You can use the calculator below to calculate the doubling time of two beta hCG samples by entering the date of the blood test and the corresponding beta hCG value for that day. If the hCG level is
decreasing the the half life will be calculated.
To calculate the doubling time of two beta hCG samples:
1. Enter the date the first blood test was drawn and the beta HCG value for
the date the sample was drawn
2. Enter the date the second blood test was drawn and
the beta HCG value for the date the sample was drawn.
This calculator is for educational purposes only
and should not be used as a substitute for the advice of a healthcare provider.
Beta hCG levels usually double
about every 2 days for the first four weeks of pregnancy. As
pregnancy progresses the doubling time becomes longer. By 6 to 7 weeks beta hCG levels may take as long as 3 1/2 days to double
hCG normally reaches a peak level at about 8 to 10 weeks and then declines for the
remainder of the pregnancy.
Morse and coworkers (2012) at University of Pennsylvania School of Medicine recommend
level for a successful intrauterine pregnancy should be
expected to increase by at least 35% in two days. A slower rate of
increase suggests a possible miscarriage or ectopic pregnancy.
For women who are having a miscarriage
beta hCG should be expected to fall 36 - 47% over two days.
A fall that is
slower than this is suggestive of an ectopic pregnancy.
About 21% of ectopic
pregnancies (pregnancies implanted outside of the uterus) have a rise in hCG similar to an
intrauterine pregnancy and
of ectopic pregnancies
have a fall in hCG similar to a miscarriage.
Serial hCG values should not be used alone to determine whether or not
a pregnancy is likely to be a successful intrauterine pregnancy, a
miscarriage, or an ectopic pregnancy.
Serial hCG values
be used in combination with clinical judgment, evaluation of symptoms and
repeat ultrasound (as needed).
Reference Ranges for beta hCG (using
the Roche Cobas®
during the first half of pregnancy
are shown below
Week of Gestation
Beta Human Chorionic Gonaotropin (mIU/mL)
6 - 71
10 - 750
217 - 7138
158 - 31795
3697 - 163563
32065 - 149571
63803 - 151410
46509 - 186977
27832 - 210612
13950 - 62530
12039 - 70971
9040 - 56451
8175 - 55868
8099 - 58176
REFERENCES 1. Ashitaka Y et al. Production and secretion of hCG andhCG subunits by trophoblastic tissue. In Segal S (ed):Chorionic Gonadotropins. New York, Plenum, 1980 p 151.
2. Pittawy DE et al. Doubling times of human chorionic gonadotropin increase in early viable intrauterine pregnancies. Am J Obstet Gynecol 1985; 299-302.
PMID:2408475 3. American College of Obstetricians and Gynecologists. Medical Management of Tubal Pregnancy. Practice Bulletin Number 3, December 1998. Washington, D.C. ACOG, 1998
4. Barnhart KT, et. al.,Symptomatic patients with an early viable intrauterine
pregnancy: HCG curves redefined. Obstet Gynecol. 2004 Jul;104(1):50-5.PMID:15229000 5.Barnhart KT, et. al. . Decline of serum hCG and spontaneous complete abortion: defining the normal curve. Obstet Gynecol 2004; 104:975–81 PMID:15516387 6. Seeber BE, Barnhart KT. Suspected ectopic pregnancy. Obstet Gynecol. 2006 Feb;107(2 Pt 1):399-413. PMID:16449130 7.Morse CB, et. Al., Performance of human chorionic gonadotropin curves in women at risk for ectopic pregnancy: exceptions to the rules. Fertil Steril. 2012 Jan;97(1):101-6.e2. PMID:22192138
8. Silva C, et al., Human chorionic gonadotropin profile for women with ectopic pregnancy. Obstet Gynecol. 2006;107(3):605–10 PMID:16507931
9. Human Chorionic Gonadotropin (hCG) on Elecsys 1010/2010 and Modular Analytics
E170 [package insert 2007-2009, VII] Indianapolis,Ind;Roche
All calculations must be confirmed before use. The suggested results are not a substitute for clinical
judgment. Neither OBFocus.com nor any other party involved in the preparation or publication of this site shall be liable for any special, consequential,
or exemplary damages resulting in whole or part from any user's use of or reliance upon this material.