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hCG Doubling Calculator

Calculate how long it's taking for the levels of the pregnancy hormone hCG to double. Enter the levels from two consecutive blood tests along with how long between the tests to see your doubling rate.
hCG Level from first test:
hCG Level from second test:
Number of days between tests:
Other names for the Beta HCG Quantitative blood test: Chorionic Gonadotropin Quant; HCG Beta, Quant; Human Chorionic Gonadotropin Quant
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hCG's Role in Early Pregnancy

hCG plays an important role during early pregnancy. As soon as the fertilized egg (known as a blatocyst) implants into the uterine lining, the hormone hCG starts producing, rapidly doubling every 2 to 3 days.

hCG is a very busy hormone, having several responsibilities in the early stages of pregnancy:

  1. hCG promotes growth of the endometrium to sustain the pregnancy. It does so by signaling the corpus luteum, which is the leftover egg sac which ovulated the egg, that it needs to produce sufficient quantities of progesterone so that menstruation does not occur and the uterine lining can continue to thicken.

  2. hCG sends out another vital message: stop producing FSH, so that ovulation does not occur. In other words, baby on board, take a rest, ovaries, for, say, the next 9.5ish months!

  3. hCG is the hormone that pregnancy tests detect to determine pregnancy: both urine-based home pregnancy tests and blood tests administered by your doctor detect hCG.

    Quantitative tests, such as the HCG Beta Quant test, detect the actual amount of hCG in your circulation and can detect very small levels.

    A qualitative test, such as an HPT, reports that a detectable amount of hCG is present: Yes or No (ie. pregnant or not pregnant). For example, an HPT that detects 50mIU/ml will report Yes, pregnant, if the hCG in the sample is at a level of 50mIU/ml or above. If you are early pregnancy testing, a No on an HPT does not necessarily mean you are not pregnant; the false negative could be that the hCG level has not yet reached the level that the test detects. Q&A: My period is late, my pregnancy test is negative - when to test again?

Like any good hormone, once its job is done, it gracefully passes the torch and steps aside. By early into the second trimester when the placenta is able to maintain pregnancy, hCG levels start to decline and then level off for the remainder of the pregnancy.


Acronyms & More

  • FSH = Follicle Stimulating Hormone
  • hCG = Human Chorionic Gonadotropin
  • HPT = Home Pregnancy Test
  • mIU/ml = milli-international units per milliliter
  • endometrium a.k.a uterine lining
  • oviduct a.k.a. fallopian tube
  • a.k.a. = also known as!
  • More cycle & pregnancy acronyms...
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