Beta-hCG Levels and What They Mean

Many pregnant people and those trying to conceive may have heard the term beta-hCG in relation to pregnancy testing and wonder what it means. Essentially, a beta-hCG test is used to confirm and/or evaluate a pregnancy via a blood test in a doctor's office.

Beta-hCG (β-hCG) is a test that measures the amount of human chorionic gonadotropin (hCG) in the blood. This hormone is produced as soon as 10 days after conception. In healthy pregnancies, levels of hCG increase rapidly in early pregnancy. An above-normal level can confirm pregnancy. Serial beta-hCG tests done over time can show if hCG levels are increasing, which is a sign that a pregnancy is proceeding normally.

Aside from this, the beta-hCG test may also be used during evaluations of fertility treatments (a synthetic form of the hormone is sometimes used to help follicles mature and trigger ovulation), as well as when there are concerns that something may be wrong with a pregnancy.

What Beta hCG Measures

Pregnancy testing involves the detection of hCG, either in the urine or blood. Both qualitative and quantitative tests can be performed. Qualitative tests determine the presence of hCG in urine or blood, and quantitative tests measure the amount of hCG present in urine or blood.

The urine test is a qualitative one in that it can only tell you if the sample is positive or negative for hCG. The same goes for the qualitative hCG blood test. A sample that is positive for hCG means there is a pregnancy, a negative result means there is no pregnancy.

In contrast, the beta hCG is a quantitative test, meaning it reveals not just if the hormone is present in the blood, but in exactly what amounts. Levels of hCG are measured in milli-international units per milliliter (mIU/ml). Beta-hCG levels are low early in pregnancy and rise throughout the first trimester and into the second trimester.

When Beta-hCG Tests Are Used

The beta-hCG test may be done to confirm pregnancy at an early prenatal doctor's visit (as a follow-up to a positive at-home or in-office urine test). But the beta hCG is not always done or necessary in routine pregnancies. Many practitioners use transvaginal ultrasound at pregnancy confirmation visits to actually see visible evidence of the pregnancy (the gestational sac) instead.

Beta-hCG can also be monitored periodically during the first trimester and second trimesters in high-risk pregnancies when there is a history or risk of miscarriage.

The beta-hCG test is also used when there are concerns about pregnancy complications, including miscarriage. In these situations, repeat tests may be performed every two to three days to evaluate how quickly hCG levels are rising.

If you are undergoing fertility treatments, your doctor may order a beta-hCG test just before or when your period is due to see if the efforts were successful. Doctors caring for women taking hCG shots to improve their chances of conception or as part of the intrauterine insemination (IUI) or in vitro fertilization (IVF) process need to carefully time a beta-hCG test to ensure that the medication has cleared the body and will not affect test results.

Beta-hCG testing has other uses as well.

Beta hCG testing can also be used to determine the age of a fetus. By measuring the amount of the hormone in the blood, a fairly precise gestational age can be determined, allowing healthcare providers to estimate the due dates and time of conception.

A beta-hCG test cannot always pinpoint the precise gestational age. However, your results—considered alongside the date of your last period—can give your doctor a general idea, as expected hCG ranges change with each passing week in the first trimester.

A beta-hCG measurement is also one part of both the maternal serum triple and quadruple screening tests done between 15 and 20 weeks gestation. These screenings are used in part as a fetal screen to assess for markers of certain fetal health problems, including Down syndrome and neural tube disorders like spina bifida.

Unrelated to pregnancy, the beta-hCG test may help diagnose some cancers.

Beta hCG Levels in Pregnancy

The following are the typical ranges of hCG levels during pregnancy. These ranges are just guidelines, as every pregnancy is different.

Remember: Whether you have high or low levels of the hormone is not the key indicator of a healthy pregnancy. This is because many factors can influence total hCG levels, including maternal smoking, weight, ethnicity, parity (the number of times a woman has given birth), and hyperemesis gravidarum (severe morning sickness).

Doctors instead look to see if hCG levels double every 48 to 72 hours from whatever level they started at. They look for this in the initial weeks of pregnancy, as it's normal for hCG levels to peak around 8 to 11 weeks' gestation, then decrease, and level off thereafter.

If Beta-hCG Levels Are Lower Than Expected

If your hCG levels are low, it is likely that another test will be performed in a few days to confirm if levels are increasing or not. If your beta-hCG levels are lower than expected and do not increase, this may indicate:

• Miscalculated gestational age: if conception occurred later than presumed, hCG levels will be lower than expected.
• Possible miscarriage: since hCG is produced by the placenta, hCG levels will be low if development stops before the placenta is formed or is finished forming.
• Ectopic pregnancy: hCG levels do not rise as expected and may plateau with ectopic pregnancies.
• Blighted ovum: the fertilized egg implants in the wall of the uterus, but the embryo fails to develop.

If one of these issues is suspected, your practitioner will do other tests, typically a transvaginal ultrasound, to determine the status of your pregnancy.

If Beta-hCG Levels Are Higher Than Expected

Higher than expected hCG levels are not as medically concerning as low hCG levels, though some rare complications can cause increased levels. Beta-hCG levels tend to rise until the second trimester and then begin to drop. Reasons your beta-hCG levels may be higher than expected include:

• A multiples pregnancy: twins or triplets could be present. multiples are not uncommon in those who have undergone fertility treatments.
• Incorrect conception date: the pregnancy could be more advanced than suspected.
  
• Molar pregnancy: a rare complication that occurs when a mass of tissue grows inside of the uterus instead of a placenta. This complication is usually discovered at around 12 weeks gestation.

Again, an atypical result will be followed up with repeat testing and/or other evaluations to figure out what is going on. If a molar pregnancy is diagnosed, a procedure called a D&C might be performed to remove the tissue.

A Word From Verywell

If you see your hCG results on a lab report before you have the opportunity to speak about them with your doctor, try not to jump to your own conclusions. While informative, a beta-hCG test is just one way that doctors gather information about—and determine the status of—a pregnancy.