Human Chorionic Gonadotropin (hCG) is a hormone linked to pregnancy and it is responsible for ensuring that the corpus luteum—i.e. what is left in the ovary after ovulation—keeps on producing progesterone once conception has been achieved.
hCG originates in the syncytiotrophoblast, that is, the outermost layer of the embryo.
The various sections of this article are assembled in the following table of contents.
Normal beta-hCG levels
The chorion, one of the outer membranes that cover the human embryo and assists in placental formation, starts producing hCG after the embryo implants in the uterus, which usually occurs within 8 to 10 days after conception. For this reason, the detection of hCG in the woman’s organism is an indicator that embryo implantation has taken place.
The time it takes for beta hCG to duplicate during pregnancy allows measuring the speed at which placental development will take place. Slow growth speed may be an indicator that there is some sort of problem or that the woman is at risk of miscarrying.
Generally, hCG values keep on doubling every 48-72 hours. This means that if your beta-hCG level is of 150 mUI/ml on Monday, it should rise to around 300 mUI/ml between Wednesday and Thursday.
Often, when the rate of increase in hCG levels between the first and second test is slow, a third and sometimes even a fourth hCG test is usually performed at two-day intervals with the purpose of analyzing how the levels are increasing.
The fact that there is no sign of hCG increase after the third and fourth test usually translates into a bad prognosis. It might be the sign of a failed or dysfunctional implantation that could likely lead to a miscarriage.
Getting back to normal after a miscarriage
A miscarriage is an involuntary loss of pregnancy. It usually occurs within the first 20 weeks of pregnancy. A woman may miscarry due to various reasons, such as chromosomal abnormalities that prevent the embryo from properly implanting in the uterus. It takes several weeks for hCG levels to get back to normal.
hCG levels at the moment of miscarriage may vary depending on how many weeks pregnant the woman was when she miscarried.
For instance, hCG levels at week six—i.e. two weeks after the first missed period—range from 1.080 mUI/ml to 56.500 mUI/ml. When hCG levels are not the ideal ones or the rate of increase is not as expected, something might be happening.
If levels do not decrease after a miscarriage, it means the hCG-producing tissue is still present in the body. The woman’s menstrual cycle will not come back until her body stops producing hCG. This may complicate things, as the woman won’t be able to get pregnant until things return to normal again.
The menstrual cycle should be back to normal within 4 to 6 weeks after miscarriage. The higher the levels of hCG are, the longer it will take for them to get back to their initial levels.