To calculate the doubling time
1. Enter the date the first blood test was drawn and the test result (HCG
level)
2. Enter the date the second blood test was drawn and test result (HCG level).
Beta hCG levels usually double approximately every 2 days for the first four weeks of pregnancy [1].
As pregnancy progresses the doubling time increases. By 6 to 7 weeks gestation beta hCG levels may take as long as 3 1/2 days to double [2,3].
The beta hCG may take more than 2 to 3 days to double in 15% of normal
intrauterine pregnancies. About 17% of ectopic pregnancies have normal doubling
times.
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 declining the the half life of the hormone will be calculated.
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.
MEDLINE 3. American College of Obstetricians and Gynecologists. Medical Management of Tubal Pregnancy. Practice Bulletin Number 3, December 1998. Washington, D.C. ACOG, 1998
All calculations must be confirmed before use. The suggested results are not a substitute for clinical
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