miscarriage symptoms, in order to make a diagnosis.

In general, however, if the hCG levels are dropping in the first trimester, this probably a sign of impending miscarriage. On the other hand, slow-rising hCG levels that do not double every two or three days in early pregnancy can be a sign of problems but can also result in a normal pregnancy.

How to Prepare for an hCG Blood Test

An hCG blood test does not require any special preparation or planning, and you do not have to fast before having your blood drawn. The results should not be affected by the time of day you get your blood drawn or the amount of water you drink before the test. That's a benefit of an hCG blood test over an hCG urine test, which is affected by the concentration of your urine.

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