Human chorionic gonadotropin (hCG) is a hormone made mainly by placental tissue after implantation. It has an alpha part and a beta part. Labs measure the beta part to avoid cross-reaction with other hormones, so clinical reports and our tools refer to beta hCG.
Beta hCG is detectable in blood before most urine tests. Levels often rise in early pregnancy then the rate of rise slows. Single values vary widely between people. Serial measurements with timing give more useful information than one number alone.
Key points
- hCG is a pregnancy hormone; beta hCG is the subunit labs measure.
- Trends over 24–72 hours are more useful than a single value.
- Normal ranges are wide, so timing and context matter.
- Serum tests are quantitative; urine tests are qualitative.
- Trigger shots, rare antibodies, or high biotin can affect results.
- Use beta hCG with ultrasound when dates allow.
How beta hCG behaves over time
After implantation, beta hCG rises and is often described by a doubling time. Early rises can be brisk. Later in the first trimester the rise slows and a peak is reached. Healthy courses vary, which is why two or more timed tests are preferred. Falling levels usually indicate a resolving pregnancy.
Units, assays, and practical notes
Labs report beta hCG in IU/L or mIU/mL. Different assays can give slightly different values. Serum tests are quantitative. Urine tests are qualitative and depend on sensitivity and hydration.
- Medicines: hCG trigger shots can keep tests positive for days.
- Interference: Rare antibodies and high dose biotin can distort results.
- Hook effect: Very high levels may appear low on some assays.
Clinical uses of beta hCG
- Confirm pregnancy: Detectable in serum before most urine tests.
- Track early progression: Serial values help assess rise or fall.
- Guide ultrasound timing: Helps choose when a scan is likely to show findings.
- Diagnose and monitor: Used in ectopic care, miscarriage care, and after molar pregnancy.
- Tumour marker: Certain germ cell tumours can produce hCG in non-pregnant people.
Our hCG calculators
Estimate gestational age from hCG levels
Have one serum result and want a likely week window? Use our Weeks Pregnant from hCG calculator. It maps your value to the most likely week band and shows the full reference table. For precise dating, plan an ultrasound when timing allows.
Compare your hCG results to the average
Already know the week? Check where one value sits with our hCG level checker by week. For a quick reference without entering your result, see the hCG ranges by week lookup.
Chart your hCG trend and doubling time
Enter two or more draws in the hCG trend and doubling-time calculator to get a fitted line, doubling or halving time, and a projection. Add a dating method to overlay the typical band for that GA. Tracking multiples? Use the twins/triplets hCG tool.
Calculate 48-hour change (two results)
With two draws only, the 48-hour hCG change calculator normalises your interval to about 48 hours and labels the change as within typical, slow, plateau, or falling.
Track pregnancy test line progression
Logging home strips? The pregnancy test line progression tracker records brand, timing, and line darkness, then charts the trend. Once you start blood tests, switch to the Weeks Pregnant from hCG calculator or the hCG trend and doubling-time calculator.
Testing and interpretation tips
- Use the same lab where possible when tracking a trend.
- Space draws by about two days when monitoring early change.
- Do not compare urine strips to lab numbers. Use one method for one purpose.
- Link results to dates, symptoms, and ultrasound planning.
Limits and safety note
Our tools are educational only. They do not diagnose or treat. Seek urgent care for severe pain, heavy bleeding, fainting, or shoulder tip pain. Discuss results with your clinician, who can interpret beta hCG together with history and imaging.
hCG and beta hCG: FAQs
What does hCG do to your body?
hCG supports early pregnancy. It signals the ovary to keep making progesterone until the placenta takes over. Levels rise after implantation and are used for lab tests and clinical monitoring.
How early in pregnancy does hCG start?
Production begins soon after implantation, usually about 6 to 10 days after ovulation. Serum tests turn positive first, then urine tests as levels rise.
What hCG level is “pregnant”?
Many labs call ≥5 mIU/mL (serum) positive. Home tests often need about 10–25 mIU/mL to show a line. Use the Weeks Pregnant from hCG calculator for a likely week band from a single value.
What is the best time of day to test?
For urine tests, first-morning urine concentrates hCG and reduces false negatives. Serum tests can be taken any time. See our pregnancy test accuracy calculator for day-by-day sensitivity.
How does hCG make you feel?
Symptoms vary. Nausea, breast tenderness, and fatigue are common in early pregnancy, but many hormones contribute. hCG alone does not predict how you will feel.
How can I compare my result with the average?
If you know the week, use the hCG level checker by week. For a quick reference table by week or by DPO, open the hCG ranges by week lookup.
How do I track if my hCG is rising normally?
Trends are more useful than one value. Use the 48-hour hCG change calculator or the hCG trend and doubling-time calculator to chart multiple draws and see the estimated rise.
Does hCG make you sleepy?
Fatigue is common in early pregnancy. It relates to many factors, including progesterone and sleep changes. hCG is not a proven direct cause of sleepiness on its own.
What does hCG do in males?
Clinically, hCG can stimulate the testes to produce testosterone and support sperm production in certain forms of hypogonadism or infertility. It should only be used under a clinician’s care.
Should I take hCG with TRT?
Some clinicians add hCG to preserve fertility during testosterone therapy. This decision is individual and requires medical supervision. Do not start hCG without a prescription.
What are the side effects of hCG medicine?
Possible effects include injection-site pain, headache, mood changes, or fluid retention. In fertility treatment, hCG can be linked with ovarian hyperstimulation risk. Report concerning symptoms to your clinician.
Who should not take hCG?
Do not use hCG for weight-loss. Only take it when prescribed for a clear medical reason. It is not appropriate for everyone, including some people with hormone-sensitive conditions.
What are the signs of early pregnancy?
Missed period, positive test, breast tenderness, nausea, fatigue, and frequent urination are common. To gauge likelihood based on timing and symptoms, try the Am I Pregnant? calculator.