Beta hcG: Definition and Mechanism
Human Chorionic Gonadotropin, or hCG for short, is a hormone produced by cells forming in the early stages of embryo development during pregnancy. Later on, it is produced by the placenta.
The functions of hCG during pregnancy are diverse and crucial for the embryo's survival and the maintenance of pregnancy.
Key functions include:
- Maintenance of Corpus Luteum Function: HCG plays a crucial role in maintaining the function of the corpus luteum in the early weeks of pregnancy. The corpus luteum produces progesterone, which sustains the uterine lining and supports the embryo's survival.
- Protection against Immune Reactions: The mother's immune system might perceive the embryo as foreign and attempt rejection. HCG helps prevent maternal immune reactions by suppressing the immune system.
- Pregnancy Diagnosis: The presence of hCG in blood and urine is a classic sign of pregnancy and is utilized in many pregnancy tests to confirm pregnancy.
When Can Beta-hCG Be Detected in a Pregnancy Test?
The hCG hormone is rapidly produced after conception, enters the maternal bloodstream, and is eventually excreted through the kidneys and urine. It can be detected in the blood six to nine days after conception and in urine after approximately 10-14 days.
The hCG level steadily increases, making a pregnancy test more reliable as the pregnancy progresses. Testing too early may yield a false result as the hCG level is still too low.
Reference Values
|
Days after Ovulation |
Mean hCG Value |
Norm hCG Value |
Urine test unreliabe |
Urine test reliabe |
|
Ovulation + 9 |
3 |
1,40-5,30 |
|
|
|
Ovulation + 10 |
5 |
1,90-13,10 |
|
|
|
Ovulation + 11 |
17 |
8-35 |
10 mIU/ml |
|
|
Ovulation + 12 |
34 |
20-59 |
10 mIU/ml |
|
|
Ovulation + 13 |
55 |
33-91 |
25 mIU/ml |
10 mIU/ml |
|
Ovulation + 14 |
89 |
57-140 |
|
25 mIU/ml |
|
Ovulation + 15 |
159 |
100-252 |
|
25 mIU/ml |
|
Ovulation + 16 |
260 |
156-433 |
|
25 mIU/ml |
|
Ovulation + 17 |
433 |
276-706 |
|
25 mIU/ml |
|
Ovulation + 18 |
700 |
473-1033 |
|
25 mIU/ml |
|
Ovulation + 19 |
933 |
626-1384 |
|
25 mIU/ml |
|
Ovulation + 20 |
1399 |
973-1998 |
|
25 mIU/ml |
What Significance Does the hCG Level Hold?
Most often, the hCG level falls within the normal range, indicating a healthy fetal development.
Elevated levels may be an indication of:
- Multiple Pregnancies: The hCG level is often significantly higher in twin or multiple pregnancies.
- Choriocarcinoma: A malignant tumor that can occur after a miscarriage or a faulty placenta.
Low levels may be an indication of:
- Threatened Miscarriage or Impending Preterm Birth
- Ectopic Pregnancy
- Biochemical Pregnancy
It is crucial to note that these scenarios are generally exceptions.
How Does hCG Affect Early Pregnancy?
The rise in beta-hCG leads to numerous changes in the female body, often before a positive pregnancy test is obtained.
Effects include:
- Cravings or Aversions: Unique cravings for sweet, salty, or sour foods are believed to be linked to beta-hCG.
- Nausea: Beta-hCG causes gastrointestinal motility issues, potentially leading to stomach contents reflux.
- Frequent Urination: Increased urination is attributed to the hormones beta-hCG and progesterone, affecting bladder muscles.
