HCG Levels in Early Pregnancy

Blood tests to measure HCG levels

Testing HCG levels in early pregnancy can help a doctor confirm the pregnancy, potentially help date the pregnancy, and diagnose some pregnancy related problems.

HCG Confirms Pregnancy

Even when a woman has no pregnancy symptoms, if her period is late, she may be pregnant. Taking an early pregnancy test can confirm this. Home pregnancy tests measure the levels of what is commonly known as the pregnancy hormone or human chorionic gonadotropin (HCG). This hormone is only detectable in women who are pregnant.

Pregnancy tests that are taken too early may result in a faint line on the pregnancy test or a negative result. A faint line within the test read time is usually a positive, while a negative test may mean there simply are not high enough levels of HCG to be detected. Wait several days and try another test.

Doctors offices often run blood-based pregnancy tests on women to confirm they are pregnant. While home tests are usually only qualitative (meaning only detects the hormone itself), a doctor's test may also be quantitative. Quantitative tests measure the amount of HCG in the blood in milli-international units per milliliter. Generally called beta numbers, a number less than 5 indicates no pregnancy, while over 25 means a woman is pregnant, according to the American Pregnancy Association.

Women who do not have any factors that could contribute to a high risk pregnancy are usually only given a qualitative test unless there is another indication something is amiss with the developing baby.

Dating Pregnancy With HCG

Women who have irregular periods or who were not actively trying to conceive might not know the date of their last period. This can make figuring out the estimated due date difficult. Normally, a fetus can be detected by ultrasound when HCG levels reach approximately 2,000. Therefore, a doctor will track HCG levels until that point and then perform an ultrasound.

Dating the pregnancy by using "average" HCG levels in early pregnancy is not considered reliable on its own. Because the range of levels can vary between women and from pregnancy to pregnancy, the levels themselves are not reliable indicators.

HCG Levels in Early Pregnancy Detect Problems

Women who have had a previous miscarriage may have their HCG levels tested more frequently in early pregnancy. Pregnant women who are experiencing pregnancy spotting may also have their HCG levels tested more often. HCG levels in early pregnancy usually double every 48 to 72 hours, dropping slightly and then leveling off somewhere at the end of the first trimester of pregnancy and staying in the same approximate range until the baby is delivered.

When beta numbers start to fall or do not rise as quickly as expected, it could indicate a possible problem with the pregnancy and a need to monitor the mother closely. The low levels of HCG could indicate:

  • Higher potential for a chance of miscarriage
  • Ectopic pregnancy, where the fetus has implanted in the fallopian tubes
  • Molar pregnancy, a condition where abnormal tissue forms, but not a developing baby

Due to the wide variation in HCG levels from woman to woman, having a lower beta number does not necessarily indicate a pregnancy complication. It only means that a physician will observe the mother closely during the first few weeks of her pregnancy.

High levels of HCG in the first trimester could be one of the first signs of twin pregnancy. Women who have taken fertility drugs are often at a higher risk for having multiple births. Doctors will watch HCG levels closely and listen for two heartbeats if they suspect more than one baby is gestating.

Monitoring HCG levels during the first trimester of pregnancy is one of the tools doctors use to determine if the pregnancy is viable. Both abnormally high and low numbers could indicate the need for more diagnostic tests..

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HCG Levels in Early Pregnancy