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:
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
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!
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.