The protein-based hormone hCG, or human Chorionic Gonadotropin, is produced by the placenta once a fertilized egg implants itself into the uterus. Also known as ‘The pregnancy hormone,’ blood tests would test for the presence of hCG to confirm pregnancy. hCG helps maintain the production of other important hormones such as progesterone and estrogen. These are essential for the healthy development of the embryo and fetus.
The production of hCG doubles in volume roughly every 72 hours, until levels peak 8 – 11 weeks into pregnancy. Levels will then decline for the remainder of the pregnancy. There may be many exceptions, however, and hCG levels can vary significantly for individual pregnancies. Low levels of hCG production do not indicate that the baby is not getting sustenance, although a consultation (and potentially an ultrasound) should follow a low hCG result.
In general, very high levels of hCG can indicate a multiple pregnancy, while very low levels can indicate an ectopic pregnancy or other complications. It may also be a miscalculation in the date of conception! For this reason, if levels are exceptionally high or low in comparison to expected levels for that time into the gestational cycle, it is good idea to go for further assessments.
Given these individual differences, and uncertainty around the exact date of conception, hCG levels are best considered in trend, and repeat tests can tell much more than a single test alone.
The hCG hormone is measured in milli – International Units per milliliter. This is shown as mIU/ml. IU – International Units is a unit used to measure the quantity; mass or volume; of a substance based on its biological activity or effect.
- An hCG level of les than 5 mIU/ml is considered negative for pregnancy. This is the expected hCG level for a non-pregnant female, but this can rise to 8 for post-menopausal women.
- An hCG level above 25 mIU/ml is considered positive for pregnancy
After conception, the doubling time, or rate of increase can be rapid. Ultrasounds will look for a gestational sac once the hCG level reaches 1000mlU/ml.
The following gives a rough guideline of the expected levels throughout the period of gestation. This shows that the range is substantial and a better indicator to consider is more qualitative in nature. What that means, is that 2 concurrent tests will show whether there is hCG present, and whether the level is rising.
|
mIU/ml |
| Lower Bound |
Upper Bound |
| Gestational Age |
3 weeks |
5 |
50 |
| 4 weeks |
5 |
426 |
| 5 weeks |
18 |
7340 |
| 6 weeks |
1080 |
56500 |
| 7-8 weeks |
7650 |
229000 |
| 9-12 weeks |
25700 |
288000 |
| 13-16 weeks |
13300 |
254000 |
| 17-24 weeks |
5060 |
165400 |
| 25-40 weeks |
3640 |
117000 |
A quantitative hCG measure is required to test the actual level relative to the pregnancy, or other conditions of the patient.
High hCG levels have also been associated with carcinogenesis, or the development of tumors, although the exact connection between hCG production and the existence of tumor is not clear.
This calculator involves taking 2 tests. As shown above, you are testing whether hCG is present, and then whether the levels are rising. In order to use the calculator, you need 2 test results for the level of hCG, and the time between tests. The tests are best taken 48 – 72 hours apart.
You will enter these measurements (hCG1, hCG2, and T).
The results are as follows:
Difference: The difference is simply the second result, less the first, to calculate how much level has increased in the time period. If you are pregnant, hCG levels should be rising. Thus hCG2 should be greater than hCG1, and the difference will be positive.
Percentage Difference: This is a percentage change in hCG level, so it is the difference between the levels, divided by the hCG1.
Doubling Time: this is the average number of hours it takes for your hCG levels to double. In 85% of normal pregnancies, hCG will double every 48 – 72 hours for the first 8 – 11 weeks of pregnancy, and the overall hCG level will peak in week 14. This is calculated using the following formula:
T₂ = T / log₂ (hCG₂/hCG₁)
One day increase: This is the percentage increase over 24 hours, as calculated from the rate of increase over time between the 2 tests.
Two day increase: This will measure the increase over 48 hours, based on the rate of growth over time between the two tests.
In general, hCG will only increase, but will increase rapidly at the start of pregnancy. At around 11 weeks, the doubling time slows, and levels generally peak at 14 weeks. After this, you can expect hCG levels to decline.
This shows generally accepted doubling times for a given base level of hCG.
- hCG under 1200 mIU/ml: 30 – 72 hours
- hCG between 1200 -6000: 72 – 96 hours
- hCG over 6000: over 96 hours
hCG diets are new weight loss fad, which are generally considered unsafe by the medical fraternity. This is partly because the reason why it works is not medically confirmed, but the causation between hCG and carcinogenesis isn’t either.
The diet involves a low-calorie intake with the ingestion of hCG to speed weight loss. On theory is the hCG boosts metabolism, enabling weight loss, yet multiple studies have shown that the weight loss is due to the lowered caloric intake alone and that the hCG works for little else than supressing the appetite.
Thus, there is no test for hCG levels which can indicate whether weight loss is taking place, as in ketogenic diets which measure ketone levels to test for a state of ketosis, when the weight loss takes place. There are a number of unknown factors, and much is as yet unproved about the hCG diet. Combining a low-calorie intake with proven methods for achieving anabolic weight loss, such as weight lifting which definitely promotes muscle building is a more guaranteed, and much safer way of achieving weight loss.
