hCG Levels Calculator

Determines doubling time and day increases based on two subsequent levels of β-hCG to assess viability of early intrauterine pregnancies.

Refer to the text below the calculator for more information about determining and evaluating hCG levels.


The discriminatory value of β-hCG levels has been improved in the recent years due to hCG assay tehniques, quality of ultrasound and clinician experience. 48-h spaced measurements of serum beta hCG may be used to help determine viability of early intrauterine pregnancies.

The expected rate of increase is approximately:

  • 49% for an initial hCG level of less than 1,500 mIU/mL;
  • 40% for an initial hCG level of 1,500–3,000 mIU/mL;
  • 33% for an initial hCG level greater than 3,000 mIU/mL.

  • Absolute difference = Second β-hCG level - First β-hCG level
  • Percentage difference = Absolute difference / First β-hCG level x 100
  • Doubling time = Time between tests in hours / log2 (Second β-hCG level / First β-hCG level)
  • One-day increase = (2(24 / Doubling time in hours) - 1) x 100
  • Two-day increase = (2(48 / Doubling time in hours) - 1) x 100

First β-hCG level
Second β-hCG level
Time between tests
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hCG Levels Explained

The discriminatory value of β-hCG levels has been improved in the recent years due to hCG assay tehniques, quality of ultrasound and clinician experience. 48-h spaced measurements of serum beta hCG may be used to help determine viability of early intrauterine pregnancies.

The expected rate of increase is approximately:

  • 49% for an initial hCG level of less than 1,500 mIU/mL;
  • 40% for an initial hCG level of 1,500–3,000 mIU/mL;
  • 33% for an initial hCG level greater than 3,000 mIU/mL.

There are several measurements that can be performed on two subsequent beta hCG samples:

  • Absolute difference = Second β-hCG level - First β-hCG level
  • Percentage difference = Absolute difference / First β-hCG level x 100
  • Doubling time = Time between tests in hours / log2 (Second β-hCG level / First β-hCG level)
  • One-day increase = (2(24 / Doubling time in hours) - 1) x 100
  • Two-day increase = (2(48 / Doubling time in hours) - 1) x 100

The table below summarizes guideline American Pregnancy Association β-hCG level ranges throughout pregnancy:

Pregnancy week β-hCG level range
Week 3 5 - 50 mIU/mL
Week 4 5 - 426 mIU/mL
Week 5 18 - 7,340 mIU/mL
Week 6 1,080 - 56,500 mIU/mL
Week 7 – 8 7, 650 - 229,000 mIU/mL
Week 9 – 12 25,700 - 288,000 mIU/mL
Week 13 – 16 13,300 - 254,000 mIU/mL
Week 17 – 24 4,060 - 165,400 mIU/mL
Week 25 – 40 3,640 - 117,000 mIU/mL

hCG begins to be produced around the time of implantation and enters maternal circulation. 5% of women have detectable hCG levels right after implantation but the majority will show positive levels by 11 to 12 days after conception. hCG levels rise during the first 6 to 12 weeks of pregnancy then decline slowly during the second and third trimesters.

Commonly, in early pregnancy, the β-hCG will double every 31 to 72 hours. As the pregnancy progresses, levels rise and the doubling time increases.

hCG may be detected by urine home pregnancy tests with sensitivity of 15 to 25 mIU, by quantitative blood test or by qualitative blood test.

Morse et al. suggest that in the case of a successful intrauterine pregnancy, beta hCG should be expected to increase by at least 35% over 48 hours. A slower rate of increase may be suggestive of potential ectopic pregnancy or miscarriage.

After 6-7 weeks of pregnancy, the best indication of a viable uterine pregnancy is presence of good fetal heartbeat on sonogram.

 

References

Doubilet PM, Benson CB. Further evidence against the reliability of the human chorionic gonadotropin discriminatory level. J Ultrasound Med. 2011; 30(12):1637-42.

Barnhart KT, et al. Differences in Serum Human Chorionic Gonadotropin Rise in Early Pregnancy by Race and Value at Presentation. Obstet Gynecol. 2016; 128(3):504-11.

Morse CB, Sammel MD, Shaunik A, et al. Performance of human chorionic gonadotropin curves in women at risk for ectopic pregnancy: exceptions to the rules. Fertil Steril 2012; 97:101.

Barnhart KT, Sammel MD, Rinaudo PF, et al. Symptomatic patients with an early viable intrauterine pregnancy: HCG curves redefined. Obstet Gynecol 2004; 104:50.

Silva C, Sammel MD, Zhou L, et al. Human chorionic gonadotropin profile for women with ectopic pregnancy. Obstet Gynecol 2006; 107:605.

Kadar N, DeVore G, Romero R. Discriminatory hCG zone: its use in the sonographic evaluation for ectopic pregnancy. Obstet Gynecol 1981; 58:156.


Specialty: Obstetrics Gynecology

System: Reproductive

Article By: Denise Nedea

Published On: July 25, 2020

Last Checked: July 25, 2020

Next Review: July 25, 2025