Beta- HCG analysis, known as pregnancy hormone, is an efficient method and is more reliable than traditional pregnancy test to determine if the pregnancy has been achieved or not. Chorionic gonadotrophin hormone (beta-HCG subunit) is synthesized only for pregnant women and is produced starting from the embryo implantation into the maternal uterus in small quantities that increase subsequently. From the moment of embryo implantation this hormone doubles their values in 4hours. This fast increase in HCG levels after conception is an excellent confirmation of pregnancy. It is also a parameter used to check the correct pregnancy development.
Which HCG levels are required to detect pregnancy?
Normally an HCG level of less than 4 mIU/ml is considered as a pregnancy absence. Below you will find normal values about HCG hormone concentration in pregnancy, even if every woman is different and some exceptions may occur:
- 3-4 weeks: 9-130 mIU/ml
- 4-5 weeks: 75-2600 mIU/ml
- 5-6 weeks: 850-20800 mIU/ml
- 6-7 weeks: 400-100200 mIU/ml
Generally, in the first trimester values increase and double every two days until reaching a concentration peak in 12-14 weeks of pregnancy that can overcome 200.000 mIU/ml. These levels are higher when there are multiple pregnancies.
When and how is beta- HCG measured?
HCG hormone can be measured in urine or blood. In the case of urine test, the sample must be collected from first morning’s urine, especially in the first stages of pregnancy. The problem of urine tests is that they have a detection limit between 20 a 100 mUI/ml. Nevertheless, HCG in blood can detect very low levels as 5 mIU/ml, it makes hormone quantification easier.
An assisted reproduction treatment as In Vitro Fertilisation is usually measured approximately 13 days after ovarian puncture, starting from those days 50mIU/ml beta would be expected.
It is possible to repeat this test to ensure pregnancy when you are assisted by reproduction. The reason is that HCG hormone is administered to induce ovulation and it is possible this is still present in blood the day of the test and can be confused with pregnancy.
