hCG levels

Human chorionic gonadotropin (hCG) is a hormone normally produced by the placenta. If you are pregnant, you can detect it in your urine. Blood tests measuring hCG levels can also be used to check how well your pregnancy is progressing.
Confirming pregnancy
After you conceive (when the sperm fertilises the egg), the developing placenta begins to produce and release hCG.
It takes about 2 weeks for your hCG levels to be high enough to be detected in your urine using a home pregnancy test.
A positive home test result is almost certainly correct, but a negative result is less reliable.
If you do a pregnancy test on the first day after your missed period, and it’s negative, wait about a week. If you still think you might be pregnant, do the test again or see your doctor.
hCG blood levels by week
If your doctor needs more information about your hCG levels, they may order a blood test. Low levels of hCG may be detected in your blood around 8 to 11 days after conception. hCG levels are highest towards the end of the first trimester, then gradually decline over the rest of your pregnancy.
The average levels of hCG in a pregnant woman’s blood are:
3 weeks: 6 – 70 IU/L
4 weeks: 10 – 750 IU/L
5 weeks: 200 – 7,100 IU/L
6 weeks: 160 – 32,000 IU/L
7 weeks: 3,700 – 160,000 IU/L
8 weeks: 32,000 – 150,000 IU/L
9 weeks: 64,000 – 150,000 IU/L
10 weeks: 47,000 – 190,000 IU/L
12 weeks: 28,000 – 210,000 IU/L
14 weeks: 14,000 – 63,000 IU/L
15 weeks: 12,000 – 71,000 IU/L
16 weeks: 9,000 – 56,000 IU/L
16 – 29 weeks (second trimester): 1,400 – 53,000 IUL
29 – 41 weeks (third trimester): 940 – 60,000 IU/L

The amount of hCG in your blood can give some information about your pregnancy and the health of your baby.
Higher than expected levels: you may have multiple pregnancies (for example, twins and triplets) or an abnormal growth in the uterus.
Your hCG levels are falling: you may be having a loss of pregnancy (miscarriage) or risk of miscarriage.
Levels that are rising more slowly than expected: you may have an ectopic pregnancy – where the fertilised egg implants in the fallopian tube.
hCG levels and multiple pregnancies
One of the ways of diagnosing a multiple pregnancy is by your hCG levels. A high level may indicate you are carrying multiple babies, but it can also be caused by other factors. You will need an ultrasound to confirm that it’s twins or more.
Levels of hCG in your blood don’t provide a diagnosis of anything. They can only suggest that there are issues to look into.
If you have any concerns about your hCG levels, or wish to know more, speak to your doctor or maternity healthcare professional. You can also call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436.
Sources:
NSW Government Health Pathology (hCG factsheet), Lab Tests Online (Human chorionic gonadotropin), UNSW Embryology (Human Chorionic Gonadotropin), Elsevier Patient Education (Human Chorionic Gonadotropin test), SydPath (hCG (human Chorionic Gonadotrophin)
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