UNM Department of OB/GYN
Womaens Health Research

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HCG REFERENCE SERVICE
HCG LEVELS DURING NORMAL PREGNANCY

 

hCG is produced by the trophoblast cells of the placenta. hCG production starts at an early stage of development, just a few days after conception, before implantation in the uterus. hCG enters the maternal circulation almost immediately after implantation of the embryo (blastocyst) on about day 21 of the menstrual cycle. hCG is approximately eighty times more potent than its sister hormone produced by the pituitary gland, lutenizing hormone (LH). The tiny amount of hCG that enters the maternal circulation on day 21 (<5 mIU/ml in serum or plasma, while too small to be detected by pregnancy tests, is sufficient to stimulate the corpus luteum of the ovary to produce progesterone. The concentration of hCG in the circulation then rises in an exponential manner, doubling approximately every two days. By day 28 (first day of missed menses) the median hCG level in serum, plasma or urine is about 100 mIU/ml. This should be detectable by all pregnancy tests. There is a very big variation in individual hCG concentrations. At this time, the extremes of normal levels are approximately 5 to 450 mIU/ml in serum or plasma samples. hCG can also be produced by early pregnancy loss (EPL) or pregnancies that fail to start or properly implant. hCG from these pregnancies can also be detected at this time (click here to see data on sources of hCG and early pregnancy loss). For this reason we suggest waiting 3 days, until day 31 (31 days since start of last period, or 3 days after missing a period) before having an hCG test. This way one can tell if one has a true pregnancy (clinical pregnancy). Circulating hCG concentration continues to increase exponentially (doubling about every 2 days). It reaches a peak at about 10 week of gestation (since last menstrual period). At which time the median hCG concentration in serum or plasma samples is around 60,000 mIU/ml. There is a very big variation in individual hCG concentrations. At this time, the extremes of normal levels are approximately 5,000 to 150,000 mIU/ml. In the next 10 weeks (10 to 20 weeks of gestation), circulating hCG levels decline, reaching a median concentration of about 12,000 mIU/ml. Again, wide variation is found among individuals, concentrations ranging from 2,000 to 50,000 mIU/ml. The hCG concentrations remains at around this level, and with this variation from this time until term (20 to 40 weeks of gestation). hCG levels are 30 to 50% higher than  in twin and multiple gestations.
   
We note the wide variation found in individual hCG levels. We also note the non-uniformity sometimes found in hCG results from different types of hCG tests (hCG tests, hCG tests, hCG + nicked hCG tests, etc.), hCG tests using different standards, and different brands of hCG tests (click here to see principal of hCG test & discordant results). Taking both of these into consideration, we infer that serum, plasma and urine hCG results can vary widely. To help you understand hCG results we provide links to 6 separate internet sites that list hCG concentrations and the range of hCG levels throughout the length pregnancy.

http://www.inciid.org/betas.html

http://www2.parentsplace.com/pregnancy/tests/qa/
0,3105,655,00.html

http://www.bobrow.net/kimberly/birth/hcglevels.html

http://www.mcl.tulane.edu/classware/pathology
/medical_pathology/prenatal/03pregnancy.html

http://www.mediconsult.com/infertility/shareware/betas/

http://www.advancedfertility.com/earlypre.htm

    It should be noted that higher than normal hCG levels can be associated with Down syndrome pregnancies and with hydatidiform mole or molar pregnancy, and that lower than unduly low hCG levels may be linked to impending spontaneous abortion, or with ectopic or extrauterine pregnancy (click here to see details on potential sources of hCG in and outside of pregnancy).

 

 

hCG Reference Service HOME PAGE

hCG Reference Service Report 2002

Principal of hCG test and of discordant results

Synthesis and degradation of hCG

Specialized tests at hCG Reference Service

False positive of phantom hCG tests

Potential sources of hCG in and outside of pregnancy

hCG levels during normal pregnancy

Refer a patient to the hCG Reference Service

About Laurence A. Cole, Ph.D.

Other important contacts

 

hCG Reference Service HOME PAGE
introduction to hCG and the hCG Reference Service

hCG Reference Service Report 2002

medical report on the experience of the hCG Reference Service, 1997-2002, with false positive hCG results, quiescent gestational trophoblastic disease and unexplained elevated hCG. The report also examines and compares the performance of professional laboratory hCG tests.

Principal of hCG test and causes of discordant results 
how the hCG test works and why sometimes it gives discord or erroneous results

Synthesis and degradation of hCG
the production of hCG in trophoblast cells, abnormal production, and dissociation, nicking and degradation of hCG after secretion

Specialized tests at hCG Reference Service
the specialized hCG assays run by the hCG Reference Service to help identify the source and nature of hCG

False positive of phantom hCG tests
false positive or phantom hCG tests, the mechanisms that cause hCG assays to give mistaken results, and the potentially devastating clinical consequences

Potential sources of hCG in and outside of pregnancy
the biological sources of hCG: normal pregnancy, early pregnancy loss, ectopic pregnancy, gestational Down syndrome, hydatidiform mole and choriocarcinoma cells, germ cell and other non-trophoblastic malignancies; pituitary hCG production, and phantom or false-positive hCG

hCG levels during normal pregnancy
the widely varying hCG levels observed during the course of normal pregnancy

Refer a patient to the hCG Reference Service
how to seek help from or refer a patient to the hCG Reference Service, the samples needed and patients history and insurance requirements

About Laurence A. Cole, Ph.D.
curriculum vitae of Laurence A. Cole, Ph.D., Director of the hCG Reference Service

Other important contacts
centers throughout the world specializing in the treatment of Trophoblastic Diseases and laboratories and scientists with expert knowledge in the endocrinology, chemistry and testing for hCG

 

 

 
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